Work out what size leisure battery you need

Q: Does this checker send my appliance list or battery figures anywhere?

No. The arithmetic runs inside your browser on the published dataset it downloads. There is no form submission, no request carrying your numbers and no analytics on them. Nothing you type is stored or sent by this site.

Q: Why 80% for LiFePO4?

LiFePO4 usable capacity = nameplate x 80% depth of discharge as a working figure. This is a convention, not a standard: a 2015 technical article on Victron's blog says '80% DOD is used' for LFP. Victron's LFP Smart datasheet publishes cycle life at 80%, 70% and 50% DoD (2500 / 3000 / 5000 cycles to 80% of nominal capacity) and a capacity-loss figure at 100% DoD; it does not prescribe a working depth of discharge. Deeper discharge is specified but costs cycles. Source: “For Lithium-iron-phosphate (LiFePO4 or LFP) which is the safest of the mainstream Li-ion battery types, 80% DOD is used.” (Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, checked 4 November 2026).

Q: Why is the answer given at the 20-hour rate (C20)?

Because a battery’s amp-hour figure depends on the discharge rate, and a headline figure does not always say which rate it uses. Banner publishes its 957 51 as 110 Ah at the 100-hour rate, 100 Ah at the 20-hour rate and 75 Ah at the 5-hour rate (Banner Technical Data Sheet – Energy Bull 957 51 (Document DBTBAT00339), checked 4 November 2026): the 100-hour figure is 10% above the 20-hour figure, and the 5-hour figure is 25% below it. Stating the rate makes batteries comparable; 5 of the 19 indexed batteries publish more than one rate.

Q: Does the checker apply a duty cycle to the fridge?

No manufacturer in the index publishes a duty cycle, so the checker never assumes one. Where a maker publishes an average, such as Dometic’s 1.1 Ah/h for the CRX 50 at +25 °C ambient, the average is used as published. Thetford is the only maker in the index that names a test standard for its daily figure: “IEC62552-2020”. Where only a rated current is published, the line is shown as an upper bound and labelled.

Q: Why does the checker refuse to use the fridge manual’s 5.0 A figure?

Dometic's CRX 50 installation and operating manual publishes 'Rated current 12 V⎓: 5.0 A'. The manual calls it rated current; it does not say the figure is an average or define it further. It is about 4.5 times the catalogue average of 1.1 Ah/h. This checker uses the catalogue average and never lets the 5.0 A figure reach the daily total. Calculators seeded from the manual will tell you to buy a bank roughly four times too big.

Q: Does the checker reduce lead-acid capacity for cold weather?

No, because the manufacturer documents checked publish it only as a graph, not as numbers. No numeric lead-acid temperature derate table is published in the manufacturer documents read on 2026-09-16 and re-read on 2026-11-04 (Victron Gel/AGM datasheet section 8 and GS Yuasa NP Application Manual Figure 7 are graphs only). Brief rule 8: never read a number off a graph. The checker reports the direction of the effect and says the figure is not published.

Q: What is the Peukert exponent and where does 1.25 come from?

Victron gives 1.25 as an approximate default Peukert exponent for lead-acid battery monitors. It is not a battery-specific sizing model. This checker does not apply that default to its energy-only estimate. Victron: “The default setting in the battery monitor for the Peukert exponent is 1.25. This is an acceptable average value for most lead acid batteries.” (checked 4 November 2026). The checker provides an energy-only estimate without discharge-rate correction. Reference exponents derived from published battery ratings are not applied to the sizing answer.

Enter your appliances and nights off hook-up for an energy-only battery estimate, with sources and assumptions shown.

How it works · Published figures · Calculator privacy

Read first. This tool applies published rules to numbers you type in. It is not a design for your vehicle and it is not a substitute for a qualified installer. Everything is calculated in your browser; nothing you type is sent anywhere.

The checker needs JavaScript so the arithmetic can run inside your browser without sending anything anywhere. With JavaScript off, every published figure it uses is in the tables below, each with its source and checked date.

Loading the published dataset…

How the checker works, step by step

The form, assistant tool and automated tests use the same calculation code. The public dataset contains 28 appliance records, 19 battery records and 30 rules, each with evidence and dates.

Normalise each load to amps at 12 V. Where a maker publishes an average (Dometic’s Ah/h, Truma’s “average approx. 1.2 A”) the average is used. Where it publishes a control range (Webasto’s 15 to 30 W) the line is a range. Where it publishes only a rated figure, the line is an upper bound and says so. Watts are divided by 12 (rule S1). For a named inverter, 230 V load energy uses published maximum efficiency and adds one normal zero-load allowance for the total on-time you enter (rule S2). This site approximation may count some losses twice; it is not a load-specific efficiency model or a guaranteed lower or upper bound. Without a model, ideal 100% conversion with no idle allowance is a lower bound. Appliance hours cannot establish total inverter on-time, and no output or startup capability check is made.
No duty cycle is ever assumed (rule S3). No manufacturer in the index publishes one. The Dometic CRX manual’s “Rated current 5.0 A” is a rated figure, not an average: about 4.5 times the catalogue average, and is interlocked so it can never reach the total.
Daily consumption is the sum of the lines; gross is daily consumption times the nights entered.
Depth-of-discharge ceiling (rule S5). Lead-acid: 50%, the depth of discharge the NCC scheme rates every class at and a figure a 2015 article on Victron’s blog calls “generally accepted”: a convention, not a standard. LiFePO4: 80%, the figure that article uses and the deepest depth of discharge in Victron’s LFP Smart cycle table: also a convention. Where the selected battery publishes its own guidance, both figures are shown.
Energy-only estimate. No Peukert or other discharge-rate correction is applied. Daily hours do not establish load overlap or a constant-current discharge profile. High active currents reduce lead-acid capacity and can require a larger bank. Rules S4a–S4d remain reference evidence; check the maker’s discharge data for the actual loads.
Temperature (rule S6). Exact numerical capacity points are published measurements. Linear interpolation between bracketing points with a 25 °C reference is a labelled site estimate for the selected battery only. Temperatures outside those points are unsupported: no endpoint is extended. Charge and discharge minima and maxima are checked separately; outside a published discharge range no capacity recommendation is given. Unknown limits remain unknown. Lead-acid figures are unadjusted because the checked documents publish curves rather than numerical capacity points.
Putting the charge back (rule S7) is a separate answer, not folded into the capacity. That answer assumes the charge arrives after each day’s use, so it is one day’s use plus the shortfall on each later day. If the recharge you enter does not replace the daily use, Victron’s sulfation warning is quoted for lead-acid.
C20 is the comparison basis (rule S8). Indexed batteries are compared using a published 20-hour or faster rating, with their actual test rate and conditions retained. A C2 rating is not relabelled C20. These energy comparisons do not establish current capability or permission to parallel batteries. Batteries publishing only a 100-hour or unstated rate remain not comparable.

The rules, with their sources

Rule S1 Manufacturer document

A 12 V load's current is its power divided by the system voltage: amps = watts / 12 V. This is the power relation P = V x I, as set out in Victron's Wiring Unlimited section 2.2 'Power', including the worked example I = P/V = 2400/12 = 200A.

Power is an expression of how much work an electric current can do. It is measured in Watts, and the symbol is P. It can be calculated using the following formula:
Victron Energy, Wiring Unlimited (Margreet Leeftink), 2.2. Power, Manufacturer document, checked 4 November 2026

If we have a 12V battery that is connected to a 2400W load. How much current is running through the cable? Answer: V = 12V, P = 2400W, I = P/V = 2400/12 = 200A
Victron Energy, Wiring Unlimited (Margreet Leeftink), 2.2. Power (worked example), Manufacturer document, checked 4 November 2026

Rule S2 Manufacturer document

For a named inverter, 230 V load energy is converted at its published maximum efficiency and nominal 12 V, with one separate normal zero-load allowance for the total inverter on-time entered by the reader. This is a site approximation: maximum efficiency is not a load-specific value, and adding idle may count some losses twice. The combined estimate is not a guaranteed lower or upper bound. Without an inverter model, ideal 100% conversion with no idle allowance is shown as a lower bound; no default model is substituted. On-time is required for active 230 V loads, from 0 to 24 hours and at least the longest active appliance duration. It is not inferred from daily appliance hours. Output capacity and startup capability are not checked.

Max. efficiency: 87 / 88 / 88% | 89 / 89 / 90% | 90 / 90 / 91% | 90 / 90 / 91% | 91 / 91 / 92% | 92%
Victron Energy datasheet: Inverters VE.Direct 250VA - 1600VA, 230V and 120V, 50Hz or 60Hz, Specification table, row 'Max. efficiency'; columns 12/250, 12/375, 12/500, 12/800, 12/1200, 12/1600 (each cell 12 V / 24 V / 48 V), Manufacturer document, checked 4 November 2026

Zero-load power: 4,2 / 5,2 / 7,9W | 5,6 / 6,1 / 8,5W | 6 / 6,5 / 9W | 6,5 / 7 / 9,5W | 10 / 11 / 12W | 12W
Victron Energy datasheet: Inverters VE.Direct 250VA - 1600VA, 230V and 120V, 50Hz or 60Hz, Specification table, row 'Zero-load power'; same columns, Manufacturer document, checked 4 November 2026

Rule S3 Convention, not a standard · Site policy

Where an appliance maker publishes no duty cycle (compressor running-time share) the checker says so and treats the published figure as what it is: a rated current is an upper bound, a 24-hour average is an average under the maker's stated test condition. The checker never assumes a duty cycle. Declining to assume one is site policy; an assumed duty cycle would be a convention, not a standard.

Energy Consumption ** (kWh/24h) 0.32 | Average Ampere Usage** (Ah/24h) 25.6 | ** According IEC62552-2020 part 3.
Thetford, 12V Compressor refrigerators (2026 range product sheet), T1090-E specification column and footnote **, Manufacturer document, checked 4 November 2026

Power consumption (AC) (ACDC models only): 40 W | Rated current 12 Vg: 5.0 A
Dometic CRX (CRX50, CRX65, CRX80, CRX110, CRX 140) Compressor refrigerator Installation and Operating Manual, 13 Technical data, CRX 50 column, Manufacturer document, checked 4 November 2026

Rule S4a Manufacturer document not implemented

Effective lead-acid capacity falls with increasing discharge current. Victron publishes a constant-current table for its AGM/Gel batteries. This checker retains that evidence but does not apply it to an unspecified daily load schedule.

Why not: Energy-only sizing: daily hours do not establish simultaneous active currents or a constant-current discharge profile. No discharge-rate correction is applied; this evidence is retained for reference.

The rated capacity of Victron AGM and Gel Deep Cycle batteries refers to 20 hour discharge, in other words: a discharge current of 0,05 C.
Victron Energy datasheet: Gel and AGM Batteries, 6. Battery Discharging Characteristics, Manufacturer document, checked 4 November 2026

The effective capacity decreases with increasing discharge current (see table 1). Please note that the capacity reduction will be even faster in case of a constant power load, such as an inverter.
Victron Energy datasheet: Gel and AGM Batteries, 6. Battery Discharging Characteristics, Manufacturer document, checked 4 November 2026

Discharge time (constant current) / End Voltage V / AGM 'Deep Cycle' % / Gel 'Deep Cycle' %: 20 hours 10,8 100 100 | 10 hours 10,8 92 87 | 5 hours 10,8 85 80 | 3 hours 10,8 78 73 | 1 hour 9,6 65 61 | 30 min. 9,6 55 51 | 15 min. 9,6 42 38 | 10 min. 9,6 38 34 | 5 min. 9,6 27 24 | 5 seconds 8C 7C
Victron Energy datasheet: Gel and AGM Batteries, Table 1: Effective capacity as a function of discharge time (the lowest row gives the maximum allowable 5 seconds discharge current), Manufacturer document, checked 4 November 2026

Rule S4b Manufacturer document not implemented

Peukert’s equation relates capacity to constant discharge current. A reference exponent can be derived from two published capacity ratings. Derived exponents are retained in battery records for information, not applied to the energy-only sizing estimate.

Peukert's equation is stated below: Cp = In x t
Victron Energy, BMV-712 Smart manual, 8. Battery capacity and Peukert exponent, 8. Battery capacity and Peukert exponent, Manufacturer document, checked 4 November 2026

To calculate the Peukert exponent you will need two rated battery capacities. This is usually the 20h discharge rate and the 5h rate, but can also be the 10h and 5h, or the 20h and the 10h rate.
Victron Energy, BMV-712 Smart manual, 8. Battery capacity and Peukert exponent, 8. Battery capacity and Peukert exponent, Manufacturer document, checked 4 November 2026

Rule S4c Manufacturer document not implemented

The default setting in the battery monitor for the Peukert exponent is 1.25. This is an acceptable average value for most lead acid batteries.
Victron Energy, BMV-712 Smart manual, 8. Battery capacity and Peukert exponent, 8. Battery capacity and Peukert exponent, Manufacturer document, checked 4 November 2026

Please note that the Peukert exponent is no more than a rough approximation of reality. In case of very high currents, the battery will give even less capacity than predicted by a fixed exponent.
Victron Energy, BMV-712 Smart manual, 8. Battery capacity and Peukert exponent, 8. Battery capacity and Peukert exponent, Manufacturer document, checked 4 November 2026

Set the Peukert exponent parameter according to the battery specification sheet. If the Peukert exponent is unknown, set it at 1.25 for lead-acid batteries and set it at 1.01 for lithium batteries. A value of 1.00 disables the Peukert compensation.
Victron Energy, BMV-712 Smart manual, 7.2.6. Peukert exponent, 7.2.6. Peukert exponent (setting 05; default 1.25, range 1.00 - 1.50, step 0.01), Manufacturer document, checked 4 November 2026

Rule S4d Manufacturer document not implemented

Victron gives 1.01 as a lithium battery-monitor Peukert setting unless the supplier advises otherwise. This checker does not apply a discharge-rate correction or treat the setting as proof of current capability.

Set the Peukert exponent at 1.01, unless the battery supplier advises otherwise.
Victron Energy, BMV-712 Smart manual, 4.6. Make Lithium settings (if needed), 4.6. Make Lithium settings (if needed), Manufacturer document, checked 4 November 2026

If the Peukert exponent is unknown, set it at 1.25 for lead-acid batteries and set it at 1.01 for lithium batteries.
Victron Energy, BMV-712 Smart manual, 7.2.6. Peukert exponent, 7.2.6. Peukert exponent, Manufacturer document, checked 4 November 2026

Rule S5-la Convention, not a standard · UK scheme test basis (NCC); convention described in a 2015 Victron blog article

Lead-acid usable capacity = nameplate x 50% depth of discharge. The 50% figure is the depth of discharge the NCC Verified Leisure Battery Scheme uses to rate every class of leisure battery, and a 2015 technical article on Victron's blog calls 50% the 'generally accepted' economic and practical depth of discharge for an AGM battery. It is an industry convention with a UK scheme's test basis behind it, not a standard.

Minimum Life Cycles at 50% Depth of Discharge (Cycles)
NCC, Verified Battery List (consumer advice page with scheme class definitions), Class table column header, UK verification scheme, checked 4 November 2026

It is generally accepted that the most economic and practical depth of discharge (DOD) for an AGM battery is 50%.
Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, Secondary source, checked 4 November 2026

NCC Verified leisure batteries are tested by the manufacturer and verified by the NCC taking into account their minimum capacity minimum and their minimum life cycles at 50% depth of discharge, into 1 of 3 classes.
NCC, Verified Battery List (consumer advice page with scheme class definitions), Introductory paragraph, UK verification scheme, checked 4 November 2026

Life Cycles 50% DoD
NCC Verified Leisure Battery Scheme October 2023, Class A, Column header, NCC Verified Leisure Battery Scheme October 2023, Class A, UK verification scheme, checked 4 November 2026

Rule S5-li Convention, not a standard

For Lithium-iron-phosphate (LiFePO4 or LFP) which is the safest of the mainstream Li-ion battery types, 80% DOD is used.
Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, Secondary source, checked 4 November 2026

CYCLE LIFE (capacity ≥ 80 % of nominal): 80 % DoD 2500 cycles | 70 % DoD 3000 cycles | 50 % DoD 5000 cycles
Victron Energy datasheet: 12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart, Battery specification table, CYCLE LIFE rows, Manufacturer document, checked 4 November 2026

Capacity loss (per 100 cycles, @ 25 °C, 100 % DoD): <1 %
Victron Energy datasheet: 12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart, Battery specification table, VOLTAGE AND CAPACITY rows, Manufacturer document, checked 4 November 2026

Rule S7 Manufacturer document

A lead-acid battery fails prematurely through sulfation if it is habitually left partially charged or operated in deficit for long periods. The checker uses this to explain why lead-acid banks that are rarely fully recharged should be sized and charged conservatively; it is a stated manufacturer position, not a number.

A lead-acid battery will fail prematurely due to sulfation: If it operates in deficit mode during long periods of time (i.e. if the battery is rarely, or never at all, fully charged). If it is left partially charged or worse, fully discharged (yacht or mobile home during wintertime).
Victron Energy datasheet: 12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart, Why lithium-iron-phosphate? / Rugged, Manufacturer document, checked 4 November 2026

A LFP battery: Does not need to be fully charged. Service life even slightly improves in case of partial charge instead of a full charge. This is a major advantage of LFP compared to lead-acid.
Victron Energy datasheet: 12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart, Why lithium-iron-phosphate? / Rugged, Manufacturer document, checked 4 November 2026

Rule S8 Manufacturer document

The answer is expressed as required nameplate Ah at a named C-rate, never as a bare Ah figure. A 2015 technical article on Victron's blog says most Ah ratings are specified at the 20 hour rate; Banner publishes three capacities (5 h / 20 h / 100 h) for each Energy Bull battery and notes that leisure battery capacity is also provided on the basis of a 5-hour discharge. A bare number is therefore ambiguous.

Most Ah ratings of batteries regardless of type are specified at the 20 hour rate.
Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, Secondary source, checked 4 November 2026

Typ / Info / Box / Ah 5 h / Ah 20 h / Ah 100 h: 957 51 4K / H8 / L5 / 75 / 100 / 110
Banner GmbH, Energy Bull product brochure, Technical data and information, Technical data and information (Energy Bull table), Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)

While the capacity of starter batteries is given in terms of a 20-hour discharge, the capacity of a leisure battery is also provided on the basis of a 5-hour discharge. For example, in five hours a 75Ah battery can lose 15A in discharge current.
Banner GmbH, Energy Bull product brochure, Technical data and information, Banner Tip! sidebar, capacity calculator page, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)

If the average power-on time is approx. 5 hours, the K5 is used. If it's approx. 20 hours, the K20 is used and if approx. 100 hours, the K100.
Banner Batterien, Battery knowledge: Hobby and leisure batteries for long-term discharge, Manufacturer document, checked 4 November 2026

Type no. 957 51; Rated capacity 75 Ah(K5), 100 Ah(K20), 110 Ah(K100)
Banner GmbH, Technical data sheet: Energy Bull 957 51 (Document DBTBAT00339), Electrical data, Manufacturer document, checked 4 November 2026

What the checker refuses to do, and why

These are recorded as rules too, graded unverified and never used to produce a number.

Rule S6b Unverified not implemented

A numeric temperature derate for lead-acid capacity is NOT applied. Both manufacturer documents checked publish the effect only as a graph: Victron's Gel/AGM datasheet states capacity 'reduces sharply at low temperatures' and shows Fig. 1; GS Yuasa's NP application manual presents Figure 7 with no table. Reading a number off a graph would breach brief rule 8. The checker reports the direction of the effect and says the figures are not published numerically in the documents checked.

Why not: No numeric lead-acid temperature derate table is published in the manufacturer documents read on 2026-09-16 and re-read on 2026-11-04 (Victron Gel/AGM datasheet section 8 and GS Yuasa NP Application Manual Figure 7 are graphs only). Brief rule 8: never read a number off a graph.

As is shown by the graph below, capacity reduces sharply at low temperatures.
Victron Energy datasheet: Gel and AGM Batteries, 8. Effect of temperature on capacity; Fig. 1: Effect of temperature on capacity, Manufacturer document, checked 4 November 2026

At higher temperatures, the electrical capacity that can be taken out of a battery increases. At lower temperatures, the electrical capacity that can be taken out of a battery decreases. Figure 7 shows the temperature effects in relation to battery capacity.
GS Yuasa, NP series sealed rechargeable lead-acid battery Application Manual, Temperature characteristics; Figure 7. TEMPERATURE EFFECTS IN RELATION TO BATTERY CAPACITY, Manufacturer document, checked 4 November 2026

Rule S9-margin Unverified not implemented

A blanket '+20% for battery ageing' design margin is NOT applied. No manufacturer document read publishes an ageing-margin figure; the 20% is a convention. Banner publishes a sizing safety factor (1.7, or 1.3 for AGM and gel) to prevent deep discharges, which is a different quantity and is not applied. If an ageing margin is offered at all it is a reader-adjustable margin defaulting to 0 and labelled as the reader's own figure.

Why not: No published manufacturer figure for an ageing margin was found in the documents read on 2026-09-16 and re-read on 2026-11-04; the widely repeated 20% is a convention. Banner's sizing guidance uses a safety factor of 1.7 (1.3 for AGM and gel) 'to prevent deep discharges', a different quantity. Spec section 2.1.4.

As a rule, 70% should be taken as a safety factor.
Banner GmbH, Energy Bull product brochure, Technical data and information, Energy Bull capacity calculator page: 'Watt : Volt = Ampere x Hours x Safety factor = Battery capacity in Ah ... 650 : 24 = 27 x 5 x 1,7 = 230Ah (K20)', Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)

With conventional batteries, the safety factor (to prevent deep discharges) should normally be 1.7 (1.3 with recombination batteries, i.e. AGM and gel).
Banner Batterien, Battery knowledge: Hobby and leisure batteries for long-term discharge, What battery do I need for my motorhome or boat?, Manufacturer document, checked 4 November 2026

Appliance current draw, as published

Every figure below is quoted from a named manufacturer document with the date it was checked, or carries the absence line. Retailer restatements are never used. The duty cycle column is the finding: nobody publishes one.

Appliance	Published figure	Basis in the checker	Duty cycle / test standard	Source
Dometic RM 5330 3-way absorption fridge on 12 V 3-way absorption fridge (on 12V) · Latest source check 4 November 2026	240 Ah per 24 h (120 W rated)	Maker publishes Ah per 24 h Maker’s notice shown before any number.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic RM5310, RM5330, RM5380 Absorption refrigerator Installation and Operating Manual (4445102234), 13 Technical data, Manufacturer document, checked 4 November 2026
Dometic RUA 5208X 3-way absorption fridge on 12 V 3-way absorption fridge (on 12V) · Latest source check 4 November 2026	346 Ah per 24 h (175 W rated)	Maker publishes Ah per 24 h Maker’s notice shown before any number.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 5208X column, Manufacturer document, checked 4 November 2026
Dometic RUA 6408X 3-way absorption fridge on 12 V 3-way absorption fridge (on 12V) · Latest source check 4 November 2026	400 Ah per 24 h (275 W rated)	Maker publishes Ah per 24 h Maker’s notice shown before any number.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 6408X column, Manufacturer document, checked 4 November 2026
Dometic RUA 8408X 3-way absorption fridge on 12 V 3-way absorption fridge (on 12V) · Latest source check 4 November 2026	420 Ah per 24 h (275 W rated)	Maker publishes Ah per 24 h Maker’s notice shown before any number.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 8408X column, Manufacturer document, checked 4 November 2026
Dometic CoolMatic CRX 50 compressor fridge 12V compressor fridge · Latest source check 4 November 2026	1.1 Ah/h at +25 °C ambient, +5 °C interior; 1.7 Ah/h at +32 °C Manual: rated current 5 A, interlocked out	Maker publishes Ah per hour at a stated ambient Interlock applied.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic catalogue page 118, 'Dometic CoolMatic CRX 50/50S / 65/65S' (section 4.24, Compressor refrigerators, 12 / 24 V DC), 4.24, page 118, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Dometic CoolMatic CRX 65 compressor fridge 12V compressor fridge · Latest source check 4 November 2026	1.14 Ah/h at +25 °C ambient, +5 °C interior; 1.8 Ah/h at +32 °C Manual: rated current 5.5 A, interlocked out	Maker publishes Ah per hour at a stated ambient Interlock applied.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic catalogue page 118, 'Dometic CoolMatic CRX 50/50S / 65/65S' (section 4.24, Compressor refrigerators, 12 / 24 V DC), 4.24, page 118, CRX 65 block, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Dometic CoolMatic CRX 80 compressor fridge 12V compressor fridge · Latest source check 4 November 2026	1.19 Ah/h at +25 °C ambient, +5 °C interior; 2 Ah/h at +32 °C Manual: rated current 5.6 A, interlocked out	Maker publishes Ah per hour at a stated ambient Interlock applied.	No published test standard found (checked 4 November 2026). Duty cycle: not published	Dometic catalogue page 120, 'Dometic CoolMatic CRX 80/80S / 110/110S' (section 4.24, Compressor refrigerators, 12 / 24 V DC), 4.24, page 120, CRX 80 block, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Thetford T1090-E 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	26.6 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 2, T1090-E column, Manufacturer document, checked 4 November 2026
Thetford T2095-E 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	26.6 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 2, T2095-E column, Manufacturer document, checked 4 November 2026
Thetford T2120-C 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	37.1 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 2, T2120-C column, Manufacturer document, checked 4 November 2026
Thetford T2138-C 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	42 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 3, T2138-C column, Manufacturer document, checked 4 November 2026
Thetford T2152-C 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	39.1 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 3, T2152-C column, Manufacturer document, checked 4 November 2026
Thetford T2160-C 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	45.8 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 3, T2160-C column, Manufacturer document, checked 4 November 2026
Thetford T2175-C 12V compressor refrigerator 12V compressor fridge · Latest source check 4 November 2026	46.5 Ah per 24 h	Maker publishes Ah per 24 h	Test standard: IEC62552-2020 Duty cycle: not published	Thetford '12V Compressor refrigerators' product range overview, 2027 range (Thetford_Overview_12V-Refrigerators_2027_EN), page 3, T2175-C column, Manufacturer document, checked 4 November 2026
Vitrifrigo C51i CHR compressor fridge-freezer (daily figure in Wh only) 12V compressor fridge · Latest source check 4 November 2026	No published 12 V current figure found (checked 4 November 2026).	No 12V figure published: the reader enters their own	No published test standard found (checked 4 November 2026). Duty cycle: not published
Eberspächer Airtronic S2 D2L diesel air heater (12 V) Diesel air heater · Latest source check 4 November 2026	34 W rated (maximum)	Only a rated figure is published: shown as an upper bound	No published test standard found (checked 4 November 2026). Duty cycle: not published	Eberspächer 'Airtronic S2 & M2 Commercial / M2 Recreational' technical documentation and operating instructions (29.2100.20.1046 Issue C), Technical Data – Heater, page 4, Manufacturer document, checked 4 November 2026
Truma Combi D 6 E diesel combination heater (12 V control side) Diesel air heater · Latest source check 4 November 2026	1.8 to 4 A control range	Maker publishes a control range, so the answer is a range	No published test standard found (checked 4 November 2026). Duty cycle: not published	Truma Combi D 6 E product page, 'Technical Details', Technical Details, Manufacturer document, checked 4 November 2026
Webasto Air Top 2000 STC diesel air heater (12 V) Diesel air heater · Latest source check 4 November 2026	15 to 30 W control range; start-up 75 W, duration not published	Maker publishes a control range, so the answer is a range	No published test standard found (checked 4 November 2026). Duty cycle: not published	Webasto 'Air Top 2000 STC – The simple and cost-effective solution' datasheet (07/24), Technical specifications table, Manufacturer document, checked 4 November 2026
Truma Combi 4 gas combination heater (12 V control side) Gas heater / combi boiler (12V control) · Latest source check 4 November 2026	1.2 A average; peak 6.5 A	Maker publishes an average current	No published test standard found (checked 4 November 2026). Duty cycle: not published	Truma Combi 4 product page, 'Technical Details', Technical Details, Manufacturer document, checked 4 November 2026
Victron Phoenix Inverter 12/1200 VE.Direct Inverter (230 V loads) · Latest source check 4 November 2026	Max. efficiency 91%; zero-load 10 W (1 W ECO)	Inverter: published maximum efficiency and zero-load draw applied	No published test standard found (checked 4 November 2026). Duty cycle: not published	Victron Energy 'Inverters VE.Direct 250VA – 1600VA, 230V and 120V, 50Hz or 60Hz' datasheet, Specification table, 12/1200 24/1200 48/1200 column, Manufacturer document, checked 4 November 2026
Victron Phoenix Inverter 12/500 VE.Direct Inverter (230 V loads) · Latest source check 4 November 2026	Max. efficiency 90%; zero-load 6 W (1 W ECO)	Inverter: published maximum efficiency and zero-load draw applied	No published test standard found (checked 4 November 2026). Duty cycle: not published	Victron Energy 'Inverters VE.Direct 250VA – 1600VA, 230V and 120V, 50Hz or 60Hz' datasheet, Specification table, 12/500 24/500 48/500 column, Manufacturer document, checked 4 November 2026
Labcraft Megalux PD1 surface-mount LED interior light, 10-32 V LED lighting · Latest source check 4 November 2026	0.48 A average	Maker publishes an average current	No published test standard found (checked 4 November 2026). Duty cycle: not published	Labcraft Megalux PD1 product page, specification table, Specification table (Product, Part No., Voltage, Watts, Current, Lumens, Dimensions, Fixing Centres, Switch), Manufacturer document, checked 4 November 2026
Labcraft Orizon 500 mm LED strip light, 12 V LED lighting · Latest source check 4 November 2026	0.48 A average	Maker publishes an average current	No published test standard found (checked 4 November 2026). Duty cycle: not published	Labcraft Orizon product page, specification table, Specification table (Product, Part No., Watts, Current, Lumens, No. LEDS, Dimensions), 12V rows, Manufacturer document, checked 4 November 2026
CBE MP2USBC double USB charging socket (USB-A + USB-C), 12 V input USB charging socket · Latest source check 4 November 2026	No published 12 V current figure found (checked 4 November 2026). Publishes only the 5 V output: 6 A.	No 12V figure published: the reader enters their own	No published test standard found (checked 4 November 2026). Duty cycle: not published	CBE MP2USBC product page, Description, Manufacturer document, checked 4 November 2026
Shurflo Trail King 7 caravan water pump, 7 l/min 20 psi, 12 V Water pump · Latest source check 4 November 2026	3.3 A rated (maximum)	Only a rated figure is published: shown as an upper bound	No published test standard found (checked 4 November 2026). Duty cycle: not published	SHURflo Caravan PRODUCT SHEET OEM 2095-204-112 / Aftermarket 2095-204-412, Trail King 7 (PDS-2095-204-112), Typical Performance @ 12 VDC table, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Shurflo Trail King II RV/caravan fresh water pump, 12 V Water pump · Latest source check 4 November 2026	3 A rated (maximum)	Only a rated figure is published: shown as an upper bound	No published test standard found (checked 4 November 2026). Duty cycle: not published	Pentair 'SHURflo Trail King II RV/Caravan Fresh Water Pump – Product Technical Data Sheet' (4029-181-A43 [B43] Rev. 05/14), Typical Performance at 12V table, page 2, Manufacturer document, checked 4 November 2026
Whale Premium submersible pump GP1352, 12 V Water pump · Latest source check 4 November 2026	3.6 A average (3 points of current against head)	Maker publishes an average current	No published test standard found (checked 4 November 2026). Duty cycle: not published	Whale RV Catalogue (Navico Group), page 12, 'Submersible Pump Range', page 12, Performance table, Manufacturer document, checked 4 November 2026
Whale Watermaster exterior water pump EP1612, 12 V Water pump · Latest source check 4 November 2026	3.8 A average (3 points of current against head)	Maker publishes an average current	No published test standard found (checked 4 November 2026). Duty cycle: not published	Whale RV Catalogue (Navico Group), page 16, 'Watermaster Exterior Water Pump Range', page 16, Performance table, Manufacturer document, checked 4 November 2026

Manufacturer notices the checker shows before any number

Dometic RM 5330 3-way absorption fridge on 12 V:

2.2 Safety when operating with DC power — NOTICE! Damage hazard. Only select operation with DC power supply (battery mode) if the vehicle engine is running and providing sufficient voltage to the light system, or if you are using a battery monitor.
Dometic RM5310, RM5330, RM5380 Absorption refrigerator Installation and Operating Manual (4445102234), 13 Technical data, Manufacturer document, checked 4 November 2026

Dometic RUA 5208X 3-way absorption fridge on 12 V:

NOTICE! Damage hazard — Only select operation with DC power supply if the vehicle engine is running and providing sufficient voltage to the light system, or if you are using a battery monitor.
Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 5208X column, Manufacturer document, checked 4 November 2026

Dometic RUA 6408X 3-way absorption fridge on 12 V:

NOTICE! Damage hazard — Only select operation with DC power supply if the vehicle engine is running and providing sufficient voltage to the light system, or if you are using a battery monitor.
Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 6408X column, Manufacturer document, checked 4 November 2026

Dometic RUA 8408X 3-way absorption fridge on 12 V:

NOTICE! Damage hazard — Only select operation with DC power supply if the vehicle engine is running and providing sufficient voltage to the light system, or if you are using a battery monitor.
Dometic RUA 5208X, RUA 6408X, RUA 8408X Absorption refrigerator Installation and Operating Manual (4445102445), 14 Technical data, RUA 8408X column, Manufacturer document, checked 4 November 2026

Depth of discharge, as published

The checker’s default figures are conventions with a scheme test basis behind them, and are labelled so. The rows below are what each battery maker in the index publishes about depth of discharge in its own document, or the absence line.

Battery	Chemistry	Maker’s published depth-of-discharge guidance	Cycle life at a stated depth of discharge	Source
Checker default, lead-acid	Flooded, EFB, AGM, gel	50%: 50% depth of discharge: NCC scheme test basis and a widely repeated convention, not a standard	NCC scheme classes are defined by minimum life cycles at 50% depth of discharge (rule I1)	NCC, Verified Battery List (consumer advice page with scheme class definitions), Class table column header, UK verification scheme, checked 4 November 2026
Checker default, LiFePO4	LiFePO4	80%: 80% depth of discharge: a working figure, not a standard (2015 Victron blog article); LFP Smart datasheet cycle life: 2500 @80%, 3000 @70%, 5000 @50% DoD	CYCLE LIFE (capacity ≥ 80 % of nominal): 80 % DoD 2500 cycles \| 70 % DoD 3000 cycles \| 50 % DoD 5000 cycles	Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, Secondary source, checked 4 November 2026
Victron AGM Deep Cycle Battery 12V 110Ah Latest source check 4 November 2026 · 6/9 published	AGM	No published depth-of-discharge figure found (checked 4 November 2026).	400 cycles at 80% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life"); 600 cycles at 50% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life"); 1500 cycles at 30% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life")
Yuasa L36-AGM YBX Active Leisure AGM 12V 95Ah Latest source check 4 November 2026 · 4/9 published	AGM	No published depth-of-discharge figure found (checked 16 September 2026).	No published cycle-life figure at a stated depth of discharge found (checked 16 September 2026).
Yuasa L36-EFB YBX Active Leisure EFB 12V 100Ah Latest source check 4 November 2026 · 4/9 published	EFB	No published depth-of-discharge figure found (checked 16 September 2026).	No published cycle-life figure at a stated depth of discharge found (checked 16 September 2026).
Banner Energy Bull 955 51 Latest source check 4 November 2026 · 4/9 published	Flooded	Never remove the entire nominal capacity from the battery! Banner recommendation: max. 50% depth of discharge (DoD) (50%)	270 cycles at 50% DoD (end of life: Not stated by Banner (range-level figure given as "up to 270" at 50% discharge depth))	Hobby and Leisure Batteries \| Banner Battery Knowledge, Manufacturer document, checked 4 November 2026
Banner Energy Bull 957 51 Latest source check 4 November 2026 · 6/9 published	Flooded	Never remove the entire nominal capacity from the battery! Banner recommendation: max. 50% depth of discharge (DoD) (50%)	270 cycles at 50% DoD (end of life: Not stated by Banner (figure given as "up to 270" at 50% discharge depth))	Hobby and Leisure Batteries \| Banner Battery Knowledge, Manufacturer document, checked 4 November 2026
Banner Energy Bull 959 01 Latest source check 4 November 2026 · 5/9 published	Flooded	Never remove the entire nominal capacity from the battery! Banner recommendation: max. 50% depth of discharge (DoD) (50%)	270 cycles at 50% DoD (end of life: Not stated by Banner (range-level figure given as "up to 270" at 50% discharge depth))	Hobby and Leisure Batteries \| Banner Battery Knowledge, Manufacturer document, checked 4 November 2026
Banner Energy Bull 968 01 Latest source check 4 November 2026 · 6/9 published	Flooded	Never remove the entire nominal capacity from the battery! Banner recommendation: max. 50% depth of discharge (DoD) (50%)	270 cycles at 50% DoD (end of life: Not stated by Banner (range-level figure given as "up to 270" at 50% discharge depth))	Hobby and Leisure Batteries \| Banner Battery Knowledge, Manufacturer document, checked 4 November 2026
Lucas LX31MF Leisure Battery 105Ah Latest source check 4 November 2026 · 3/9 published	Flooded	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Numax LV26MF Sealed Leisure Battery Latest source check 4 November 2026 · 4/9 published	Flooded	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Numax XV31MF Sealed Leisure Battery Latest source check 4 November 2026 · 3/9 published	Flooded	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Platinum LB6110L Leisure Battery 12V 100Ah Latest source check 4 November 2026 · 3/9 published	Flooded	No published depth-of-discharge figure found (checked 4 November 2026).	70 cycles at 50% DoD (end of life: Not stated by Platinum (column headed "PRODUCT LIFE CYCLES @50% DOD"))
Trojan 27TMX 12V Deep-Cycle Flooded Battery Latest source check 4 November 2026 · 4/9 published	Flooded	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Exide Equipment GEL ES1200 Latest source check 4 November 2026 · 4/9 published	Gel	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Exide Equipment GEL ES1300 Latest source check 4 November 2026 · 4/9 published	Gel	No published depth-of-discharge figure found (checked 4 November 2026).	No published cycle-life figure at a stated depth of discharge found (checked 4 November 2026).
Victron Gel Deep Cycle Battery 12V 110Ah Latest source check 4 November 2026 · 6/9 published	Gel	No published depth-of-discharge figure found (checked 4 November 2026).	500 cycles at 80% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life"); 750 cycles at 50% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life"); 1800 cycles at 30% DoD (end of life: Not stated; the datasheet lists the figures under the heading "Cycle design life")
Fogstar Drift 12V 105Ah Lithium Leisure Battery Latest source check 4 November 2026 · 6/9 published	LiFePO4	No published depth-of-discharge figure found (checked 4 November 2026).	3500 cycles at 80% DoD (end of life: Not stated by Fogstar)
Renogy Core Mini 12.8V 100Ah Lithium Iron Phosphate Battery Latest source check 4 November 2026 · 7/9 published	LiFePO4	Weighing only half of the lead-acid counterparts, the battery can be safely discharged to 100% Depth of Discharge (DOD), delivering twice the energy. (100%)	5000 cycles at 80% DoD (end of life: 80% EOL (as printed: "5000 Cycles (80% DOD, 80% EOL)"))	Renogy Core Series 12.8V 100Ah Mini Deep Cycle Lithium Iron Phosphate Battery (RBT12100LFP-M) – User Manual, Introduction (p. 1), Manufacturer document, checked 4 November 2026
Roamer 105SMART5 MAX 12.8V 105Ah LiFePO4 Latest source check 4 November 2026 · 6/9 published	LiFePO4	No published depth-of-discharge figure found (checked 4 November 2026).	8000 cycles at 80% DoD (end of life: Not stated by Roamer)
Victron Lithium Battery Smart 12,8V/100Ah Latest source check 4 November 2026 · 6/9 published	LiFePO4	No published depth-of-discharge figure found (checked 4 November 2026).	2500 cycles at 80% DoD (end of life: capacity ≥ 80 % of nominal); 3000 cycles at 70% DoD (end of life: capacity ≥ 80 % of nominal); 5000 cycles at 50% DoD (end of life: capacity ≥ 80 % of nominal)

The number on the box often hides its discharge rate

Capacity is stored here as every rate the maker publishes, never one number. Banner publishes its 957 51 at three rates; the “110Ah” on the retail listing is the 100-hour figure and the 20-hour figure is 100 Ah. The comparison retains each published test rate and its conditions.

Battery	Marketed as	Published rates	Box figure vs 20-hour figure	NCC list	Where sold	Source
Banner Energy Bull 955 51 Flooded · Deep cycle (maker’s term) · Latest source check 4 November 2026	72 Ah, 20-hour rate (C20) UK brochure (05/16) lists it as "72ah / 85ah" (20hr/100hr).	55 Ah at the 5-hour rate (C5) 72 Ah at the 20-hour rate (C20) 85 Ah at the 100-hour rate (C100) Peukert n 1.241 derived from C5 and C20; reference only, not applied to sizing	0% 5-hour figure 24% below	Not on the lists checked	No UK retailer link recorded.	Energy Bull – On Board Power für Hobby und Freizeit (Banner Energy Bull brochure, German language), Technische Daten und Infos table, columns Ah 5 h / Ah 20 h / Ah 100 h, Manufacturer document, checked 4 November 2026
Banner Energy Bull 957 51 Flooded · Deep cycle (maker’s term) · Latest source check 4 November 2026	100 Ah, 20-hour rate (C20) Banner's product page and technical data sheet lead with K20 = 100 Ah; UK retail copy says "100/110Ah", the 110 being the K100 (100-hour) figure.	75 Ah at the 5-hour rate (C5) 100 Ah at the 20-hour rate (C20) 110 Ah at the 100-hour rate (C100) Peukert n 1.262 derived from C5 and C20; reference only, not applied to sizing	0% 5-hour figure 25% below	Class B, NCC/VB/B/006: 100 Ah, 200 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £159.29 checked 4 November 2026 No affiliate programme found Alpha Batteries £159.98 checked 4 November 2026 No affiliate programme found	Banner Technical Data Sheet – Energy Bull 957 51 (Document DBTBAT00339), Electrical data, Manufacturer document, checked 4 November 2026
Banner Energy Bull 959 01 Flooded · Deep cycle (maker’s term) · Latest source check 4 November 2026	115 Ah, 20-hour rate (C20) UK brochure (05/16) and Tayna list it as 115 Ah / "115ah / 135ah" (20hr/100hr).	90 Ah at the 5-hour rate (C5) 115 Ah at the 20-hour rate (C20) 135 Ah at the 100-hour rate (C100) Peukert n 1.215 derived from C5 and C20; reference only, not applied to sizing	0% 5-hour figure 22% below	Class B, NCC/VB/B/007: 115 Ah, 200 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £230.04 checked 4 November 2026 No affiliate programme found	Energy Bull – On Board Power für Hobby und Freizeit (Banner Energy Bull brochure, German language), Technische Daten und Infos table, columns Ah 5 h / Ah 20 h / Ah 100 h, Manufacturer document, checked 4 November 2026
Banner Energy Bull 968 01 Flooded · Deep cycle (maker’s term) · Latest source check 4 November 2026	230 Ah, 20-hour rate (C20) Product page and technical data sheet lead with K20 = 230 Ah.	180 Ah at the 5-hour rate (C5) 230 Ah at the 20-hour rate (C20) 250 Ah at the 100-hour rate (C100) Peukert n 1.215 derived from C5 and C20; reference only, not applied to sizing	0% 5-hour figure 22% below	Class B, NCC/VB/B/010: 230 Ah, 200 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £378.98 checked 4 November 2026 No affiliate programme found	Banner Technical Data Sheet – Energy Bull 968 01 (Document DBTBAT00339), Electrical data, Manufacturer document, checked 4 November 2026
Exide Equipment GEL ES1200 Gel · Not stated · Latest source check 4 November 2026	110 Ah, 20-hour rate (C20) Product page states "Capacity 110.0 Ah" without a rate; the Exide range leaflet heads the same column "Capacity Ah (20h)". Retail name "G110".	110 Ah at the 20-hour rate (C20)	0%	Class A, NCC/VB/A/077: 110 Ah, 600 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £225.28 checked 4 November 2026 No affiliate programme found	Exide – All Ranges Battery Solutions (full range leaflet, Marine and Leisure type list), MARINE AND LEISURE TYPE LIST – EQUIPMENT GEL; columns Code / Wh* / Capacity Ah (20h) / CCA (EN) / L W H (mm) / Box Type / Hold down, Manufacturer document, checked 4 November 2026
Exide Equipment GEL ES1300 Gel · Not stated · Latest source check 4 November 2026	120 Ah, 20-hour rate (C20) Product page states "Capacity 120.0 Ah" without a rate; the Exide range leaflet heads the same column "Capacity Ah (20h)". Retail name "G120".	120 Ah at the 20-hour rate (C20)	0%	Class A, NCC/VB/A/077: 120 Ah, 800 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £209.71 checked 4 November 2026 No affiliate programme found	Exide – All Ranges Battery Solutions (full range leaflet, Marine and Leisure type list), MARINE AND LEISURE TYPE LIST – EQUIPMENT GEL; columns Code / Wh* / Capacity Ah (20h) / CCA (EN) / L W H (mm) / Box Type / Hold down, Manufacturer document, checked 4 November 2026
Fogstar Drift 12V 105Ah Lithium Leisure Battery LiFePO4 · Not stated · Latest source check 4 November 2026	105 Ah, rate not stated Fogstar states "Nominal Capacity 105Ah" with no discharge rate.	105 Ah (rate not stated)	cannot be compared: no 20-hour or faster rate published	Not on the lists checked	Fogstar £299.99 checked 4 November 2026 Could not be established	Fogstar Drift 105 Specification (sheet linked from the product page), FULL SPECIFICATIONS – CELL INFORMATION, Manufacturer document, checked 4 November 2026
Lucas LX31MF Leisure Battery 105Ah Flooded · Dual purpose (maker’s term) · Latest source check 4 November 2026	105 Ah, rate not stated The Lucas sheet heads the column simply "AH"; no rate is stated.	105 Ah (rate not stated)	cannot be compared: no 20-hour or faster rate published	Class B, NCC/VB/B/013: 105 Ah, 220 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £125.84 checked 4 November 2026 No affiliate programme found	Lucas Leisure & Marine Battery Data Sheet – Lucas Supreme Leisure/Marine – Sealed MF (LX range), Lucas Supreme Leisure/Marine - Sealed MF; columns Reference / ETN / AH / CCA (EN) / L (mm) / W (mm) / H (mm) / Weight Kg / Layout / Terminal / Hold Down, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Numax LV26MF Sealed Leisure Battery Flooded · Not stated · Latest source check 4 November 2026	100 Ah, 20-hour rate (C20) Catalogue column "Ah. Cap. @20hr rate" = 100; Tayna sells the LV26MF as "12V 95Ah".	100 Ah at the 20-hour rate (C20)	0%	Class C, NCC/VB/C/048: 100 Ah, 75 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £109.20 checked 4 November 2026 No affiliate programme found	Numax battery catalogue (Manbat/Ecobat Battery UK house brand catalogue) – Battery specifications special types, Numax sealed leisure and marine range; columns Type / Ah. Cap. @20hr rate / E.N. Cold start / Bench charge AMPS / L (mm) W (mm) H (mm) / Weight Kg / Layout / Terminals / Base holdown / Notes, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Numax XV31MF Sealed Leisure Battery Flooded · Not stated · Latest source check 4 November 2026	110 Ah, 20-hour rate (C20) Catalogue column "Ah. Cap. @20hr rate" = 110; Tayna sells the XV31MF as "12V 105Ah (CXV31MF)".	110 Ah at the 20-hour rate (C20)	0%	Not on the lists checked	Tayna Batteries £107.11 checked 4 November 2026 No affiliate programme found	Numax battery catalogue (Manbat/Ecobat Battery UK house brand catalogue) – Battery specifications special types, Numax CXV sealed leisure and marine range; columns Type / Ah. Cap. @20hr rate / E.N. Cold start / Bench charge AMPS / L (mm) W (mm) H (mm) / Weight Kg / Layout / Terminals / Base holdown / Notes, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Platinum LB6110L Leisure Battery 12V 100Ah Flooded · Not stated · Latest source check 4 November 2026	100 Ah, 20-hour rate (C20) Guide column "Ah (C20)" = 100.	100 Ah at the 20-hour rate (C20)	0%	Not on the lists checked	Tayna Batteries £95.33 checked 4 November 2026 No affiliate programme found Alpha Batteries £114.99 checked 4 November 2026 No affiliate programme found	Platinum Leisure Product Guide (Platinum International), BATTERY SELECTOR - BY BOX SIZE; columns PRODUCT RANGE / PRODUCT REFERENCE / LIFE CYCLES @50% DOD / L (MM) / W (MM) / H (MM) / Ah (C20) / V / LAYOUT / TERMINAL / HOLD DOWN / NCC CLASS, Manufacturer document, checked 4 November 2026 (maker’s document read on a distributor server)
Renogy Core Mini 12.8V 100Ah Lithium Iron Phosphate Battery LiFePO4 · Not stated · Latest source check 4 November 2026	100 Ah, 2-hour rate (C2; 0.5C) Renogy states "Rated Capacity 100Ah (0.5C, 25℃)": 0.5C corresponds to a two-hour discharge, recorded as C2. No C20 test is inferred.	100 Ah at the 2-hour rate (C2; 0.5C), 25 °C	—	Not on the lists checked	Renogy UK £179.99 checked 4 November 2026 Awin	Renogy UK – Core Mini 12.8V 100Ah Lithium Iron Phosphate Battery (product page, Specs tab), Specs – Specification table, Manufacturer document, checked 4 November 2026
Roamer 105SMART5 MAX 12.8V 105Ah LiFePO4 LiFePO4 · Not stated · Latest source check 4 November 2026	105 Ah, rate not stated Datasheet: "Nominal Capacity CN Typical 105 Max 116 Ah"; no discharge rate stated.	105 Ah (rate not stated)	cannot be compared: no 20-hour or faster rate published	Not on the lists checked	Roamer (manufacturer shop) £419 checked 4 November 2026 Could not be established	Roamer 105SMART5 MAX 12.8V 105AH 300A LiFePO4 – Datasheet, Battery Specification, Manufacturer document, checked 4 November 2026
Trojan 27TMX 12V Deep-Cycle Flooded Battery Flooded · Deep cycle (maker’s term) · Latest source check 4 November 2026	105 Ah, 20-hour rate (C20) Trojan lists all four rates side by side; the 20-Hr figure is 105 Ah. Tayna's product page (read 2026-11-04) lists "Capacity (C5) 85 Ah" first, then C10, C20 and C100.	85 Ah at the 5-hour rate (C5), 27 °C, end voltage 10.5 V 97 Ah at the 10-hour rate (C10), 27 °C, end voltage 10.5 V 105 Ah at the 20-hour rate (C20), 27 °C, end voltage 10.5 V 117 Ah at the 100-hour rate (C100), 27 °C, end voltage 10.5 V Peukert n 1.235 derived from C5 and C10; reference only, not applied to sizing	0% 5-hour figure 19% below	Not on the lists checked	Tayna Batteries £189.68 checked 4 November 2026 No affiliate programme found	Trojan Battery Company – Data Sheet MOTIVE 27TMX, ELECTRICAL SPECIFICATIONS, Manufacturer document, checked 4 November 2026
Victron AGM Deep Cycle Battery 12V 110Ah AGM · Deep cycle (maker’s term) · Latest source check 4 November 2026	110 Ah, 20-hour rate (C20) Datasheet: "The rated capacity of Victron AGM and Gel Deep Cycle batteries refers to 20 hour discharge, in other words: a discharge current of 0,05 C."	110 Ah at the 20-hour rate (C20), 25 °C, end voltage 10.8 V	0%	Not on the lists checked	Tayna Batteries £265.63 checked 16 September 2026 No affiliate programme found	Victron Energy datasheet – Gel and AGM Batteries, 12 Volt Deep Cycle AGM table, columns Article number / Ah / V / l x w x h mm / Weight kg, Manufacturer document, checked 4 November 2026
Victron Gel Deep Cycle Battery 12V 110Ah Gel · Deep cycle (maker’s term) · Latest source check 4 November 2026	110 Ah, 20-hour rate (C20) Datasheet: "The rated capacity of Victron AGM and Gel Deep Cycle batteries refers to 20 hour discharge, in other words: a discharge current of 0,05 C."	110 Ah at the 20-hour rate (C20), 25 °C, end voltage 10.8 V	0%	Not on the lists checked	No UK retailer link recorded.	Victron Energy datasheet – Gel and AGM Batteries, 12 Volt Deep Cycle GEL table, columns Article number / Ah / V / l x w x h mm / Weight kg, Manufacturer document, checked 4 November 2026
Victron Lithium Battery Smart 12,8V/100Ah LiFePO4 · Not stated · Latest source check 4 November 2026	100 Ah, rate not stated Victron states "Nominal capacity @ 25 °C* 100 Ah" with footnote "* Discharge current ≤1C"; no C-rate label such as C20 is given.	100 Ah (rate not stated), 25 °C	cannot be compared: no 20-hour or faster rate published	Not on the lists checked	No UK retailer link recorded.	Victron Energy datasheet – 12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart, Battery specification table, column LFP-Smart 12,8/100, Manufacturer document, checked 4 November 2026
Yuasa L36-AGM YBX Active Leisure AGM 12V 95Ah AGM · Not stated · Latest source check 4 November 2026	95 Ah, 20-hour rate (C20) Page title "12V 95Ah 850A(EN)"; table states "Capacity (20hr) 95 Ah".	95 Ah at the 20-hour rate (C20)	0%	Class A, NCC/VB/A/017: 95 Ah, 429 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £219.95 checked 4 November 2026 No affiliate programme found	GS Yuasa UK – 12V 95Ah 850A(EN) - YBX Active® Leisure AGM series battery (L36-AGM product page), Specification tab, Manufacturer document, checked 16 September 2026
Yuasa L36-EFB YBX Active Leisure EFB 12V 100Ah EFB · Not stated · Latest source check 4 November 2026	100 Ah, 20-hour rate (C20) Page title "12V 100Ah 850A(EN)"; table states "Capacity (20hr) 100 Ah".	100 Ah at the 20-hour rate (C20)	0%	Class B, NCC/VB/B/026: 100 Ah, 223 cycles at 50% DoD list October 2023; discharge rate not stated by the scheme	Tayna Batteries £151.37 checked 4 November 2026 No affiliate programme found	GS Yuasa UK – 12V 100Ah 850A(EN) - YBX Active® Leisure EFB series battery (L36-EFB product page), Specification tab, Manufacturer document, checked 16 September 2026

Completeness bars show how many specification groups each maker publishes. Roughly 40% absence for supermarket and own-brand batteries is expected; a brand that publishes nothing is telling the buyer something.

Common questions

Does this checker send my appliance list or battery figures anywhere?

No. The arithmetic runs inside your browser on the published dataset it downloads. There is no form submission, no request carrying your numbers and no analytics on them. Nothing you type is stored or sent by this site.

Why does the checker divide by 50% for a lead-acid battery?

Why 80% for LiFePO4?

LiFePO4 usable capacity = nameplate x 80% depth of discharge as a working figure. This is a convention, not a standard: a 2015 technical article on Victron's blog says '80% DOD is used' for LFP. Victron's LFP Smart datasheet publishes cycle life at 80%, 70% and 50% DoD (2500 / 3000 / 5000 cycles to 80% of nominal capacity) and a capacity-loss figure at 100% DoD; it does not prescribe a working depth of discharge. Deeper discharge is specified but costs cycles. Source: “For Lithium-iron-phosphate (LiFePO4 or LFP) which is the safest of the mainstream Li-ion battery types, 80% DOD is used.” (Victron Energy blog, technical article (2015): Batteries: Lithium-ion vs AGM, checked 4 November 2026).

Why is the answer given at the 20-hour rate (C20)?

Because a battery’s amp-hour figure depends on the discharge rate, and a headline figure does not always say which rate it uses. Banner publishes its 957 51 as 110 Ah at the 100-hour rate, 100 Ah at the 20-hour rate and 75 Ah at the 5-hour rate (Banner Technical Data Sheet – Energy Bull 957 51 (Document DBTBAT00339), checked 4 November 2026): the 100-hour figure is 10% above the 20-hour figure, and the 5-hour figure is 25% below it. Stating the rate makes batteries comparable; 5 of the 19 indexed batteries publish more than one rate.

Does the checker apply a duty cycle to the fridge?

No manufacturer in the index publishes a duty cycle, so the checker never assumes one. Where a maker publishes an average, such as Dometic’s 1.1 Ah/h for the CRX 50 at +25 °C ambient, the average is used as published. Thetford is the only maker in the index that names a test standard for its daily figure: “IEC62552-2020”. Where only a rated current is published, the line is shown as an upper bound and labelled.

Why does the checker refuse to use the fridge manual’s 5.0 A figure?

Dometic's CRX 50 installation and operating manual publishes 'Rated current 12 V⎓: 5.0 A'. The manual calls it rated current; it does not say the figure is an average or define it further. It is about 4.5 times the catalogue average of 1.1 Ah/h. This checker uses the catalogue average and never lets the 5.0 A figure reach the daily total. Calculators seeded from the manual will tell you to buy a bank roughly four times too big.

Does the checker reduce lead-acid capacity for cold weather?

No, because the manufacturer documents checked publish it only as a graph, not as numbers. No numeric lead-acid temperature derate table is published in the manufacturer documents read on 2026-09-16 and re-read on 2026-11-04 (Victron Gel/AGM datasheet section 8 and GS Yuasa NP Application Manual Figure 7 are graphs only). Brief rule 8: never read a number off a graph. The checker reports the direction of the effect and says the figure is not published.

What is the Peukert exponent and where does 1.25 come from?

Victron gives 1.25 as an approximate default Peukert exponent for lead-acid battery monitors. It is not a battery-specific sizing model. This checker does not apply that default to its energy-only estimate. Victron: “The default setting in the battery monitor for the Peukert exponent is 1.25. This is an acceptable average value for most lead acid batteries.” (checked 4 November 2026). The checker provides an energy-only estimate without discharge-rate correction. Reference exponents derived from published battery ratings are not applied to the sizing answer.

Where next

Split charge relay or DC-DC charger? Whether your alternator can charge the battery this checker sized.
Mains chargers by published charge profile: the route to a full charge on hook-up or at home.
Methodology: the evidence grades, the absence line and the freshness ladder.
Corrections: if a maker’s document says something different, send the URL.

Cable sizing and fuse sizing are deliberately not on this site. The voltage-drop figures repeated across the UK campervan web trace to a US marine standard and one manufacturer’s house recommendation; the European standard for 12 V DC installations in leisure vehicles (BS EN 1648) has not yet been read here. Until it has, each charger record links the maker’s own cable and fuse table instead.

This site publishes what manufacturers and standards bodies have published. It does not design electrical installations and is not a substitute for a competent auto electrician or a habitation check.