ABYC E-13 (2025) for Boat Builders: The Lithium Battery Data Sheet to Ask For

Boat builders and marine electricians who design around lithium house banks keep running into the same gap: the battery is chosen, but the data the electrical design needs is missing from the supplier’s spec sheet. The biggest gap is the battery’s short-circuit current, which drives fuse selection. This guide covers what changed with the 2025 ABYC standards, which batteries they apply to, and the data sheet to ask your battery supplier for before you sign off a design.

This guide is general information as of 30 October 2026, not engineering or legal advice. The ABYC standards are sold by ABYC and ANSI; buy the current text and have a qualified marine electrician apply it to your boat.

Short answer

• ABYC E-13-2025 (Lithium Ion Batteries) applies to installed boat battery systems over 500 Wh. It revises the 2022 edition.
• A single 12.8V 50Ah LiFePO4 battery is already 640 Wh, so almost every marine lithium house battery falls in scope.
• ABYC published the 2025 updates to E-11 (AC and DC electrical systems) and E-13 in Supplement 65 in August 2025, and points builders to the 2027 model year.
• Your electrician needs the battery’s short-circuit current to choose a fuse with enough interrupt rating. A BMS short-circuit trip setting is not the same number.
• Ask for a written data sheet per model, backed by test reports, before you approve a battery for a build.

What changed in 2025

On 5 August 2025 ABYC announced its 65th supplement to the “Standards and Technical Information Reports for Small Craft”. It updates 14 standards, and ABYC names E-11, AC & DC Electrical Systems on Boats and E-13, Lithium Ion Batteries among the main ones. A-31 (battery chargers and inverters) is also on the list. ABYC says the updated standards and its compliance tools are meant to help the industry prepare for the 2027 model year.

The ANSI webstore listings confirm the editions: ABYC E-13-2025 revises E-13-2022 and “applies to installed boat battery systems over 500 watt-hours (Wh)”. ABYC E-11-2025 revises E-11-2023.

Outside North America, ISO 23625:2025 (Small craft, lithium-ion batteries) was published in March 2025 and replaced ISO/TS 23625:2021. ISO says it covers the selection and installation of lithium-ion batteries on boats, and the safety information the manufacturer must provide, for batteries and battery systems with a capacity greater than 500 Wh.

Clause numbers and the exact wording are in the standards themselves. This guide does not reproduce them; use it as a list of what to ask your supplier for, and check each item against the text you buy.

Does it apply to your battery?

Watt-hours are nominal voltage × amp-hours. The scope is worded around the installed battery system, so add up the whole bank, not just one battery, and confirm against the scope clause.

Battery (nominal)	Energy	Over 500 Wh?
12.8V 30Ah	384 Wh	No, on its own; a bank of two is 768 Wh
12.8V 50Ah	640 Wh	Yes
12.8V 100Ah	1,280 Wh	Yes
12.8V 200Ah	2,560 Wh	Yes
25.6V 100Ah	2,560 Wh	Yes

If you are replacing a lead-acid battery by case size, our BCI group size chart for LiFePO4 helps match the box before you get to the electrical data.

Short-circuit current: the number most spec sheets leave out

A LiFePO4 battery has very low internal resistance, so a dead short can draw a fault current far above any normal load. The fuse or breaker nearest the battery has to interrupt that current safely. Its interrupt rating (AIC) is the largest fault current it is rated to clear, and your electrician compares it with the battery bank’s available short-circuit current.

That is why the short-circuit current has to come from the battery maker, measured on the model you are buying. Two common mix-ups:

• BMS short-circuit trip setting. Many data sheets list the current at which the BMS trips, or how fast it reacts. That is a protection setting, not the fault current the cells can deliver before the BMS opens.
• Peak or surge discharge current. This is an operating limit for loads such as inverters and windlasses. It is not a short-circuit rating either.

Interrupt ratings also differ a lot between fuse types, and some fall as voltage rises. Blue Sea Systems’ published ratings for its marine fuses show the spread:

Fuse type (Blue Sea Systems example)	Published interrupt capacity
Class T (e.g. 400 A)	20,000 A at 125 V DC
MRBF terminal fuse (e.g. 300 A)	10,000 A at 14 V DC; 5,000 A at 32 V DC; 2,000 A at 58 V DC
ANL (e.g. 400 A)	6,000 A

These are one maker’s typical market examples, not LJY products. Check the rating of the exact fuse you install. A fuse that suits a small 12V bank may be under-rated for a larger bank or a 24V system, which is why the short-circuit current matters.

Inrush when an inverter is first connected is a different problem from a short circuit; see our inverter pre-charge and BMS trip guide for that.

The data sheet to ask your supplier for

Use this list when you write an OEM battery spec or approve a battery for a build. Ask for each value in writing for the exact model, and for the test report or document that backs it.

Item	What to ask for	Why the designer needs it
Identity	Model number, chemistry (LiFePO4), nominal voltage, capacity in Ah and Wh	Scope check and bank sizing
Short-circuit current	Value in amps from a test on this model, with the test method and report number	Fuse and breaker interrupt rating
BMS protections	High and low voltage, high and low temperature, overcurrent; what each one does	Knowing when and why the battery will disconnect
How the BMS disconnects	MOSFET or contactor; current rating; whether there is an alarm or warning output before shutdown	Battery switch, alarm and backup-power design
Charging	Charge voltage, current limits and temperature window	Programming chargers, alternator regulators and solar controllers
Operating temperatures	Charge and discharge ranges	Choosing the battery location
Ingress protection	IP rating with the test report, not just a label	Locations exposed to spray or flooding
Mounting	Restraint and orientation instructions	Securing the battery for the boat’s sea state
Series and parallel	Maximum number in series and parallel; voltage match needed before connecting	Bank design
Safety test reports	Which standard (e.g. IEC 62619, UL 1973), which lab, which model	Matching the battery to the standards the builder accepts
Transport and handling	UN38.3 test summary and SDS for the same model	Shipping and site files; see our LiFePO4 battery SDS guide
Owner’s manual	A manual that states the values above	Owners and service technicians need the same data

Our battery certification verification guide explains how to check that a test report really covers the model you are buying.

Switches, alarms and installation location

Battery switch, disconnect, ventilation and location rules are in E-13 and E-11; your electrician applies them. What the electrician needs from the battery supplier is how the battery behaves:

• whether the BMS disconnect is a solid-state switch or a contactor, and what happens to it if the BMS loses power
• whether the battery gives a warning before it shuts down, so critical loads such as engine starting and navigation lights can be planned around a shutdown
• the IP rating, backed by a test report, if the battery will sit where it can get wet
• the maker’s guidance on ventilation and fire protection for the compartment

Where LJY fits

LJY Energy is a Shenzhen supplier and OEM/ODM coordinator for LiFePO4 batteries, not a manufacturer. For marine projects we request the data sheet items above from the manufacturer for the specific model, including the short-circuit current from the source pack’s test report. We don’t print a short-circuit figure until that test report exists, and we don’t describe any battery as meeting ABYC E-13. Further certification and testing are arranged per project, with fees borne by the buyer.

See our marine battery solutions, the 12.8V RV and marine private-label program, the 12V OEM battery block and the 24V LiFePO4 battery series. Dealers can also read our RV lithium battery dealer buying guide, or browse the full product range.

FAQ

Is the BMS trip current the same as the short-circuit current?

No. The trip current is the BMS protection setting. The short-circuit current is the fault current the battery can deliver, which the fuse has to be able to interrupt. Ask for both, and for the test report behind the short-circuit figure.

Do I need a Class T fuse?

It depends on the battery bank’s short-circuit current, the system voltage and the fuse’s published interrupt rating. Blue Sea Systems, for example, rates its Class T fuses at 20,000 A at 125 V DC and its ANL fuses at 6,000 A. Your marine electrician makes the choice once the short-circuit current is known.

Does E-13 apply to a 12V 50Ah trolling or house battery?

A 12.8V 50Ah battery is 640 Wh, which is over the 500 Wh threshold in the 2025 edition. Work it out from the data sheet for your battery, and add up the whole installed bank.

Do I have to follow ABYC?

ABYC is a nonprofit that develops safety standards for boat design, construction and repair, and says its standards guide more than 90% of boats built in North America. Whether your boats must follow them depends on your customers, certification programs and insurers, so check those requirements directly.

Sources

• ABYC: “ABYC Publishes Updated Standards for Boat Building and Repair” (Supplement 65, 5 August 2025)
• ANSI webstore: ABYC E-13-2025, Lithium Ion Batteries
• ANSI webstore: ABYC E-11-2025, AC and DC Electrical Systems on Boats
• ISO 23625:2025, Small craft — Lithium-ion batteries
• Blue Sea Systems: Class T fuse 400 A specifications
• Blue Sea Systems: MRBF terminal fuse 300 A specifications
• Blue Sea Systems: ANL fuse 400 A