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Long Beach Marine Electric connects boat owners with licensed, insured marine electricians for boat lithium battery conversion: replacing lead-acid house banks with LiFePO4 batteries and re-engineering what charges and protects them. A lithium conversion is a system change, not a battery swap. Chargers, alternators, inverters and the battery management system all have to be set up for lithium, which is why the US Harbors guide to switching stresses professional installation to avoid equipment damage and insurance complications.
What happens on the first visit
- An energy audit: what you run, how long you're away from shore power, and how much usable capacity you need. That sets the bank size.
- Survey of the charging sources (shore charger, alternator and regulator, solar, generator) and whether each can be set for lithium.
- Check of battery location, ventilation, cable runs and space for the BMS, fusing and disconnects.
- Review of the start battery and how it stays separate from the house bank.
- A written design: battery model, charging changes, protection devices and a fixed price.
What lithium gets you
LiFePO4 batteries trade a higher upfront price for weight, usable capacity and life. A Group 24-size 100 Ah lithium battery weighs about 20–25 lb against roughly 50 lb for an 80 Ah lead-acid battery. Lithium can be used to 80–100% of its rating, where lead-acid should stop at about 50%. And lithium is rated for 3,000–6,000 cycles against 300–800 for conventional batteries, per US Harbors' 2026 guide.
In practice, a 200 Ah lithium bank gives roughly the usable energy of a 400 Ah lead-acid bank at under half the weight. That's why conversions make the most sense for boats that anchor out, live aboard, or run inverters for long periods away from the dock.
Why it isn't a drop-in swap
- Charging profiles. Lithium needs different absorption and float settings. A charger or solar controller left on a lead-acid profile can overcharge or undercharge it.
- Alternators. A lithium bank can draw a stock alternator at full output until it overheats. Most conversions add a DC-DC charger, such as the Victron Orion-Tr Smart (from about $160), or an external regulator with temperature sensing.
- The BMS can disconnect the bank. If the battery protects itself by switching off, everything on that bank goes dark, and an alternator still charging into it can be damaged. The system has to be designed for that event.
- Start battery. Most conversions keep a lead-acid start battery so the engine can always start.
ABYC E-13 covers lithium-ion battery installations on boats, and insurers and surveyors increasingly ask whether a conversion follows it.
What a conversion costs
Published 2026 prices put LiFePO4 batteries at about $500–$800 per 100 Ah. A typical 200–400 Ah house-bank conversion adds a DC-DC charger or regulator, a lithium-capable shore charger if the existing one can't be reprogrammed, fusing, a battery monitor and labor. Most conversions run several thousand dollars in total, and the design decides the number. See the boat lithium conversion cost guide for a line-by-line breakdown.
Insurance, warranty and who pays
Lithium conversions are owner-paid upgrades. Before you buy batteries, call your insurer: some ask for documentation that the installation follows ABYC E-13, or that it was done by a qualified installer. You'll get a written design and a fixed price before work starts, and a summary of the installation for your insurer and future surveys.
What's included
- Energy audit and bank sizing
- LiFePO4 battery installation and secure mounting
- BMS integration and disconnect planning
- DC-DC charger or alternator regulator
- Charger and solar profile reprogramming
- Class-T or appropriate main fusing
- Battery monitor installation
- Installation summary for insurer
DIY vs cheap fix vs proper lithium conversion
| Factor | DIY | Cheap operator | Proper marine work |
|---|---|---|---|
| Approach | Drop-in battery swap | Batteries + new charger | Whole charging system designed for lithium |
| Alternator | Unchanged | Unchanged | DC-DC charger or regulated alternator |
| BMS disconnect | Not considered | Not considered | Planned for, alternator protected |
| Fusing | Existing fuse | ANL fuse | Fusing rated for lithium fault current |
| Insurance | Undocumented | Invoice only | Documented to ABYC E-13 |