A brief sum up of lithium boat battery

Solar-powered boat battery charging

Due to their ability to receive a high current bulk charge, some owners choose to charge LFP exclusively utilizing solar power.

This works, at least in locations with enough sunlight, because you can charge the battery with as much power as the solar panels will provide at their maximum output.

Additionally, it suggests that the BMS may simply replace the PV panels without causing any damage once the batteries have reached the desired SOC.

The obvious drawback of year-round traveling is the lack of sunlight throughout the winter.

In this situation, I would suggest either incorporating alternator charging using a DC-DC charger or keeping a small portable generator and an LFP mains charger on board for those brief, overcast winter days.

Major charge at 220V

In order to maintain the charging voltages within the required ranges, the majority of contemporary marine battery chargers now come equipped with a LiFePO4 charging regime.

When utilizing an LFP charger, LFP can be safely left unattended since they don’t want to be charged continuously, even in float mode.

However, you can use a conventional, single-stage Lead Acid battery charger in AGM mode if you frequently monitor the batteries’ status and shut off the charger as soon as the required SOC or peak voltage is met, definitely no higher than 14.6V–14.2V is safer.

It’s crucial to look for the automated equalization cycle, in which the charging voltage is raised to 15.5V or higher for a number of hours when utilizing a non-LFP-type shore power charger.

This needs to be turned off since if it’s on, the LFP cells will be wiped off.

Hybrid facilities

Contrary to what “experts” claimed, a hybrid Lead Acid/LFP bank is completely secure and can even provide the best of both worlds in the case of Lead Acid/LFP. For years, boaters had been advised not to combine multiple battery chemistry in a single bank.

Here, a single LFP is being used to expand the capacity of an existing Lead Acid house bank; not a 50/50 split between Lead Acid and LFP.

The essential assumption is that the Lead Acid battery maintains great physical condition while controlling the excesses of the LFP.

The LFP battery will be charged up to the pre-programmed upper voltage that set on the BMS (usually set for approximately 90% SOC), which is simply linked in parallel with the Lead Acid house bank.

The Lead Acid bank will continue its own charging at this point, and the BMS will stop permitting charges to the LFP.

When the voltage of the LFP hits 12.8V, it will naturally discharge first, and the Lead Acid will then start to generate electricity.

The bank just shuts down and allows the Lead Acid batteries run as usual once the voltage falls below the LFP’s BMS low voltage threshold.

Which Lithium battery should you select for boat?

Such a hybrid system operates on the principle of continuously topping off the LFP battery to reduce the workload on the Lead Acid batteries.

The alternator diodes are equally safe as the charge is transferred to the Lead Acid bank and the BMS is turned off.

Even though this concept has been tested and shown to work safely by a number of trained marine electricians, ISO and ABYC both indicated that mixing battery chemistry, such as Li-ion and Lead Acid, is not advised and will not be approved for certification.

Maritime insurance companies will consider the latter when drafting their coverage.

On a boat, we would only utilize LFP batteries. Other li-ion batteries in use today are just not made for marine situations.

When it comes time to upgrade, we suggest that you think about installing an LFP house battery bank because the advantages of quick charging, increased usable capacity, longer life, and the capacity to leave them partially charged for a periods of time outweigh the slight increase in initial cost and the need to modify a few charging system components.

No matter how little, we also advise implementing solar charging infrastructure because it will complement LFP cells even in the UK’s less sunny areas.

Depending on its equipment, projected electrical usage, and planned use, every boat is unique.

Before just putting a lithium battery in your boat, it is highly recommended that you get professional counsel.