Lithium batteries on boats and other equipment is becoming much more attractive to boaters. Particular attention should be paid to Lithium Iron Phosphate for boats and RV use etc. This version of lithium is the most stable. Read more about Lithium batteries on boats here.

Although the title ‘Lithium Batteries on Boats’ mentions boats, the content can easily transfer to recreational vehicles and caravans too. The research I did on this subject was based around my wanting to update, in the future, my boat’s aging leisure bank. My current bank consists of Trojan T105’s that are now more than 10 years old and still going strong. When they fail, I’m going to replace with Lithium Iron Phosphate, also known as LFP and LiFePO4. I’ll explain why later.

There are particularly good reasons to consider lithium batteries on boats , as opposed to lead acid. These include: –

They are lighter than Lead Acid batteries.

More usable capacity

Maintenance free

Capable of accepting high charge rate.

Long life, safety and stability.

I really was in for surprises as I researched switching from lead acid to Lithium technology. I found out very quickly that the only type of Lithium battery I can use on my boat is Lithium Iron Phosphate, LiFePO4 (also known as LFP) and variants. The reason for using this type of battery on a boat is because they are far less likely to suffer a ‘thermal event.’ No one wants a fire onboard.

Something you may not know, is that standard alternators are much better suited to lead acid technology than Lithium. The reason for this is that as a lead acid battery receives power from the alternator and charges, it develops a resistance that reduces the output of the alternator. This prevents the alternator from overheating and damaging itself. Lithium, however, offers little resistance.

This results in the alternator pouring maximum current into the battery for extended periods. What can happen, apart from alternator damage through overheating, is that when the Lithium battery is 100% charged its management system stops accepting charge instantly. When this happens, the elevated level of current provided by the alternator has nowhere to go! This will inevitably cause damage to the alternators internal diodes and could destroy the alternator along with parts of your electrical system. There is an easy solution that we can discuss shortly.

Lithium batteries need a battery management system to operate, these can be external, or you can purchase batteries that have their own BMS built in. This is the same system that will slam the door on alternator output when the battery is full.

An uncomplicated way to avoid the damage.

The easy solution mentioned above, is to fit a Victron Argofet voltage splitter into the output of the alternator. The output from the alternator is the feed to the Victron. One of the Victron’s outputs should go directly to the lead acid starter battery, and the second output should directly feed the Lithium Iron batteries. If the battery management cuts the alternator off the starter battery will soften the load on the alternator and avoid damage.

I have named Victron simply because I have found their equipment to be first rate over the ten years that I have been using them and they have my trust, they asisst in making using Lithium batteries on boats so much easier.

A very real advantage of installing a perfectly balanced LFP system in a boat or recreational vehicle is that it gives you the possibility of completely removing the gas system used for cooking! I do not need to mention the safety value of doing that. The electrical storage density of LFP is almost 100% available for use in powering electrical cooking without damage to the batteries. Added to that, the lack of resistance in the batteries allows extremely elevated levels of charge.

The change from lead acid to LFP technology is extremely appealing. The initial investment is certainly higher, but I do believe that over time the system would pay for itself. I strongly believe that Lithium batteries on boats is the future.

As an afternote. I strongly advise that if you are considering the change over to LFP technology you should get the assistance of a reputable supplier. Remember that if you’re considering using lithium batteries on boats, cheapest is cheap for a reason!

I’m going to have to change my 10 year old leisure bank at some point and am convinced that LiFePO4 is the way to go, so I’ve been researching suitable batteries and found this one. Take a look. I usually use ebay myself because I can compare like for like performance. This 280AH unit from EcoWorthy looks very promising, great price, great reviews and brilliant performance. No need for a seperate battery management system as the battery carries its own.