What Type of Battery Is Best for a Boat?

There are many different battery options for a boat, from deep cycle lead-acid to AGM or newer lithium iron phosphate. While some lithium models are still more expensive than traditional variants of lead-acid batteries, they have some significant advantages, like their longer lifespan, which will more than pay for themselves many times over. 

Let’s dive in and explore the different types of batteries, their pros and cons, and the different factors you should consider when choosing which one is right for you.

What To Consider When Choosing a Battery for Your Boat

Battery Chemistry

Traditional Lead-Acid

Traditional lead-acid batteries are not a good option. While they are cheap to buy, they have a poor depth of discharge and require a lot of maintenance. On a boat, you need to be able to use it for extended periods, which can drain it and leave you stranded. 

Since they have a high self-discharge rate and cannot be discharged completely, if you discharge them too much, you will need to replace them too quickly, eliminating those initial savings. 

Deep Cycle Lead Acid Marine Batteries

A deep-cycle lead-acid model overcomes the shortcomings of traditional lead-acid batteries, which cannot be discharged past 50% of their capacity. Deep-cycle models do not have that issue. 

However, they still only have limited charge cycles, typically lasting only a couple of years before they need to be replaced. They also weigh a lot, making your boat less fuel-efficient, and are prone to leakage if tipped over.   

AGM

The absorbent glass matt (AGM) also utilises lead-acid chemistry. It is similar to deep-cycle lead-acid in that it has a lower self-discharge rate and lasts longer than traditional models. The difference is it handles vibrations better and is not prone to leaking. However, it weighs even more than its counterparts and still must be replaced every few years.

Lithium Iron Phosphate

Lithium Iron Phosphate, or LiFePO4, is a newer model with several advantages. They have the best depth of discharge, reaching nearly 100%, they are much lighter in weight, and perhaps most importantly, they will last for 10 – 20 years. They also work great in cold and heat and are not prone to thermal runaway like their predecessors, the lithium-ion batteries. 

The disadvantage is they may cost a bit more than lead-acid. However, the cost is dropping every year. When you factor in their significantly longer lifespan, that extra upfront expense will pay for itself since you may need to replace your lead-acid model five times before replacing your LiFePO4 once. 

LiFePO4 is the same as most modern, high-quality solar generators, like the EcoFlow DELTA 2 MAX. These generators provide versatile options for powering electronic devices, appliances, and anything else you want to bring on your boat. 

You can even recharge them and your boat’s solar battery using solar panels for extended trips at sea. The EcoFlow DELTA 2 Max Solar Generator (PV400W) comes with its own 400W solar panel. 

There’s another high-performance LFP marine battery option for boating enthusiasts.

EcoFlow’s new 12V 100Ah Lithium Trolling Motor Battery offers fast solar panel charging* and 6,000 cycles (charges/discharges) before its capacity decreases to +/- 80%.

Speaking of solar, you can stay SunSmart and charge your phone at the same time with EcoFlow Power Hat.

Maintenance and Safety

All lead-acid batteries require maintenance to keep them in top condition and extend their lifespan. This may include topping up fluids, using a trickle charger when not in use for extended periods, and careful storage considerations since they can be prone to leaking and off-gassing toxins. LiFePO4 requires no maintenance and presents no such safety issues. This is one reason why houseboats use LiFePO4 solar generators. 

Battery Size and Weight

Depending on the size of your boat and how much gear you carry, size and weight can be a significant factor. All lead-acid models weigh a lot and take up a lot of space for their capacity. Switching to LiFePO4 can reduce the battery weight by as much as 70%, and since they have a better charge density, they pack much more power into a smaller size. 

It means you can get a lighter, smaller battery that will still start your boat and run it continuously. Smaller lead-acid may not have enough power to start your motor. 

Another generator option is the EcoFlow Smart Generator, which runs on petrol or propane gas. This provides versatile options for those already carrying additional fuel. 

A final option to consider is an EcoFlow Delta Pro + 800W Alternator Charger. This portable power station can be charged with the alternator charger you put on your boat to charge while the engine is running. It has plenty of capacity for a large ship with many electronic devices, and you won’t risk draining your boat’s batteries. 

Durability

You want a battery that will work in cold and heat and will not be prone to reducing its lifespan if it is discharged too much. LiFePO4 wins hands down in that category. 

Frequently Asked Questions

Final Thoughts

Boating is an exciting adventure we all love, but nothing is worse than having a battery die on you because it was improperly maintained, reducing its lifespan. Lithium marine batteries are the best choice all around: they are durable, lightweight, safe, and require no maintenance. 

In fact, LiFePO4 models are the choice in high-quality solar generators, like the EcoFlow DELTA 2 Max Solar Generator (PV400W). You can bring it on your boat to power your electronic devices, saving your lithium marine batteries for running your boat; you can even use it to recharge your marine batteries. And its 400W solar panel means you can recharge it on the water!

*Requires a Solar Charge Controller (Not Included)