12V 100Ah LiFePO₄ Battery Review: The Best Switch I’ve Made for My Boat

If you’ve ever hauled one of those old, heavy marine batteries out to your boat and worried it wouldn’t last the day, you’ll know exactly why I started looking for something better. Not too long ago, I decided to upgrade to a 12V 100Ah LiFePO₄ battery for my trolling motor, and honestly, I haven’t looked back since.

What immediately jumped out at me was the weight—this thing is seriously light. My old battery felt like a gym workout every time I moved it, but the LiFePO₄ battery is about half the weight. I was almost suspicious when I first picked it up! It makes loading and unloading the boat so much easier, especially after a long day on the water.

The real difference, though, comes once you’re actually using it. With my old lead-acid battery, I’d start the day at full power, but by the afternoon, my trolling motor would start slowing down. It was always a gamble—would I make it back to the dock, or would I be paddling? The LiFePO₄ battery keeps a steady, strong output all day. Even late in the afternoon, I’m still getting the same power as when I launched.

Another thing I like? No maintenance. With my old battery, it was always recommended to check the water levels and watch for corrosion—honestly, I never really kept up with all that (and I’m guessing I’m not the only one). With this lithium battery, that stuff just isn’t an issue at all. Plus, the built-in BMS (battery management system) means I don’t worry about overcharging or draining it too far—it takes care of itself.

If you’re wondering about lifespan, here’s what I found: lead-acid batteries are known for not lasting as long as you’d hope, especially if they get drained down a lot. This LiFePO₄ battery is supposed to last for several thousand cycles, which is way more than you typically get from a regular marine battery. I haven’t had it long enough to test those limits myself, but so far it’s been dependable every time I’ve used it.

Now, a quick heads up: you can’t just use any charger with these. I picked up a 12V 20A LiFePO₄ charger that’s made for these batteries. If you use your old lead-acid charger, it might not charge properly or could even damage your new battery, so it’s worth grabbing the right charger from the start.

Also, for camping trips, it works great for running lights, small accessories, and keeping everyone’s phones charged. I haven’t tried it with a solar setup myself, but I’ve read a lot of good things from others using it for that. If you go that route, just double-check your solar controller is compatible with lithium batteries.

A couple common questions I get:

Can you use this for a car or outboard motor? No—this isn’t a starter battery. It’s meant for deep-cycle use, so it’s great for things that run over a long period, like trolling motors and RV electronics, but not for starting engines.
Will my alternator charge it? Sometimes. Some newer alternators are fine, but always check if yours puts out the right voltage (14.2–14.6V is the sweet spot for lithium).

If you want to check out the exact products I use, here are the links:
Battery: 12V 100Ah LiFePO₄ Deep Cycle Battery on Amazon
Charger: 12V 20A LiFePO₄ Battery Charger on Amazon

Bottom line: This battery has made my time on the water so much less stressful. I get more time fishing and less time worrying if my battery’s going to quit on me. If you’re tired of messing with heavy, finicky old batteries, this upgrade is absolutely worth considering.

If you have questions about how it’s working for me, or want to share your own experience, leave a comment below