Thread: lithium ?
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Old 10-19-2019, 05:47 AM   #8
twistedtree's Avatar
City: Gloucester, MA
Join Date: Jan 2013
Posts: 6,181
I hate to nit pick, but on a boat you would (should) only consider LFP (LiFePO4) batteries. Other Lithium Ion variants like LiPo are too volatile to be safe on a boat where you can't easily get away from it in the event of a problem. So if you are considering Lithium-Ion batteries, only consider LFP.

Setting the economics aside, thee are two huge operational benefits to LFP on a power cruising boat.

First is that you don't need to worry about when you last brought you batteries up to full charge, and whether you really got them all the way to full charge. This is the obsession of LAx battery operation, and it just doesn't matter with LFP. So instead of always thinking about managing your battery charge level, you can just focus on boating. To me, this is a huge improvement in daily operation of the boat.

Second is that the dreaded "absorption" phase of charging is non-existant. So instead of having a 2 to 3 to 4 hr tail on charging your batteries, something that really sucks when you are at anchor, LFP batteries will accept full charge current right up until they are full.

I have LFP batteries deployed in an off-grid house as a trial in advance to putting them in my boat, and I love them. They are worth every penny. Off solar, they are fully charged much sooner each day, leaving lots of solar power to run other things during daylight. And when the generator does run, my recharge time has gone from 7 hrs down to 2:30. They run cool, don't off gas explosive hydrogen, aren't full of acid that will burn you and everything around it, and aren't full of toxic lead. And depending on how you go about, cost per usable Ah or kWh of power is as low 1.5x the cost of quality AGMs.

I don't think I'll ever use a LA house battery again.
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