I recently upgraded to a lithium battery on the trolling motor. Works great, less weight, all that jazz. This is more of a PSA…. Unless you have a Bluetooth battery that you can track discharge on, your trolling motor battery tester will say 100% till it’s completely dead. I didn’t drain the battery yesterday but used the snot out of it and kept hitting the button to see what was left. 100% all day till the end. Then it dawned on me how these batteries work, they discharge 100% till they are almost 0%. Your trolling motor battery tester is more than likely not designed to test lithium batteries. Long story short, you probably need to change it.
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Great topic!
I’d add that if you get a “budget” lithium battery that does not have a built-in BMS (battery management system) to take the savings and spend it on a basic BMS from Victron. Or similar. There are two things you don’t want to do to a lithium battery.
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Let it go under about a 20% SOC (state of charge) this can damage the battery long term
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“Over charge” it be bringing it to 100% SOC after every use. Then letting it sit idle with a 100% charge for weeks on end. This too can damage the battery long term and reduce its shelf life. If you have an Apple product you may have noticed in recent years they don’t recharge their iPhones or MacBooks back to 100%. The built-in intelligence typically recharges only to about 90%.
My normal routine is to only recharge my Epoch lithium battery the night before I go fishing. And only if the battery SOC is 50% or less. I usually get 1-2 trips out of a charge before I decide to recharge it.
Cheers!
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I presume these can be used for any lithium battery? (The website mentions that it was designed for Victron Energy Lithium NG batteries).
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Good catch, I linked to the wrong section.
Does your typical onboard charger charge lithiums? Or do you need a special charger for them?
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I’m going to give a short, then long answer.
No & it depends.
When you say “typical” that has a broad meaning. I would say your typical onboard charger that’s designed strictly for flooded technology then no. (Flooded, AGM, etc…) But these days many typical onboard chargers can be purchased with a lithium charging option. This is a really good read (minus the buy our brand marketing blah blah blah) on the typical differences.
This is the biggest difference in a short answer.
A lithium battery charger works similarly, except that it has a higher voltage per cell and a more narrow voltage tolerance. Additionally, a lithium battery does not have a trickle charge when it is at full charge.
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That’s what I suspected, thanks!
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You can also simply install a shunt on the negative terminal of the battery attached to a cheap battery monitor. It will let you know the state of the battery charge at all times. I was going to hook one up to mine but I really have no need for it, my alternator charges my batteries when I am running and I occasionally plug it in at the house.