Choosing a trolling motor battery

onthewater102 said:

My how things change in 4 years.

Lithium batteries are down to less than $300 for a 50 amp-hour battery...given the weight savings alone they're attractive - ditching the issues of memory and the need for proper trickle charging to avoid sulfating is awesome...faster charge times, no capacity penalties for partial charging and a much more consistent power output curve???

I will never be buying another lead-acid or AGM trolling motor battery again.

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Agree 100%

Be nice to see the prices drop. I'm thinking by the time I need to replace my battery, the lithium 100ah will be at $150!

I put my $$$ where my mouth is (or, erm, fingers are? modern times are so confusing adapting old sayings.)

Either way - I ordered a 50amp Ampere Time LiFePO4 from Amazon after reading more reviews of different brands than I can remember. They seemed to consistently get positive comments from people using them in solar home energy systems FWIW.

We'll see how it stacks up as a trolling motor battery.

From what I read on lead-acid type battery research reports, we only get use of about 50% of a lead-acid battery's stated capacity before the voltage has dropped low enough that it will start adversely affecting the performance (digital circuits especially). If that's true then I should be getting comparable use time from the 50amp lithium as I was with my size 29 SLA's previously. Hopefully that's true.

What is definitely true out of the box is that it weighs a bit less than 15lbs instead of 61lbs which will help a lot in a little tin boat, not to mention it's so much smaller that I can tuck it in a recess at the back of the compartment which previously was filled by the big SLA battery.

The weight savings is huge. I have a grp 31 battery that is about 65#. All that weight I keep adding to the boat really starts to add up.

onthewater102 said:

From what I read on lead-acid type battery research reports, we only get use of about 50% of a lead-acid battery's stated capacity before the voltage has dropped low enough that it will start adversely affecting the performance (digital circuits especially). If that's true then I should be getting comparable use time from the 50amp lithium as I was with my size 29 SLA's previously. Hopefully that's true.

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I have read the same things, but most seem to agree that you can discharge a lead acid battery to 70-80%. Those group 29s were probably ~100ah, so that would give you 70-80ah of usable capacity. Most fisherman wouldn't use that much in a typical outing with a 24-36 volt motor, multi day camping trips or tournaments, maybe.

The big difference there being what you said, that lead acids will gradually lose voltage. Lithiums will generally stay pretty flat until they quit altogether.

I would like to make the upgrade, but my current batteries still have a couple years left. Hopefully by then lithiums will have come down in price even more. Right now they are getting close to penciling out for me, but not quite there.