Lithium Trolling Motor Batteries

I have a Alumacraft Competitor 205 Sport with a MinnKota Terrova 36v trolling motor. I spend most of my time running the TM casting for walleye / Muskie / Bass, do a little bit of crank trolling early in the season (Under 2mph) but looking to add a kicker motor to solve that situation. I have been running Duracell Group 31 AGM’s the past 3 seasons and noticed towards the end of last year I wasnt getting the performance out of them that I would like. ( Which is expected) I have been researching Lithiums as a direct replacement, and am getting lots of information, but not very consistent information. My first thought was I NEED to have three Brand XYZ 100ah batteries, the price tag for that is about $2100. Amped Outdoor has an 80ah Batter and the price tag would be $1700 for 3. I then ran into the Ionic 50ah batter threads on some of the forum boards. These are real intersting as the price tag for 3 is $1000 right now. My main question for those that are running Lithiums, Is 100ah overkill? Is 50ah not enough and will be regretting not getting the bigger ah? Is the 80ah Goldylocks? Just trying to get some more knowledge on this situation. FYI I reach out to a couple different companies and my current charging system will work for all the batteries I am looking at. Thanks for some info.

My understanding is LiFePO4 batteries are recommended to be discharged to 20%, discharging more will impact life of the battery. If you run 50ah LiFePO4 batteries down to 20% that would give you 40ah, if you run 100ah lead acid batteries to 50% that would give you 50ah. I don’t run LiFePO4 batteries but I think 50ah is too small.

The answer you seek is a simple math question, You need to find out how many amps your trolling motor draws at the average setting you use it at. If it draws lets say 10amps for easy math you will get 10 hours run time till the batteries are dead using the 100amp batteries. Using the 20% rule stated above that would be 8 hours run time. With a 50amp batteries that would be 5 hours run time or 4 hours if using the 20% factor. So I would start by finding out how many amps your trolling motor uses when in use to answer your question.

The other question you need to ask is do you run them in cold weather? If you do, lithium is not a good option. Below 32 degrees the performance degrades and they cannot be charged below freezing.

So, if you fish in the cold or charge in the cold it’s not a great option. I did a bunch of research and the only option is to get a warmer for them….which is just one more thing to deal with.

I run 36V, too, and wanted to get away from lead acid. Still the best option IMHO until lithium can handle cold weather.

Matt Moen wrote:

So, if you fish in the cold or charge in the cold it’s not a great option. I did a bunch of research and the only option is to get a warmer for them….which is just one more thing to deal with.

Norsk is making lithium batteries with an integrated heater core that warms the battery up to a safe charging temperature before starting the charge cycle. So maybe starting to get around the “one more thing to deal with” aspect?

bigstick56 wrote:

I have been running Duracell Group 31 AGM’s the past 3 seasons and noticed towards the end of last year I wasnt getting the performance out of them that I would like. ( Which is expected)

Is that normal for AGM battery lifespan? I thought they were supposed to last longer than a standard lead acid battery.

gim wrote:

<div class=”d4p-bbt-quote-title”>bigstick56 wrote:</div>
I have been running Duracell Group 31 AGM’s the past 3 seasons and noticed towards the end of last year I wasnt getting the performance out of them that I would like. ( Which is expected)

Is that normal for AGM battery lifespan? I thought they were supposed to last longer than a standard lead acid battery.

I haven’t personally had any kind of of wet battery in a trolling motor application be very good past 4 years….after 3 years it still worked fine, but noticed a slight decrease in performance. For my experience this is normal and expected, I could be wrong though.

Michael C. Winther wrote:

<div class=”d4p-bbt-quote-title”>Matt Moen wrote:</div>
So, if you fish in the cold or charge in the cold it’s not a great option. I did a bunch of research and the only option is to get a warmer for them….which is just one more thing to deal with.

Norsk is making lithium batteries with an integrated heater core that warms the battery up to a safe charging temperature before starting the charge cycle. So maybe starting to get around the “one more thing to deal with” aspect?

I hadn’t seen that….could be a huge help. I’ll have to look into it. Thanks for posting.