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suggested battery size in Ah for 36v Minn Kota (50amp draw) on older 21ft center console

Capt Miles

New member
I am awaiting a 112lb, 36v Terrova model Minn Kota to arrive. Meanwhile I am prepping out the boat. I fish a lot on a 1984 Mako 21B on the ocean. Boats of this age are heavier than more current boats so I kept that in mind when I ordered the 112lb model. I am hoping to stay in position without using my anchor for as long as possible. 6-8 hrs would be great.

Anyways, I'm hoping that someone with a similar sized trolling motor could assist me with what size 12V batteries they used to maximise time on the trolling motor. I see the recommendations of at least 100Ah batteries but I'm thinking I need greater. I'm looking at 120Ah and 150Ah batteries but the 150Ah batteries start to get up there in size.

Also, does anyone have any thoughts on the Lithium batteries? Cost is large but does % of use vs wet cell warrant the increase in price and the idiosyncrasies of lithium?

Also, any suggestions on which battery maker to go with or stay away from would also be appreciated.

Thanks in advance for any input.
 
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I run 2 deep cycle group 24's for my 24v 70# due to space limitations. Your draw is roughly 8 amps more on the 112 at 36v. We can troll/hold all day in the upper Niagara at low to moderate speed settings. What it comes down to though is space/weight limitations, and what kinds of currents and wind you are dealing with.

If you have the capacity for 3 group 31's, I wouldn't hesitate to run with those. 27's at a minimum. Run time varies widely depending on boat load, wind, currents, motor speed setting, etc. Deka batteries are pretty popular, a decent Deka deep cycle 31 should give you 105 ah or so. I run Interstates simply because I know the dealer near me, and have good luck with those.

I can't comment on the lithium as I have no experience with them for trolling.
Most important, check electrolyte levels frequently on the wet cells and charge every night.
 
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I run 2 deep cycle group 24's for my 24v 70# due to space limitations. Your draw is roughly 8 amps more on the 112 at 36v. We can troll/hold all day in the upper Niagara at low to moderate speed settings. What it comes down to though is space/weight limitations, and what kinds of currents and wind you are dealing with.

If you have the capacity for 3 group 31's, I wouldn't hesitate to run with those. 27's at a minimum. Run time varies widely depending on boat load, wind, currents, motor speed setting, etc. Deka batteries are pretty popular, a decent Deka deep cycle 31 should give you 105 ah or so. I run Interstates simply because I know the dealer near me, and have good luck with those.

I can't comment on the lithium as I have no experience with them for trolling.
Most important, check electrolyte levels frequently on the wet cells and charge every night.

I think this is where I post my reply. Just figuring out this site. Jay, thanks for your reply. I am definitely going with 3 31's with at least 100Ah each. More likely 120-125Ah each. I fish a variety of conditions from no wind and/or current to strong wind and/or current. (3-4 MPH current and/or 15mph wind) I'm trying to get a feel for just how long I might expect the batteries to last. I was glad to hear that you run a 70lb of thrust motor all day on a 24v system at low to moderate amperage. That is helpful for me to know. I would also like to go with the product the local battery dealer keeps in stock unless someone speaks up against a certain brand. Due to where they are going to be mounted I will be going with a sealed wet cell (AGM) because checking the electrolyte every night would be too awkward. I have the same issue with my starting batteries so I go exclusively with sealed batteries. Hopefully someone else will weigh in with their experiences with a 36v system and a boat similar to mine. thanks again. Miles
 
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