Group 24 or Group 31 Batteries

[GarryB]

Which setup would provide the most run time on the water when ran at the same speed?


2 group 31 top of the line AGM batteries with a 24v Minn-Kota Ultrex or 3 group 24 top of the line AGM batteries with a 36v Ultrex?

[103817]

Originally Posted by GarryB

Which setup would provide the most run time on the water when ran at the same speed?


2 group 31 top of the line AGM batteries with a 24v Minn-Kota Ultrex or 3 group 24 top of the line AGM batteries with a 36v Ultrex?

Minn Kota does not publish their actual amp draw numbers (at partial throttle) required to answer your question. For example, you would need the actual amp draw on each motor at say 50 pounds of thrust.

[Lmbkiller]

Get the 36v and a lithium 36v battery and u win

[Ltrain]

Originally Posted by GarryB

Which setup would provide the most run time on the water when ran at the same speed?


2 group 31 top of the line AGM batteries with a 24v Minn-Kota Ultrex or 3 group 24 top of the line AGM batteries with a 36v Ultrex?

Well if you're buying a 36v motor you should run the best batteries you can afford. Group 31 would be it

Same goes for a 24v motor, I'd still go with group 31.
I wouldn't base my trolling motor purchase off what size battery i could get, rather id base my battery purchase off what size troling motor i have and how much room in the boat i have.
The only thing that would stop me from installing group31 batteries for any motor i have would be if they physically wouldn't fit in the battery location.

I don't know if that really answers your question but that's my take
.
Btw i run 5 group 31 batteries on my boat. They are regular lead acid, as I couldn't spring for AGM at the time. I am hoping when its time to renew in a couple years I am in a position to get the 31 AGM

[Wall-i-Lama]

Originally Posted by ltrain

Well if you're buying a 36v motor you should run the best batteries you can afford. Group 31 would be it

Same goes for a 24v motor, I'd still go with group 31.
I wouldn't base my trolling motor purchase off what size battery i could get, rather id base my battery purchase off what size troling motor i have and how much room in the boat i have.
The only thing that would stop me from installing group31 batteries for any motor i have would be if they physically wouldn't fit in the battery location.

I don't know if that really answers your question but that's my take
.
Btw i run 5 group 31 batteries on my boat. They are regular lead acid, as I couldn't spring for AGM at the time. I am hoping when its time to renew in a couple years I am in a position to get the 31 AGM

X2.

[GarryB]

Yes, space is the issue. I should have said that in my original post. My battery compartment has room for 2 group 31 or 3 group 24 batteries.


If both the 24v and the 36v trolling motor are run a full speed, which sytem would run the longest.


Thanks

[DW]

Originally Posted by GarryB

Yes, space is the issue. I should have said that in my original post. My battery compartment has room for 2 group 31 or 3 group 24 batteries.


If both the 24v and the 36v trolling motor are run a full speed, which sytem would run the longest.


Thanks

The winner is the 24v and two group 31s.

A group 31 typically has 100 amps capacity; a group 24 typically 80 amps. MK rates a 24v with 56 max amp draw and the 36v with 52 amp draw.

Therefore, at full speed the 36v with group 24 is 80/56 = 1.4 hours

the 24v with group 31 is 100/52 = 1.9 hours

Assuming draw is discontinued at 50% depth of discharge actual time is half of the above.

MK does not provide data for demand at partial power. As power is reduced with equal level of the thrust, the 36v system will out last the 24v system below some point of equal thrust. However there isnt enough information provided by MK to calculate the crossover amount of thrust to calculate that point.

The other variable is that as power and draw is reduced, more amps can be drawn from a battery.

[Ltrain]

Originally Posted by DW

The winner is the 24v and two group 31s.

A group 31 typically has 100 amps capacity; a group 24 typically 80 amps. MK rates a 24v with 56 max amp draw and the 36v with 52 amp draw.

Therefore, at full speed the 36v with group 24 is 80/56 = 1.4 hours

the 24v with group 31 is 100/52 = 1.9 hours

Assuming draw is discontinued at 50% depth of discharge actual time is half of the above.

MK does not provide data for demand at partial power. As power is reduced with equal level of the thrust, the 36v system will out last the 24v system below some point of equal thrust. However there isnt enough information provided by MK to calculate the crossover amount of thrust to calculate that point.

The other variable is that as power and draw is reduced, more amps can be drawn from a battery.

No problem with the math, yes the 24v( gr 31) a wot will last longer than the 32v (gr 24) at wot. But the 36v does alot more work at wot and that's not how you would measure real world productivity. For example if it takes your 24v 80 ilb thrust motor 2/3 (66%) power to troll 2mph thats around 54lb or 34.5 amps draw. Now 54lb thrust is only taxing that 112 36v motor at a little over 48% power ,so that about 27 amp draw . So 100/34.5=2.89 hr runtime for 24v 80 lb group 31
80/27= 2.96 hr runtime for 36v 112lb group 24. Plus the advantage is you have lot more power 112 vs 80 if you really need it. The 36v motor wins out even handicapped by the small batteries.

What you should really do is find a place to put that third group 31 battery, either under console, in storage compartment, somewhere. Look what it would do with equal batteries vs 24v. 100/27= 3.7 hr runtime, almost an hour more. Now i picked these numbers for the basis of math. My 36v motor was able to troll Erie , 18.5 tyee at 1.5mph with group 29 for 8 hours.
No way you're coming close with a 24v motor.

[oldlund]

You could do 3 group 24 lithiums. https://www.cabelas.com/shop/en/trac...marine-battery. These might be better than the group 31 agms.


Sent from my iPhone using Tapatalk Pro

[Ndstallmann]

Rule of thumb in batteries weigh Equals power. So does 3 size 24 batteries weigh more the 2 size 31 ? And full speed is not the test you want to do, cause the 36 volt is going to go faster. You want to compare the same speed in the water. I don’t have the weight chart in front of me, but I would buy the setup that had the most battery weight.