Btry Longevity Problem

Hi Everyone,

I need advice on how to get more life out of every re-charge for my trolling motor. My set up is a 80 lbs transom mounted Minn Kota (2 years old, on 3 year old btrys) on an Alumacraft Dominator 175 CS boat. I have two on-board 12-volt batteries that run the trolling motor.

The problem is that at most I get 2 hours of trolling motor time out of the btrys, at a variety of thrust (mostly 50 – 70%). I feel this is below average longevity from what I hear other people say they get.

I did have the batteries checked, and after charging they are at 12-volts. But how do I know how long the batteries should last? I would hate to go out and buy new batteries and get the same performance. These are international batteries.

I did call Minn Kota and learned that the current drain at max on this motor is about 40% more than the equivalent 70 lbs version so maybe that is part of the problem.

Any comments would be great.

Thanks!

What size batts and is this a 24 volt system? Does the Minnkota have the maximizer system on it?

My guess is a bad battery, full charge should yeild 13+ volts. Have them load tested. I use mine daily and get 3-5 years out of a set and with good batterys never ran out of power in a full days fishing. Good onboard charging system also helps batterys last longer. Plug it in whenever your not fishing.

After rereading your post are these deep cycle batterys??

What batterys do you have?

Deep cycle?

CCA?

Reserve Time?

Charger?

Amps of charger?

Time left on charger?

Jon, thanks for your reply. I’ll do my best to respond accurately. These are 12-volt batteries that together make a 24 volt system. Is there a different way to measure battery size?
Also, I dont know what the maximizer system is?

Thanks!

Shaley and Chuck, thanks for your replies! I’ll do my best to respond.
I’ve been told these are deep cycle 12-volt batteries (brand name International), that when together make up the 24 volt system that runs the trolling motor. I have a cranking btry for the engine, but beyond that I dont know what battery options exist. What is CCA?
I also dont know what is meant by reserve time. Is that something I look up somewhere?
You ask about charger, do you want to know what kind of on-board charger I have? It is a minn kota unit (and I pretty much do leave it plugged in whenever the boat is in the garage, which is more than it is in the water), but I dont know what is meant by amps of charge, or time left on charge. Is this something I shoudl look up in the manual?

Thanks!

Batteries come in several different size or “Groups”. On the small side are the 24 and 27 group batteries. On the big side, there are the 29 and 31 group batteries. Size does matter and the bigger the better.

So if you have 2 group 24 batteries in your 24 volt set up, they will never last as long as 2 group 31 batteries.

In addition to group size, there are reserve capacity, and amp ratings. Again, the more the better.

So, you may have a decent set of group 24 batteries that don’t last long due to size.

You may have one good battery and one not so good. The set will only be as strong as the weakest link.

If you Minnkota has speed setting like 1-2-3-4-5 rather and infinite variable, the motor will draw essentially as much power at a 2 or 3 setting as the highest setting or 5. All variable motors come with a maximize system that draw only the power needed to run the motor at the setting selected.

As mentioned, a fully charged battery will generally test out at 13+ volts. At 12 volts fully charged, they may be on their last legs.

Personally, I would not go any lower than a group 29 battery in a 24 volt system.

You want to invest in a decent battery charger. One that will turn off when the batteries are fully charged.

-J.

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If you Minnkota has speed setting like 1-2-3-4-5 rather and infinite variable, the motor will draw essentially as much power at a 2 or 3 setting as the highest setting or 5. All variable motors come with a maximize system that draw only the power needed to run the motor at the setting selected.

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Minnekota motors will draw somewhat equally to the number you have the trolling motor set at. What I mean by that is that if you are running at a setting of 10 on your trolling motor you would be drawing 40 amps (or whatever the max of your particular motor is), at a setting of 5 you would be drawing 20 amps. They said it’s a fairly linear line as far as speed setting to amp draw.

My PD65 draws 40 amps max from what I was told…..with auto and co-pilot adding a small amount more draw (.5 amps each I think).

So, based on that I can figure that at a speeding setting between 6-7 on my PD65 I should be drawing about 25 amps. Since reserve capacity is based on 25 amps, I can figure that any particular reserve capacity on a battery would be how long it will last using 6-7 power setting on my trolling motor. This time would obviously be x2 for a 24v system.

The reserve capacity of the Interstate SRM-29 is 210min (420 min since I have two of them). So, theoretically I should get about 7 hours usage at speeding setting of 6-7.

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If you Minnkota has speed setting like 1-2-3-4-5 rather and infinite variable, the motor will draw essentially as much power at a 2 or 3 setting as the highest setting or 5. All variable motors come with a maximize system that draw only the power needed to run the motor at the setting selected.

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Minnekota motors will draw somewhat equally to the number you have the trolling motor set at. What I mean by that is that if you are running at a setting of 10 on your trolling motor you would be drawing 40 amps (or whatever the max of your particular motor is), at a setting of 5 you would be drawing 20 amps. They said it’s a fairly linear line as far as power setting to amp draw.

My PD65 draws 40 amps max from what I was told…..with auto and co-pilot adding a small amount more draw (.5 amps each I think).

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They will with the maximizer.

-J.

The Powerdrive 65 V2 with digital maximizer will pull 40 amps at a speed setting of 10. It will draw around 7 amps at the lowest setting.

So, it does not draw the same power at all settings…..at least based on what Minn Kota says.

Re-read my original post. I’m referring to older Minnkota’s with individual speed settings. (No maximizer) They essentially pull the same amps on speed 1 as on 5. Your motor has an infinate speed setting.

-J.

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Re-read my original post. I’m referring to older Minnkota’s with individual speed settings. (No maximizer) They essentially pull the same amps on speed 1 as on 5. Your motor has an infinate speed setting.

-J.

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Sorry…I misread your original post, but that still does not change what I am saying. The older trolling motors draw different amps at different speeds…..drawing the max amount of power at a full.

You are saying that a 36 lb thrust motor with settings 1-2-3-4-5 will last as long at 5 as it will at 1? That does not make sense and still does not follow what Minn Kota says. I don’t know how you can turn an electric motor at different speeds without changing the amount of power required.

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Re-read my original post. I’m referring to older Minnkota’s with individual speed settings. (No maximizer) They essentially pull the same amps on speed 1 as on 5. Your motor has an infinate speed setting.

-J.

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Sorry…I misread your original post, but that still does not change what I am saying. The older trolling motors draw different amps at different speeds…..drawing the max amount of power at a full.

You are saying that a 36 lb thrust motor with settings 1-2-3-4-5 will last as long at 5 as it will at 1? That does not make sense and still does not follow what Minn Kota says. I don’t know how you can turn an electric motor at different speeds without changing the amount of power required.

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What Jon said is correct. I don’t remember exactly how it worked (I am electrically stupid) on the older motors that didn’t have infinite adjustable speed. It drew the same all the time and adjusted the speed through resistance or something like that. I had one of those older motors and know from experience it would last the same amount of time regardless of what speed I ran it on.

I stand corrected.

Trolling motors without maximizer technology as Jon mentioned do not vary in power draw as they divert the extra power to a speed coil on the lower unit which heats up and heat is dissipated by the lower unit being in the water.

It turns out Minn Kota customer service provided me with info that was not accurate. This would have been good to know a couple years ago…..would have made it to the duck blind quicker!