Adding third battery to an existing 24 volt trolling motor system

[salmicropterus]

I have heard this can be done to help sustain a hard day's fishing. I can't find any good wiring maps or information on it. Anyone familar with this kind of set up? My system is a Minn-Kota 74 with two 12 volt batteries and a seperate main battery for starter and accessories

[Team_Dougherty]

You can not add a third battery to a 24V trolling motor setup to extend run time. If you hook it in series you would have 36V and would blow your motor. You could only hook it in Parallel to one battery. This way you would still have 24V but the two batteries, in parallel, would then become one big battery and the single battery would drain faster than the two in parallel there by not extending your run time.

You can add two batteries to your system to extend your run time. You can hook each pair in parallel then connect those pairs in series to double your run time.

[salmicropterus]

You can not add a third battery to a 24V trolling motor setup to extend run time. If you hook it in series you would have 36V and would blow your motor. You could only hook it in Parallel to one battery. This way you would still have 24V but the two batteries, in parallel, would then become one big battery and the single battery would drain faster than the two in parallel there by not extending your run time.

You can add two batteries to your system to extend your run time. You can hook each pair in parallel then connect those pairs in series to double your run time.

Thanks but a question-in an older KVD book he makes mention of doing this but he includes the starter battery as one of the batteries in the four battery system. I had wanted to keep the starter/accessory battery seperate from the TM system. What would be the negatives of doing it that way? Thanks again and I appreciate the help

[jim payne]

As mentioned before you can add two batteries one to each side of the motor and you can get double the run time. Are you running two trolling batteries and one starting battery now or are you using the starting battery as the two for the trolling motor?

[jim payne]

Opps sorry re read your post and you are running three batteries. What you probably read from KVD deal was they added one extra battery and used the start battery as the fourth. You can do that but you take the chance of being stuck on the lake with a dead starting battery.

[salmicropterus]

Opps sorry re read your post and you are running three batteries. What you probably read from KVD deal was they added one extra battery and used the start battery as the fourth. You can do that but you take the chance of being stuck on the lake with a dead starting battery.

Thanks for your response. That is right and that was my concern. I wanted to keep the two systems seperate. I don't know where I'd find the room for two extras-one yes but two doubtful plus that is a lot of extra weight

[Way2slow]

If you have the room, you can add two batteries, one on each battery, in parallel with each of the TM batteries.

You didn't say what size/capacity batteries you have now. You may just need to increase the size battery you're using. A quality group 24 is approx 80Ah, a 27 is approx 105Ah and a 30/31 is approx 120Ah. Notice I said quality, with some of the cheap batteries you can get, there's not telling what you might have.

Now, If you have group 27's and they are good batteries, giving you 105Ah and you are running your TM a 15 amps that "could" give approx 7 hours of run time. If you added a small 50Ah battery in parallel to each, that would give you approx 155Ah, which at 15 amps could give you approx 10 hours of run time.

What ever you did with one battery, you would have to do the same identical thing to the other, or you would have the equivelant of one big battery and one little battery in series which would damage the little battery.

[jim payne]

What type of outboard and size are you running?

[salmicropterus]

If you have the room, you can add two batteries, one on each battery, in parallel with each of the TM batteries.

You didn't say what size/capacity batteries you have now. You may just need to increase the size battery you're using. A quality group 24 is approx 80Ah, a 27 is approx 105Ah and a 30/31 is approx 120Ah. Notice I said quality, with some of the cheap batteries you can get, there's not telling what you might have.

Now, If you have group 27's and they are good batteries, giving you 105Ah and you are running your TM a 15 amps that "could" give approx 7 hours of run time. If you added a small 50Ah battery in parallel to each, that would give you approx 155Ah, which at 15 amps could give you approx 10 hours of run time.

What ever you did with one battery, you would have to do the same identical thing to the other, or you would have the equivelant of one big battery and one little battery in series which would damage the little battery.

I have Deka 27s. They have been pretty good but in all the wind we have been having I am finding myself "conserving" the batteries to make till weigh-in time, which I hate. I know the answer is ultimately to go to a 101/36 volt system but don't have the bank to get that done right now. The idea to add the two smaller batts is a good one if executed the way you said

[salmicropterus]

What type of outboard and size are you running?

225 Optipopper with a separate Deka 27 starter battery 1000 cca

[Jig Man]

I definitely would not include my starting battery on an Optimax.  It takes a lot of juice to crank them on cold days.

[TommyBass]

Seems like alot of work to put in two parallel sets... unless you are really running through that much battery a day.  If you were going to do that 4 battery approach you could just as easily take two extras and just replace the other two when they run down.

[Way2slow]

The last thing I would want to do is be wrestling with 60 lb batteries in and out of a battery compartment.

The Deka's are as good as you can get, I'm suprised to see someone on here beside me runs them.  Are your's the DC27's, the flooded cell deep cycle's.  If so, that's part of your problem.  While they are great batteries, they are only 90Ah batteries.  If they are the DP27's they are only 80Ah batteries.   If you went to their DC31's, they would give you 105Ah. 

Now, with all that said, it sounds like you're pretty heavily Tourny Fishing and I would have gone with a different battery.  The Trojan SCS225 gives you 130Ah capacity, that's the equiv of adding another battery in parallel to the ones you have.   If you decide to change, shop around, you can find them from $125 - $225.

Also, if you're running down the batteries you have now, DO NOT let anyone talk you into AGM,s like the Optima's etc.  They will give you even less run time than you are getting now.  Those that say they don't run down, are not using them as hard as you are.  They last a longer life, but they will not give you as much runtime.  Check out the Amp hour (Ah) capacity on any of them and you will see.  There is nothing magic about them, Ah is what determines run time, period.  If you can find the Ah, check the Reserve minutes, that's you second best indicator.  That's how many minutes the battery will last with a 25 amp load.  Just because it's an AGM, versis a Flooded cell (wet cell), the AGM can't make magic.  Minutes are minutes.

[salmicropterus]

This is all good stuff and thanks to everyone including thosewho PMed me. The Dekas have been good but when you are leaning on the TM in hydrilla and 20mph winds, they poop out too soon. It's the Amp hour deal. The 27s are a pretty tight fit in the Triton and I don't know how I could jam in another two batteries plus that's a lot of weight. I think the upgraqde just mentioned is probably the best course of action.  Jigman is right, I have a 1000 A cca starter battery and on a cold morning it can sound sick back there