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  1. #1
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    mixing batteries in 36v series

    I'm going from a 24V trolling motor to a 36V one. Last year while I was on a spring fishing trip, one of the batteries for my trolling motor went bad. I decided to just replace both batteries since I wasn't sure how old they were and didn't want the other one suddenly giving out too. I was in a small town and bought two new batteries from a Napa store. They are a no-name battery. My question is, when purchasing a new battery to go along with those other two to complete the 36V series, does it matter if they are different with regards to battery size or cranking/reserve amps? Do I need to try and buy a battery that is as close to the other two as possible? Thanks

  2. Member
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    #2
    Operationally it makes no difference. Size wise, get one close to the others. The battery with the least capacity will go down 1st. If your others are 80 amp/hour duplicate. Your system will act like the smallest battery in the system.

  3. Member
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    #3
    So if I'm understanding correctly, only the run time will be affected by this and not performance aspects like total output, right? The reason I ask is that I'm really not very concerned with total run time since I'm rarely on the water for more than 6-8 hours and am not the type of fisherman that puts the trolling motor on 70% and zips down miles of shoreline. I've never come close to running my batteries down with my 24V trolling motor unless I didn't charge them between outings, which has only happened once or twice. I'd like to get something similar to what I already have, but just wasn't sure if my 3rd battery happened to be a size 24 instead of a 29 or had a little less reserve capacity if that would just affect total run time or if it would adversely affect the power output of the trolling motor.

  4. Member
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    May 2010
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    #4
    36v is 36v....Like John said try to get same ah as current batteries.
    Jimmy
    Phoenix 721
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    28.5 Bravo

  5. Member
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    #5
    Will do...thanks for the help

  6. Member
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    #6
    The downside with unmatched batteries is when the weakest one is discharged there is still 24 volts to run the motor and the other two batteries will force current through the discharged one which destroys it rapidly. Having a voltage meter display where you can see it will help to alert you when the weak one is low much better than trying to notice you need more throttle. The deep cycling of the weak one will decrease its life dramatically.

  7. Member
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    #7
    Quote Originally Posted by Ann-Marie View Post
    The downside with unmatched batteries is when the weakest one is discharged there is still 24 volts to run the motor and the other two batteries will force current through the discharged one which destroys it rapidly. Having a voltage meter display where you can see it will help to alert you when the weak one is low much better than trying to notice you need more throttle. The deep cycling of the weak one will decrease its life dramatically.
    Thanks for that information. I'm going to try to get as close as I can to the batteries that are currently in the boat, so I don't run into problems like this.

  8. Member lpugh's Avatar
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    May 2009
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    Sacramento Ca
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    #8
    Quote Originally Posted by Ann-Marie View Post
    The downside with unmatched batteries is when the weakest one is discharged there is still 24 volts to run the motor and the other two batteries will force current through the discharged one which destroys it rapidly. Having a voltage meter display where you can see it will help to alert you when the weak one is low much better than trying to notice you need more throttle. The deep cycling of the weak one will decrease its life dramatically.
    I have seen extreme cases of this reversing the polarity of the under capacity battery
    Thank You Leon Pugh