Using 12 volts from a 24 volt bank?

paulskirocks
paulskirocks Solar Expert Posts: 84 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Somebody mentioned a unit that allows you to use 12 volts off of a 24 volt battery bank, while still keeping the batteries balanced, but I can't find it in my threads... Anyone recall? Thanks
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Using 12 volts from a 24 volt bank?

    DC to DC converter like this: http://www.solar-electric.com/12to24or24to.html
    (There are others; that's just the easiest one for me to reference.)
    Sometimes called "DC autotransformer" but that's a dubious description. :roll:
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #3
    Re: Using 12 volts from a 24 volt bank?
    Cariboocoot wrote: »
    DC to DC converter like this: http://www.solar-electric.com/12to24or24to.html
    (There are others; that's just the easiest one for me to reference.)
    Sometimes called "DC autotransformer" but that's a dubious description. :roll:

    Yea, I know about that, but this was something that lets you tap 12 volts off of the 24 volt bank, but not unbalance the batteries...
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: Using 12 volts from a 24 volt bank?

    I believe the RV units (I found one once, but it is not an obvious/easy search to find) are wire to do what the unit Marc linked to... See the last diagram in this app note:

    http://www.solarconverters.com/equala.htm

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Using 12 volts from a 24 volt bank?
    paulskirocks wrote: »
    Yea, I know about that, but this was something that lets you tap 12 volts off of the 24 volt bank, but not unbalance the batteries...

    Can't draw off half a battery bank and keep the whole even. The more drawn, the greater the imbalance.

    Other than the converter, there's the expensive option of separate 12 Volt battery charged from the 24 Volt bank via an MPPT charge controller.
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #6
    Re: Using 12 volts from a 24 volt bank?
    BB. wrote: »
    I believe the RV units (I found one once, but it is not an obvious/easy search to find) are wire to do what the unit Marc linked to... See the last diagram in this app note:

    http://www.solarconverters.com/equala.htm

    -Bill

    OK, thanks, I see the part about being an equalizer... That's what I wanted, afterall...


    Cariboocoot wrote: »
    Can't draw off half a battery bank and keep the whole even. The more drawn, the greater the imbalance.

    Other than the converter, there's the expensive option of separate 12 Volt battery charged from the 24 Volt bank via an MPPT charge controller.

    Supposedly the autotransformer allows you to do what I want to do, according to the manufacturer...

    Attachment not found.
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