Battery wiring

babernathy
babernathy Registered Users Posts: 1
in Off Grid Solar & Battery Systems #1
I’ve got 8 6V 225Ah batteries wired in series to power my 48V water pump system. Can I boost my system capacity to 48V 450 Ah by adding a set of 2 6V 225Ah batteries (wired in series) in parallel to my existing bank of 8 batteries?

Thanks
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    Re: Battery wiring

    you would get 54V 225Ah...
    edit: oops, missed the parallel word... my bad

    change to: you would get 54V 225Ah... if all in series
     
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Battery wiring

    Welcome to the forum.
    babernathy wrote: »
    I’ve got 8 6V 225Ah batteries wired in series to power my 48V water pump system. Can I boost my system capacity to 48V 450 Ah by adding a set of 2 6V 225Ah batteries (wired in series) in parallel to my existing bank of 8 batteries?

    Thanks

    :confused:
    Putting a string of two 6 Volt batteries (12 Volts) in parallel with a string of eight 6 Volt batteries (48 Volts)?
    That would fry the 12 Volt battery string.

    To boost the bank to 450 Amp hours @ 48 Volts you need another eight of the same battery.
    Do not mix battery types/capacities/Voltages/ages/conditions. All bad.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Battery wiring

    in addition to what coot said it will also fry the 48v bank because that bank will keep unloading its power into the smaller bank which will fry.

    when paralleling batteries they have to be identical to each other. this means that if you were to have for instance 8 6v 220a batteries of brand abc in series that the next string to be added in parallel should be exactly the same right down to the brand and model number and this should be done within a year or so for batteries that are not heavily used or abused. this is because an aged or abused battery, even if the same make and model, will be different than that same battery when new.

    so why do this so exactingly? it's because when batteries are different that charging and discharging will be different for the batteries and when one battery or group of batteries does most of the work then it/they will fail sooner than the others.
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