Adding battery to my small test system

smoothisfast
smoothisfast Registered Users Posts: 16 ✭✭
in Solar Beginners Corner #1
I currently have a 12.8v 4500 mAh LFP pack made by batteryspace. It is charged by 2 15W solar panels using a LFP charge controller. I want to add another 12.8v 4500 mAh pack to the system. Would I run into issues if I connected another pack in parallel to the first pack?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Adding battery to my small test system

    i would say no to any problems unless the battery you have now has been abused or is more than a year old. paralleling to old or abused batteries with a new one will drag the new one down to the level the old one is at.
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  • smoothisfast
    smoothisfast Registered Users Posts: 16 ✭✭
    #3
    Re: Adding battery to my small test system
    niel wrote: »
    i would say no to any problems unless the battery you have now has been abused or is more than a year old. paralleling to old or abused batteries with a new one will drag the new one down to the level the old one is at.

    Instead of putting in a 2nd battery with the same amperage could I put a higher amp battery say a 9.9Ah as a 2nd battery in parallel to the 4.5Ah. Would that work?
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #4
    Re: Adding battery to my small test system
    smoothisfast wrote: »
    Instead of putting in a 2nd battery with the same amperage could I put a higher amp battery say a 9.9Ah as a 2nd battery in parallel to the 4.5Ah. Would that work?

    Do you wish to burn up your charger? While we don't know what the charger's specs are, it's output would be complicated by 2 different parallel loads, possibly summing both together for a fast death.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Adding battery to my small test system
    smoothisfast wrote: »
    Instead of putting in a 2nd battery with the same amperage could I put a higher amp battery say a 9.9Ah as a 2nd battery in parallel to the 4.5Ah. Would that work?

    Not a good idea to parallel a 4.5 Amp hour and 9.9 Amp hour battery: the charge rate would be either too high or too low for one of them, so you either chronically undercharge the 9.9 or quickly overcharge the 4.5.
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  • smoothisfast
    smoothisfast Registered Users Posts: 16 ✭✭
    #6
    Re: Adding battery to my small test system
    Cariboocoot wrote: »
    Not a good idea to parallel a 4.5 Amp hour and 9.9 Amp hour battery: the charge rate would be either too high or too low for one of them, so you either chronically undercharge the 9.9 or quickly overcharge the 4.5.

    I understand now, I'll add a 2nd battery with the same amperage in parallel.
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