Battery type

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System
System Posts: 2,511 admin
in Off Grid Solar & Battery Systems #1
I am looking for a battery that can be discharged daily in 1-2 hours and recharged (nightly). With a long life. Any ideas?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #2
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    Re: Battery type
    The above are the ones I would start looking at.

    LFP are going to be light and expensive. Need additional electronics on a "per cell" basis to keep them in their proper operating voltage range (neither too high or too low).

    Flooded Cell NiCads are the gold standard for Aircraft. May have issues with Cadmium disposal/recycling.

    AGM are probably going to be the cheapest.

    People have been pushing "super capacitors"--but I am not sure they are either cheap or long lasting. Their energy density is not very high, plus managing power over a wide voltage range complicates things too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
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    Re: Battery type

    Why are you going to do with it?

    Tony
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  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    #4
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    Re: Battery type

    David your question is to vague.. You talking an AA battery a 1000ah FLA 2v cell?And discharged in 2 hrs ? at what rate?
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  • jpistrit
    jpistrit Registered Users Posts: 11 ✭
    #5
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    Re: Battery type

    You need to think about the "discharged in 1-2h" part of this equation. There is a definate effect on battery life of rapid discharge of a battery (like you would see in a computer UPS).

    If you want your batteries to last, you only want to take half or a little more of the charge out of them in a single discharge (which means you need a larger battery than you would first think).

    As for batteries able to maintain a high discharge rate, a number of types will do that. LeadAcid batteries (starting batteries) for cars are designed for very high discharge rates, but discharging them deeply will damage them.

    AGM batteries are a reasonable choice - they can support a pretty high discharge rate, and also dont self-discharge very much.

    However if you assume you're buying a 100AH battery and taking 100AH out of it in an hour, your battery won't last very many cycles. Plan for a 50% discharge at the most and use a technology that supports a C/1 or C/2 discharge rate (C/1 means, discharge the capacity of the battery in one hour, C/2 means 2 hours, ie. half as fast as C/1, etc.)
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