battery question

leeelson
leeelson Registered Users Posts: 18 ✭
in Off Grid Solar & Battery Systems #1
I'm using Centennial CB4D gel batteries in a hybrid, grid tied solar installation (Xantrex 6048). At night I can either use batteries or the grid. The utility charges a small amount for use at night (about $3/month). I want to determine whether it is cost effective to use batteries at night. To do this, I need to know how much deep cycling decreases the average life of a battery, and what the typical battery life is.

Any help is appreciated.
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #2
    Re: battery question

    Thats easy. $3 per day is a bargain, jump at it.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: battery question
    zoneblue wrote: »
    Thats easy. $3 per day is a bargain, jump at it.

    Yup.
    Compare the utility per kW hour cost to the off-grid production cost and it is a big, big difference almost everywhere in the world.

    Most gel batteries are not suitable for deep cycle use. A few are. As such they won't 'like' cycling anyway. If the maker provided data regarding cycle life to depth then they may be okay, but it's sometimes hard to get that data even for batteries meant to be used that way.

    You can't really express things as "average life of battery" or "typical battery life" because there are so many different batteries even within one type (FLA, AGM, GEL, etc) and so many different usages (each system is unique).

    One constant: deeper cycle depth = shorter cycle life.

    Without knowing the specs on the particular battery and what your overnight discharge depth would be it's impractical to try and estimate an effect on battery life.

    But it's about 99% certain to be more expensive than $3 per month.
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