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Thread: Battery Capacity calculations

  1. #21
    Join Date
    Jun 2007
    Center of Nowhere, NOR CAL

    Default Re: Battery Capacity calculations

    Well, opinions do differ on the exact max charge rate available from PV. My system calculates to be about 4% of capacity from PV. Do have generators and chargers here, that can do about 13% charge rate without any PV input. To me, if one's system reaches Float almost every day, the occasional need for 10-ish% rate can be provided by gensets and AC chargers. Some battery manufacturers recommend occasional high-rate charge (C/10), to renew plate exposure to the electrolyte, thus maintaining capacity.

    This approach works for my system with my batteries. Batteries do need more charge as they age, as they become somewhat less eficient. Will add some more PV to systems here, but this is not due to need, just doing the addition because it is fun, and can reverse even more of my previous conservation measures.

    Different battery technologies can have somewhat different needs. And, always consult the battery manufacturer's data for information on any specific battery. YMMV, Vic
    Off-Grid, Sys1: 1280 AH 48 V bat, 5.250 KW STC PV, Classic 150, WBjr, MX-60, MN KID, Xantrex Stacked SW+ 5548s; EU6500isa, 21KW Kubota diesel gens, misc Honda Eu gens
    Sys2: 1280 AH 48 V 4KS25 Surrettes, 5.88 KW STC, Two Classic 150s, WBjr, MX-60, MN SPDs, Stacked X SW+ 5548s; Kohler 18 KW LP, EU 3000isa gens, HB DC Charger, Midnite Breakers/boxes. Thanks for this great Forum!

  2. Default Re: Battery Capacity calculations

    Lee - thanks for the spell check!

    I have the week off work so I'll see if i can get more tweaks built into the calculator this week :)

    I also got my 400w of solar panels mounted.. so ill do a little post with pics once i finish "prettying" up the wiring :)

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