recovering batteries with long absorption?

unicornio
unicornio Solar Expert Posts: 217 ✭✭
in Off Grid Solar & Battery Systems #1
unfortunately this winter I cycled my batteries so wild, after a great season of gray skies, so much rain (very good!), and after several problems (now repaired) with the diesel genset ... and too some problems more ... ;-)

however, I have spent some time getting to know how was the actual state of the batteries after some years having abused them, and I think that either, I have come to retrieve them, or maybe they would not have suffered too much to reach about 20-30% of SOC over some days...

the case is that after spent some hours measuring densities, voltages, temperatures ... etc, I have been determined either, as I (finally!) finished the fine tuning of the FlexNet DC, and to know for sure when the battery is really at the maximum of charge, reaching the process of FN DC "met charge parameters", with at full charge density too, determining which are the amps actually return when this situation occurs ...

these settings after i've managed to match perfectly the densities of all the vessels and return to have a healthy battery without having to have spent time in doing long battery equalization processes with high voltages ...the battery is a exide opzs classic solar 985Ah /C120 with a 8 years of use with some abuse, but never we have a energy shutdown in all this years!...

extending time of stages of absorption up to 4 hours, lowering the return amperes parameter, to reach a point where the charge amps are stable for several days (and do not get down more) with fully charged batteries, is the best way to know when the densities are the maximum and all vessels the same, when the FN DC reaches the state of charge parameters met ...in this case I had to low from 15 amps, which was the theoretical figure with which BDNF would have to set up, down to 13 amps, that are when the bateries are at maximum density... maybe this means that my batteries are a little tired...but i know now when are at full charge...

all this to tell you guys, that I'm more relaxed now, and I think I achieved more intimacy with the state of my batteries! ... it was well worth the hours spent to reach this sublime state! ... hehehehehe
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: recovering batteries with long absorption?

    i don't know if the word recovering is good to use or not, but for fla batteries that aren't in a state of inequality that a longer absorb charge once in awhile could help to insure they've reached 100% soc. if the batteries need an eq charge because of wider variations in the cells, a longer absorb charge may not cut it to bring unequal cells back to equality due to lower currents. the absorb charge is certainly gentler on the batteries than the eq charge, but water can just be added to the electrolyte in a higher maintenance condition that an eq would most likely present. the hydrometer readings will indicate if they are unequal or not and an extended absorb charge could take longer to reach 100% soc as the hydrometer readings would show. many of the threads on major fla batteries have been indicating that they need this bit of extra to bring them up to 100% soc as indicated on the hydrometer readings making this an actual needed part in a normal charge.
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