Thank you for letting me ask questions, it is greatly appreciated.

I purchased four type 27 102 amp hour batteries four weeks ago in preparation for a move to some very remote property in the Oregon desert.  The batteries will be used in conjunction with my three 45 watt solar panels.

I wired them in parallel and hooked them up to a "fully automatic" battery charger at 2 amps
to keep them topped off thinking that the charger would only charge if needed.  Imagine my surprise when I checked on them and they were almost too hot to touch and were dry.

I replaced the batteries but kept the fried ones.  I re-filled them with distilled water and charged them to see if I could I use them at all.

Surprisingly, they held 49, 58, 63, and 84 amp hours respectively.  I hooked them up individually to a 50 watt headlamp and feeling I had nothing to lose deep cycled them until the light dimmed and calculated the amp draw accordingly.

Since I have them I would like to put them to some use.  I know it is unwise to wire four batteries that are not identical together but it would be nice to have a backup battery bank and I could always charge them with the generator as I use it for other, larger needs, or purchase another panel for these battery as a separate system.

Would I only get the benefit of the worst battery in the bank?  Is it even wise to fool around with batteries in this condition.  I'm not sure how this works.

Thanks for the help,



  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    Re: Batteries

    Go ahead and use them as a back up, what have you got to lose?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Batteries

    i had a similar circumstance with 3 batteries i was trying to keep trickle charged without regulation on them. it same result even with low current as you have. those batteries didn't last much longer the best one of which lasted another 1/4 year after the first 2 died. mixing them will cause a simultaneous failure among all 4 as it is true that they all will be as good as the worst in the bunch and do not put them with the newer replacements.
    i do think you need a regulator to maintain your batteries and a larger bulk charge current to charge them. do read up on both the bulk charge and float charge.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Batteries

    Severe overcharging causes plate shedding. The specific gravity will read low and the electrolyte will appear darker as if there is graphite disolved in it.