solar battery restoration

leaf
leaf Solar Expert Posts: 37 ✭✭✭
in Off Grid Solar & Battery Systems #1
Hey everyone, I'm a newbie to the forum. I'm not really a newbie to solar but I'll probably seem like one after this post ;-)

I use a 12V solar panel, controller and deep cycle battery system in my RV (water pump, lights, laptop, stereo, that kind of thing). I seem to have a knack for wrecking batteries though. The latest one is that I fried the controller by shorting something out when I was rewiring a switch. I disconnected the panel and the controller and battery from each other, and then connected the battery to a charger on mains power (240V where I live).

The charger output is for 12V batteries so I assumed this was ok, and I checked on the battery for the first few days and it was fine. But some time later (a week or so?) I noticed the charge had crept up and when I looked at the battery it was fizzing, leaking and definitely over charged. I disconnected it and it's been sitting for a month now.

What I need to know is:

- what's the best way to determine the relative health of the battery now?

- are there any other things apart from cleaning and topping up the water that I can do to restore the battery?

- was the leaking and fizzing caused by the battery charger, or is it more likely I damaged the battery with the short that took out the controller? (I've charged a failing battery from the mains powered charger and not had it fizz before).

tia,
Leaf.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: solar battery restoration
    leaf wrote: »

    - was the leaking and fizzing caused by the battery charger, or is it more likely I damaged the battery with the short that took out the controller? (I've charged a failing battery from the mains powered charger and not had it fizz before).

    tia,
    Leaf.

    I'm leaning toward the charger failing to properly perform a 3 stage charge, and unless it's an expensive charger claiming 3 stages, it's more likely a simple bulk charger, that cooked your battery.

    If the battery has removable caps, you can add distilled water till it touches the lower base of the filler neck, and hope for the best.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: solar battery restoration

    Flooded cell batteries are usually pretty rugged and will withstand overcharging--As long as the plates are still covered with electrolyte--If the plates were exposed--then all bets are off.

    Best way to check the battery is to first charge it, then put a load on it and run it to what should be 50% capacity (i.e, 100 AH battery, run ~50 AH out of it) and then use a hydrometer (measure specific gravity) or digital volt meter (measure resting voltage after a couple hours of no load).

    If the batter supports the load and shows that it is only ~50% discharged--just continue to use it.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • leaf
    leaf Solar Expert Posts: 37 ✭✭✭
    #4
    Re: solar battery restoration

    Ok, thanks. The cells were still under water, just. But above that there are these blobby shaped bits of something hard sticking out from the wall of the cell, that I assume formed while the battery was fizzing. I've tapped one with a screw driver and it fell off into the acid. Does this matter?


    Mike, is a three stage charger something specific to deep cycle batteries? Because I've used this charger on car and truck batteries and had no problems before. It's a 2200mA charger but I don't know how it charges.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: solar battery restoration

    Some battery reading for you:

    Deep cycle chargers: http://store.solar-electric.com/bach2.html
    Battery FAQ's: http://www.windsun.com/Batteries/Battery_FAQ.htm

    You managed to hurt a FLA with a 2 Amp charger? :confused: Maybe something else was wrong (reverse polarity, battery near ruined anyway, shorted charger controls).

    This lump you saw ... was it sort of dull yellowy-creamy-white?

    Above all, check the Specific Gravity in each cell with a hydrometer. Look not only for low readings (below 1.200) but inconsistent ones.

    Generally Flooded Lead Acid batteries will take a lot of abuse. But there are limits.
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  • leaf
    leaf Solar Expert Posts: 37 ✭✭✭
    #6
    Re: solar battery restoration

    The charger was hooked up to the battery and the battery was still connnected to the house wiring which I was using periodically (water pump, stereo). I'm not sure if I am supposed to do that with that charger, so maybe that was the problem?

    Are you suggesting measuring the specific gravity like Bill, or should I just do it now without doing anything else to the battery first?

    The lumps are either brown or grey, same colour as the wall they're attached to (looks like a metal bar running down the middle of the battery). The brown looks like corrosion.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: solar battery restoration

    "You managed to hurt a FLA with a 2 Amp charger? :confused: Maybe something else was wrong (reverse polarity, battery near ruined anyway, shorted charger controls)."

    an unregulated 2a charger given enough time can overcharge a battery. the noises he heard was the electrolyte being boiled away and what boiled away needs replaced with the distilled water. it may take longer to overcharge a battery when the charging current is lower and the lower it is the longer time it takes to overcharge it until it reaches an equilibrium point between the natural self-discharge and the amount charging. the use of regulating circuits is a necessity when it comes to charging a battery as it is too difficult to watch for the unregulated charger for when it reaches the critical point of overcharging. contrary to myth, a battery does not stop charging just because you are only feeding it 1 or 2% of the capacity in current in an unregulated charger. there is still going to be a voltage differential between the battery (which may be about 14.4v at its charged voltage) and the open circuit voltage of the charger that is often greater than 16v or 17v. this differential wants to continue the charging until the voltages are equal between the 2 and would in theory stop at the open circuit voltage of the charger. it will stop just prior to that point when it is replacing the self-discharge current. at that point damages to the battery may already be there.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: solar battery restoration

    Niel;

    He said the plates weren't exposed, and it's hard to imagine anyone leaving a battery charger on that long. On the other hand, there clearly is damage here so ... And we don't know how well-regulated the charger is. Some automatic chargers do indeed cut of at charge point, others are about as automatic as a piece of wire. I know; I've poked inside a lot of them. Cheap chargers are bad news for batteries, that's for sure!

    To the OP:

    We're going to assume you actually mean "house" here and not the inverter running off the battery you were trying to charge (yes, some people do :roll:). In which case the use of other things shouldn't affect the charger's ability at all. I'm suspecting your charger. Grey-brown lumps sounds like plate deterioration, consistent with over-charging. It is "terminal" (pardon the pun).

    Do as Bill suggested; let it rest, check the SG on every cell, and pray to Plebium, god of battery plates! :p

    Most likely you are looking at the need for a new battery. Along with it, get a good charger.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Re: solar battery restoration
    Cariboocoot wrote: »
    ...and it's hard to imagine anyone leaving a battery charger on that long.

    Are you looking at ME? :blush::roll:

    -Bill "Life is what happens while your RV batteries are on trickle charge" B. ;)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: solar battery restoration
    BB. wrote: »
    Are you looking at ME? :blush::roll:

    -Bill "Life is what happens while your RV batteries are on trickle charge" B. ;)

    But Bill; you are the clever one who always recommends people put these small chargers on timers.
    Or have we just found out why? :p

    I've yet to over-charge a battery. Maybe I should try it sometime, eh? :D
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