Nasty blue battery corrosion. Why so bad? What is it?

SolaRevolution
SolaRevolution Solar Expert Posts: 410 ✭✭
in Off Grid Solar & Battery Systems #1
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These T105s were neglected and completely dead. They had a 32 panel Quad lam array with an old APT mercury switch charge controller keeping their voltage high while the sun was shining. The battery enclosure was not vented and there were rodent nests in the walls. There was a very strong urine stench. Yuck!:cry: The T105s had bare copper bus bars which were partly eaten away and covered in this thick, grainy, blue corrosion. In some places under the busbars it seemed to have congealed into a brown clay-like lump. I've seen small amounts of blue stuff that looks like this plenty of times but never so uniformly thick. I got a few grains of it in the gauntlet of my rubber gloves and felt it burning almost immediately. It stripped the chrome off of my wrenches and it took two lbs of baking soda to neutralize what was on my tools and what left on the Tyvek covered floor of the enclosure. It did not seem to have leached though the Tyvek.

I cleaned up the T105s and the copper bus bars and recycled them. I scraped everything else into a sealed 5 gallon bucket and will take it to the Hazardous Waste pick-up next time it's in town.

What is this stuff? This seems far worse than any batteries I've dealt with before. Much "hotter". I'm wondering if the amonia from the rodent urine was reacting to make it so bad.:confused:

-Alex



The T105s have now been replace with ( 8 ) L16RE-Bs, a used 48v inverter and an FM-60. (Old owner passed on. New owners asked for a "minor" fix until they figgure out what their long term needs are.)
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: Nasty blue battery corrosion. Why so bad? What is it?
    SolaRevolution wrote: »

    I cleaned up the T105s and the copper bus bars and recycled them. I scraped everything else into a sealed 5 gallon bucket and will take it to the Hazardous Waste pick-up next time it's in town.

    What is this stuff? This seems far worse than any batteries I've dealt with before. Much "hotter". I'm wondering if the amonia from the rodent urine was reacting to make it so bad.:confused:

    -Alex

    Looks like classic copper sulphate to me. Possibly the result of vigorous outgassing spreading sulfuric acid vapors over the copper. The exposure continued over a long period of time, letting the layer get thick. Since the sulphate goes into chemical combination with the copper and is "used up" forming the crystals, there has to be more than minor exposure to let it get that bad.

    The burning and damage to tools means that there was still active sulfuric acid present in the moisture on top of the batteries.

    Maybe Acid Rain falling on exposed battery tops? :-) Depending on what part of the country and how the batteries were mounted.

    Really careless handling of hydrometer with electrolyte in it? Hard to explain the uniformity of the corrosion that way.

    Rodent urine would cause a different type of corrosion, I think.

    Just water rinsing, followed by baking soda seems like the right way to go. If you rinse before neutralizing, watch out where the runoff goes....
    SMA SB 3000, old BP panels.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Nasty blue battery corrosion. Why so bad? What is it?

    that was a result of the voltage being held too high and the electrolyte just boiled away every day. copper corrosion is usually green so the blue tint may be the result of an alloy in the bus bars or maybe the rodents loved to go #1 on them allot. yuck, i feel for you on the cleanup.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Nasty blue battery corrosion. Why so bad? What is it?

    It's what one would expect to see under the circumstances. Nothing special, just corroded copper.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #5
    Re: Nasty blue battery corrosion. Why so bad? What is it?
    niel wrote: »
    that was a result of the voltage being held too high and the electrolyte just boiled away every day. copper corrosion is usually green

    Copper chloride is greenish yellow, copper sulphate is blue, copper carbonate is brown, copper oxides range from red to black. Generalized corrosion from atmospheric exposure covers a wide range of colors as a result, but that that blue looks like pure copper sulphate.
    SMA SB 3000, old BP panels.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #6
    Re: Nasty blue battery corrosion. Why so bad? What is it?
    inetdog wrote: »
    copper sulphate is blue, that blue looks like pure copper sulphate.
    Exactly. And we can still buy it in bulk here for farm use etc.
    http://www.copperinfo.co.uk/copper-compounds/copper-sulphate.shtml
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