Odd Battery Issue

Steven Lake
Steven Lake Solar Expert Posts: 402 ✭✭
in Off Grid Solar & Battery Systems #1
Okay, here's an odd one for you. I've got one battery in a two battery 24v system that decided to go tits up tonight. However, here's the weird part with it. I checked it against a voltage meter and it's showing 13.5v, so fully charged, but if you try to pull any amps off it, you get nothing. And I mean literally nothing. Even my mini-tester is like "What battery?" It sees the full 13.5v as though it's charged, but when it tries to pull amps the most I get, even on a complete dead short is like 20ma. No joke. Even the charging unit poked at it and was like, "Yeah, and? What do you want me to do? It's fully charged." Yet almost zero amps come out like its dead. I needed to swap the batteries in the unit anyways as the condition of the second one tells me they were at EOL, so I just went ahead and junked the bad battery and kept the other around as an emergency spare in case I have a battery go and I can't wait to get a new replacement. Anyhow, with that said, what do you guys think happened to the other battery? I've never seen one act like that before. IE, act fully charged yet deliver almost zero current. Any thoughts or insights?
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Comments

  • Johann
    Johann Solar Expert Posts: 245 ✭✭✭
    #2
    I think a connection between the plates inside the battery broke or corroded off and is creating an open . The moister between the broken connection acts like a conductor , but that will allow only a very small amperage to flow and still could allow for the full voltage to read.
    I almost bet if you put one probe of the amp meter on the positive or negative post and the second probe right in the battery water of any of the cells you probably get a higher amperage out of it. Go cell to cell and you may even find out which cell is the bad one.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #3
    As Johann said, you have an open cell. If you follow his advice to stick a probe into the cells, make sure you are dressed appropriately for an explosion of hot sulfuric acid. You really need to know what you are doing if you are going to stick conductive materials into a battery cell.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Steven Lake
    Steven Lake Solar Expert Posts: 402 ✭✭
    #4
    lol, nah, I'm not that adventurous. Besides, I was just curious why it acted that way, but your explanation makes a whole lotta sense. Even so I needed to change that battery pack anyways as it was already having capacity issues with it before this. So its untimely death finally gave me an excuse to do it. ;) :P
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  • Steven Lake
    Steven Lake Solar Expert Posts: 402 ✭✭
    #5
    Okay, I've got a second battery now doing much the same thing, but not quite as severe. It appears to give kind of a mediocre showing current wise (a normal battery about blows up my test unit, but this one only gives out about 1/2 to 2/3rds of its nearest cousin) despite being fully charged, and appears like it wants to give out full amps, and is trying its best to, but starts fading noticeably after about a minute. It doesn't die out completely. It goes from about 2/3rds of the capacity of an identical battery to about half, then about 1/3rd over a period of a couple of minutes and then just kinda hangs there but never goes lower. Well, it does eventually when it's fully drained, but I mean during the time it still registers as fully charged. Is it possibly some bad cells or broken leads like the other battery, or is the battery just dead and needs to be RMA'ed? It's still got a year left on its 3 year warranty, so I can turn it in for a free replacement, which I really should do, but even so I figured to ask you guys about it with the intent of learning something about battery oddities. ;)
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  • Steven Lake
    Steven Lake Solar Expert Posts: 402 ✭✭
    #6
    Nevermind. I hooked the battery up to a charger and topped it off, then switched it over to a dead load amperage tester to see if it was the battery or my equipment having issues and when I flipped the switch the battery ate itself. So I guess that now makes two batteries with a bad internal structure or open cell or something that broke it. Needless to say it was quite fun watching the battery go out with a bang...quite literally. lol.
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