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Post by GO30 on Nov 25, 2021 9:30:27 GMT 12
I pulled the battery out of the farm bikes to give them a charge due to little use over covid. One was a motobat 12V 7.6ah Absorbed glass mat. It's about a year old. Metre showed it was at 11.9V when it went onto charge. It was in my Yammy WR250F.
I put it on the 2.7amp max toy charger, one used for years, and all looked good. But when I went to swap it last evening I found the battery very warm, nearly hot, and puffing up quite a bit. Off the charger and placed in the yard away from things flammable quickly.
Checked the next battery, pretty much the same thing, after being on charge for a while and again after 12hr, cool as a cool thing but not as much as a refrigerated cucumber.
That suggests it is a battery issue not a charger issue.
Any ideas on what may have happened? Any idea on whether there is a way to see whatever it is coming or happening? Any idea what may have happened if I left it on charge? Any idea what will happen if I nail the dodgy battery with a .223? 
If anyone want to know what happens to a AGM 36ah battery when you hook it into my grunty charger before you read 'Do not use on batteries smaller than 50ah' I can tell you. You get a black rectangular box that is good for bugger all. Opps and Bugger!!!
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Post by grounded on Nov 25, 2021 11:44:07 GMT 12
If it is a cheapy charger, it is also likely to be unregulated. So simply, the battery was charged too hard for too long and that equates to heat. For an unregulated charger of 2.7A, you wouldn't want the charger on the battery for any more than 3hrs. If the charger was fully regulated, you can get away with a Charger current of no more than 50% for AGM/Gel. Now the Batteries are cold, what does the Voltage now sit at? The only other cause maybe a dud battery. If a cell is shorted, then it would simply boil the battery. The Cold Voltage test will tell you if the battery is still OK or if a Cell is dud. I would seriously suggest you get one if these. www.trademe.co.nz/a/motors/car-parts-accessories/batteries-chargers/listing/3360741650Fully automated and fully regulated and does all the standard 3 stage charging plus some extras.. Can be left on indefinately. Capable of charging from 1A all the way to 15A for bigger batteries or a quick charge to get a flat one started quick. Has a Maintanance charge, which is another word for equalisation. I have seen simple chargers that have none of these features for twice the price. |
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Post by GO30 on Nov 25, 2021 18:58:04 GMT 12
The charger is OK. It's done a lot of batteries over the years and none have done what the yellow bugger did. It's also been left connected for long periods and been fine. The other bike battery is now chocker and fine. It was hooked up this time yesterday and off about 20 minutes ago so been on a solid 24hrs. The meter says dead, the fact it looks like a balloon would suggest the meter is accurate  I suspect it has to be in the battery. Another has been ordered. I have 2 Victron (??) Chargers, the blue ones that are flash, but both are grunters and too big for a pip squeak 7ah battery, even a 36hr, bugger. Both put out 30amps, one singularly and the other will charge 3 at once. Got a 24v 26amp one ordered today for the farms bank, 24V 400ah. For emergency use off a genny and while I get the solar tracker built. Oh a though just popped into the fuzzy head. When I first hooked that no dead battery on the lights said 'fully charged', I thought Bollocks and then noticed it was set on 6V. I then flicked it to 12 and it changed to the charging light. It was on 6V for maybe 15-20 seconds. Could that have triggered something with the batteries internals? |
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Post by grounded on Nov 26, 2021 6:09:08 GMT 12
No it would have survived a short period on 6V. If anything, it would have been the charger that would not have liked it.
The Balloon shape aspect is a give away. Even though it is producing Hydrogen, it'll never float. The balloning suggests the Plates are bad and will be shorted together. That comes from age and sulfation, perhaps caused by being left uncharged for far too long, but not a charging problem.
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Post by GO30 on Nov 28, 2021 10:18:48 GMT 12
Had a close suss yesterday now its cooled down. Reading 8.4V and yeap there is something going on inside for sure. You can see it's compartmentalised and 4 look fine and it's the 2 in the middle that have gone bad. Maybe the 4 good compartments are still fine, thinking 8.4V / 4 good compartments/cells = 2.1V * 6 compartments/cells if all were still good = 12.6V it should read. It's that possible or me reading more into it than I should? When I fire up a new battery by putting the acid in, how long should I wait before using it? I have the new one but haven't dropped the acid. A statement I've had to make previously but for a very different reason |
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