Alkaline battery. Internal short?

[kb3ouk]

I watched a guy hook a battery charger that had a 200A setting to use as a starting boost to a lawnmower with a dead battery so he could start it. Got it started and let it run a few seconds then shut it off. I walked past it about 10 minutes later and heard what sounded like something boiling, and could smell something. Looked and saw the steam coming out of the battery. here what happened was after shutting the mower off, he left the charger on but still had it up on 200 amps, needless to say, it got shut off pretty quickly after I discovered what was happening.

[KM1H]

Use a zener set just a bit over bias voltage?  One of those newfangled TO-220 current limiters mentioned on here recently may be a little too hi tech.

[W4NEQ]

I watched a guy hook a battery charger that had a 200A setting to use as a starting boost to a lawnmower with a dead battery so he could start it. Got it started and let it run a few seconds then shut it off. I walked past it about 10 minutes later and heard what sounded like something boiling, and could smell something. Looked and saw the steam coming out of the battery. here what happened was after shutting the mower off, he left the charger on but still had it up on 200 amps, needless to say, it got shut off pretty quickly after I discovered what was happening.

A 200 amp charger is obviously really big for a 25 ah mower battery, but gassing (Hydrogen) is normal at relatively high charge rates.  The amperage rating on most lead acid chargers is the maximum - most allow high current until reaching 14 to 15 volts, then taper off to float as the battery is charged.  A good rule of thumb for normal charging is 10% of AH capacity.

[Opcom]

   I bought a bunch of Eveready AA alkaline batteries a couple of weeks ago. They were fresh batteries with a 3/18 use by code. I put 10 in a series connected battery holder for later use. Tonight, I was sitting nearby and I began to hear a sizzling, crackling noise and noticed an acrid smell. After looking around I found that the noise was coming from the battery holder. One of the AA cells was hot and leaking. None of the others were even warm. I replaced the bad cell with another and the problem did not repeat.
   I've never seen this before. Do batteries occasionally develop internal shorts and boil themselves to death?

Ed

I think that question was answered.   Did you successfully return the battery for a replacement or did its disposal method prevent that?

What does one do, besides moving away, when a primary battery is doing this? If it explodes, someone could be hurt, but they have vents. They can be very hot though. On the other hand, a piece of equipment could be damaged or it could spray chemicals everywhere.. At what point, if any, should someone try to retrieve the cell and place it in a safe area?

This may be one reason why YLs don't usually like projects on the dining room table.

[Edward Cain]

Hi Opcom,
   I bought these online and I haven't bothered to inform the seller. They were only 40 cents each. Out of 60 batteries, this was the only one to give trouble, so far. If another does the same, I will probably contact the manufacturer.

   Thanks to all who responded.

Ed

[N7BDY]

Exploding car batteries .  I've been a mechanic all my life so I've seen it happen a few times .  I blew up a battery once early on in my carreer ,  you learn fast .  They arent kidding when they say to shut the charger off before installing or removing the cables     Didnt hurt me but sure scared the crap out of me .  Hydrogen and sparks dont work well together ala the Hindenburg . They treat shop uniforms with something so that acid doesnt hurt the material as bad as straight cotton ....... but if you get sprayed in your untreated civvy  clothes you'll look like a homeless person after you run it through the wash machine the first time .

When I had my shop I noticed ANYTHING around the battery storage area either rusted ,  or if paper or cloth would disintigrate over a short time .  Even the unnoticable acid fumes are nasty on things .  No equipment was near that area or it surface rusted .  In the old days ( hell , I'm old ) anything with a dry cell battery in it had evidence of a leaking battery and corroded .  The new batteries are MUCH  better in that respect .  I cant remember when I had a flashlight or radio eaten up by acid .  But maybe the Chinese batteries are opening up a new chapter