Rev. 1, 31 Mar '04
Tim M: He went to un-hook the new 12v battery from the charger .... KA-BOOM! It sounded like a pistol went off in the shop. When he unhooked the charger, a spark set off the hydrogen fumes from the battery and blew the caps off and the side out. I was hollering, "Is it in your eyes?" but he couldn't hear me because he was deaf from the explosion. Got him out to the hose and washed his head (told him to get the baking soda but he wouldn't); just burned his forehead a little. He was happy today that his hat is OK.
Doogie: we set the battery on the charger, and forgot about it for about a week. Boiled it dry almost. I never bothered to check. Turned the key and KA-BOOM! Battery exploded.
Alan P: While working on my riding mower, I leaned over to crank it and BANG !! Blew the entire top off the battery, showering me with plastic and acid, The force of the explosion ruptured my left eardrum and cancelled a much anticipated dive trip to the Keys. Gave me a healthy respect for lead-acid batteries, and the explosive properties of hydrogen.
Marvin: Yes it can and will happen. I am a slow learner as I have blown up 5 of them: 6 volt, 12 volt, and one 24. I am still in one piece but lucky. I was leaning over the 24 and all that saved me was it blew the bottom and sides out and not the top. My hearing isn't too good anymore.
Bove: I learned that lesson when I was 15. I charged batteries with a Nash generator driven by an electric motor. All I did was remove the wire from the battery after charging and BANG! The battery side was blown completely off and I ran to the cellar sink. I survived just fine and never did that again. One should learn something every day.
Jackie Z: Took the three mile drive down to Wally World one hot summer afternoon in my '77 Granada. Was in the store about an hour. When I got into the car and hit the switch, I heard the starter pull in and then there was one loud THUD and the right hand front corner of the hood jumped up. I then had no further electric power. I found that the battery case top was now separated from the body of the battery on two sides.
Bay Bridge Sue: One of our electricians at work leaned over a stack of batteries (part of our power backup at work) and the wrench in his top coverall pocket (a little one, think like 5/16" OE) shorted out one of the cells on one of the batteries, and the explosion took out 3 1/2 batteries and sent him to the hospital to have sulphuric-acid-impregnated battery case chunks removed, and have all the holes neutralized. The sound was akin to a 10 gauge shotgun going off right next to you - from across the building. The electrician retired following this. His comment at the time was it was like a bomb going off under him. He was lucky he had safety glasses *and* a face shield on; looking at his coveralls and the shield, he would have probably lost an eye and part of his face in the explosion. The batteries were industrial 6 volt units with separate removable cells. And it only took shorting one cell of one battery to take out a few batteries. I was told he was lucky the whole stack of 96 didn't go up and take out the building (and all 6 of us inside!)
Ed, MI: For you tough folks out there, these batteries aren't filled with hydrochloric acid, the stuff in your stomach, but SULFURIC acid, which is much, much, stronger stuff. You play and you WILL pay.
BG: I left a "no maintenance" battery on my Sears 6-amp charger for several days, and it blew while I was away. Made quite a mess. Does anybody have an idea why this happened?
Ricks: Fixed rate chargers are bad news. Once a battery is fully charged, it takes only a few milliamps to keep it up. . It will absorb additional current, but that all goes into heat, and into breaking down the water into hydrogen and oxygen - in the perfect ratio to explode. 2.3 volts per cell is the magic number not to exceed if you want to keep your battery a long time, and not boil out the water. That's 6.9 volts for a 6 volt battery, and 13.8 for a 12 volt battery. Automatic chargers are the only good ones. Schauer had the first good patents, having bought them from my late neighbor nearly 40 years ago. . Chargers are like comparing a third brush generator to a modern one. If a charger doesn't say "Automatic," use it only for metal plating and de-rusting.
As you know, a fire or explosion requires fuel and ignition. Hydrogen and oxygen in or above a battery are the fuel, and a spark is the ignition. A spark can occur inside a defective or damaged battery, as well as at the post when an active charger is removed. The hydrogen and oxygen that explode batteries are released only when a battery is charged at too high a rate, or overcharged. Otherwise, you would be adding water all the time.
For safety sake, and for the life of your battery, use only Automatic chargers. . Don't even use a trickle charger or "Battery Maintainer" unless it says Automatic - and its detailed description specifies "float charge" or less than 100 milliamps final current. They get ridiculous prices for those battery maintainers, and for less money you can get a 6 or 10 amp Schauer Automatic that will safely maintain a battery indefinitely.
* Polarity: be sure to get positive to positive. Color coding cable ends or terminals is a good idea. Black or brown is standard for ground, and Red for positive if hot. If your old car has a positive ground system, then yellow would be a good idea for the hot negative. It should alert the unwary and the color-blind of the difference.
* Make sure all hot battery connections in your car are covered by insulators at all times. This will protect from the wayward wrench.
* Charger: always connect to hot side of battery, then frame or cold side, then apply charger power. Again, always unplug the charger from the wall before disconnecting from battery.
* Disconnecting battery: Don't touch hot side - just disconnect cold side, preferably away from the battery. Once the cold side is ungrounded, no current can flow. If your car has a battery disconnect switch, it should be on the cold side.
* Jump-starting: always connect the hot side cables first, then connect each cold side cable to the bumper or engine - away from the battery.
* Inspect your battery for signs of leakage - liquid splatters or corroded terminals. Those are sure signs of overcharging.
*Except when cold, a generator or alternator should not put out more than 2.3 volts per cell (6.9 or 13.8). When first disconnected from a charge source, a good, fully charged battery will reflect that voltage, then drift lower as its surface charge dissipates over several minutes or hours. Then its voltage should be 2.1 per cell (6.3 or 12.6). Fun Projects http://www.funprojects.com/ makes an electronic voltage regulator that replaces the cutout on a Ford third brush generator, improving safety, optimizing charging, and extending battery life.
*One final precaution: a battery can develop a short in a cell at any time. When that happens, The remaining cells get overcharged - even by most automatic chargers. You know there's a problem if the charge current never falls to near zero when full charge should have been reached.
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