Where does the magic smoke go?

JerryS · Mar 16, 2012

Suppose, just for discussion purposes, that some old near-sighted dumbazz connected the leads of his battery charger bassackards and left it connected overnight. What would be the effect on the charger, and what would be the effect on the battery? Just hypothetically speaking, of course.

twopop · Mar 16, 2012

if the battery was completely dead and would normally except a charge,then the battery would be charged backward.the charger would not be hurt

Anonymous-0 · Mar 16, 2012

If the battery being charged voltage is low enoungh, it will reverse the polarity of the battery

Russ from MN · Mar 16, 2012

I have a Century charger thats made for dumbazz people. If you hook it up backwards a little light comes on, says (reverse polarity) !

ShadetreeRet · Mar 16, 2012

If the battery has any charge in it to speak of, you will either get fireworks or toast the charger, or both.

biggerred · Mar 16, 2012

The horn sucks, the radio listens, and the lights cast shadows!!

Little Ed · Mar 16, 2012

Just for discussion purposes, I have seen this done. If it didn't spark real big (in your imagination)so that you wouldn't have supposedly noticed, then you probably charged it bassackwards, and you will need to totally discharge it,and recharge it with the correct connections. It probably shortened the life of the battery, but I would not get rid of it till it supposedly quit working.

flying belgian · Mar 16, 2012

I know someone who did that. Not me of course. It did not hurt the charger but the battery would not take charge.

PJH · Mar 16, 2012

Jerry - you're lucky you didn't blow your ears off, hypothetically speaking, of course. I had a lawnmower battery that some old near-sighted dumbazz connected the leads of his battery charger bassackards on, and like the others said - it reversed the polarity. + was now -, and - was now +. It didn't seem to shorten the life of the battery any, and as long as one remembered to hook the red cable to the black post and the black cable to the - well anyhow, you know what I mean.

Paul

Glenn Warner · Mar 16, 2012

I know a fella that had a ford 8N and they were positive ground , the battery was not dead but didn't crank over real well.He had been charging 12 volt batteries , and the ford had a 6Vin it, he put the + lead on positive and - on the negative turn on the charger , and started to go for some coffee, that battery lasted about 25 seconds before it blew up . he thought it was a bomb exploding , had battery acid all over some up to 50 feet away . lucky for him he wasnt still close to it

David G · Mar 16, 2012

biggered, that is just plain funny.

Thanks for the laugh

641Dave · Mar 16, 2012

(quoted from post at 04:30:59 03/17/12) biggered, that is just plain funny.

Thanks for the laugh

X2

Hay_Man · Mar 16, 2012

I was working for a company that ran 165 kw power plants powered by Detroit Diesel engines. They had large 12v batteries to start on. Our dumb-azz shop boy put new clamps on the battery charger. Guess what....Unbeknownest to me, Black was now Pos. Red was now Neg. I hooked it up to start the DD engine, standing next to the battery. When I pushed the starter button, BOOM! Acid all over me and in my face, thank goodness I had safty sunglasses on or it would have been in my eyes. That battery EXPLODED. It was so loud I still have the ringing in my ears from it 15 years later........Be Careful! They will Explode!

Billy Shafer · Mar 17, 2012

I was in a generator room. When two 8Ds blew up. You are correct sounded like a bomb going off. That was years ago and I can still hear the sound.

UncleTom · Mar 17, 2012

It will pop the diodes for sure in the charger. The diodes change the ac current to dc.And maybe other things too.

RodinNS · Mar 17, 2012

You probably fried the regulator in the alternator... depending on how hard/fast of a charge you pushed into the battery. Beyond that it won't likely make any difference to the charger and certainly none to the battery.

Rod

Geo-TH,In · Mar 17, 2012

If you have a smart charger, it would see you connected it backwards, just for discussion purposes, and nothing would happen.

Depending on the size of the manual charger and condition of the battery, you would see sparks as soon as you connected it and my guess is that it would short out the diodes in the charger or melt an electrical connection inside the charger, unless you have a 200 amp charger.

Then, just for discussion purposes, you may need a new battery.

It may damage the alternator's voltage regulator and diodes. Don't think anything may happen to a generator.

After you discuss this, would you let us know what happened?
George

old · Mar 17, 2012

To many variables. Depends on the charger and the state of the battery. If it is a good charger it would kick the breaker out in the charger so no harm. If the battery was dead the battery would take a back wards charge and then the battery would pretty much be shot. Seen more then one battery that was charged back wards by the way

Janicholson · Mar 17, 2012

Darkon theory of delumination. Failed lightbulbs are coated in dark dust from collecting blackness when working. Hand held battery operated dark suckers (often called flash lights) provide further evidence : cut open a dead battery and you will find it completely packed with black. Jim

JerryS · Mar 17, 2012

The battery, an old one I keep around as a spare, was on the bench, so no alternator damage. It shows 12.6 volts, but I don't know how to determine its polarity---and I'll admit after hearing some of the horror stories on this board I'm not eager to screw around with it. The charger, on the other hand, doesn't seem to want to do anything.

Hay_Man · Mar 17, 2012

If you have one or if you are using a volt-ohm meter to check it with, it will indicate the polarity. I don't know how you are seeing the 12.6 volts.

Texasmark1 · Mar 17, 2012

I have read the replies and if a person witnesses something, you just can't argue with that.

However. Putting a 1 1/4" wrench across the +/- terminals has the amperage capacity to get the battery really hot really fast. Potential for explosion......excellent.

However, a battery charger with usually something like 20 AWG wires connected the wrong way has no mechanism to blow the battery up......discharge it and attempt to recharge it in the opposite direction, but blow it up.....I don't think so.

On blowing out the alternator diodes by polarity reversal, 20 awg wire is rated for 5 amperes in short distances. Those diodes are good for 1/3 of 120 amperes for a 120 ampere alternator. Yes connecting a battery in reverse order, or an industrial charger, like an auto repair shop, or service station is surely a kill the diodes mechanism, but the chargers that most folks have....I don't think so.

Mark

Hay_Man · Mar 17, 2012

You don't Think so? Here.......

[b:aa0469e652]These instructions were written for general automotive type battery chargers[/b:aa0469e652]

DANGER! RISK OF BATTERY EXPLOSION FROM HYDROGEN GAS. MAY RESULT IN BLINDNESS, SERIOUS INJURY, PERMANENT DISFIGUREMENT AND SCARRING.

Batteries generate explosive hydrogen gas, even during normal operation. People have been injured by battery parts flying in an explosion. They can explode under normal operating conditions, such as starting your car. They can explode under abnormal conditions, such as jump starting, or if short circuited by a tool. They can explode in a parked car or sitting on a table.

Hydrogen Gas....Very Explosive....

barnE · Mar 17, 2012

Had at least one batt charged backwards and it recovered completely. Dave

Texasmark1 · Mar 18, 2012

Well sir the subject matter you quoted is the gas generated from
charging, not blowing up a battery from too much reverse current.
Different subject all together....other than you might be referring to
the amount of hydrogen that is emitted in the process. But if my
Chemistry 101 is still up to date, the hydrogen is a byproduct of the
charging cycle, not the discharge cycle.

Mark

Hay_Man · Mar 18, 2012

I googled "Tractor Battery Explosion" an found lots of incidents of batteries exploding. Here's one from a guy that worked in a Battery Reconditioning Shop. Seems batteries can short out internally without evidence on the outside. Then explode when you push the starter button or turn the key to start. Which isn't the original question but draws attention to a critical safety issue, none the less. If someone reading about the dangers of a 12v battery exploding in their face and is made aware of the extreme danger, I'm glad I helped draw attention to the danger. Here's what he said:

crystalized acid on the plates settled to the bottom over time and once they join as a sludge on the bottom of the battery you have fused cells ... these cells can be usually be identified by placing the battery at full charge for a couple of minutes in the beginning with the covers of the battery cells off and if one cell bubbles more profusely than all the others and smells like sulphur turn off charger and leave it alone for at least an hour than take it off the turned off charger and take it to the scrap yard or be prepared for an explosive event.

I'm not disagreeing with anything said above, just warning that it was like a stick of dynimite going off next to me and a fast trip to the ER to get my eyes checked out, after a strip down and yard shower. And a battery can explode just sitting on a table.........

Hay_Man · Mar 18, 2012

I had another battery explode in a Chev. Impala about 1971 or so. Me and another hand was going to use his car to jump off a Light Plant, Detroit Diesel Engine. Big Battery. Guess it was shorted out or something. Anyway the car battery exploded when I pushed the starter button on the Gen Set.....I guess I have been using jumper cables and Battery chargers for 45 yrs. or so and have had 2 battery explosions. Both envolved pushing the start button on the engine........

Hay_Man · Mar 18, 2012

.>

Texasmark1 · Mar 19, 2012

Pushing the start button closes the circuit and if the load is
approximating a short circuit, as a large discharged battery
could do, then you are obviously at risk.

Automotive owners manuals that I have read tell you how to
jump a battery. You connect the positive leads and tie each
negative lead to the frame of each respective car. Then get in
the car and drive one against the other allowing the bumpers to
touch completing the circuit. If there is a chance of a battery
blowing up as a result of it's internal condition, or that of the
load battery, you will not be struck by flying H2 SO4 and H2O, or
Pb.

Course if you have a modern car with a plastic bumper this trick
won't work.

Mark

Where does the magic smoke go?

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