Automotive question

Batteries explode when sparks ignite hydrogen gas. The ground side will spark just as easily as the postive side if connecting/disconnecting under load.

Gunner

"Gunner" wrote: Batteries explode when sparks ignite hydrogen gas. The ground side

^^^^^^^^^^^^^^^^^ Gunner, the sloppy thinking and misdirection that dominates your politics is spilling over into your technical world. Shame! We were talking about sparks to ground. If you think the battery is under sufficient load (discharging over a period of a few days) to create a dangerous spark when disconnected, then, by all means, disconnect the remote end of the ground cable and insert the ammeter there.

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Well ... with jumper cables, the ground connection is supposed to be at a distance from the battery terminals -- somewhere on the chassis.

Batteries also explode when you bend over one with the caps off to check the level while you've got a lit cigarette in your mouth, as a friend discovered. Luckily, there was someone, and another working car, to drive him to a hospital to get cleaned up. :-)

AFIK -- he still smokes.

Enjoy, DoN.

A) I agree with the those suggesting an ammeter in the ground leg. THIS IS WITH THE CAR OFF.

You may see 40-50 mA. with doors closed, etc. [Make sure there's no underhood light.] If it's more, pull fuses one at a time. There may well be multiple fuse boxes, by the way.

I'm going through this with a friend's car. Despite a new battery [several actually; the battery people have tried ....] and a 40mA draw, his keeps dying. I think his issue is he drives his car once every two weeks, and then not very far. I have a Harbour Fright battery cutoff and $10 bolt-in charger for him.

B) To check the charging, don't worry about amps. Start the car, measure the battery voltage at fast idle. It should be ~14v. Turn on the headlights, rear window defrogger, blower etc. You should hear the motor drag down, and maybe the belt sing slightly. But you should still get ~14v, although you might need to give it another 1000 RPM.

Never ever disconnect the battery on a running car. It's a vital part of the equation. If you disconnect it, you get what is called a "load dump"

-- the voltage shoots up to ~65V until, several hundred msec later, the voltage regulator manages to get it down to reasonable levels again. [The effective inductance of the alternator is ~~1H; that's why nothing happens quickly.]

By that time, many of the exquisitely expensive electronic gadgets on board may have let some of their magic smoke out....

As for jump-starting:

1) A battery being charged may vent hydrogen. 2) Hydrogen + sparks == kaboom.

It's the jumped battery that is getting rapidly charged after starting. So I make it point to disconnect the first end at the jumping car. In a perfect world, you could just use the block/frame for the ground connection, but lately it seems like everything exposed under the hood is plastic or the wrong shape to clamp onto.

Nope...I learned that with jumper cables and a bit of coat hanger.

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

The sloppy thinking and misdirection that dominates your politics is apparently leading you to show your buffoonishness to all the readers.

Heads up Leo....any spark is dangerous in the presence of a flammible gas, no matter how small.

You think your vehicle, under normal maint drain wont spark when you pull either lead?

All of my vehicles must have been "special". You on the other hand...must have been "special needs"

Gunner

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

Yes..thats what is supposed to happen. Most folks will simply stick it on the neg side of the battery. And yes...it will spark with either

I took a non smoker to the hospital for treatment when a battery blew on him. Something about that nasty spark when using the lifiting lug on the side of that 350 Chev as a ground lug..in the presence of hydrogen

Gunner

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

As a kid back in the early 70's, I worked at the local Searz auto center installing batteries (amongst other things). I installed many, many, many thousands in the few years I was there.

Back then, customers brought their car to the 'battery line' and we installed/checked and or whatever while they milled around and watched. We also did voltage regulators, alternators, the occasional generator (remember those?) starters and related stuff.

One night we were swamped with battery installations, and while working with one customer, noticed another checking his electrolyte level with a Bic lighter.

Before I could even yell it went off in his face and splashed down several others watching, including a fellow employee who luckily had his back turned. It blew the top off of all six cells which wasn't all that common for battery explosions back in those days... 3 or 4 cells was much more typical. (Why? I couldn't tell you...)

The customer with the lighter, other than for a few superficial facial scratches came out relatively unscathed. He was about about 10' from the shop eye washer at the time, and we had him in there flushing away within seconds. None of the other's complained of eye exposure, but use of the shop hose and bathrooms was popular for a while.

I heard Searz payed for a lot of clothes and paint over this incident. Today they would have been sued back to the stone age.

Were any policies changed after the accident? No. It was business as usual for as long as I worked there, and I remember seeing the same set-up driving by that shop for years afterwards. Amazing. They didn't even mandate the use of safety glasses.

Believe it or not, this was the only battery explosion I witnessed, or even heard of that actually happened at our shop! Searz made sure new kids were up to speed with battery safety before being let loose, and it looks like it payed off. Those cable connection and jumper cable procedures, if followed, are actually real world effective.

However, maybe once a month or so, a customer showed up with a blown up 'core' battery. Even less often, one would also be sporting facial injuries.

Almost all claimed jumper cable use, or the act of battery cable connection/disconnection to be the source of ignition.

Erik

I was driving on the 57 Freeway (So. California) about 5 yrs ago when there was a WHOOMP under the hood, a reverse dent came up on the far front and all the dust under the hood spurted out, at 55mph.

Pulling over, I lifted the hood to find the top of my battery missing. Not a shred anywhere to be found.

Amp gauge showed normal, and it restarted just fine. I ran as gently as I could to the Autozone, and bought a new battery and installed it in the parking lot.

Never could figure out why it went Kaboom!, as everything was normal and nominal and I put another 200,000 miles on the new battery (which is still in the truck and starts it every two weeks.

Gunner

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

It's those Martians, i tell you! They tried to read your mind, but the foil in your hat blocked their ray. Then your battery exploded when they upped the power! ;-)

[snip]

I would bet on a bad voltage regulator overcharging the battery and thus generating too much hydrogen and oxygen, coupled with a blocked relief vent, so the overpressure popped the top off the battery. Note that the hydrogen and oxygen probably did not ignite, for lack of a spark.

Joe Gwinn

Internal short/spark.

Oooooo! tHAT explAINS THE BLacK hELicoTERS!!

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

Yet the same regulator is still on the truck.

Might have been a vent tube...shrug...scarred the piss out of me at the time

Gunner

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

Thats my thinking. There wasnt a bit of dust left anywhere in the engine compartment......I thought the radiator had exploded for the cloud of smoog coming out everywhere

"Obama, raises taxes and kills babies. Sarah Palin - raises babies and kills taxes." Pyotr Flipivich

That is actually a scary thought but easy to figure.

Consider this : Lead shakes down into the bottom and starts building a small hill of conduction metal. This then reaches upward and shorts out plates. Or almost shorts. High current occurs only in the battery - likely between plates or cells. High current and hydrogen and oxygen is generated. It likely didn't explode just pressured and exploded. The gas might have detonated post explode from sparks being produced.

Martin

Mart> >

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Could be. But if there was a real Hydrogen-Oxygen explosion, I am skeptical that there would be any battery left. That's why I opted for a blocked vent.

Joe Gwinn

If it was under normal charging rate there wouldn't be a lot of hydrogen /oxygen mix in there. And it likely wasn't at a real flammable level. So when the broken plate in the battery arced it just popped the top off. I've seen the same thing a few times with batteries in various equipment. If you want to see real fireworks try a shorted battery with low fluid levels that has boiled down. Those make a nice fireball...

You may notice that in battery explosions, the battery above the liquid level is gone, from the liquid level down the case is still there. When it happened to me, the two battery poles were still there. Started the truck and used it to drive to a water source to wash off the acid. As a side note, it was nearly as loud as a shotgun going off.