when starting up my car, i heard a loud noise from the engine bay, and found out that the battery exploded! Blew up the top of one of its cells, and had some acid spilled around.

this was the original white benz battery. What could have caused it to happen? Was it my disregard for the maintenance of the battery? Was it caused by something else, like overcharging by the alternator? Was the overcharging worsened by the banzai runs i've been making lately, which overstressed the battery? The strange thing is that it exploded on startup, and the battery was being drained.

so i had the battery replaced, albeit with a non-benz brand, which had a warranty of 5yrs. Could this happen again? I am bringing in the car to the Benz service center in one week - what should they check?

thanks for any advise.

Dont MB batteries run on distilled or tap water, rather than acid??



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Agron
1989 300E
Monotoned Smoke Silver
97 Style Replica E420 Rims 205/55/16
Euro Headlights
Clear Corners
20% Tint
12" Sub-enclosure

like all lead-acid batteries, they contain sulfuric acid. One needs to add distilled or tap water to compensate for evaporation losses. Maybe the electrolyte level has dropped below a minimum level that overstressed the battery and caused the explosion.

i want to know what caused it so i can prevent it in the future ...

Did the shop that removed and replaced the damaged battery wash down the underhood and battery area with a basic neutralizing agent so you don't get rust holes, paint problems, or surprises for your skin/eyes next time you are working under the hood?

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JCE
87 300E, 65k miles
Smoke Silver

i had them douse the battery area with a pailful of water.

unfortunately, the foam insulation above the battery has been exposed to the acid and since it absorbed the acid, it cannot be washed off. The exposed foam insulation has broken down and crumbles when touched. I'll try to rinse off whatever acid has remained there and be on the lookout for other affected parts.

Bobbyv, you need to flush the affected areas with a solution of water and baking soda ASAP. Otherwise, any residual acid will continue to eat things. Buy a couple of boxes and really flush the area good. Let it sit for about 30 minutes and then flush again with the hose. Keep an eye on it, and it you see any evidence of continued acid action do it again. PLEASE WEAR SAFETY GLASSES AND OLD CLOTHES.

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Jeff Lawrence
1987 300e
1989 300e
2000 Dodge Grand Caravan SE

[This message has been edited by jeffsr (edited 07-18-2000).]

My guess is that a defective cell produced huge amount of gases when the starter was running. It was because hundreds of amp of DC current went thru the defective cell electrolyzing the water. If you jump start you car, that battery may blow up in front of you.

My guess may not be correct but it is good idea to keep a distant from the diabled car during the final step connecting a jumper cable to jump start the car. Take all the precaution as suggested by the manufacturer.

David

yes, it looks that way, that the surge of current exploded the gas in one cell. Maybe the electrolyte level was too low and it overheated. If that was the case then i was remiss in not maintaining the battery properly.

and yes, now i am more wary about anyone being near the battery when the car is being started and also when it is being jumpstarted. Previous to this experience, i did not pay much attention to it, and saw the thing as something inert - an appliance, if you will.

well, the battery brand was Benz (probably OEM), and hopefully this is just a fluke and does not happen to all of you benz owners ...

Yes... this post is OLD.

But.. It happened to me today. Went inside a parts store to get a new bulb for the backup light. Replaced the bulb. Turned off car (had passenger in the car, so it was left running), and then immediately went to start the car again (to reset the bulb failure light) - heard this loud BANG! Turned off car, looked at outside of car thinking that a baseball or something large hit it with great speed...nothing. Opened trunk, thinking maybe a spray can exploded and saw smoke....thought something shorted and popped....Looked some more and within seconds saw that the battery cover was disturbed and there was some fluid on the ground that was making the concrete sizzle (Acid).

Good thing I was at the front door of an autoparts store. Unfortunately, the force of the explosion also ruined the little vent flap device on the 1/4 panel wall.

The battery was a Varta (white in color) battery.

I don't know if the turning off and immediate turning on of the engine had anything to do with the explosion...But if I were to do it again, I would wait 5 seconds before re-starting. Then again...maybe it was time for it to depart (with a bang)....or it was bad karma...or someone wished it on me, in which case they better watch their bloodpressure, since now they have a bit of karma coming their way.

Please... carry a pair of rubber gloves in your car - And be Careful!

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

Aye,

Chemical resistant gloves at your local Home Depot for $2.97 + tax

Come in 4 sizes and are orange in color

__________________
2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)

FYI

http://www.ecozen.com/batdict1.htm

"Gassing -- Gassing occurs when more charging current is being fed to the battery than it can use. The excess current produces Hydrogen and Oxygen gases. Some gassing is normal, but excessive gassing can indicate that the batteries are being overcharged. The gases released are explosive if a spark or flame occurs, so adequate ventilation must be provided. This is even more problematic for sealed batteries due to pressure build up. Batteries normally start gassing at about 80-90% of full charge. A common fallacy is that you should stop charging as soon as the battery starts gassing. If you quit charging at that point, you will never get a full charge. Most good quality chargers reduce the current when the battery reaches this point to prevent excess gassing."

Could be a combination of an old battery and an agressive charging system, leading to a hydrogen bubble, and when the car was started, an internal spark in the cell ingnited the hydrogen.

< >>

....many times the spark is from a loose/poor connection a the bat. terminal itself. I am sure you have all heard that little 'PoP" sometime when bat connection is starting to fail..That pop is a spark..
... and a good reason to always make the neg. the jumper cables last hook-up on the engine frame , away from the battery, so if a spark does occur , you will not ignite battery fumes that accumulate over the bat from attemps to start a car ..

Just to be a bit pedantic, I thing the gas created it H2SO4 or hydrogen sulfide (or is that H2S its been a while since I cracked a chem text). Mucho volatile.

More importantly...

This illustrates why it is vital that when jump starting ANY vehicle, the last connection of the cables should be a negative connection and should be at a good ground location far from the battery itself. The final connection will always create some sort of spark and lead-acid batteries create this gas. Imagine hanging over the battery one jumper in hand when that lets rip -- talk about your chemical peels. (Not to mention permanent blindness, life long scars, and, if you happen to be inhaling at the time, upper airway swelling and sudden death... Just food for thought.

On adding "tap water" to a battery. I'm not a purist prude by any stretch, I use zerex in the rad and chevron motor oil but: tap water -- no matter how good it tastes will shorten the life of the battery. Impurities introduced to the fluid will encourage crystals to precipitate out of it and sit on the bottom of the cell. Once they accumulate and touch the lead plates the battery is kaput. A gallon of distilled is what, 3 bucks at the drug store? If you use five percent of that topping up a wet cell I'd be surprised.

<
This illustrates why it is vital that when jump starting ANY vehicle, the last connection of the cables should be a negative connection and should be at a good ground location far from the battery itself. >>

Never thought of that....

My dad always told me to replace my battery every two years whether it needed it or not, so I do that. When I buy a used car, I replace the battery. I think due to this, I always have a healthy electrical system and a solid battery. The battery is one thing that can really leave you stranded. Also if there is any corrosion around the terminals it is likely leaking, so replace it. Just some advice from my dad!
Brian

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Brian W. Heitman

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