Kolbjorn S

I was going for a peaceful morning run with my 993 to pick up a cappuccino, started it up in the garage, BOMM !!!!! Like a rifleshot from underneath the hood. Seconds later and smoke pours up around the front. In a state of shock and with the heart in my throat I run after some tools and quite possibly set record for removing a battery from a 993. It was blown to bits:

I dried up all acid and poured in buckets of soap water, and it seems I saved it all, I can see no visible acid-damage.

Amazingly I had a similar incident in 2004 - see THIS TREAD - when the battery (original, still under parts warranty) unknowingly cracked. Since then, I've been using a Porsche battery trickle-charger.

I bought a new 70amp original Porsche battery which I installed today, and I can eliminate any alternator issues: After 10 mins idle (as per owner's manual) it charged 13.98 V, and after an hour's drive (to reset the computer) it charged 14.13 V. I then went on to check the vent hose, I blew in it but the first time it appeared blocked. However next time I tried it appeared completely open. I conclude the reason for the explosion was either a blocked vent-hose or a short-curcuit in one/some of the battery cells. I will take the car on a lift to investigate the venting since this could explain both incidents.

I've learnt this:
- If using wetcell batteries, replace it for preventive measures every 2 years.
- Preferably use a yellow-top Optima drycell battery (not available where I live).
- A Porsche-tech recommended 74amp or 75amp instead of the original 70amp.

Mark in Baltimore

Wow, that's frightening. Let us know what the battery gurus say.

Marv

Baking powder would be a good thing to use as an after wash. It is a base and will help neutralize any remaining acid.

Sprinkle in a generous amount and add some water to get it to a soup like form and then follow with a clean rinse of water afterwards.

Allen

I seem to remember Robin of p-car.com had the same thing happen about (3) or so years ago...

Garth S

Remove all the trunk carpets and hose them down ... small droplets of sulfuric acid will take days before their damage to fabric shows - but the attack starts immeditally.

last toy

Follow the advise about dosing with baking soda. Water will not neutralize acid, you need a strong base to do that. There may be enough strength left to be neutral to the touch but may be a slow long term issue. I forget my chemistry, but you can test the ph with litmus paper. Ask a pharmacist. The chances are you stopped immediate acid damage but you want to be sure. Did you recently have the battery charged?

Monique

Can someone answer my venty hose question?

Do not have one in my car as the battery is attached to a very simple and sturdy base plate. Does a standard 993 have a vent hose? A pic please.

2ndof2

Wow.....exploding rear windows and now this????? Whats next...suspension failures while cornering? Oh yeah, we've had that too! Craziness!

Kolbjorn,
You drive that car much or does it sit alot? It must not be related to use...I get the impression Robin drives his car quite a bit. Can't wait to find out why this happened and glad it didn't cause any visible damage to your ride.

Bruce SEA 993

Hey Jean-Pierre,

How are you? Yes the std 993 has a vent hose...I just re attached my vent with a better set up. My Mercedes mechanic gave me some extra Interstate vent adapters so I used it from the battery to the tube that is mounted in the car.

Cheers

Monique

Doing great Bruce. Thanks for the info.

Hope to be in SEA sometime soon. Cheers,

Kolbjorn S

I use a Porsche trickle-charger.

I don't drive it too much simply because I've got less than a mile to the office so I try and avoid using the P-car since the engine never heats up, besides work does not involve driving. Then when work is over my 3 1/2 year old daughter is waiting and after we've played then my day is done and I'm too tired to drive !

To second Bruce, yes it has, because the Porsche battery has a small plastic vent outlet. So the hose is there to avoid any potential spill in the compartment. As long as it's not blocked... I'll take a pic tomorrow. Is the RS originally equipped with a battery without a vent?


Re baking soda, many thanks for this advice - tomorrow I'll find some!!

Kolbjorn S

Here's a pic of a spare battery showing the vent hose which I believe could have been blocked, circled in red:


I overlooked this! Indeed the acid went into a small portion of the carpet, and today I cleaned it up a bit using bikarbonate soda (baking powder), but fortunately it seems there is no visible damage. I am otherwise definetely abandoning using 70amp battery!
A small DIY summary:
Here's the updated "S"-version toolkit:

then the technician, who could not believe she was allowed to empty a can of baking soda in the 993!!

Garth S

Hey, I need a cutie tech like that She's a perfect fit for R&R of the rear seat and glass area too - can't start training too early!

The only battery kabooms I've seen are a result of overcharging: I know that your subsequent voltage checks of alternator output look OK - so that suggests that the regulator is fine. You might flip the DVOM to AC volts scale, and look for an AC signature. Sometimes, one or more of the ( nominal 6) rectifier diodes blow and the regulated DC may look normal - but is not. Just a thought ...
Re battery size, I'd never worry about the CA or CCA rating: all the battery is to a running car is a buffer to the alternator - which filters spikes, etc. If enough CA's are available to start the car, any battery from ~300CCA up will do - the more, the better. So, any good group 48 battery will do.

tj90

THe Autozone battery I bought last year has a vent tube as well if anyone is looking at a lower cost alternative. An explosion would happen if there was an internal short (exothermic) or if there was alot of gas that did not vent around the battery and there was a spark. I think the battery can explode without any fault of the car - maybe its the porsche battery construction?

c993k

Time for some Red Tops! They don't explode or leak. Chris