Overheated battery!?!?

[767driver]

I had my '88 Carrera out for a long ride consisting of a 115 mile round trip on 40 - 60 mph two-lane roads today. Not thrashing it, just a normal drive. At some point I started smelling something "hot". It didn't smell like oil or frankly even electrical in nature. I stopped and checked the engine compartment and everything seemed ok. I kept smelling this subtle stink all the way home, however.

When I got home I opened the front and got a wiff of something. I pulled the trunk carpets up and the battery was so hot I could not hold my palm on it for more then 2 seconds. A tiny bit of battery venting had occurred and the label on top of the battery was distorted around the area of the vent line attachment.

I immediately removed the battery and cleaned the area with baking soda and water. I did not test any voltages or anything like that but I am assuming this is due to overcharging caused either by alternator or voltage regulator failure.

Any help is appreciated.

[Porsche_monkey]

Reinstall. Measure the charging voltage. Post result.

[Gogar]

As soon as you get a chance to check voltage, start up the car and check the voltage at the batter, with the engine at 2-3000 rpm or something. If it's much above the 14s, then your voltage regulator is probably bad and you should replace.

[rnln]

- hook the batery back on.
- measure the v before you start the car.
- measure the v after you start the car (idling). If your v is way more than 14.5 at this point. Stop. might be your alternator is over charging.
- measure the v while driving. If your v is way more than 14.5, alternator over charge.

[767driver]

I will do the above momentarily. I checked the V with the battery out of the car and it is 13.52. I then removed the caps and the plates were exposed due to very low water (Interstate 850 CCA battery from 2003 according to sticker on batt.). Topped off with distilled water the V is now 13.31 at the battery.

I will reinstall and check accordingly. I'm thinking the batt is old and just about timed-out anyway at this point.

[RSTarga]

I had a similar experience, it was a loose ground connection

[767driver]

Assuming I"m using my meter correctly I had the following results:

Battery by itself was around 13.3V.
Battery in car during start was around 11.7V.
At idle about 15.3 to 15.6V.
At 3000rpm about 17.6V.

[Black_Hat]

replace voltage regulator

[JohnJL]

Its your regulator. Assuming your alternator is an OEM-type with the internal regulator you need to remove the whole unit and either switch in a new unit or have your alternator repaired.

Dont just replace your battery, you'll cook that one too.

[Tigerrat]

Yep, voltage regulator cooked the battery. I did this once in an airplane on my first cross country. Ken

[mackskibum]

+1 on voltage regulator. DO NOT DRIVE! You will fry other things- I lost tach, speedo, alarm module, clock, a couple of relays, auto heat module sevral years ago. I installed a voltmeter as my next mod....

[rnln]

base on my experience, replace VR or rebuild alternator. After that, don't be supprice if the batery is gone or will be gone soon after that.

[piscator]

Second Rnln's comment -- check out the old battery with a load tester like this one:

http://www.amazon.com/Actron-CP7612-Battery-Load-Tester/dp/B0009XQUJI/ref=sr_1_3/186-8792637-6432158?ie=UTF8&s=automotive&qid=
1246857589&sr=1-3

There's a good chance the old battery needs replacing.

piscator