Daily Puzzler - dead battery & burning plastic

[teamfee3]

1986 911 Carrera, SW chip, cat bypass, B&B dual exhaust, factory reman alternator last winter and new Interstate battery. Daily driver, 30 mile - 45 minute city/hwy one way commute. Has 92K on it. Battery light is not on, no alt belt noise.

Left the turn signal or something on one cold day at work and came out to a dead car, jumped it, and had no problems. The cold has set in here in the teens - 30's. Long Xmas holiday so it sat for 3-4 days and again dead. Jumped it, ran it, no problems if I drive it to work and back. Sits again over New Years and takes forever to jump start and there was a small puddle under the battery after trying to jump it but nothing since. Now, it smells like burning plastic everytime I start it for about 15 minutes.

Any ideas?

[1990C4S]

Measure the voltage at the terminals before you jump it and after it is started....post results here.

[tharbert]

The chemistry of a lead/acid battery creates less energy as it gets colder. Colder batteries have higher resistance so produce slightly lower voltage, meaning...batteries on the edge will tend to fail as temperatures drop. That seems to be what's happening to you. I'd take the battery down to your LPS and have them load test it. I think you'll find it's kaput.


As the battery charges, it produces hydrogen gas. Sometimes, a little acid will bubble into the vent tube and be forced out. If the puddle did a commendable job of cleaning your concrete, it was acid. If it wasn't acidic, it either didn't come from your battery or the battery has sulfated enough to change H2SO4 to H2O...kaput battery.

You may want to invest in a battery tender. It will actually help your battery to last longer.

[nineball]

you should also consider an agm-style battery for your replacement. kinetik, stinger, odyssey, and optima all make them now and i would suggest looking for them in that order.