Could a bad battery cause this?

[dienstuhr]

My '85 Carrera 3.2 has been running fine all summer.

It had not been driven for nearly two weeks when I started it last night. Cranked a long time and finally fired. Had trouble keeping an idle and stalled. Ran OK on a 10-minute drive to my first stop. Was stopped for 10 min, very hard to restart, with a giant backfire. Then stopped for gas, filled with premium, another huge backfire. I caned it a bit after that and it seemed to be running OK. Then stopped for the night in the garage, left it for a few minutes, then tried to restart and NOTHING, no warning lights, no cranking, just dead.

Put the battery on a charger overnight and this morning the charger still indicated "charging". Would not crank. Connected jumper cables to my GTI's battery and the 911 fired instantly and idled well. Disconnected cables and it restarted again with not as strong an idle.

I'm taking the battery in to be checked but any other ideas?

Thanks,

Dallas

[mhackney]

Did you measure the voltage at the battery with a volt meter? And then again while the car is running? This can provide some diagnostics into the battery and charging system. It does sound like your battery is dead (how old is it?) but you also want to check your charging system (alternator, voltage regulator and wiring) to make sure it is working properly too.

[dienstuhr]

Thanks!

Haven't had a chance to run any tests on the battery. It is two years old and stored indoors over winter.

d.

[DRACO A5OG]

Could be the alternator too.

You really should check the voltages, cold and while car is on then an hour later the sitting voltage.

[James Brown]

An 85? I don't suspect it's a battery. They either work or they don't. Check plugs/ wires/filters/nice in the intake things like that. Motec needs 12V but most of the processor uses 5V. Lights bright with engine running? Big culprit on cars that sit for awhile then run poor is corrosion forming around sensors and air ports. You have a scan tool?

[dicklague]

ALWAYS suspect the battery. Put a load test on it and see if it is any good. @ 2 years....could be bad.

Clear the battery [and cables] before doing anything else.

[andyt11]

James, what scan tool are you talking about? There's no port or anything like that on these cars. If the battery is not the problem he's left going through the engine management with a multimeter is he not?

[rick-l]

Diehard batteries used to do this. Just suddenly go open.

[911obgyn]

Be careful jump starting a car with a dead battery and removing jumpers if the battery is shorted or really dead it may smoke the alternator.