Old battery or something more complex?

[jjcollier]

My car sat for a few weeks while I was on business travel and I forgot to undo the cable. Car needed a jump when I got back (it was realllly dead).
I've since driven the car a lot and had no problems.
Yesterday, my wife had to drive it and ended up with car dying on her in traffic. Rainy weather and the headlights, windshield wipers, blower fan, and radar detector were all one. She got about 8 miles away from the house and the car died.
This sounds like a two-year old battery that couldn't take the drain of all those things running at once, but I am surprised that the alternator couldn't keep up.
Does anyone feel like this is a bigger problem than just a new battery?
Thanks.

[2.7RACER]

jjcollier,
The alternator is not the best way to totally recharge a dead battery.
It's best to recharge the battery asap with a small charger over a several hour period.
You may want to consider a battery maintainer plugged into the cigarette lighter if you don't drive for extended periods.

[Rusty Heap]

Best bet would be to get a battery load tester, they're cheap and the only real way to test a battery state of charge.

Cheap at $20, I've got a digital read-out one like this that was maybe $30.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90636

[AvonGil]

Jump starting a car with a really dead battery is the best way to fry the alternator. Certainly dump the battery, especially if its old. Your alternator is probably shot too.

If your battery was really dead when you jumped it, then the car might have some kind of current leak. Perhaps a faulty door sensor? Do your windows go up and down even after you take the key out and open and close the doors once?

[jjcollier]

That's all really helpful info, thanks. I've had the car out this morning, no rain, and it seems fine. I checked the battery pre-start with an ohm meter and it was showing about 12.62 and then around 12.27 after starting.
I'd been told before that it was hard to kill the Bosch Alternator.
I'll have to try the windows thing and see what's up.
Thanks again.

[glenncof]

I take my suspect batteries to Sears for a charge and pull-down test. Then I know if good or bad.

The hand held tester seems like a good idea but you'll need charger also if testing battery alone. Something that handles 100A load at 12V = 1200W I would be careful with if low cost. Cranking at 1000A ? Not sure what this thing does.

But the running voltage should go up ~13.4V, not down.

Battery is lot easier to change than alt.

[Rot 911]

Originally posted by jjcollier
I checked the battery pre-start with an ohm meter and it was showing about 12.62 and then around 12.27 after starting.
I'd been told before that it was hard to kill the Bosch Alternator.

You may have succeeded if your voltage with the car running truly is 12.27.

[T77911S]

you can also take the battery to ADVANCE, they check them along with starters and charging system's for FREE!

[rgdalacrity]

I have a 1987 Carrera Targa that had the same problem. It turned out to be the window thing that "AvonGil" mentioned.