left lights on... car dies when jumper cable removed. alternator shot?

[saucys4]

I have owned an optima red top battery for four years. Recently, my battery light has been coming on intermittently but I have driven several thousand miles and have not yet had any problems. I only drive about once a week and take short trips around my town but I have also gone on a few 3 hour trips and havent noticed any electrical problems. I had come to the conclusion that it was just a voltage sensor. Last night I left one of my interior lights on which drained my battery. I hooked up my jumper cables and my dead s4 started but as soon as I removed the negative ground terminal jumper, it died. I tried again while letting the cars idle for a few minutes and even held the rpms up to ~3k but it died within seconds of removing the jumper cable. could a dead battery be causing this or is it a bad alternator?

[A62TURBO]

Those batteries suck when they die.

[zillarob]

Try a new battery (gonna need one anyway) and keep an eye on the votage, might get lucky.
Those symptoms can be indicative of a bad alt but an internally shorted battery can do the same.

[flyingfish2626]

Totally dead battery will do that for sure.

[KFC_Or_Bust]

Sounds like the battery and alternator are dead, even if the battery is stone dead, a car will run on alternator only until you shut the car off or use accessories.

[zillarob]

Sounds like the battery and alternator are dead, even if the battery is stone dead, a car will run on alternator only until you shut the car off or use accessories.

Not always

[saucys4]

Sounds like the battery and alternator are dead, even if the battery is stone dead, a car will run on alternator only until you shut the car off or use accessories.

That's what I thought... I don't want to buy a new battery and have it die soon after if the alternator is damaged. But it doesn't make sense that a single interior light that was left on could have damaged the alternator.

Anyway I borrowed a slow battery charger and will see if it holds any charge overnight.

[fshowcars]

I have owned an optima red top battery for four years. Recently, my battery light has been coming on intermittently but I have driven several thousand miles and have not yet had any problems. I only drive about once a week and take short trips around my town but I have also gone on a few 3 hour trips and havent noticed any electrical problems. I had come to the conclusion that it was just a voltage sensor. Last night I left one of my interior lights on which drained my battery. I hooked up my jumper cables and my dead s4 started but as soon as I removed the negative ground terminal jumper, it died. I tried again while letting the cars idle for a few minutes and even held the rpms up to ~3k but it died within seconds of removing the jumper cable. could a dead battery be causing this or is it a bad alternator?

the battery is junk... it is dead. live somewhere cold and that would have died on you the first night it was around freezing. very common with german cars to have high demand on batteries... the battery light was a good indication it was going to go... what is your voltage around when cranking? does it just drop to 0?

[AJ88CAB]

Start with the basics... If you haven't done this yet, remove the battery connectors and cleans the posts and clamps. They may look good, but if they are even a little corroded this might be why the battery is not charging and the car stalls when the charger is disconnected. Reconnect after cleaning and try starting again with the charger to see if it keeps running, if it stalls it is most likely the alternator.

As for the battery it may not be toast just yet, see this tech article on maintaining Optima batteries.
http://www.batteryminders.com/batter...pe-battery.pdf

Good luck...

[ECS Tuning-Audi]

I would at least put the battery on a charger first ( leave it over night). Reinstall and see if it holds a charge. Most car batteries last about 5 years, after that your on borrowed time.

Start with that and see what happens.

Good luck!

Jason

[Scotty@Advanced]

If your alt light is coming on then it's likely the alternator. However a weak or dead alternator can kill a battery over time so I'd bet that you'll need both.