left lights on, killed batt. Charge or replace?

[Gilles]

Originally Posted by Starter986

I would remove the battery... hook up another battery.. start the car... remove that battery (with the car running)... hook up the dead battery... and let it "charge" for about 15 minutes.

I'd then shut off the car... hook up the battery charger... and the battery would register just enough juice to allow the charger to do the job. Has worked every single time I've encountered that problem.

I would not feel comfortable disconnecting the battery while the engine running as you may damage their sensitive electronic systems and may be more expensive than a new battery..

[paulofto]

I had a dead battery a year ago after leaving the lights on. It was only 2 years old at the time. I connected my Schumacher maintainer and it charged after a few hours. Fired right up and I haven't had an issue since. BTW, if I'm not going to drive for a few days, I connect the maintainer. And of course it is always connected when the car hibernates over the winter.

[wwjd]

thanks, all, MUCH appreciate the advice. I found a decent slow charger to borrow, so I might as well give that a shot.

Unsure how old it is - bought car used - so I shall check on that as well, and replace if needed.

[1PorscheBoxster986]

Originally Posted by wwjd

thanks, all, MUCH appreciate the advice. I found a decent slow charger to borrow, so I might as well give that a shot.

Unsure how old it is - bought car used - so I shall check on that as well, and replace if needed.

There should be a sticker on your battery that shows when the battery was manufacturer. It can say the month and year (April 2014) or some will have digit code like tires (example: 4018) which means it was manufactured during 40th week of 2018. If your battery is more than 5 years old, it might be time to replace it after this incident.

[rexcramer]

Originally Posted by Gilles

I would not feel comfortable disconnecting the battery while the engine running as you may damage their sensitive electronic systems and may be more expensive than a new battery..

Ditto, that doesn't sound like a very good idea. Maybe try hooking the batteries up in parallel?

[Starter986]

When the car is running... it's all alternator. When the car is running there is a slight charge delivered to the battery (preparing it for the next "start"). Remove the battery when the car is running and... voila. Car keeps running (assuming a properly functioning alternator).

What? A Porsche is the only car with sensative electronics? I've done it on my Edge, and the electronics on it are FAR more sensitive than a 98 Porsche.

Has worked for me since, um, the 70's.

Cheers!