Battery question

[ayacucho]

My 06 Boxster had a dead battery yesterday. Not completely as interior lights and front hood locks still operated. Put the battery on my Battery Tender Jr. yesterday and 24 hours later the solid red (charging) light on the tender is still lit. How long will it take to charge completely.

Thanks

[jmatta]

A maintainer is not meant to re-charge a dead battery; it's purpose is to keep the battery level at an acceptable voltage. I would put the battery on a trickle charger and bring it to 12.65 volts (full charge), then put it on the maintainer. If it's never been dead before, you may find this will work; otherwise, you're looking at a new battery.

[mikefocke]

Generally operate to charge within a narrow voltage range and thus a fully discharged battery is below the voltage at which the maintainer will kick in.

Jump start the car and go for a 45 minute drive with accessories off. Then bring it back and put the battery on a maintainer for 24 hours. Then remove from the maintainer for 24 hours and place a load tester on the battery at as close to 70 degrees as you can get. The result will tell if your battery is good.