Battery suddenly dead - 986 Forum - The Community for Porsche Boxster & Cayman Owners

roland3337 · 10-28-2015, 10:18 AM

I've got a 2002 Boxster with a battery that is less than 18 months old. When I tried to take it for a drive today, the battery was completely dead. There were no lights on that I know of, and nothing plugged into the 12v outlet. I'd only driven it a few days ago, and it was just fine. Very puzzled. Any thoughts?

NewArt · 10-28-2015, 11:05 AM

Does it take a charge if you drive it?

amitmishra4 · 10-28-2015, 11:14 AM

Check the alternator, sometimes there are no warning signs when it goes out. Same exact thing happened to me.

kjc2050 · 10-28-2015, 11:22 AM

Buy yourself a cheap battery tester & check the alternator with engine running, and battery with the engine off. This will enable you to determine where the issue is, assuming it's either battery or alternator.

Gelbster · 10-28-2015, 11:25 AM

Roland,
I doubt you'll solve this with keyboard mechanicing.
You need a meter that tells you the SOH (State Of Health) of your battery.
The old Milton rapid-discharge meters are obsolete now.
You need to recharge slowly with a new fangled charger that won't fry the battery like the old big 20 amp chargers would.
The new chargers also have a maintainer and de-sulphate function . So they are way more useful and effective at reviving a battery and keeping it in good shape.
The $5 Trickle Charger your Grandpa uses is not a good idea anymore!
Then you need a different meter and a fuse diagram to track down the 'dark current'a.k.a "Parasitic Loss" ,or key-off draw.
If you understand the basics, have the equipment and the patience it is a rewarding mental challenge.
When you are done,suggest you add a polarised charging cable connected directly to the battery terminals (fused)that allows you to charge without opening the Frunk.Make sure the connectors are weather proof and Klutz proof.
Enjoy !

roland3337 · 10-28-2015, 12:20 PM

Haven't tried yet. I will put a trickle charger on it when I get home tonight, and then I will try it in the morning and get back to this thread.

Gelbster · 10-28-2015, 12:25 PM

"The $5 Trickle Charger your Grandpa uses is not a good idea anymore!"
If the battery is totally discharged(as you say) ,a trickle charger may not be effective for many days.
The modern chargers make automatic adjustments for this issue.
Did you check the electrolyte for level and Specific Gravity?