My car was dead......battery wise. Why?

[Jeff396]

Hey all,

I went to take my '02 Boxster S out the other day and it was totally dead. Not just dormant where the key in the door will wake it up but dead. I managed to hook up my batter charger to the fuse panel and a ground and got the front trunk open to charge the battery.

Question is, why does it do this. This is a battery I got just this last Summer so that should be fine. Do these cars have some sort of constant draw? I've tried hooking it up to my Battery Tender Jr., as I did on my older cars, but the green float light rarely comes on. It seems to stay in a state of constant charge with the red light on and the unit will get a bit warm. I can't remember exactly how long the car sat but I would guess it was just over a week with the weather we've had. Any ideas?

Jeff

[Meirschwartz]

how old is your battery?

[Cajundaddy]

Common issues are switches or relays that stick closed and leave lights energized. Trunk courtesy light killed my battery twice due to a sticky switch. You can connect an amp meter and disconnect fuses one at a time to isolate the problem circuit.

[jwgn777]

Why don't you remove the battery and charge it then take a hydrometer test and see if the cells are good. Then load test it. Just to see what the integrity of the battery is. Even if the battery was new you would want to see if you had a defective battery before checking the rest of the system. How long was the vehicle sitting before your last start? JW

[Cajundaddy]

Originally Posted by jwgn777

Why don't you remove the battery and charge it then take a hydrometer test and see if the cells are good. Then load test it. Just to see what the integrity of the battery is. Even if the battery was new you would want to see if you had a defective battery before checking the rest of the system. How long was the vehicle sitting before your last start? JW

From the OP: Got battery last summer, only approx a week since last start. Probably a sticky trunk switch, not the battery.

[Jeff396]

Thanks for the suggestions.

So I take it the Battery Tender should work on this car. There most likely is something that isn't shutting off that should. I'll check the trunks first and then move on to the fuse pulling so I can narrow down the issue and report back.

Jeff