Help! Electrical Problems...battery dead overnight!

A few weeks ago my car was completely dead when I went to start it to go to work. The completely dead thing.....key gets locked in ignition, no clock, no nothing..... I figured since the battery was 4 years old, then maybe it had just died. So I bought a new one last week, and everything seemed to be fine for about a week. Then, yesterday I get this strange message "System Failure, go to workshop" Little picture of what looks like a lightning bolt on it. This morning I was about to go out for coffee and the car is absolutely dead again...the same as before. So, by deduction it would seem that the problem must be electrical, since it's killing a brand new battery within hours. My PCM screen died a month back and I've been delaying getting a new system as my music works perfectly and I didn't use the NAV system very much anyway. Could it be possible that the PCM is the issue? Any advise appreciated. Sean

Could be a number of problems including leaving radar detectors, phones or other devices plugged into the hot socket but your Cayman has already given the best answer "System Failure, go to workshop". Did you replace the old battery with an OEM or another brand?

I leave my radar detector plugged in to the charger near the handbrake, but always turn it to the off position when I leave the car....you are suggesting that this may still be the culprit for killing a new battery (non OEM, but same size as OEM)? This would be almost rediculous - I would always leave this in my old M3 , often forgetting to turn it off (and it would stay on as there was a constant charge) and still fine in the morning. I guess a trip to the shop may be required. Thanks for your reply.

I got several erroneous errors reported after my battery died recently, but they went away after driving a time or two with a new battery . A new battery does not necessarily have a full charge (mine didn't). I don't know how long your commute is, but if you are sure the new battery got a chance to fully charge and you are sure nothing was left powered on, it sounds like there may be something wrong with the car. Probably worth getting it checked out. You might want to start with having the supplier test the battery . That will be a much cheaper solution than anything else on the car! hope that helps, Dave

See page 140 of your Owner's Manual. It is possible that the radar detector is still drawing enough current or not really off to discharge the battery since the sockets are hot even if the ignition is off. Porsche warns "do not operate additional accessories for more than 5 minutes when the engine is off" . Was your stop for coffee more than five minutes and the RD plugged in? And as Dave added your new battery may not be fully charged which would make it worse. That would be my first check.

I had this happen on my last car. Battery died after a few years suddenly. Nothing surprising since that happens. I replaced it, and within a couple of days, same thing. Checked the new battery and they said it was fine, just out of juice. Turned out there was a short in the the power window system that was constantly draining the battery so it only took a few days to run down from being new. I'd bet it is some kind of similar problem causing a constant drain on the battery . Probably gonna have to get the electrical system looked at.

I agree - there's something in the electrical system that's not working correctly and draining your battery . I have a V1 and I often leave it plugged into the foot-well socket, with the switch on the detector turned off and never had a drain problem. Get your electrical system checked - odds are it's a warranty fix unless there's more than 50k miles or the car was put in service more than 4 years ago - have it looked at. brad brad

And it is very easy to forget to turn off the detector when you thought you had. That could kill an undercharged battery overnight. Hopefully it is as easy as that but as others say if you are certain you turned the device off than the next step is to check the for an electrical problem with the car.

Since the radar detector in question was a V1, I think Santa Fe could be on to something here. One thing about the V1 (I just recently acquired one) that surprised me was how hot - not warm, hot - the unit got on a 3.5 hour trip. The temperature of the case was hot enough that it was difficult to hold it for more than ten seconds or so. This implies that the V1 draws A LOT of power, and if you left it on all night I have no doubt it could have an impact on the battery 's charge level. Though the V1 does have an LED that stays lit while it's on, it is subtle, and in daylight I think I could easily make the mistake of leaving it on.

if you have a good DVOM hook it up to the batt. and tell me the reading with car off/on

I would have a look at the alternator . I had a similar problem in my Audi TT it was 5 years old and the battery died. I bought a new one and it lasted a week and died again. Alternator was not charging the battery . The car was running completely off the battery for a week and got drained.

sup homes...fixed ?