Electrical - battery drain

[sturgedm]

First off I must share my extreme disappointment with Holebert's dealership.  Wow, I thought I'd seen the worst but ... wow not impressive at all.

Had my 99 boxster in their shop three times for a dead battery.  First time they charged it up and told me to drive my car more.  They checked all the electricals, the battery, and everything they could think of.

Second time (1 week later) they told me the battery had "sulfated" that is why it lost charge and I had to jump it each morning.  They put in a new battery $$$.

Guess what, next morning, car would not start, had to jump it again.  Now they say it needs a new alternater. $645 in parts and $350 in labor.

I am taking my car back to Brandywine Porsche .. but I am interested in ideas on what might be the cause of a nightly battery drain.

 

 

[Larry Herman]

Most modern cars have quite a bit going on, even when shut down for the night.  Little systems draw power from the ecu to the radio etc.  You can use a digital meter with a DC amp function to measure the current draw at rest to see if it is excessive.  It is possible that something is not going into its "sleep mode" and is continuing to draw power at a normal "on" rate.

In any event your car should easily last a month or so between charges with the battery connected.

[LouZ]

If you are not mechanically inclined or just don't want to mess around, yhere are a couple of things that you do quite easily.

Check that the courtesy lights are off when the doors are shut (should be obvious).

Check the hood, trunk and glove compartment lights. Open each and immediately feel the light, if it's HOT, then it is likely staying on when the door, hood or trunk is closed.

 

Now, if you are adventurous, Larry offered the solution. Shut everything off, open the hood and pull out the light. Disconnect the negative cable, put a digital ammeter between the battery and cable and read the amp draw. (Here, I'm not sure of the draw that is acceptable on a Boxter) If it is higher than allowable, then remove 1 fuse at a time and see when the amps drop significantly. This will identify the fused circuit that is giving you the problem. Now refer to the label and see what is tied into that particular fuse circuit. Yuu will at least have it narrowed down to a few possibilities, at which point, you can look further for the culprit, or take it in and have the shop concentrate in that area first.

 

Good luck.

[michael lang]

Just out of curiosity, does your car have power seats with memory? I don't know 986's that well so I don't even know it that was an option. If your car does, and you genuinely feel like the shop has misdiagnosed the problem I'd be inclined to agree with what Larry had suggested. Somewhere in your car is a control module staying awake. I'd be leaning towards one of the door control modules, it memorizes seat positions, operates the seat motors, mirror motors, & window motors. It is likely that one of those is not "going to sleep" after the car has been turned off. Just a guess, again I don't even know if your car is equipped that way.

[Xplorer]

Had the car been in an accident or in for any other repairs shortly before the battery drain problem started? Is the car normally stored inside or is it left outside? The drains might be clogged causing the interior to fill with water (behind the driver's seat)? I would approach the dealership for some sort of monetary reimbursment or free service.

[mpsboy]

michael lang wrote:

Just out of curiosity, does your car have power seats with memory? If your car does, and you genuinely feel like the shop has misdiagnosed the problem I'd be inclined to agree with what Larry had suggested. Somewhere in your car is a control module staying awake. I'd be leaning towards one of the door control modules, it memorizes seat positions, operates the seat motors, mirror motors, & window motors. It is likely that one of those is not "going to sleep" after the car has been turned off. Just a guess, again I don't even know if your car is equipped that way.

I don't know 986's that well so I don't even know it that was an option.





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