Hello all.

I have been having intermittent battery drain problems on my 2000 911 since I bought it used last year. I went through one battery the first time I my car was dead (jumped it), but then it kept happening even with the new battery. Every few weeks my battery would be dead. After a jump, things would basically go back to normal. I purchased a porsche battery maintainer, and I have used that sparingly, but the problem keeps coming back.

I am fairly convinced I could have a small drain with the alarm. There is always one short horn beep every time I lock the door with my fob. I have done a lot of searching around and I realize that the car should not be beeping when it locks... this indicates that a "zone" is open. The question is: will this open zone / beep issue cause a battery drain over the course of several days/ weeks?

I should also state that about a week after I bought the car I put in a Kenwood iPod head unit. I have heard that an improper install could have created the open zone issue - i.e. that the car senses that the original head unit has been removed.

Lastly, I should clarify that I drive this car 40 miles daily (with the exception of the weekend). I always lock the door (always getting the one beep) when I am not in it.

Thanks for any help and suggestions!

Dave

 

You may have two different problems. There is an easy fix for the beeping if it's due to the new head unit.(do a search). You should address that first to see if something else is also open.

Driving the car daily, you should not be having battery problems. Have you checked the alternator?

 

The beeping is because there is an open circuit in the alarm system (but it sounds like you know that). It can be from the console being open, a door, or the radio grounding wire. When you changed the head unit, there was a ground wire on the frame. Make sure that ground is connected to the new head unit. Make sure your console is properly closed. I have to give mine a smack for proper closing (it's tight).

I have been studying the battery charging also... I replaced the battery when I bought the car and it only lasted 2 years - it was an Optima - it should have lasted longer. I replaced the alternator just to be sure then I watched the voltage carefully every time I drove the car (which is daily). I found that the first time the car was started for the day, it would charge at full charging rate (voltage goes to ~14v). After about 30 minutes of driving the charging rate slowly drops until it is no longer charging. Subsequent trips during the same day will never cause full charge rate again. Just to make sure the battery is properly maintained, I put the charger on every Friday overnight because I don't have confidence that the car is adequately charging the battery. Just opening the door causes a 3 amp drain on the battery.

I hope this helps...

 

Thanks guys.

Good recommendation - figure out the root cause of the beep before doing anything else, since it should be an easy fix.

Alternator check is also a good idea. I will keep a close eye on my voltage meeting on the dash while commenting to work. I've been lax on using my battery tender, but I think that's also a great idea - just use it over the weekends.

My question to you all is: Would the beep upon locking cause enough of a leak over time to slowly draw down the battery? I am hoping that once I fix the beep issue, my problems will go away and I'll never need the tender again.

Dave

 

It depends on what is causing the beep.

 

I wouldn't think the beep can be related to the battery issue. It is simply the car security system telling you that something has not been properly secured. There is no additional monitoring going on because of that.

 

Depends on what is open..Could be something like a trunk light.

 

See if you can get a volt /amp meter with long(er) leads, clamp it on the battery and feed the cables up through the back of the hood lid so the actual meter sits up on top near the windscreen . Close the hood down, close all the doors and see what your drain is. Anything more than a few milli-amps and you have something that is not right. It will give you an idea on how much the drain is, That will tell you what it possibly could be based on the amount of drain ( milli-amps ) you see . Also, making sure the trunk light is not staying on. You can do that by quickly opening the hood (after it has been closed for a while) and immediately touching the light bulb. Is it HOT... you might have found your problem as Wynovio suggests.

 

I'm having a similar problem in my Dodge Durango. My battery drains over night,but with my truck the brake lights will sometime come on randomly when the car is off. They are not fully lit but very dimly lit. If anyone has any ideas what that could be,i'd be all ears.

 

This could work, but you will have to wait a while... There is a chart in the service manual that shows the drain over time. Man, there are a lot of things still turned on when you get out of the car. A bunch shut down after 5 minutes, some 30, 5 days... You should be OK if you wait an hour or so.

 

Hello everyone,

Thought I would post the resolution, since it's quite interesting.

Apparently one of the three diodes in my alternator was fried. When the car shuts down, one of these diodes will be randomly "active". When the third faulty diode happen to have been chosen, my car would be draining 3 amps as it sat there, car off, locked, etc. When the other two diodes were chosen upon car shutoff, everything would be fine. This explains the intermittent nature of the problem.

Apparently the car horn on lock is not the cause... dealer says it is only causing a few milliamps of drain, which is nothing to be concerned about for a daily driver.

I have to say, paying the $$$ for a new alternator sucked, but I am so glad to get this problem past me.

Thanks everyone for your help!

Dave

 

For what it's worth, I've had the lock beep ever since I got the car ('02 C4S) a couple of years ago, and I rather like the confirmation that the locking system is engaged when I walk away.

All the doors, the nose cone and the engine cover successfully lock, so maybe the console compartment or glove box isn't registering, but can't get excited about that -- no issues with battery.

 

Wow, I thought the beep was from my car alarming itself? turns out that I too am having battery drain issues. Mine is a 00 as well and I did change out the HU. I will check and make sure it's properly grounded!

 

Proper grounding isn't necessarily the fix. Do a search on non-oem head unit installs. If i remember correctly, a grounding wire has to be cut and taped to prevent the alarm (horn) from sounding.

Update: Here is a link to a thread that explains this.

http://www.renntech.org/forums/topic...ker-and-alarm/