Question regarding the dreaded battery drain issue

teamgs · #1 08-26-2008, 10:19 PM

Greets,
Sunday, my wife called me to tell me that our '03 X5 had a dead battery. She said that she couldn't remember anything being left on, but that she did remember the radio not turning off with the key like it used to. She shut it off manually.

I charged the battery and made sure to tell her to ensure that the radio was turned off manually until I could diagnose further. The car went dead again yesterday. I checked for current drain with a clamp on DC ampmeter, but could see none. The battery was at 13.8 v when the car was running. I had the battery tested at Kragen and they could find no issues with it. It is 1.5 years old.

Last night, I left in on the charger overnight with a 2 amp charge rate, and took it off this morning at 6:30 when I left for work. My wife came out at 9:00 and it was dead again!!!

I have already replaced the final stage resistor about a year ago.

The only thing odd that I see is that sometimes the radio won't shut off, and some times it does. However, even if it is shut off manually, there is always a faint glow on the upper line of the radio display, and the clock still stays on in that line as well.

I will pull the radio fuses tonight, to see if that temporarily cures the issue, but I would appreciate any insight that you all might be able to give.

Regards,

Gary

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msammy · #2 08-27-2008, 12:28 AM

Gary, definitely pull that radio fuse to see if that's the problem. The clock display and the intermittent radio on/off when shutting the car off is not normal. Sounds like the radio is bad and it's not allowing the car to go into "sleep" mode. Your car needs less than 50mA of current draw to properly go into "sleep" mode and not drain your battery (I can provide details on testing current draw, but it will require an expensive Fluke multi-meter to test). Do you have an iPod or cell phone plugged in and charging overnight? That could do it as well. Let us know how the radio fuse pull goes tonight!

teamgs · #3 08-27-2008, 01:02 AM

Hi!
Unplugged fuse 75 in the back, and the radio light went out. I forget...is the shift light supposed to also go out after 30 min or so?

The clamp meter reads to the 100th of an amp, but still might not have the sensitivity. Since there isn't large current when it is off, I could just hook up my other multimeter and test it, as it is much more sensitive. That may be the way to go, and eliminate the circuits one by one.

Regards,

Gary

Weasel · #4 08-27-2008, 01:39 AM

The BMW specs for amperage when a car is fully asleep is no higher than 40 miliamps. If you have a 40amp/20amp clamp, that should be accurate enough for you. It generally takes about 16 minutes for the whole car to go fully down, as it goes down in stages. So if you're reading amperage across the main power or ground with all the latches latched and the car fully down, it should be under 40 miliamps.

If you leave the passengers door open and just latch it closed with a screwdriver and leave the glovebox open, you can get to the front fuses as well. If it has been 20 minutes and it is still drawing too high an amperage, you can pull fuses one at a time to find what lets it go down. Just don't put them back in immediately as that could wake it back up partially making you wait another few minutes... Good luck and happy hunting!

teamgs · #5 08-27-2008, 02:03 AM

Thanks!
It is getting late here, and it appears as if pulling the fuse that shut off the radio light and clock display might have done the trick. When the car was first turned off, the shift light and a green light on the window or door lock button were both lit. About 20 min later, the shift light is still on, but the little green light is out now.

I can't recall in my car if the shift light stayed on or off.

I am just going to let it sit overnight with only the one fuse pulled, and see what happens. I'll test the voltage in the morning.

Regards,

Gary

Weasel · #6 08-27-2008, 08:16 AM

I think the shift light stays on anyways.

teamgs · #7 08-27-2008, 10:59 AM

Thanks for that weasel.

I am still looking for the cause. I came out this morning, and the battery was drained to only 6 volts. I hadn't pulled the radio fuse, I found out. (It was late and I was tired...doh) I had pulled an systems monitor fuse (I think) which did turn off the radio display.

I will have to hook up my multimeter, and start pulling fuses to see where the drain stops I guess. We are going up to our condo in Tahoe this weekend, so I am bringing a set of sockets, and will just disconnect the battery when we are not driving. What a PITA!

Regards,

Gary

03BamaX5 · #8 08-27-2008, 11:53 AM

Quote:

Originally Posted by teamgs

Thanks for that weasel.

I am still looking for the cause. I came out this morning, and the battery was drained to only 6 volts. I hadn't pulled the radio fuse, I found out. (It was late and I was tired...doh) I had pulled an systems monitor fuse (I think) which did turn off the radio display.

I will have to hook up my multimeter, and start pulling fuses to see where the drain stops I guess. We are going up to our condo in Tahoe this weekend, so I am bringing a set of sockets, and will just disconnect the battery when we are not driving. What a PITA!

Regards,

Gary

We have the SAME EXACT PROBLEM..

This just started last week with us. Same year x5 as well. I did not see your post or I would have not started another.

Yesterday I pulled fuse #7 (5 amp) in the glove box ... Then in the back I pulled fuse #72 (30 amp) (its the first one from the top) and #73 that is 5 amps as well.

The radio still stayed lit up. If the radio is off manually then it should not draw on the battery. I think what is happening is the radio staying lit draws plus it allows something else to draw that takes the battery down.

My battery is new and only 1.5 months old so I know its not the battery.

I'm leaning toward the ignition switch and/or head unit.

Brandon

Weasel · #9 08-27-2008, 12:45 PM

unfortuneately there are so many control modules in these vehicles, and they all affect one another. The ingition switch tells other modules that it's on, telling them to turn on and give power to other modules, and so on. Odds are, if the radio is staying on, its because something is still feeding it power, not because it is bad itself. And whatever is staying on is probably keeping other things on as well.

You could play around in the WDS wiring diagrams through the link on the top of the page, and go further up the power supply tree and dig in elbow deep! Which is why most people bring this kind of shit to the dealer... to give me the headache instead... But from the sound of it, you have some electrical experiance and knowhow, and with access to the wiring schematics can make some headway. Just keep in mind that all control modules, some built into components like the radio... have to be programmed/encoded to the vehicle upon replacement. Requiring the dealer anyways!

teamgs · #10 08-27-2008, 08:51 PM

I have some new data...I decided to test the battery outside of the car, and there is no drain. So I think that the battery is OK. However, when connecting my multitester inline to the battery and the car, I get a 4 amp draw with everything supposedly off. No wonder the battery is be drained so quickly. Not sure at this time why my clamp meter didn't detect this.

I have currently pulled all the fuses in the back, and no difference.

I am looking for a module that another user said they removed behind the glove box. I am not speaking of the final stage resistor , though.

Sooo...no answer yet, but still digging!

Thanks for all the help!

Gary

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