Parasitic Battery Drain e53
 

Hey Guys - I'm new to this forum. Have been on BimmerForums since 2007 for my 1998 M3 e36 vert and my wife's 2005 X5 e53 SAV -- but learned this forum digs deeper into the X5. I've searched for parasitic battery drain threads and found lots of theories (FSU, NAV, TSU, Aux Fan, Radio, gear shift light/sleep mode, etc.)

Our X5 has a parasitic battery drain that started June 5th. Replaced the dead BMW battery (don't know if orig, we're 2nd owner) and alternator tested fine, so thought we were good to go. June 27th, car won't start again -- jumped, runs fine. July 8th, no start -- this time alternator showing drain. Replaced (115K-mile) alternator with new Bosch. July 19th, no battery power again. Thru all of this, never any warning lights on dash.

Re-charged the battery. With multi-meter bridging disconnected neg battery cable/terminal, and all power off, still reads a draw of .40 amps. Pulled/replaced all fuses in glove box and trunk while watching meter for any drop to normal, but nothing.

Now my friend/indy mechanic is checking it. Has ruled out the radio, Aux fan, TCU, FSU, NAV, sleep mode. Today says it may be the electronic trunk latch and is doing further testing. Fortunately, he's not charging me by the hour for diagnostic and gave me a free loaner 325ci.

Can anyone weigh-in with other theories/thoughts? Thanks much.

The X needs to go to "Sleep" in order for the amperage to drop. If something is keeping the X awake, the amperage will never drop to the point that it doesn't drain the battery. Any after market options like a remote start or extended remote lock/open module installed?

Yeah, I'm aware of the sleep mode after 16 minutes -- light goes out on the gear shift. No aftermarket add-ons -- only a BMW aux kit for the radio/CD player and we've removed that just in case (and don't need anymore anyway).

Did you register your battery or simply did a swap? Many people say it's not required for E53 but doesn't hurt to do it. I did it on mine and never had any issues.

http://www.munichmotorsport.com/wordpress/?page_id=164

I'll check with my mechanic whether it was registered when installed. I think so, but not sure. Thanks.

The IBS service system listed E53s though and not dong so can result in "power consumption reduced" it says. I am staying in Campbell til the month of the month and i can help you register it using my Carly. I think the fee is only $10 (it doesn't go to me).

Not according to this post.

https://xoutpost.com/1064595-post2.html :thumbup:

Mine is the damn tcu again. The one that was in my X5 was bad completely and when reconnected killed the battery.

The new one worked fine for a few weeks and now its killing the battery but at least it still works.

I am SO replacing the entire stereo system in my X5 at the end of the month.

This will eliminate the tcu, nav disc unit, cd changer and the nav head unit with a radio that will completely turn off when I cut the car off.

I dreaded losing the ability to reset the mpg and such but its worth it for peace of mind not having to worry about a dead battery.

My tcu is waking up and draining the battery and sometimes it doesn't shut down at all to start with. Took awhile to verify it but that's what mine is doing.

Got mine out of the shop last week. Guy said it was the audio/nav module that prevented the car from staying in sleep mode. 4 years and 3 batteries later it's finally (hopefully?) gone.

My dads 2000 x5 has been having a battery drain also. We changed batteries, alternator, changed the Headunit, disconnected various components / pulled fuses trying to figure out where the draw was coming from. Dealership had it for 2 weeks and charged 700 for diagnosing saying it was the instrument cluster. Replaced that. Still killing the battery. Finally took it to a private guy that does independent diagnosing for dealerships in the area. He had it for a 4 hours and was able to get it fixed:

"Memory wire" on the head unit
Rear defrost
Headlight switch
And rear drivers side tail light

all drawing a current when the vehicle was "asleep". Not sure exactly what he did to fix the issues because his explaination was very technical. But my advice is to find someone that specializes in electrical. Not all dealers / Indies are able to handle these issues without throwing money at it. The last guy charged $400 and it was fixed 100%