Technical battery drain issue.. Please help!
Posted: Thu Nov 17, 2011 11:57 pm
Hi guys, just picked up my new to me 2007 misano red RS4 last week and first off I must say what an incredible car. It is everything I was wanting and more. I looked the car over top to bottom when purchasing it and it is in great condition. Everything works flawlessly, great service record, and I was convinced it was in perfect health....until I left it parked without driving it for about 10 hrs and came out to a dead battery.
Being an engineer I measured voltage acrossed the bat with a meter and it was 8 volts....realllllly dead...and noticed the bat was recently replaced about 2 months ago indicated by the Sticker on the side of the battery. I found this strange as I didnt remember leaving anything on or open. So I put the bat on my digital charger which said the battery was still servicable and brought it back up to full charge slowly over many hours and placed it back in the car. I then went for a drive and everything was great and working properly. Voltage with car running was ~14 volts so alternator is doing its job. Got back home and parked the car, turned it off, unbuckled, opened the door, closed the door, locked the doors, and sat in the car for a few moments to see if I could find anything obvious staying on draining the bat. Well...good thing its quiet in my garage cause very faintly I could hear the fan in the back of the navigation unit on. I know there is a shut down period for things like that and thought maybe if I sat in there it would turn off after a period of time....well i sat in there for 1 whole hour and it was still on.
So my next step was to measure exactly what was going on in terms of current drain on the battery. So i hooked up my Fluke multimeter to the battery and positive lead to measure current. Took the key out of the ignition, opened the door, closed the door, locked the doors, and waited a bit for the car to go to sleep. The lowest the current draw got to after about 20 mins was 3 amps! or 3000mA. No wonder I had a dead battery! So next I pulled the 20 amp fuse titled "radio" from the panel and repeated the same test. Current draw was all the way down to .3 amps or 300mA. This was a lot better but still higher than what I knew it should be. So then I also pulled the 10 amp fuse titled "Instrument Cluster and Navigation" and performed the same test again. The current drain then read a mere .04 amps or 40mA which is a very acceptable reading and would last weeks at that level before the battery was dead.
So ive identified the problem....something is keeping my navigation unit and stereo amps from turning completely off! I need suggestions on where to go from here guys. So far I have two ideas but would love you guys to chime in and let me know what you think.
1. My nav (rsn-e) is on firmware version 0150 which is a somewhat older version, and I have read places that there is a bug with some combinations of ecu and nav software versions that keeps them from communicating properly and the nav from properly shutting down completely.
2. Whenever the instrument cluster is on in the car there is a faint "buzzing" that comes from behind the cluster area. I know there are several relays mounted behind there and I am wondering if one is bad, as bad relays commonly buzz, and it is not fully dis-engaging when it should be, letting just enough juice through to the nav to keep it awake even though it shouldnt be.
Sorry my first post is so long and technical but I am anxious to get this little issue taken care of so I can get back to enjoying this incredible car. Thank you in advance for any suggestions, help, information, or ideas. Look forward to enjoying this forum.
Being an engineer I measured voltage acrossed the bat with a meter and it was 8 volts....realllllly dead...and noticed the bat was recently replaced about 2 months ago indicated by the Sticker on the side of the battery. I found this strange as I didnt remember leaving anything on or open. So I put the bat on my digital charger which said the battery was still servicable and brought it back up to full charge slowly over many hours and placed it back in the car. I then went for a drive and everything was great and working properly. Voltage with car running was ~14 volts so alternator is doing its job. Got back home and parked the car, turned it off, unbuckled, opened the door, closed the door, locked the doors, and sat in the car for a few moments to see if I could find anything obvious staying on draining the bat. Well...good thing its quiet in my garage cause very faintly I could hear the fan in the back of the navigation unit on. I know there is a shut down period for things like that and thought maybe if I sat in there it would turn off after a period of time....well i sat in there for 1 whole hour and it was still on.
So my next step was to measure exactly what was going on in terms of current drain on the battery. So i hooked up my Fluke multimeter to the battery and positive lead to measure current. Took the key out of the ignition, opened the door, closed the door, locked the doors, and waited a bit for the car to go to sleep. The lowest the current draw got to after about 20 mins was 3 amps! or 3000mA. No wonder I had a dead battery! So next I pulled the 20 amp fuse titled "radio" from the panel and repeated the same test. Current draw was all the way down to .3 amps or 300mA. This was a lot better but still higher than what I knew it should be. So then I also pulled the 10 amp fuse titled "Instrument Cluster and Navigation" and performed the same test again. The current drain then read a mere .04 amps or 40mA which is a very acceptable reading and would last weeks at that level before the battery was dead.
So ive identified the problem....something is keeping my navigation unit and stereo amps from turning completely off! I need suggestions on where to go from here guys. So far I have two ideas but would love you guys to chime in and let me know what you think.
1. My nav (rsn-e) is on firmware version 0150 which is a somewhat older version, and I have read places that there is a bug with some combinations of ecu and nav software versions that keeps them from communicating properly and the nav from properly shutting down completely.
2. Whenever the instrument cluster is on in the car there is a faint "buzzing" that comes from behind the cluster area. I know there are several relays mounted behind there and I am wondering if one is bad, as bad relays commonly buzz, and it is not fully dis-engaging when it should be, letting just enough juice through to the nav to keep it awake even though it shouldnt be.
Sorry my first post is so long and technical but I am anxious to get this little issue taken care of so I can get back to enjoying this incredible car. Thank you in advance for any suggestions, help, information, or ideas. Look forward to enjoying this forum.