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Hey guys, Ive had this issue with this new car since I got it and I have found a work around for it just so I can have the vehicle working every day but I would like to actually address the problem.
When I got the car, it would drain the battery while it was off and it wouldnt start. For a while I would ensure the car was being charged after work every other night but this got old. I have tried everything I can think of to address this. I have changed and registered the battery, tried 2 different alternators, replaced the IBS wire, cleaned the grounds, checked all the fuses inside and out. I even bought a FLIR to check to see what's draining the system when its off but nothing shows up warmer in either fuse box. I installed a remote battery cutoff from ebay, it automatically cuts the batteries connection if the voltage gets lower than 11.5v - so I dont have to worry about it dying every night now. This was my work around, but since installing an ultragauge and seeing my voltage while driving, I found another issue which may be related.
The ECM Voltage on the Ultragauge shows that I am oftenly over 15V (up to 15.8V) even if I charge the battery, this wasnt an issue before. I have had a lithium battery in the trunk for my audio system and once it started charging like this, my battery ballooned, so I ended up removing my system until this is resolved.
My next thought was to try another alternator, maybe I just got 2 junk alts, but I am sick of wasting money shotgunning parts on the car with no results. Unfortunately, the closest MINI shop is almost 5 hours away - so I wouldnt be able to have them dig into it. I read on a thread that someone had similar issues and their Stereo Image was what was causing parasitic draw, so that could be the issue, or possibly the ECM?
Im hoping someone can help give me some other ideas to try and diagnose this.
UPDATE: After getting a tune through Prototype-R, my voltage sits around 14.8V - so I no longer have the over volting issue!
Two different alternators, plus everything you've tried make me suspect the ultragauge is the problem. At the very least, I'd suggest throwing a "real meter" on the battery and confirming that the ultragauge isn't lying to you.
FWIW, I use a USB charger with a built-in voltmeter in my cars. It's a very simple way to keep an eye on your battery and alternator. You'll be able to see a worn-out battery before it leaves you stranded. About $10, and hey - you need a USB charger anyway, right? ;-)
Two different alternators, plus everything you've tried make me suspect the ultragauge is the problem. At the very least, I'd suggest throwing a "real meter" on the battery and confirming that the ultragauge isn't lying to you.
FWIW, I use a USB charger with a built-in voltmeter in my cars. It's a very simple way to keep an eye on your battery and alternator. You'll be able to see a worn-out battery before it leaves you stranded. About $10, and hey - you need a USB charger anyway, right? ;-)
It shows over 15V with a ZR13S and Autel Scanner. I will hook up a voltage gauge shortly and see if the voltage shows differently than the ODB2.
If you disconnect power from the alternator or starter or both, is the Grand Canyon-sized drain reduced?
The drain remained with the Alt unplugged, I have not tried the starter though. I will test and see.
I know 6A is a massive amount of draw, comparable to having 2 phones charging and a light on while the car is off. You would think with that amount of draw, whatever it is would light up like a christmas tree with the FLIR camera....
The drain remained with the Alt unplugged, I have not tried the starter though. I will test and see.
I know 6A is a massive amount of draw, comparable to having 2 phones charging and a light on while the car is off. You would think with that amount of draw, whatever it is would light up like a christmas tree with the FLIR camera....
I mentioned disconnecting the alternator and starter as they could be candidates for a high amperage draw. If you get no joy, set up your multimeter to monitor the 6A draw and then remove fuses (1) under the hood and (2) in the JBE one at a time to identify the circuit that is drawing the high current.
I mentioned disconnecting the alternator and starter as they could be candidates for a high amperage draw. If you get no joy, set up your multimeter to monitor the 6A draw and then remove fuses (1) under the hood and (2) in the JBE one at a time to identify the circuit that is drawing the high current.
I pulled every fuse inside passenger side and under the hood, including the relays and the draw remained. This is what left me scratching my head. I didnt know there were more under the fuse box, Ill give that a try too.
I pulled every fuse inside passenger side and under the hood, including the relays and the draw remained. This is what left me scratching my head. I didnt know there were more under the fuse box, Ill give that a try too.
Did you remove or voltage drop test the 4 fusible links in the A406 power supply fuse panel?
Are you doing the parasitic draw tests after the car falls asleep?
How old is the alternator? sounds like a bad diode causing a parasitic draw/ overcharge. did you unplug it from battery etc and test or just unplug communication wire green and black that goes to computer
Last edited by Jawa; Feb 2, 2026 at 12:21 PM.
Reason: wrong explanation
How old is the alternator? sounds like a bad diode causing a parasitic draw/ overcharge. did you unplug it from battery etc and test or just unplug communication wire green and black that goes to computer
The Alternator was change out twice, it had no effect. The 15V issue was solved after getting a tune flashed. I havent had an issue with voltage since.
