MHD/xHP and Battery Drainage

[Marcoose]

I've installed both MHD and xHP on the Z4 about 3 years ago.

Hopefully totally unrelated, but in the last 3 months I've been having massive issues with battery drainage. Something is staying on after the car is off. The battery is OE, 14 months old, and the alternator is brand new.

The thing is, Friday morning I've reverted both engine and transmission maps to stock for the upcoming SMOG test. And drove over 200 miles to reset all gizmos. And lo and behold, the battery stayed fully charged through the weekend. With the ongoing issue, I was expecting it to drop to approximately 60%. Go figure.

With all that, has anybody experienced problems with MHD/xHP and battery drainage ? Is there even anything in the MHD/xHP modules that could keep something on after power off ?

Thanks.

[cyam]

Originally Posted by Marcoose

I've installed both MHD and xHP on the Z4 about 3 years ago.

Hopefully totally unrelated, but in the last 3 months I've been having massive issues with battery drainage. Something is staying on after the car is off. The battery is OE, 14 months old, and the alternator is brand new.

The thing is, Friday morning I've reverted both engine and transmission maps to stock for the upcoming SMOG test. And drove over 200 miles to reset all gizmos. And lo and behold, the battery stayed fully charged through the weekend. With the ongoing issue, I was expecting it to drop to approximately 60%. Go figure.

With all that, has anybody experienced problems with MHD/xHP and battery drainage ? Is there even anything in the MHD/xHP modules that could keep something on after power off ?

Thanks.

I am running both. Neither has ever caused a battery drain issue, and I cannot figure how they could.

I have had battery drain issues. Took it to the dealer and they lazily just changed my battery (good for me, but they didn't really diagnose the issue). Still it did solve my battery drain issue - makes no sense.

[Marcoose]

Thanks. I’ve reverted the car to stock two weeks ago, and the drainage continues. Obviously it’s not the new maps.

[smokinu454]

Were you leaving your wifi adapter plugged in? If I leave mine in and the car sits for more than a day I get the battery discharged error on startup. If it’s unplugged, no discharge. Happens every time, same story on my last F10.

[Marcoose]

Ha! Good point. No, it's been unplugged for months.

The battery drainage was happening even with the car in stock mode.