I have a 2011 S Clubman. I know this is the R56 side but you guys get better responses than the R55 side.

A few days ago I was cruising on the highway. I downshifted to pass someone and the dash suddenly lit up like a Christmas tree. I lost power steering, the indicators, ac, radio all stopped working. I tried pulling over and once my RPM was under 3000 everything went back to normal. I tried recreating for troubleshooting. If I start driving normally, (slowly) shifting at 3000 or below, I have no issues. If I drive spiritedly, once I get over 3k the symptoms reappear. I have an ultragauge which shows 18/ 19+ volts when the symptoms appear. If I push in the clutch and the RPMs drop below 3K, the car goes back to normal. I get 14 volts at idle, car starts the first time every time with no issue.

I've seen alternator voltage regulator issues in the earlier R56 but don't know if the 2011 has that as well or if the voltage is controlled by the ECM. Don't know if replacing the alternator will fix the overcharging symptoms or if this is a ECM issue. Don't know what else could be the cause. Please help.

 

Like you said,, sounds like the voltage regulator. I am rather new to Mini's but have seen similar in other vehicles. Most modern voltage regulators are built into the alt itself and that is the only thing on the car actually producing voltage. I would look there 1st. Caution, over charging your battery for extended time periods can cause them to over heat and boil over. You might want to take a peak in your battery compartment as well.

 

Thanks. I’ll start there. I haven’t really driven it so no worries about the battery.

 

Sounds more like an alternator issue. The alternator is controlled by a PWM signal sent from the ECU. 18 or 19 volts is way out of line. The software on the S limits max voltage to 15 volts although they raised it to 16 on the JCW for some reason.

Something else I've seen is that lithium batteries have a charge controller built in that protect the battery from overcharging. Some of these are set as low as 14.8 volts. When it goes over that the battery disconnects and you loose everything momentarily. SatNav will reboot, power steering disengages, etc.

Charging voltage after start will be higher immediately after starting then settle down to 14-13.8'ish. From my testing the voltage will peak highest when the power steering is actively turning and the vehicle is accelerating while not fully warmed up.