[RPA8888]

Checking with any M50i owners on this.

I've read that when BMW developed the N63TU3 engine, in order to improve fuel efficiency, they engineered a feature where the power to the alternator is disabled unless the car is coasting (foot off of the accelerator or brake) - meaning that the alternator therefore is not providing power regeneration to the battery. I've tried to study any available information on this that may correlate this to owners having problems with the battery output as a result. I also read something (and this may or may not be factual) where BMW replaces batteries periodically because of the root problem.

I would be interested to know if any M50i owners are experiencing or have experienced any battery related or charging system related issues.

Thanks.

[Blue87]

If that was the case, then I don't believe the battery would be able to maintain charge with my driving style. It's been about 15 months and I have yet to experience issues with the battery. If that is how the system is designed, then maybe it topping the battery off during morning preconditioning.

[mmm50i]

I’ve had my car since Nov 2021 (MY22), never experienced any battery issues. My driving is 80% city and 20% hwy.

[pshovest]

BMW has used a similar charging strategy since the E60. It reduces fuel consumption. It is also misunderstood and frequently mischaracterized. BMW monitors the battery's charge-discharge current and regulates the alternator's output to keep this current close to zero. The electrical system determines the battery's State-of-Charge (SOC) during the sleep cycle and will adjust the charging profile to keep the charge between 60-80%. Earlier Bimmers had the ability to only charge the battery during overrun, but this only occurs if the battery's SOC is over some threshold, ~80%. G05's likely use a similar strategy. The system is complicated, it works and results in excellent battery life. My '15 435i's original AGM battery will be 10 years old next month. My E60 & E70 battery life is almost as good at >8yrs. Plug a voltmeter into the cigarette lighter and monitor it as you drive.

[TurtleBoy]

BMW has used Brake Energy Regeneration on its vehicles starting in 2008. We have not seen any battery issues due to this.

[RPA8888]

Originally Posted by pshovest

BMW has used a similar charging strategy since the E60. It reduces fuel consumption. It is also misunderstood and frequently mischaracterized. BMW monitors the battery's charge-discharge current and regulates the alternator's output to keep this current close to zero. The electrical system determines the battery's State-of-Charge (SOC) during the sleep cycle and will adjust the charging profile to keep the charge between 60-80%. Earlier Bimmers had the ability to only charge the battery during overrun, but this only occurs if the battery's SOC is over some threshold, ~80%. G05's likely use a similar strategy. The system is complicated, it works and results in excellent battery life. My '15 435i's original AGM battery will be 10 years old next month. My E60 & E70 battery life is almost as good at >8yrs. Plug a voltmeter into the cigarette lighter and monitor it as you drive.

Good information. Thanks.
It appears that the technical review that I read was possibly a partially-informed or ill-informed over simplification.

[jad03060]

Depending on how and where you drive, you might want to periodically put the battery on a maintainer charge, especially in the winter where especially during startup with all of the electrical loads from seat heaters, steering wheel heat, armrests, rear window, lights, and just the starting process, can suck a lot of power out of the battery...and, the cold temperature will decrease the ability to output power, too. A long highway trip because there's often not that much opportunity for regenerative activation of the alternator may not help, unlike a more conventional alternator operation. BMW tends to use a monster alternator and AGM batteries, so when it deems it's time to recharge, it can dump a fair amount into one.

It all depends on your use pattern. For the average person, it works fine and saves some fuel. My first BMW after I retired, did not see regular use, and needed a battery after a year. I then started to put it on a battery maintainer and the next one lasted 7-years...your results may differ!

[RPA8888]

Originally Posted by jad03060

Depending on how and where you drive, you might want to periodically put the battery on a maintainer charge, especially in the winter where especially during startup with all of the electrical loads from seat heaters, steering wheel heat, armrests, rear window, lights, and just the starting process, can suck a lot of power out of the battery...and, the cold temperature will decrease the ability to output power, too. A long highway trip because there's often not that much opportunity for regenerative activation of the alternator may not help, unlike a more conventional alternator operation. BMW tends to use a monster alternator and AGM batteries, so when it deems it's time to recharge, it can dump a fair amount into one.

It all depends on your use pattern. For the average person, it works fine and saves some fuel. My first BMW after I retired, did not see regular use, and needed a battery after a year. I then started to put it on a battery maintainer and the next one lasted 7-years...your results may differ!

Good information.
I have my 911 on a CTEK maintainer. I probably will do the same thing with the X5.