2011 clutched alternator

[JHZR2]

Has anyone with a 2011 N55 setup noted a clutched "smart" alternator? Is there a new economy gauge with a battery picture on it?

I went to a comparison driving event at a local BMW dealer, and drove a 2011 535i. It has the smart alternator - clutched, water cooled. It was kind of neat. Keeps load off the engine, and then adds load upon deceleration.

It was kind of weird though... It would engage anytime that I let off the throttle, or so it seems. But there must be power electronics between the alternator and battery, because once I hit the brake enough, something would engage that would really slow the car fast.

It felt kind of like a car that is equipped with the emergency brake assist function, where when the brake is hit hard enough and it thinks it is a panic stop, it helps engage the brakes harder.

And depending upon the exact position of the brake pedal (pressure) it would either engage this clampdown or not. I believe this was the alternator, per the explanation the BMW rep gave to me.

Anyway, anyone else note this tech? Does the 135i have it?

Thanks!

[ORIGIN M.]

Enter BMW EfficientDynamics...

Not sure about the current 1er, but all these good things will slowly make their way into the entire BMW lineup!

[Bavarian MW]

This is a BMW technology not offered in the current 1 Series. You are correct that it is in the new 2011 5 Series model, as well as the newest 7 Series, and Active Hybrids. This technology will be making it into future vehicles, as stated. See the following link for the BMW information, specifically the part about the alternator! Hope this helps! --MW

http://www.bmw.com/com/en/insights/t...eneration.html


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Make use of every Watt: by charging the battery only when your BMW is braking, coasting or decelerating, Brake Energy Regeneration improves fuel efficiency by up to three percent and ensures that the full power of your engine is available for acceleration.

Today's vehicles require much more electrical energy than older models, due to the much wider array of electric and electronic on-board comfort and safety systems. This energy is created by the generator (also known as the alternator) which converts the engine's power output into electricity. In conventional systems, the generator is permanently driven by a belt connected to the engine.
BMW's Brake Energy Regeneration operates differently: the generator is activated only when you take your foot from the accelerator or apply the brake. The kinetic energy that would otherwise go to waste is now used efficiently, converted into electricity by the generator and stored in the battery.
Producing electricity in this highly efficient way delivers an additional advantage: when you apply the accelerator, the generator is deactivated - so the full power of the engine can be directed to the drive wheels. Brake Energy Regeneration thus increases fuel efficiency while simultaneously enhancing driving dynamics. As a safety precaution, the Brake Energy Regeneration system monitors the level of battery charge and will, if necessary, continue to charge the battery even during acceleration to prevent a complete discharging of the battery.

[jeremyc74]

It seems like the system on the 135i reduces charging when you're accellerating, but the alternator doesn't de-clutch like this new system.

For an example of what I'm talking about, when you sitting at a light, turn the A/C on and the fan at full blast, and rev the engine. You'll hear the fan speed drop because the voltage is being reduced. I think this is because the ECU thinks you're about to pull out.

Note: I've observed this only on my car with a manual transmission, and it only seems to happen after everything is up to operating temperature, or possibly once the battery has been topped off after startup.