Quote:
Originally Posted by BGBF18
Cool, thanks for looking that up. Would be awesome to know for sure.
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I've been made aware of other sources of info by BMW from a master/senior tech at the dealer I work at.
Turns out that BMW's S-Gate (which I did know of) has a Wikipedia like section called Technipedia (which I didn't know of), within this (amongst much other info! It's very interesting for a BMW geek like me!
) is a section for the Alternator in Drivetrain>Engine electrical system>Alternator>Intelligent Generator Control (IGR).
It starts by saying this was introduced 'Since about 2004', and 'In marketing, IGR is often also designated as "brake energy regeneration".' (which is the term we know for our M3s).
In this it describes switching off the alternator to save fuel and allow more of the engine's power to go to the wheels (when the battery has enough charge).
If the battery is at a high state of charge the alternator only charges on the over run/braking (something I've only ever seen on my long trip to the Nurburgring (I'm in SE England). I have a meter on the dash displaying volts, as well as ECT. When cruising/accelerating it was showing battery voltage of 12.3-12.6v ish, AFAIR).
If the battery charge is middling it'll only provide enough power for electrical consumers when cruising/accelerating and won't charge the battery (quite how it would stop any charge going to the battery it doesn't say, and personally I would make an educated guess that it doesn't. But that the charge rate is minimal. Voltages I see at this level are about 13-14v, ish
).
On the over run/braking it still charges at full capacity.
If the battery charge is low enough* the alternator will charge full time at full capacity, just like old fashioned charging systems. (I typically see in between 14-15v here).
*Annoyingly the techipedia doesn't say at what thresholds these different charging strategies are deployed!
Their is no mention of an alternator clutch, it talks about switching on/off the alternator (an ambiguous term), but more clearly it also mentions activating or energising the alternator, which to me is a clear reference to electrically switching it on.