Gdetrailer wrote:
You have a built in "regulator" (older alternators used a separate regulator which was often mounted near the battery), many newer alternators also communicate with the vehicles BCM (Body Control Module) and the BCM will control the alternator rotor current and has charging curves that it will follow.
Thanks for your long explanation on how altenators work. I already was aware of most of what you said as I used to be an EE before retirement.
However I'm not sure that I laid out any "misinformation" in my long post explaining what happens in my case - including what is implied and stated in Ford's published performance specifications for their V10 engine 130 amp alternator. Our motorhome came with twin coach batteries and I doubt that Winnebago would expect them to burnout/destroy/blow fuse links/whatever on the chassis alternator system under any conditions that these batteries might be in - including them being completely flat. Our Ford motorhome has a computer controlled 5-speed (6 speeds internally) TorqShift transmission, so most likely the altenator also has what you call a BCM to go along with the other computers on board. It's indeed keeping the alternator from over-heating under heavy current loads - probably as you say via control of rotor current - hence protecting it during recharge of low RV batteries ... as I would expect to be happening. By the way, our motorhome's engine has a huge radiator fan that of course does two things - it sucks air through the radiator to cool it and pushes air back onto the alternator to cool it. Just as a side point, our motorhome can continue to travel with a blown alternator .... just run the built-in generator when going down the road and tape the boost control "ON" so that the generator is supplying all engine current by means of the coach and starting battery being all connected together in direct parallel ... as Winnebago designed it.
Regarding flat vehicle batteries - I have throughout my life had some "flat" vehicle starting batteries and after jump starting the engine - let the engine idle for hours to bring the flat battery back up. This is even including 1950/1960's era engines with their vintage generators and alternators in cold Michigan winters. I'm of the opinion that modern alternators are capable of more than we think.
The marine community expects a lot out of their boat engine alternators all the time and I don't think that all of their marine engine alternators are necessarily the special marine versions with sophisticated battery charging circuits built in.
I doubt that ambulance packages include better technology alternators .... just maybe a bigger one, or maybe two instead of one, of the same type that came stock on my E450 chassis.
