Alternator cold and hot set points

[Yoshimura]

My UHG description states that

The PROMASTER-280XP-SE g/u alternator uses a special internal voltage regulator ... has a set point of 14.7 volts cold and 14.2 volts hot if batteries are at full charge.

I know regulator have a set point but what are cold and hot set points? Are they related to the alternator temperature?

[booster]

Originally Posted by Yoshimura

My UHG description states that

The PROMASTER-280XP-SE g/u alternator uses a special internal voltage regulator ... has a set point of 14.7 volts cold and 14.2 volts hot if batteries are at full charge.

I know regulator have a set point but what are cold and hot set points? Are they related to the alternator temperature?

No external regulator like a Balmar?


The alternator is a Nations but made by DC Power Engineering and is based on Denso designs. Our original upgrade was to a DC Power 250XP so it would have the same internal regulator as have, I am pretty certain.


The way ours behaved was similar to what DC Power had related to me. It was said to have 3 stages of turn down of the output, which was actually a change to the field voltage, but it also turned down the output voltage with the amps reduction. It did not start to taper off the output until over 250*F, measured at the laminations on the case, which is pretty hot. The output post (where a Balmar would measure), was small amount cooler most of the time. If not charging a lot of amps it didn't do the heat cutback, but did reduce the voltage output based on some internal algorithm, I think. Once we had driven over an hour, approximately, it would drop to about 14.3-14.4v of output and then periodically drop zero for a short time before turning back on and going back to 14.3-14.4v. This was apparently to check the system battery voltage to see if it needed further heavy charging at the high voltage. If I turned on the heater fan to full speed while it was off, it would come back on at 14.7v as it thought the battery was lower.


I always thought the 14.4-14.7 voltage was too high for long drives which could be on full batteries, so I got a lower voltage regulator from DC Power, that ran at about 14.4v initially and dropped to about 13.8v after a while, so much better for the batteries. I don't know if they still have that regulator available. Ours has been removed because we are no using the remote regulator setup, but it is around here someplace so it might have number on it.