Masters degree credit available for alternator charging question

[sfedeli3]

Gary,

You had to spin-up the original Motorola and Delco-Remy alternators
to pull-in/excite the field. If you get a new/used Leece-Neville
alternator, you will see an immediate charge (self-exciting). My coach
had the same behavior when I would first power up. Usually, I would
not see any charge until I hit the highway and got the revs up over
2000, then the amps would peg-out at 150 or so for a while and slowly
come back down to 50 or so. My new Leece-Neville shows a 14.2 volt
charge at 50 amps as soon as the engine spins over and starts. The
amps slowly drop back as the batteries get topped off again.

Shane Fedeli
85PT40
Hershey, PA

. --- In WanderlodgeForum@yahoogroups.com, "hippieforever3"
wrote:
>
> I'm posting this here rather than the FC forum bcause it may be a
> generic issue across models.
>
> I've looked a few diffent versions of the charging / starting
> schematics and can't find anything that explains what I'm seeing.
>
> Consider this sequence;
> 1. Turn on master power switch in the battery compartment
> 2. Observation - dash voltage is showing 12+ to 13V, no current
> 3. Turn ignition key
> 4. Observation - dash voltage momentarily drops to 10.5V
> 5. Engine starts
> 6. Observation - Dash voltage rebounds to approx. 11.5V, no current
> 7. Momentary tap on the throttle, approx. 1500rpm or more
> 8. Observation - Dash current now showing +50a to 100a, voltage starts
> to climb toward 13-14 volts
>
> It's steps 6 - 8 that mystify me. I can understand the voltage
> rebounding after the starter surge but why no current before revving
> the engine?
>
> This implies a relay somewhere that only kickes in after a little rpm
> rev. I don't see it on any of the various BB schematics I've got. Is
> there an internal relay in the alternator?
>
> Has anyone else seen this or do I have some "custom" configuration?
>
> Movin on,
> GPSGary
> 1984FC35
>