Cessna 210 charging problem

"John Clonts" writes:

I am now able to reproduce my charging problem.

Engine off, Bat and Alt on:
Bus voltage: 24.8
Supply to Voltage Regulator: 22.6
Voltage Regulator Output to Alt Field: 21.6

I'm thinking maybe I should rig a jumper from Bus to the Voltage regulator
to see if the problem has to do with that 2.2v drop through the "Alt/Reg" 5A
circuit breaker, the Alt side of the master switch, and the Overvoltage
relay.

Any comments from you electrical gurus out there?

Those readings sounds almost OK to me....

a) I'm assuming the bottom end of the field is grounded.

b) With the engine NOT running, the voltage regulator keeps
thinking "More power, Scotty" and raises the field voltage
as far as it can. The 1 v. drop across the VR sounds fine
to me.

c) The 2v drop from the bus to the VR-in is bothersome. You can
find such 2 or 3 ways. [Or rather, if it was legal for you to...]

1) Using a DVM, put one probe on the bus, and the other on the VR
input. Set to 2v fullscale. Still see a drop that big? Leave the
one probe on the bus, and move the other one one step upstream. Is
that a fuse/breaker? Iterate until you see what point has the drop.

2) Leave it on for a while and then FEEL for the hot connection.
But see 3)....

3) If the other poster is correct, the field resistance is ~~15 ohms,
vs the ~3 ohms of an auto 50A/13.8 volt alternator. That means the
max field current is ~1.8 amps. That feels low, but I've not worked
on a 28VDC system in decades, and then it was not the alternator..





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