Gen 1 high output....( over 16v )

[combatmech]

Howdy all,
I'm still having some electrical issues.
Both alternators have been re-worked, checked good and autozone. batteries check good at 12.3v prior to starting.

Cranks right up, Gen 1 light stays on, Gen 2 light goes out.

Measured voltage at front battery. Shows rapid discharge.

Checked voltage from Gen1...40 plus volts. ( flux from 40 to 55v )

Checked back battery voltage...12.2

Checked Gen2 output 14v

Checked voltage at positive and negative bus bars....fluxing...couldnt get a good reading.

Just to try something different...I unhooked the slave plug wires thar go to the bus bars. Hooked battery wires back up and gave it a shot. Truck wouldnt start...got a click from the starter but no crank.

Is the slave plug wiring really required to be hooked up?? Or can the whole thing be removed?

My voltmeter has not EVER worked.

Is it possible that something is wired backwards???

Very confused.....

 

[Krempely]

Hello from California!

My CUCV: '84 M1009 all original 24 volt (cigarette lighter added 2 years ago for power)

I have had a Gen 1 light on for the past 8 months. Took readings at Gen 1 (driver side alternator) and it was putting out 35 volts consistently. YEP 35 volts checked and confirmed. Gen 2 (passenger side) was putting out 24.6 volts. Oddly enough both batteries read 12.3 volts each with engine running. Obviously not enough to maintain the charge of the batteries. Had several experienced mechanics look at it and they were as confused as me. I swapped out the alternators with other CUCV alternators and NO CHANGE.

Any advice? And no, I don't want to convert it 12v. I like knowing that I can slave start any of my NATO equipped trucks and 12v would not help.

MVCC Northern Recon Group
Corey

'84 M1009
'86 M1008
'66 M35A2
'53 M135
'43 MB

 

[Keith_J]

This is a control issue, check voltage on the #1 and #2 terminals on the alternators. Then trace to the diode on the cab side. Use the diode check on your voltmeter, you know how to check a diode, right? Remove it from the circuit, then check for continuity using the red voltmeter lead to the anode (non-banded side of diode) and black to the cathode. Using the positive charge carrier notation, current flows from anode to cathode because "A" comes before "C", just a mnemonic. If you switch from the red-anode, black cathode to red cathode, black anode, the diode should be open. Diodes are check valves.

 

[combatmech]

Right...thanks Keith. The truck is in the shop...they found multiple issues. Still working on it.