Voltage Drop with Load

[tgtaylor64]

I have grown accustom to my CUCV operating perfectly (alright, just well) and then all of a sudden, develop a weird problem. My recent one is that now my voltmeter will slightly deflect when I turn my headlights on, brake, or even hit the turn signal. It will track with the turn signal flashing! In the past, it was solid in the green, now it is slightly less then I put on a load. Voltage at the batteries while running at idle is ~14.5 VDC. Any suggestions?

 

[cranetruck]

If the volt meter is wired to the batteries there should be no visible deflection for light loads. If there is a resistance between the battery and the load and the volt meter is wired to the load side of that resistance, you will see a deflection.
Check you connections, a poor connection is equal to a resistance and will cause an undesired voltage drop...

 

[cranetruck]

If the volt meter is wired to the batteries there should be no visible deflection for light loads. If there is a resistance between the battery and the load and the volt meter is wired to the load side of that resistance, you will see a deflection.
Check you connections, a poor connection is equal to a resistance and will cause an undesired voltage drop...

 

[lindyp38]

so its not alternator related?

 

[Keith_J]

Alternators are directly connected to the batteries. If you are seeing voltage drop on the dash gauge, then the issue is in the bus where the volt meter is connected. I don't have the wiring diagram handy, just trace the meter to where the loads are connected. Sounds like a bad connection, probably ground connection. Corrosion is the likely culprit.

 

[Keith_J]

I replied to this thread, only to have a volt meter issue arise . The gauge is dead on startup, hitting the panel around the gauge brings it alive and functioning proper.

I took the bezel off and connected a volt meter to the connector, it gets voltage so I cleaned the connections with no improvement. The voltmeter measures 530 ohms on the bench and reads properly at 28 volts input.

I am perplexed. I think the meter doesn't like the mounting stress. Still have to test the volt meter relay. Will do the Doghead mod while that relay panel is out.

 

[doghead]

Could be a bad voltmeter relay.

 

[Keith_J]

It was the meter itself, the needle was getting pinched between the dial back and the glass. I took it apart by carefully prying the crimped bezel, then carefully bent the needle. Checked it out with 28.8 volts from a regulated power supply before crimping it back together. It is now in the replacement parts box.

 

[forest522]

Interesting, who would have thought it was so simple as a pinched needle. I would have spent hours tracing wires and uttering new curses.

Did I understand correctly that the volt meter is made to read 24 vote but is somehow reduced inside to receive and show a 12 volt reading?

 

[Keith_J]

Interesting, who would have thought it was so simple as a pinched needle. I would have spent hours tracing wires and uttering new curses.

Did I understand correctly that the volt meter is made to read 24 vote but is somehow reduced inside to receive and show a 12 volt reading?

The first clue was the meter needle would move to correct position when I banged the dash with my fist. But this solution was getting more painful so the root cause had to be found. I tested the voltage going to the meter, it was fine. So I determined it was a meter issue.

I got a replacement which afforded me the luxury of taking the old one apart. And I managed to fix the old one so all is good.

 

[cpf240]

The meter, for some dumb reason, is rated for 12v. There is a resistor on the back of it to allow it to function correctly with the 24v that is supplied to it. Should have just used a 24v rated meter, like the other MVs use.

 

[donalloy1]

Clean all landings on Buss and apply liberal coat of Penetrox A-13. You will be very happy with results!