Can Grounding straps / Grounds cause OVERCHARGING?

[Hotshot]

Still fighting my strange over voltage situation. After a new Valeo Alt/VR and every Motor checked, and grounds checked.


Battery is perfect, and other than motors drawing, I can’t figure out what’s causing this. Maybe I got a bad new Alt vr, but ,h old one was doing the same thing....

Every time I think I solved it, it’s all good for a bit and then comes back. Normally at a light at idle and I see the voltage doing it’s 13.2-14.7 dance light on. Step on gas, up to 15.5 it goes and the central locking light glows bright. I know if I turn the lights off all hell will break out.

Then I will start it up again and it will be all good. Just holding 13.8-14.2 like a rock pending on if the heat or lights is on..

So I’m putting it on the lift and pulling the ground strap and cleaning it.

I’ve done every other ground point. So polished it’s shiny.

Thoughts.

http://https://youtu.be/p3V0Cf1Meio

[john walker's workshop]

Warranty the Valeo and try another one. I've had good luck with them, so far.

[Hotshot]

Originally Posted by john walker's workshop

Warranty the Valeo and try another one. I've had good luck with them, so far.

Das ist der plan Monday.

[Tea Tray]

Did you check both ends of the ground and alt output wires?
Battery connections, chassis ground points, including the hard to access ones in the front and by the fuel filter.
More than once in 40 years I’ve found bad battery connections cause both under and over charging issues.

[Arctic Rat]

Have you confirmed the accuracy of the gauge, with a second one directly to the battery? Just a thought

Joe D

[Hotshot]

Originally Posted by Arctic Rat

Have you confirmed the accuracy of the gauge, with a second one directly to the battery? Just a thought

Joe D

yes.

[bickyd]

I am by no means an expert on these cars. Diodes in alternators can fail gradually and allow more alternating current than designed for. They also block the direct current from the battery to the alternator field wiring. When they fail partially , the direct current can energize the field coil windings and set up an electrical flux. The line resistance of the copper in the winding is enough to cause a parasitic draw and drain batteries just as the alternating current passing through the diodes can overcharge and gas out a battery. You can test the alternator from the positive terminal and the frame of the alternator for both A/C and D/C outputs with a meter while the alternator is out.

[Hotshot]

Originally Posted by Tea Tray

Did you check both ends of the ground and alt output wires?
Battery connections, chassis ground points, including the hard to access ones in the front and by the fuel filter.
More than once in 40 years I’ve found bad battery connections cause both under and over charging issues.

I did. Turns out one of my ground straps Was pretty bad. Replaced all of them.

Also, Upon Further digging as to why my heat quit ( during the overvoltage issue ), My own solder joint gave loose and was probably bouncing around arcing the motor causing this issue.

It was this issue that i isolated before with this problem. Bucked up and got a new motor on order.

With the Ground straps new and the grounds mirror shiny the voltage is BANG ON.

Little embarrassing but I think its fixed.

[Hotshot]

Originally Posted by bickyd

I am by no means an expert on these cars. Diodes in alternators can fail gradually and allow more alternating current than designed for. They also block the direct current from the battery to the alternator field wiring. When they fail partially , the direct current can energize the field coil windings and set up an electrical flux. The line resistance of the copper in the winding is enough to cause a parasitic draw and drain batteries just as the alternating current passing through the diodes can overcharge and gas out a battery. You can test the alternator from the positive terminal and the frame of the alternator for both A/C and D/C outputs with a meter while the alternator is out.

Good to know. I should try this with my 3 spare SC ( not 3.2 ) Alts to learn this!

[bickyd]

This site and the members have helped me exponentially, I am delighted to give back any way I can.