Not Charging after Madd bypass.

-
French demon said:
Jos, I don't know what does mean "Fify", but you're right. :)
The ammeter bypassing eliminates some of bulkhead connectors problems. More precisely, the weakness of the little terminals of the two big wires of the ammeter which easily burn or melt the plastic connector under the alternator charge current amperage.

View attachment 1715931915
(picture from Madd Electrical website)

François
Click to expand...

Fify is Fixed It For You

I've seen plenty of bulkhead problems that weren't related to the ammeter wiring.
 
Typical alternator will charge up to 16v wide open but will normally self regulate via the functional voltage regulators limit of about 14.7v. The modern square back uses resistance to ground on one of the fields to regulate its output voltage. The points type regulators on the single field round backs uses duty cycle to average a 14.7v output over time, ie. an on and an off 12v 'excitation' duty cycle instead of a smooth regulation of power. If this theory helps In diagnostics....?
 
I see your point @French demon. When I restored my 69 Barracuda the first time in about 1994, I was under the dash and accidently crossed the hot post on the ammeter gauge to a post on the gas gauge with a wrench. I toasted the fuel gauge. That is when I learned two valuable lessons.
1) Any time you are up under the dash, disconnect the battery.
2) There is a hot 12 volt wire up under the dash just waiting to ruin your day.
 
Just a little update. I finally got it all figured out. I had 3 problems that I think all happened at the same time. The alternator and voltage regulator were both fried. Then to top it off the hot wire from the alternator was broken and shorted in a spot that you can't see with the blower on. I picked up an alternator and regulator and tried it. Still no joy. First test after that was to run a wire direct from the alternator to the battery. Instant success, charging at 14.4 volts while running. I had done this same test with the old alternator and there was no joy so that told me I had an alternator problem. I replaced the voltage regulator just in case seeing as they are cheap. I have now run a new wire to the starter solenoid and everything is working as it should, finally. I am not very good with electrical and a 3 part problem can really set me back a while. I am glad this one is over. The only thing I can guess is that the main charging wire shorted out and took the alternator and voltage regulator out with it.

Jack
 
Great news as I was watching intently. I ran a 10ga wire from the alternator (with a fusible link) to the Batt post on the starter relay and left all other wires intact. Battery is charging perfectly fine and ammeter is now just a dummy gauge. Still hooked up but not much, if any, charging current going through it. You can see discharge on it with the engine off if you turn on lights, etc but nothing else.
 
Coyote Jack said:
Just a little update. I finally got it all figured out. I had 3 problems that I think all happened at the same time. The alternator and voltage regulator were both fried. Then to top it off the hot wire from the alternator was broken and shorted in a spot that you can't see with the blower on. I picked up an alternator and regulator and tried it. Still no joy. First test after that was to run a wire direct from the alternator to the battery. Instant success, charging at 14.4 volts while running. I had done this same test with the old alternator and there was no joy so that told me I had an alternator problem. I replaced the voltage regulator just in case seeing as they are cheap. I have now run a new wire to the starter solenoid and everything is working as it should, finally. I am not very good with electrical and a 3 part problem can really set me back a while. I am glad this one is over. The only thing I can guess is that the main charging wire shorted out and took the alternator and voltage regulator out with it.

Jack
Click to expand...

Thanks for the update. It certainly is difficult to "see what we can't see" so to say...........
 
yes just be careful not to connect up the old wire again.... if the short isn't visible in the run in the engine bay it going to be at the bulkhead or under the dash

main protagonist when it comes to shorts under the dash would be an ammeter

they are held into the metal dash pod by their contact/ studs, which are insulated with plastic top hat washers through hole and fibre washers either side..... if those washers ware or melt alternator current flows direct to earth and you melt the main feed wire and potentially the bulkhead connector...and ...even worse stuff near by..

ammeter in this state can be fixed.. you just need to re insulate where the 2 fat studs pass through the guage caseing and do the inner and outer half height brass nuts up nice and tight.

Dave
 
Dave999 said:
yes just be careful not to connect up the old wire again.... if the short isn't visible in the run in the engine bay it going to be at the bulkhead or under the dash

main protagonist when it comes to shorts under the dash would be an ammeter

they are held into the metal dash pod by their contact/ studs, which are insulated with plastic top hat washers through hole and fibre washers either side..... if those washers ware or melt alternator current flows direct to earth and you melt the main feed wire and potentially the bulkhead connector...and ...even worse stuff near by..

ammeter in this state can be fixed.. you just need to re insulate where the 2 fat studs pass through the guage caseing and do the inner and outer half height brass nuts up nice and tight.

Dave
Click to expand...

I did the Madd bypass. There is no longer a direct feed to the dash. The ammeter has been replaced with a voltmeter in the new Intellitronix digital dash.

Jack
 
One thing not to overlook is to running an equal size ground cable to the alternator, and make sure you have a good ground to the engine block and chassis. I am putting coil on plug ignition with my EFI install and will ground each head too.

There is no reason to pass high amp loads through the bulkhead connectors. I put LED's inside the cabin of the car, move all high amp drawing circuit feeds to a 12V distribution lug under the hood and use relays on any circuit that has an amp draw of more than a handful of amps.
 
You must log in or register to reply here.
-

Back
Top