m35a2 over charging !

[BrandonZ]

I purchased my first m35a2 a month ago "1971" and noticed it wasn't charging the batteries "exciter wire wasn't hooked up" so I plugged it into a 24 volt wire and now it's over charging. I bought a new regulator and it didn't help.tried to adjust it with the screw and no change. So I bought a different alternator and still over charging. Batteries had 23.0 volts before I started it. i had to press starter switch a couple times to get it to roll over and it rolled slow but started. Wile warming it up I was watching the Guage and stayed in the green for about 15 sec then creped up into the red. So I checked the output with a multi meter and it's pushing 32 volts a keeps going up. Maxes out about 33.6 ish volts. I'm at my wits end with this thing. Any help would great. Oh and I cleaned up the wires at the alternator didn't do the frame side tho. Thanks

 

[gimpyrobb]

Your low voltage of the batterys might have blown both regulators. Can you recognize bad parts in a circuit? I'd pull the reg out and look. Might also try to charge/test the batterys individually. Might have a bad one.

 

[74M35A2]

The stock alternators use a remote battery voltage sensing wire. If this wire has no voltage on it when running, the regulator keeps trying to increase system voltage until it reaches the target set point. This is likely your issue. Check for voltage on all wires with ignition switch on but engine not running. Voltage over 29.0 will cook batteries fast. Modern alternators are protected against this, even the Chinese Delco clone units.

 

[rustystud]

The stock alternators use a remote battery voltage sensing wire. If this wire has no voltage on it when running, the regulator keeps trying to increase system voltage until it reaches the target set point. This is likely your issue. Check for voltage on all wires with ignition switch on but engine not running. Voltage over 29.0 will cook batteries fast. Modern alternators are protected against this, even the Chinese Delco clone units.

The M35A2 alternator only uses 3 wires. One is ground, one is power out and the last is 24 volt in from the Master switch to energize everything.

 

[BrandonZ]

Your low voltage of the batterys might have blown both regulators. Can you recognize bad parts in a circuit? I'd pull the reg out and look. Might also try to charge/test the batterys individually. Might have a bad one.

Even changing 2 alternators and 1 new regulator? The back battery was 10.35 volts and front was 12.+ volts when I went to start it. I'm sure that's why it rolled over slow but still started. But a bad battery could cause this problem? The original exciter wire was cut and with the switch "on" I checked for voltage and it's dead. And thee wire I have it hooked up to is #53. I think it's the water temp sensor wire but has 24 volts and makes the alternator start working. I know it's not the right wire but if the original exciter wire is dead and I need to kick in the alternator will this wire work. I got the truck with a mechanical temp Guage

 

[rustystud]

Even changing 2 alternators and 1 new regulator? The back battery was 10.35 volts and front was 12.+ volts when I went to start it. I'm sure that's why it rolled over slow but still started. But a bad battery could cause this problem? The original exciter wire was cut and with the switch "on" I checked for voltage and it's dead. And thee wire I have it hooked up to is #53. I think it's the water temp sensor wire but has 24 volts and makes the alternator start working. I know it's not the right wire but if the original exciter wire is dead and I need to kick in the alternator will this wire work. I got the truck with a mechanical temp Guage

I don't believe in "pick a wire any wire" kind of repairs. If your original exciter wire is bad then run a new one. Your only going to cause yourself more problems down the line.

 

[BrandonZ]

I checked out batteries and 1 was junk would this make it want to over charge? And yes I know I need to run a new wire just haven't got that far. I'm going to run a few new wires in this thing

 

[porkysplace]

I checked out batteries and 1 was junk would this make it want to over charge? And yes I know I need to run a new wire just haven't got that far. I'm going to run a few new wires in this thing

Not sure where your located but member Jeffmule (General Jims Surplus in Clare) was selling the new correct 6TL batteries for $125 last year when I replaced mine.

 

[BrandonZ]

OK so I'm going to buy new batteries but don't know what size to get. I don't want to buy something too small in CA or CCA it had 2 interstate workhorse 950 CCA batteries in it. So I'll get something close to that but what would be considered too small for this application?

 

[dmetalmiki]

As mentioned previously, re wire the trigger (sensing) wire. (do not wish to be too laborious ..but) the actual Power out and leveling attained IS governed by B.E.M.F. (yawn! (back electromotive force)) Phew..google it, it makes interesting reading and will help you understand what is going on. Good luck.

 

[porkysplace]

OK so I'm going to buy new batteries but don't know what size to get. I don't want to buy something too small in CA or CCA it had 2 interstate workhorse 950 CCA batteries in it. So I'll get something close to that but what would be considered too small for this application?

It guess it depends on how you plan to use the truck . If you plan on getting in water over the batteries 6TL's is the way to go as they are sealed . Also if you plan on driving it in the winter to small of a battery will shorten the life of your starter ( there is a reason most heavy equipment has at least 2 8D batteries) . Car batteries are probably fine down south , but here in michigan I will stick with 6TL's. I'm sure there will be other members that will argue these points.

 

[rustystud]

It guess it depends on how you plan to use the truck . If you plan on getting in water over the batteries 6TL's is the way to go as they are sealed . Also if you plan on driving it in the winter to small of a battery will shorten the life of your starter ( there is a reason most heavy equipment has at least 2 8D batteries) . Car batteries are probably fine down south , but here in michigan I will stick with 6TL's. I'm sure there will be other members that will argue these points.

Totally agree. I myself have two 6TL's in my truck.