Yet Another Generator Question! 1949 Roadmaster

[Dan O]

Generator/battery  problems persist - Someone at a parts shop said, "just disconnect the battery lead and if it dies you are not getting proper function from your generator".  Well, I did that and it died immediately.  Is that a valid test?  If not is there any kind of quicky test for this?

 

I have had my generator rebuilt and replaced the voltage regulator on my 1949 Roadmaster 76c - all bench tested.  I drove it a while and it suddenly died leading me to believe the charge was not getting from the generator to the battery.  I did polarize the regulator per the manual when installing the bench tested generator and regulator but then the regulator fried itself. 

 

So, I got a new regulator installed, wrapped any poorly insulated wires and tested all the ancient wires for continuity and they seem to be fine.  I would think it would be ok to hit the road but how can I test if the charge is getting from the generator to the battery itself?  If there is not some easy test I'll go to a shop.  It is just TOO  HOT in Houston to work on cars this summer but I got the ol' car fever bad.

 

 

Edited August 6, 2016 by Dan O (see edit history)

[Beemon]

Check the battery voltage and make sure it's ok with a multimeter. You'll know if it's being charged because the voltage at the battery should rise when the generator kicks in. I'm not familiar with 6V systems, to give any specific information, but that's how I've tested my generator and alternators before. 

[Guest]

49 minutes ago, Beemon said:

Check the battery voltage and make sure it's ok with a multimeter. You'll know if it's being charged because the voltage at the battery should rise when the generator kicks in. I'm not familiar with 6V systems, to give any specific information, but that's how I've tested my generator and alternators before. 

Greetings

        I read in the Buick manuals for these 30 amp generators that it takes 20 miles of "normal" driving to return the prestart state of charge after the load used by starter pulled from battery. I have a throttle set knob in the dash on my 39 Spec. After starting I raise the rpms and let it sit at a higher idle. The gauge stays centered for a moment, then jumps to full charge. Takes a few minutes, then comes back to center. If you "short cycle" by starting and stopping its hard for an old generator to keep up with drain load of starter. Generators dont even charge at Idle, which is why some switch to alternators. You can buy 6v alternators that look like generators and then save fuel and noise charging at idle! Competent generator repair folks ask U 2 bring regulator&generator both in to match the settings of the two.Hope this helps. The what ifs are too numerous for me to do long distance diagnosis. Good luck!

[49_buick_super]

4 hours ago, Dan O said:

...I did polarize the regulator per the manual when installing the bench tested generator and regulator but then the regulator fried itself....

 

 

Maybe, just maybe, the polarization didn't go right.  If the generator isn't polarized properly the points in the regulator can arc and burn.

Also, you mention old wiring.  Lots of room for charging problems there.  But if the regulator fried, I think you've still got problems in the generator.  If you've got the 49 shop manual, look at section 10-29-d.

 

Dan

[Guest]

48 minutes ago, 49_buick_super said:

 

Maybe, just maybe, the polarization didn't go right.  If the generator isn't polarized properly the points in the regulator can arc and burn.

Also, you mention old wiring.  Lots of room for charging problems there.  But if the regulator fried, I think you've still got problems in the generator.  If you've got the 49 shop manual, look at section 10-29-d.

 

Dan

If the generator isn't polarized it can turn into a motor. It's called "motoring a generator" very costly mistake on the big powerplant  units. If it's doing this and you remove the belt with the batt unhooked. Hook it back up, if juice it may spin for ya! Not good for car units either!

[Ttotired]

The battery disconnect method only works if the generator is producing enough power to run the engine, at idle, they normally arnt.

DO NOT DO THIS TEST WITH AN ALTERNATOR

I assume your car will have either an amp meter or charge warning light in it, if the light stays on after starting and giving the car a rev, its not charging.

If its an ammeter, same thing, it should swing over to high charge with a rev (this is not long after starting)

For those that dont know, generator systems are rather unforgiving if its not all set up right and without the correct gear, you cant set it up right, so my best advice is to take the wires off the generator, charge the battery overnight, then take the car (much better to set everything on the car) to a trusted auto electrician. All things being equal, you should get your car back in less than a day (giving them time to "work around" it), if somethings broken, then it might take longer

[old-tank]

22 hours ago, Dan O said:

...wrapped any poorly insulated wires...

 

 

Electrons flow over the surface of the wire strands.  If exposed the strands turn green and electrons don't flow readily.  Replace those wires or splice in new sections.