Generator question

R

RichBooth

Junior Member
My Model A Ammeter always bounced into charging when the engine was running at medium idle or better. The other day, I noticed it never went above zero. When running, battery voltage seems to stay at 6.15v

Since noticing that I added a 6v relay in anticipation of adding 12v LED headlamps. The relay “chatters” something fierce, a sign something is up with my power.

How does one test a generator to see if it is running properly.
 
Are you running a cut-out alone? Or do you have some sort of voltage regulation?

The 6.15 kind of indicates no charging from your generator. I would expect a battery being charged to be in the 7.2 to 7.8 volt range.

Joe K
 
Are you planning to go 12-volt? Adding 12-volt anything to a 6-volt system is confusing to me. Do you still have a 3-brush generator?
 
You won't get 12V out of a 6V battery, relay or no. Boost converters are made only for negative ground systems. LED headlights are available in 6V, go with those.

If your battery is reading below 7V with engine at high idle, it is not being charged. Probably generator cutout or alternator regulator.
 
@rotorwrench @joe k

Have not installed anything but a 6v relay that energizes when the key is “on”. One leg of the coil goes to ground (+6v) and the other to negative stud on starter.

The plan is to use that relay to turn on a 6v to 12v converter that will power the headlights. Before I invested too much time, effort and green, I did bench test this and it works swimmingly. The converter will be mounted inside the headlight shell.

The problem I’m having, though, is separate from the above, because the 12v stuff is still sitting in my workbench (less the relay, which is chattering).

The generator is factory. It has the cutout on the top, but I did not open it, yet, because I don’t know what I’m looking for.
 
@badpuppy
At the risk of getting slightly off topic, but a valid conversation, my boost converter is isolated from ground, and the headlight switch is isolated, as well. I believe I should be able to run the booster without issue.
Booster
Lens
LED
 
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Sometimes just writing things down goes a long way to solving the problem. Placed on the “Super Spider Man Thinking Cap” and decided to see if the generator is, well... generating. It is. Open circuit about 21v. That lead me to think the problem must be in the mystery device called a “cut out”. I opened that, and near as I can tell, it is a double coil that opens a winding at certain current/voltage level. I did immediately see a small wire that was badly corroded and disconnected from common (ground). I suspect the cutout is the culprit.
 
"Have not installed anything but a 6v relay that energizes when the key is “on”. One leg of the coil goes to ground (+6v) and the other to negative stud on starter."


If your car has the ignition wired as it left the factory you can not use the
switch for controlling anything else.


Bob
 
Bob C said:
"Have not installed anything but a 6v relay that energizes when the key is “on”. One leg of the coil goes to ground (+6v) and the other to negative stud on starter."


If your car has the ignition wired as it left the factory you can not use the
switch for controlling anything else.


Bob
Click to expand...

The pop up switch fell apart and has been replaced with an on off switch. One leg of the switch goes to the 6v positive on the starter and the other goes to the points. I attached the relay to the normally open side that connects when the switch is on. It works fine when not running. It chatters when running.
 
The pop up switch fell apart and has been replaced with an on off switch. One leg of the switch goes to the 6v positive on the starter and the other goes to the points.
Click to expand...
With that set-up, when the points close, it's a direct short to ground.

What exactly is a "IPCW CWC-7006 7" Plain Round Conversion Headlight"? They just show the front of it. It appears to be a substitute of some sort for a sealed beam headlight.
 
I assume "6V positive on the starter" means your system is negative ground, in which case your booster should work ok. If that was a typo, then you may be disappointed. Check continuity between the two black wires. If they're common, then the converter is not isolated and will shut down if you try to connect it with common positive - unless, as you say the bulbs are completely isolated.

The points provide intermittent ground, opening to discharge the coil, which would cause the relay to chatter. You will need a separate switch to a solid ground point to operate the relay.
 
If the generator has a cut out relay then it's a 3-brush type. The cut out is only there to bring the generator on line after the engine starts turning it post start up. It works off residual magnetism from polarizing the generator field shoes.

These old systems only put out a limited amount of current to keep systems operational and charge the battery. When you start adding in a 6 to 12-volt inverter, it takes even more amperage to run the head lamps than normal and they already tax the system normally. If your going this route, you should consider converting it to a one wire alternator so that it can generate enough current to run those lights and the inverter.

LED headlamp bulbs don't focus well in the headlamp reflector so be aware that they may be brighter but they may not have any reach for distance in front of the car. Halogens would likely do a better job but you may want an alternator either way.
 
The converters these days are very efficient, LEDs even more so. Rich's setup will probably burn maybe 10W total as opposed to 70W with 50CP bulbs.
 
Any pictures of the generator and cutout? You mentioned 2 coils, so it sounds like a 1932 or later generator with a cutout coil and voltage regulator coil. These were used on early Fords with a radio installed. Need pictures or more description to know what you have, but your mention of 21 volts tells me the generator is putting out fine, but the cutout isn't closing to connect the generator output with the battery.


BTW, I have seen the fine ground wire broken from the ground connection several times, and if you are lucky you can just solder it and things will be fine again.
 
The LEDs may not use much of any power but the inverter has to use power just to boost the voltage no matter what the load is. How much, I don't know but it's just one more component to crap out on you when driving at night. I always carry an extra incandescent bulb when driving at night. I never had any problems seeing down the road with standard bulbs. I don't drive it much at night though so it's not much of a worry anymore.
 
rotorwrench said:
The LEDs may not use much of any power but the inverter has to use power just to boost the voltage no matter what the load is. How much, I don't know but it's just one more component to crap out on you when driving at night. I always carry an extra incandescent bulb when driving at night. I never had any problems seeing down the road with standard bulbs. I don't drive it much at night though so it's not much of a worry anymore.
Click to expand...
Same with me. My 28 has all stock original lights, and it shines down the road just fine. My reflectors are original and have good silver plating.
 
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