3 Brush Generator

[sieber60]

My 54' panhead still has a 6 volt system and 52 series generator. Recently I discovered that when I turn the head lights on it starts running bad. I checked the voltage at the battery and it was 6 plus.... until I turn the lights on and then the voltage drops to 3 volts. I haven't tested the cut out relay yet but thinking that might be my problem. Probably will put a Cycle Electric generator on but want to trouble shoot first so I know what is going on.

Any thoughts are appreciated.

Thanks
John

[PRG]

Howdy sir,

Unlike the more primitive charging/control arrangement on Indians, or industry standardized format as seen with Miller and Lucas, HD’s is pretty unique. You essentially have two charging systems in one. For convenience we’ll call it primary and secondary. Fire up your machine, the cutout activates battery voltage to the smaller field coil for which the third brush regulates this reduced output to serve your non-headlight electrical needs. Switching on your headlight sends voltage to the second field coil which steps up secondary generator output to overcome that 4.5-5 amp load.

Compromised connectivity from ignition switch to that pole atop your generator or a poor internal connection/shorted field coil will result in no boost in output on the secondary side, and especially at low rpm urban riding, resulting in declining battery voltage as the primary is not designed to support full electrical system demand. Your third brush does not provide adjustment latitude to offset this shortcoming. Cycle Electrics are great but so is your stock generator. Converting to two brush operation with an electronic regulator will will making charging a non issue. In overview, as outlined in HD’s conversion instructions, without major alteration, you are joining both field coils, making a few internal wiring changes such that the two poles on your generator now serve as an armature brush output and field coil power input. Your new regulator will likely be 4 wire: a ground, an armature output, field coil input and battery voltage. I acquired a VTronic a decade ago (fits within stock cutout housing), an Erdos hollow shell which was then mod’d to accommodate to Lithium Iron 18 amp batteries in parallel and have not touched the charging system since.

[sieber60]

Peter,
Thanks for the info

After a little further investigation I checked the voltage at the battery with the switch in the on position and voltage was good I then checked the voltage at the battery with the switch in the lights position and found a drop to 1 volt... currently checking for loose wires as it seems like connectivity may be a concern.

I will post once a discovery has been made.

[T. Cotten]

Always start at the ground wire, John!

And check for resistance between the body of the generator and the motor case just in case,...

....Cotten

[exeric]

Always start at the ground wire, John!

And check for resistance between the body of the generator and the motor case just in case,...

....Cotten

I want to learn about these things, so, In case of what, Tom?

[T. Cotten]

I want to learn about these things, so, In case of what, Tom?

In case somehow the generator has become insulated from the chassis, Eric!

(Its much more prevalent with Indians, naturally.)

If the gasket is well goobered, and even the mounting bolts with the immortal Loctite,..

Then it is prudent to do a resistance check between the generator body and the frame; its a simple diagnostic before tearing your hair out.

....Cotten
PS: A ground wire might even fix it with no disassembly at all, but don't have it judged.

[exeric]

Thanks for the reply, Tom. I did have a ground problem with an Indian some years ago and it was perplexing. Appreciate the clarification.

[tfburke3]

Peter,
Thanks for the info

After a little further investigation I checked the voltage at the battery with the switch in the on position and voltage was good I then checked the voltage at the battery with the switch in the lights position and found a drop to 1 volt... currently checking for loose wires as it seems like connectivity may be a concern.

I will post once a discovery has been made.

If this is without running a drop to 1v is indicating a bad battery.regardless of a loose switch or ground wire,the battery is seeing enough load to reduce to 1v.The generator maintains the charge but charged battery should not show a drop to 1v as soon a lights are on.
Tom

[joe fxs fxr]

If this is without running a drop to 1v is indicating a bad battery.regardless of a loose switch or ground wire,the battery is seeing enough load to reduce to 1v.The generator maintains the charge but charged battery should not show a drop to 1v as soon a lights are on.
Tom

My thoughts too.

[sieber60]

All of the input is helpful. Thank you

Let me try to explain what I have done so far.

Battery was the first place I looked. I made sure I had a full charge and tested the voltage, it was 6V. Then I tested the Specific Gravity... 12.5 in each cell.

Checked all connections ( per advise above) after discovering that I had a voltage drop when the motor wasn't running. Found a few connections on the panel behind the tin slightly loose. Checked voltage again and found an improvement in voltage (Not running) with the switch in the light position.

Next I went for a ride and then tested voltage. running and not running. I found that the cut out relay either didn't send the correct request to the generator for an increase in output when the lights were turned on or the generator is not able to meet the demand.

With the bike running I could only get about five volts at the battery with the lights on.

Even if I convert to two brush or cycle electric I want to figure out what is going on, so all input is being considered.

John

[Jerry Wieland]

All of the input is helpful. Thank you

Let me try to explain what I have done so far.

Battery was the first place I looked. I made sure I had a full charge and tested the voltage, it was 6V. Then I tested the Specific Gravity... 12.5 in each cell.

Checked all connections ( per advise above) after discovering that I had a voltage drop when the motor wasn't running. Found a few connections on the panel behind the tin slightly loose. Checked voltage again and found an improvement in voltage (Not running) with the switch in the light position.

Next I went for a ride and then tested voltage. running and not running. I found that the cut out relay either didn't send the correct request to the generator for an increase in output when the lights were turned on or the generator is not able to meet the demand.

With the bike running I could only get about five volts at the battery with the lights on.

Even if I convert to two brush or cycle electric I want to figure out what is going on, so all input is being considered.

John

John The cut-out relay is not a regulator. It is a polarity sensitive switch. It's function is to close when the generator voltage is greater than battery voltage providing a 'route' for generated current to get to the battery. This situation only can happen when the engine is running and the generator generating. The cut-out relay opens when the generator voltage is lower than battery voltage. This situation should only occur when the engine is off or at very low RPM and prevents battery electricity from going to ground thru the generator and eventually draining the battery.

When you turn the switch to the light position unregulated current is sent thru one of your field coils in the generator and should boost generator output by the approximate amperage as needed for the lights - this amperage output is designed into the system and is not easily changed. This seems to be the step that is failing in your situation.

Jerry

[tfburke3]

You should be able to turn the lights on with the bike not running and the lights should stay bright and battery at full 6v for at least an hour or so.
Do a load test on the battery.A loose connection will lower the load on the battery ,tightening will increase the load with lower resistance.If you can test voltage do it under a load,lights on.Many chargers will indicate full charge which only means something if you have a good battery.A good battery will keep the lights on for along time and will fry the wiring with a short and no fuse.
Tom