Lighting Coil Voltage

[ticktock]

Hey all,

 

Here is a question I have. I believe I have the answer but I will share the problem and share my thoughts and see what you guys think.

 

My tail light blows bulbs as fast as I can put them in. I turned my lights on the other day and the first one in the circuit, right side, brighter than the left. I pulled out my Fluke and tested the stator and I get 20 - 22 volts at idle. I then plugged in the stator power wire to the loom and tested for power at the tail light. I had 7.2 volts at idle. On the head lights I had 8.1 - 8.4, and on the left I had 7.4 - 7.8. What could be causing this?

 

I think that I may have a bad voltage regulator. I guess that I could have pulled the wire on the voltage reg. and tested the circuit again without the lights hooked up in case they blow. I should have troubleshooted some more but I didn't have the time to do this. Also, is ground going to play that big of a role in this? The loom is grounded well, on metal without paint. I soldered all of my connections after making cuts to the loom for changing my wiring around. I had the tail light problem previous to changing things around but I don't remember the lights being so dim. I revved it up a little but it was hard to test the circuit and it did not change the volt output. The stator output did go up to 23 when revved.

 

Thanks for your time, This is one of those questions you think you have the answer but sometimes its better to ask around and see what others think.

 

Adam

[Surfrjag]

someone correct me if im wrong but i think the voltage regulator is supposed to be grounded. does yours have a good connection?

[ticktock]

someone correct me if im wrong but i think the voltage regulator is supposed to be grounded. does yours have a good connection?

 

 

There is only the blue wire on the voltage regulator, but the ground wire is located under the voltage regulator, the ground wire is on the bolt with the reg. like it was in the rear of the bike.

 

Adam

[So Cal Suspension]

Hey all,

 

Here is a question I have. I believe I have the answer but I will share the problem and share my thoughts and see what you guys think.

 

My tail light blows bulbs as fast as I can put them in. I turned my lights on the other day and the first one in the circuit, right side, brighter than the left. I pulled out my Fluke and tested the stator and I get 20 - 22 volts at idle. I then plugged in the stator power wire to the loom and tested for power at the tail light. I had 7.2 volts at idle. On the head lights I had 8.1 - 8.4, and on the left I had 7.4 - 7.8. What could be causing this?

 

I think that I may have a bad voltage regulator. I guess that I could have pulled the wire on the voltage reg. and tested the circuit again without the lights hooked up in case they blow. I should have troubleshooted some more but I didn't have the time to do this. Also, is ground going to play that big of a role in this? The loom is grounded well, on metal without paint. I soldered all of my connections after making cuts to the loom for changing my wiring around. I had the tail light problem previous to changing things around but I don't remember the lights being so dim. I revved it up a little but it was hard to test the circuit and it did not change the volt output. The stator output did go up to 23 when revved.

 

Thanks for your time, This is one of those questions you think you have the answer but sometimes its better to ask around and see what others think.

 

Adam

Your lighting voltage straight out of the stator should be about ~9.4-9.7 volts at idle, and spike to about ~33-37 when you rev it. Sounds like you might have a stator taking a dump, or you have a small short somewhere.

[blowit]

Hey all,

 

Here is a question I have. I believe I have the answer but I will share the problem and share my thoughts and see what you guys think.

 

My tail light blows bulbs as fast as I can put them in. I turned my lights on the other day and the first one in the circuit, right side, brighter than the left. I pulled out my Fluke and tested the stator and I get 20 - 22 volts at idle. I then plugged in the stator power wire to the loom and tested for power at the tail light. I had 7.2 volts at idle. On the head lights I had 8.1 - 8.4, and on the left I had 7.4 - 7.8. What could be causing this?

 

I think that I may have a bad voltage regulator. I guess that I could have pulled the wire on the voltage reg. and tested the circuit again without the lights hooked up in case they blow. I should have troubleshooted some more but I didn't have the time to do this. Also, is ground going to play that big of a role in this? The loom is grounded well, on metal without paint. I soldered all of my connections after making cuts to the loom for changing my wiring around. I had the tail light problem previous to changing things around but I don't remember the lights being so dim. I revved it up a little but it was hard to test the circuit and it did not change the volt output. The stator output did go up to 23 when revved.

 

Thanks for your time, This is one of those questions you think you have the answer but sometimes its better to ask around and see what others think.

 

Adam

 

 

I am a little confused by what you are explaining but I will offer some 101 fundamentals to maybe help. The lighting side coil is a shared or single phase wind with chassis ground reference. This means one wire to ground = max stator potential. The reg works to shunt power to ground at a given voltage. They usually work or they don't by design. Because the system has a very low power potential but higher voltage potential, it is possible for larger electric loads to not cause problems with no voltage regulation but small loads (tail light) to blow easily. As the load increases, the voltage will naturally decrease because a load is doing the same thing a reg would do which is shunt or eat power.

 

A blowing tail light is a sign of high voltage. Low voltage is a sign of either a weak stator or leakage to ground somewhere usually. It is possible that the reg is failing and I have seen it but reg leakage without total failure is rare. The best way to test this is amperage from the stator at the low watt condition. Test in mA for accuracy. Remember that the bulbs wattage is at 12V. if you are not at 12V, you must reduce the voltage in the calculation to estimate wattage. IE, 12V/55w = 55/12 = 4.58A. V=IR, 12/4.58A=2.62ohms. At 7V, 7V/2.62ohms=2.67A, 2.67A*7V=18w. Not trying to baffle you with numbers but trying to help understand that half the voltage does NOT mean half the power. You need to know how much current you should see at a given voltage to know if the stator is doing what it should. You should test current at no place else than right off the stator.

 

Also, remember that many meters, including your Fluke, is designed to work best at 60hz. The banshee AC power is all over the map and a function of RPM. A scope is the only true way to look at the power from the stator due the changing frequency. The peak the peak voltage is analyzed, then just take the root mean square (RMS) of that and you got it.

 

 

Brandon

Mull Engineering