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electrical outrage

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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This is driving me and my neighbors nuts.

First some background. I posted not long ago about a problem with my turn signals where they turn on but don't blink while the engine is idling. They blink only when I rev the engine. Initially I suspected the charging system, so I ran through the tests in the stator papers and found that one of the r/r leads failed one of the diode tests. Not surprising since these units are known to be shoddy on old GS's. Fine, I could use a new r/r. But I don't think that's what's causing the turn signal problem and here's why.

When the engine is idling, the turn signals don't blink, and the voltage across the battery terminals is slightly lower than 12V, which is not surprising. But they don't start blinking until I rev the engine high enough to get 12.2V across the battery. Why don't they blink at 12V? Doesn't this indicate more than a charging problem? Here are some other clues:

-The turn signal relay works (clicks on and off) when removed from the bike and powered with a 9V battery.

-When the turn signal relay is removed, the voltage across the two dangling leads is about 11V while the engine is idling. Why doesn't this activate the relay?

-When the headlamp is turned off the turn signal works fine at idle. (!!!)

It looks to me like there is not enough current to activate the turn signal relay at idle during normal operation. There are three things I can think of that would cause this:

1. Something else on the bike is drawing too much power (short)

2. There is too much resistance in the turn signal circuit (bad connection). I measured about .5 ohms in the circuit "downstream" from the relay, which includes the turn signal lamps. Is that high?

3. The relay is faulty. But as I said it works with a 9V battery. Could it be drawing too much power?

Suggestions or corrections from someone who knows about electrical systems would be greatly appreciated.

-Graeme
 
blink

blink

When the headlamp is turned off the turn signal works fine at idle. (!!!)
you answered your own question think about what your quote is telling you about power required to make the system work, you need full amps and volts with the other draws to make it function, any thing less will not allow proper operation
 
your bike is not charging correctly, the signals wont flash below 12.2 volts because both the relay and the bulbs are requiring power, alone the relay works on a 9 volt battery but try powering the lights and relay with the 9volt battery and it wont work..
 
Most turn signal flashers use heat generated by the current of the signal lamps to cause a metal bar to flex, opening the circuit. Current goes off, bar straightens out, contacts close, current flows again. Repeat as necessary.

That's why the flash rate changes when a lamp burns out - less current through the flasher, bar doesn't flex as quickly (or not at all.)

Lamp current is determined by the lamp resistance and the system voltage. Lower voltage means lower current, which can affect the flash rate of the flasher.

The fact that turning off your headlamp allows it to work properly makes me think that it's a voltage problem. Headlamp on will pull the system voltage down somewhat. Headlamp off lets the voltage rise - just enough it seems.

If your rectifier/regulator is indeed faulty, it may be causing a low voltage condition that is just enough to make your turn signal act up. I'd suggest going ahead and fixing the R/R problem and checking the turn signal again.

Dave
 
But the signals don't flash when I rev the engine to charge to 12V. So the system needs to be more than fully charged, which suggests a power draw larger than it should be. Or is the voltage supposed to be higher than 12V at idle?
 
Pukeyshoes,

You have to remember that even though you may have 12V at the source, you may not have the amps (or current) to do the job. Given the fact that you are revving your engine and getting only 12.2V is indicator enough that your charging system does not work (as you pointed out) and therefore your battery is extremely weak. I weak battery may still register 12V when you put your leads on it, but as soon as you put a load on it, the volts will likely drop since you don't have the amps to do the job. As pointed out by Hinerad, the signal relay works when it heats up the mechanism. That heat is generated by amps NOT volts.

I don't see this problem getting solved until you have the charging system back up to snuff and a fresh battery in there.

Good luck 8O
Jon
 
Thanks everyone for all your help.

jonr said:
Given the fact that you are revving your engine and getting only 12.2V is indicator enough that your charging system does not work (as you pointed out) and therefore your battery is extremely weak. I weak battery may still register 12V when you put your leads on it, but as soon as you put a load on it, the volts will likely drop since you don't have the amps to do the job. As pointed out by Hinerad, the signal relay works when it heats up the mechanism. That heat is generated by amps NOT volts.
Click to expand...

No, I am revving the engine until the flashers work and that is something like 2500 rpm, producing a voltage of 12.2V. If I rev higher I can get a higher voltage. I know the voltage is not dropping below 12V because I'm monitoring it with my voltmeter.

I know current is what drives the flasher not voltage, but it should be proportional to voltage (right?). V=IR (voltage = current x resistance). Resistance is constant, and I'm keeping voltage constant, so current must be constant. So by holding voltage at some level I can keep current constant.

Also my relay works by magnetism not heat... I opened it up :D

Sounds like the consensus is fix the r/r, then worry about the flashers if they still don't work. This is what I will do unless someone has a better idea.

Thanks,
Graeme
 
Ok..

in a 12v auto/motorcycle electrical system, the battery alone should test at ~12.7 volts (pretty sure) if properly charged.

With the engine running, and at 5000RPM, you should see no less than 14 and no more than 15.5 volts. (Right from the factory service manual.)

So, from what you describe, you have either just a bad R/R or both a bad stator and a bad R/R. Often, if the regulator has failed, it was caused by 1 or more phases of the stator giving up the ghost. And, if the stator is not bad yet, running the bike too much with a failed regulator will all but guarantee a failed stator sooner or later..


The turn signals are just a secondary symptom of undervoltage in your entire system.
 
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