GL1100 stator story

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mickster

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Mar 11, 2012
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cambridge, il
Ok, Just thought I would post my findings. A few days ago (possibly a week) it was brought up in these forums that a poster was wondering if he had ruined his stator by running his driving lights every day for a month. I was very interested in this because, while my 83 goldwing is quite pathetic as far as the headlight at night, with the added driving lights, its very well lit. I was concerned about running these lights because by watching the voltmeter it was obvious that I was using everything my stator could deliver to run these lights. What I wanted to know for sure is:

Will using a stator at full load long term cause it to prematurely fail?


I looked into an article that explained the charging system of a Gl1000. It can be found here:

https://www.randakks.com/TechTip73.htm

The GL1100 is the same system with the exception that the rectifier and regulator have been combined. Combining these two units was probably a cost savings and due to electronics getting smaller every year. It would also help on troubleshooting since there was only one "box" to fail instead of two.

If you read the above article it explains in detail how the charging system works and is regulated. What it gets down to is that on this type of charging system, any extra current that is generated that is not needed is passed to ground (basically the regulator is like a small heater element that will generate heat with any left over electricity. The stator is running at full load all the time (on my bike, each section of the stator is generating approximately 9.5 amps AC at 3000 rpms regardless of load).

So what it gets down to, go ahead and run any accessories that you want, if you don't use the electricity, the regulator is just going to dump it to ground (safely).

Now, as far as why its designed this way instead of like what a car has is probably due to cost and space. To be able to vary the output of the stator would require using a rotor with windings (to create a variable electromagnet ) instead of permanent magnets. Then you would need slip rings or brushes to get the variable current to the windings. This would increase cost, need more space, and also add problems down the road if the brushes/slip rings were in need of service.

As far as stators failing on a GL1100 my best guesses are:

1) age (insulation breaking down, cold solder joints at the junctions)
2) quality of original part (I am sure if they spend twice as much on the stator to raise either its specs or quality it would never fail, but that pretty much goes for all parts)
3) design (once again raising the specs can make anything better, but a designer has cost/space issues with everything).
4) running bike with a bad battery (explained below)
5) shorted regulator/rectifier (would cause same problem as a bad battery)

This pretty much also rules out any chance that running extra lights or accessories is going to shorten the life of the stator. There is one exception to this. If you drag the system down below operating voltage (like push starting a bike and then driving it around with a battery with a dead cell). This will cause the the current output to be higher than normal because the voltage will be lower than normal. What happens in this situation is that the charging system will be dragged down below 12 volts and will have above normal current due to excessive load.


Hope this helps someone out there,
mickster
 
thats an interesting read but i always thought the damage was done at low speeds - the bike consumes the same wattage and when the voltage goes low the current goes high. When the current goes high the insulation and connections start to fail. When the connections start deteriorating they become a resitor holding back more voltage which increases the current even more. Never really concidered the high speed aspect of it - am I off the mark on this?
 
Yes that would be true and could easily be monitored by a voltmeter on the bike. What is happening is the output is so low that the regulator is basically removed from the equation and the heavy load causes the voltage to be out of spec and in turn the current would be out of spec in the opposite direction.

That really shouldn't be a problem since the only thing that would cause that situation is drastic overload (like a bad battery/bad reg) or unrealistic low rpm for the needs of the bike (drop to a lower gear if moving, increase idle speed if standing still). As long as you have 12 volts (which you would want anyway otherwise your battery would be dead at the end of your ride), you should not be causing any damage. A good rule of thumb is the battery should be at a slight charge at all times.

Also, yes bad connections not only cause further heat and damage, they also change the properties of the circuit causing things usually to go even farther out of specification. Since there is only two connections from the stator to reg/rec, its definitely worth double checking to make sure that the connections are good. I just checked my bike today and both connectors are fine, but at 30 years old I imagine my bike is not the majority.
 
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