Re: Charge Coil Resistance Test
Re: Charge Coil Resistance Test
I'm not a motor expert, but I do have some expertise in electronics so here's a little disortation on the resistance test that may help you decide what to do.
The charge coils are basically a lengthy piece of continuous varnish coated copper wire wrapped around an iron core. A resistance check will only provide the straight DC resistance which is determined solely by the wire material, diameter and length - and temperature, somewhat. The properties that actually determines the output of the coil are the inductance and speed at which the flywheel magnet passes by the core. A resistance check cannot give you that. But, inductance is directly related to the number of turns of wire that are wrapped around the core - more turns, more inductance. Consequently, the resistance can give you a reasonable test of the coil's status.
All that said, you asked, "do charge coils usually start going bad by having LESS resistance?" In a nutshell, yes. What typically happens to a charge coil (if it doesn't just open up - max resistance) is that a few turns get shorted to each other through the varnish coating. This has the effect of removing some turns. Fewer turns means less inductance which means a lower output. Lastly, temperature can play another role besides changing the resistance a little. When the coil heats up or cools down, there is expansion and contraction which can cause turns to short only when hot or only when cold. Even a DVA test can miss this problem.
So, when a charge coil measures questionably against known good specs with a known good meter, you may as well change it. The important parts of that statement is known good specs with a known good meter.
As for the power pack possibly causing this problem - certainly a possibility. But both the power pack and charge coil can affect each other's performance. The power pack is the "load" for the charge coil and the charge coil is the power source for the power pack. What gets confusing and frustrating is when you change one and the problem goes away only to return later. That's frequently because a good strong power pack might be able to handle a weak out put from the charge coil, but the charge coil may keep deteriorating - and visa versa.
But then there is the matter of cost vs. likelyhood of failure vs. difficulty in replacing. The power pack for your motor costs a bunch more than the charge coil, but with solid state components, is much more likely to fail and much easier to replace.
Now you decide whether or not to pull the flywheel.
