Re: Low resistance


"PW" <user@xxxxxxxxxxx> wrote in message
news:gfkbbr$6jb$1@xxxxxxxxxxxxxxxxxxxxxxxx
I need to measure the resistance of some motorcycle alternator coils
They should be about 1.5ohm
I have a cheap DVM, which is of little use at this value
Is there a simple way to do this keeping in mind that I have Zero
electoral knowledge.
Thanks

The coils will have higher "resistance" (reactance) when AC current is
applied, if you can find a wall wart with AC output (possibly a dial-up
modem wall-wart) with approx' 12V output - hook it up with a dial or
indicator bulb in series, a gross difference in brightness between any two
identical windings would indicate a problem. You can also make use of your
meter on its AC voltage range for a more precise indication.

If you really do need an actual DC resistance measurement, the easiest way
is to apply a regulated (and known) current to the winding and then measure
the voltage developed, from there its a simple Ohm's law calculation: V/A=R.

This topic comes up frequently on News:rec.motorcycles.tech so the regulars
have had plenty of practice giving advice.


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