[TR] Battery Drain

[Randall]

Looks like Tony has covered most of the things I was going to say <G>

My (cheap HF) test light just barely glows a little bit at 80ma, probably
not enough to see in sunlight.  Even at 100ma, it's still just a dim orange
glow.  And of course with the lamp in the circuit, the leakage will be much
less than at full voltage.  200ma is enough to drain the average battery
below where it will start the car in a week.

I have also seen dust & dirt cause problems, even problems that only
occurred at certain times.  My motorhome would leak about 200ma but only
when it was rainy or there was dew on the grass; problem turned out to be
mud caked around a battery cable joint.  Most extreme case was my Audi, that
would kill the battery overnight, but only once every few months.  I finally
found the culprit more by chance than anything else; happened to walk by the
car one night after dinner with some friends and saw the rear window
defogger light on!  Apparently there was just enough salt spray on the relay
that if dew settled on it, the combination would pass enough current to pull
in the relay.  By morning it would be dry, so nothing would seem to be on!

Measuring currents this small on a car can be kind of tricky, especially if
anything has a capacitor.  The current to charge the capacitor can easily be
enough to pop the fuse in a DMM set to the milliamp range.  So it's best to
start with the leads shorted, and then open them when everything else is set
to make your measurement. 

Another possibility is a bad battery.  Apparently the battery I put in the
TR3 in 2009 was defective from the factory, even though it didn't die
completely until TRfest 2010.  The tester at O'Reillys showed 70% charged,
even though it wouldn't even try to crank the motor.

-- Randall