On Sun, 10 Dec 2006 22:11:16 -0500, Larry wrote:

snip

Is now a good time to remind everyone that a solar panel
MUST...MUST...have a blocking diode in series with it because it will
DISCHARGE the battery in darkness with reverse current if it doesn't?

Couldn't interest in my newly patented "blacklight bulb" could I?
Turn it on and the room goes black. Ideal for night-shift workers
trying to get some sleep during the day..... g.

This diode is PROBABLY located in the charge controller, hence the one-
way resistance reading. NEVER HOOK A LIGHTED PANEL TO YOUR OHMMETER or
when it's connected to a battery!

An ohmmeter supplies its own (known) voltage (they do have a battery,
unused in multi-meters for current and voltage measurement readings)
and calculates the resitance by measuring the current drawn across the
"resistor" and using the old e=ir formula, or r = e/i to be more
precise, giving the resistance.

I think it's probably better to say "DON'T EVER ATTEMPT TO MEASURE
RESISTANCE BY CONNECTING AN OHMMETER TO A POWERED CIRCUIT" and leave
it at that..... To use an ohmmeter, one has to power off and start
disconnecting things, one side of things, at least, anyway.....

Regards,

Bruce Nichol
Talon Computer Services
ALBURY NSW Australia

If it ain't broke, fix it until it is...