Mufedit,

A DVM cannot measure the resistance of a voltage source, because the DVM has a battery inside

which is itself supposed to be the only voltage source. The DVM is aligned to it. So a DVM can only

measure the resistance of passive resistors. What you need to do is to apply a load resistor and measure the current

and the voltage in one go. If you multiply the current times the voltage then tune the load resistor for where the

calculated power is maximum, you know that the impedance of the battery is equal to that resistance where the power

is maximum. This is because maximum power is transferred when the impedance of the source is

equal to the impedance of the load (resistor).

I can't really say where the carbon comes from, unless it is from the ignition source, the black may be magnesium oxide?

:S:MarkCoffman