On 02/01/2013 21:50, Rick Hughes wrote:

Agree ...That was the problem I saw with a really low value shunt ...
leads are going to have appreciable resistance


As long as the connecting leads can handle the current and are "low"
resistance, the resistance of the leads makes no difference to the
measurement.

The voltage drop is only measured across a fixed known resistor in
series with the connecting leads. The voltage drop in the connecting
leads carrying, say, 100Amps is not being measured.

Cheap and commercially available low value shunt resistors (milli or
micro Ohms) come with 4 terminals. Two terminals will handle the 100Amps
and the other two connect to a high impedance volt meter. The current in
the connecting leads to the voltmeter is vanishly insignificant.

http://en.wikipedia.org/wiki/Four-terminal_sensing

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