[jcassity]

i happen to have a few different shunts lying around because i dont have an analog meter i can put in series with a circuit to read higher amps.

normally (today) we dont really use AmpMeters.... on things. even in automobiles the makers use milli volt drops across a calibrated resistance wire to show you a gauge that is graduated to visually display "amps"... its actually a volt meter !!! on your dash. in all technicallity, cars actually simply apply the difference of potential technique to give you a needle deflection.,, not very accurate nor what would be a good lab tool.

shunts are a lab tool.
we put a shunt in series with the power feed buss or wiring.
this shunt is laboratory calibrated to its specific internal resistance allowances.

it normally has a lug landing screw terminal one each end.

it normally is stamped with its rating in m/V and Amps.

in my case to read high amps i used my spare 100amp 50mv shunt.

Now you can use a cheap analog meter and read the m/v drop across the *shunt*.

Next you use your calculator and as an example..... the formula is

milli volt meter reading / shunt stamped millivolt Rating * shunt stamped amps rating = amps

example--
with your analog meter across the shunt you read .019mv so your amp draw is...
.019mv / 50mv * 100A = .038Amps