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Old 05-05-2012
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Re: Wiring & Installing A Battery Monitor

This is a nice thread that I just read for the first time. To its original point I think one helpful comment is that once you install a shunt such as this you should change your thinking to consider the shunt as the new GND and stop thinking of the battery (-) as GND - it no longer is. If it helps, when doing a diagram you could draw the battery and shunt together with a box around them and the GND symbol on the far side of the shunt.

Also you can remember that a shunt is just a carefully calibrated piece of very very low resistance metal - not something functional and not something that can break . To put it in perspective the shunt in the original example (500A=50mV) is a 0.0004 ohm piece of metal which is equivalent to ~1' of 2AWG wire. The monitor and that positive wire to the shunt could both fail and it would still be exactly equivalent to a 1' 2AWG wire.
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