Shunt

Re: Shunt

As n3qik says--the shunt can take large amounts of current (typically for RE systems ~100-500 amps) and you hook up a voltmeter to read the voltage drop--which then scales to current (i.e., 0.05 v or 50 mV = 100 amps).

The shunts are typically installed between the negative battery terminal and the ground common/bus (all current going into or out of the battery runs through the shunt).

You can see some example of shunts here.

Now, normally a shunt is used to measure high currents and you don't want to wire that current through a Amp Meter (either because the meter is not big enough--or you want to mount the meter some distance from the battery bus).

But, you can also install a battery monitor which will use the shunt to measure the current flow through your battery bank.

Basically a Batter Monitor keeps track of all of the current flowing out of, and back into, your battery bank (Amp*Hours or Watt*Hours)--It basically becomes the gas tank gauge for your battery bank--much more accurate than measuring resting voltage (which you cannot accurately do if you are charging/discharging your battery bank). And much easier than using a hydrometer to measure the specific gravity of your bank (and cannot be done with AGM/Sealed batteries).

A Battery Monitor will give you a very accurate reading of your bank's State of Charge (i.e., 82%)--plus a bunch of other information too. Also very nice if you are not the only person taking care of the RE system... Spouses, kids, visitors, etc.--much easier to tell them to not run your bank under 50% discharge by looking at the meter.

-Bill