What size wire for monitor?

[Sandybar]

I just recently installed a dual 6 volt battery system and in the process of putting in a monitor. I have the shunt installed but want to know what size of wire do you use for the negative side battery cables. I would like to make my own to custom fit.

Thanks,

[JimD]

I have a remote monitor setup in my rig that measures both voltage and current. I am also an electronic technician so know about these sort of things.

The monitor wire size can be minimal as there is basically no current flowing to the meter. The current that is being measured at the battery through the shunt is being tapped off as a voltage, probably in the micro volt range. I used 18 gauge wire as that is what I had on hand.

I routed the wiring from the battery down under the coach and then up the other side. The wire was enclosed in spiral wrap for protection. I put the display in a little box and have it mounted low under my oven as this was a clear area. I included a switch where I could shut off the display but have never turned it off in over a year.

I recommend you put an inline fuse on the positive wire that feeds the display. Put the fuse right at the battery. This will protect the line in case of a short. I blew my fuse once when my wire got pinched in my battery's slide out tray. I used a 1 amp fuse to protect the 18 gauge wire I used.

I must say I love the display and watch it all the time. I am constantly aware of my battery status and current being drawn. You will see the current go up a bit with lighting, water pump, and especially an inverter.

[Sandybar]

Thanks Jim D,

What size wire from the negative battery terminal to the Shunt and then to the negative terminal on the load side.

Thanks again.

[JimD]

You can use 18 gauge for all as it is a very common automotive wire size and easily obtained.

The shunt is basically providing a very small voltage drop across it that can be measured. It will be an extremely small voltage that the meter will be calibrated to read and shown as the current being drawn. It may only be millivolts or microvolts. The shunt is made so as to not knock down your 12 volts to the coach. You are measuring the voltage drop across a piece of metal.

You could even go to a smaller gauge wire if you want. I went 18 gauge as it works better with my crimp and solder connectors and is easier to work with. Heck, you could probably even feed your meter with a cat 5 cable which has wires about 24 gauge.

Wire size for this application is not a big concern as there will be no current flowing out to the meter. The meter is just measuring voltage for both inputs. One voltage will be 12 volts and the other may be only .01 volts (wild guess).