wiring in simple battery meter

[chaplinfj60]

good am all,
so i ordered this off amazon, thought it would do what i want for a in the camper battery meter but why do i need this funky bar. i just dont under stand is all.

Amazon.com

 

[Bebop]

amp reading comes from there

 

[chaplinfj60]

so any little light? will that be on 10 percent of the time.

 

[Bebop]

The bar goes between your ground post and the wires, that's it.

 

[chaplinfj60]

ohh snap. light just came on... i also am putting in a usb charger. so this could be my load?

 

[Bebop]

anything you put on the battery is a load.

edit: make a diagram of your install

 

[PAE]

The bar is called a "shunt" the meter is sensing the amp draw across the shunt its the most accurate way to check in and out going amperage.

 

[chaplinfj60]

thanks
makes sine why i need it.

 

[pcorssmit]

Where the light bulb is shown on the diagram (Load) is all of the electrical stuff in your camper. You aren't wiring in a separate light bulb. Think if the "Load" as your fuse block.

Connect the shunt directly to the battery negative terminal, then connect the negative wire (coming from the camper) to the other side of the shunt. Then run 4 wires to the shunt: positive, negative, and one from each side of the shunt (the yellow and blue wires on the diagram. (Ignore the "External power supply" on the diagram, you don't need it). The 4 wires running from the power meter to the shunt can be small (I used 4-wire telephone wire on mine) since they are not carrying any current. The positive and negative wires for the power meter must be run directly to the shunt.

The shunt is the "sender" for the gauge (just like you'd have a sender for an oil pressure gauge). It is measuring the voltage drop across the shunt, and comparing it to the battery voltage, to determine how much current is going through the shunt.

 

[chaplinfj60]

Very good explanation. Thank you.