Correctly installing a 12v power meter after coach master

I'm not sure why this has to be done after the master switch. My shunt/meter is right at the battery. It measures any current the coach uses, on the negative side.

At the risk of sounding obvious and stupid; dvms measure the voltage of what their attached to. If you connect it to the battery then you measure the battery. If you connect it to a fuse panel inside the RV then you’re measuring the volts after lots of connections and other loads. No right or wrong. It just depends on what you are trying to measure.

Connect it to the common negative battery ground.

BTW I may be wrong but I think the meter you are looking at only measures amps in one direction and if so would not be useful to me for battery monitoring.

As I interpret your input the master switch is the salesman switch which controls the solenoid and NOT the power to/from the battery.

This is a battery shunt for a battery monitor. I'm reasonably sure the switch you're describing is not analogous to the full battery disconnect switch in the picture.

To be clear the left hand cable connected to the battery post is for a parallel connected battery.

The shunt needs to connect to the negative side of the battery. If you want this to work don't install a switch between the two.

2oldman wrote:
I'm not sure why this has to be done after the master switch. My shunt/meter is right at the battery. It measures any current the coach uses, on the negative side.

Thats a good point.

Big Katuna wrote:
At the risk of sounding obvious and stupid; dvms measure the voltage of what their attached to. If you connect it to the battery then you measure the battery. If you connect it to a fuse panel inside the RV then you’re measuring the volts after lots of connections and other loads. No right or wrong. It just depends on what you are trying to measure.

Most of my camping is off-grid. Have a 300 watt inverter and a single deep cycle battery that runs a 19" Samsung tv. Like to know how much battery is consumed while watching movies off-grid. One cold winter, I was running the propane furnace on the lowest setting overnight. Ran the battery so low I couldn't start the generator, had to run the engine for a while for the battery to catch up. This might not be the best meter to use. Found it cheap on ebay. What meters are most people installing?

If the meter is the same as the one on Amazon (the diagram you posted is identical) then apparently it's intended for one way drain and not charging. Note that the diagram shows the use of a 12V power supply and not a battery.

If you want cheap use a digital voltmeter which can help. Maybe even free at HF. Tables will give you the state of charge (SOC) for the battery voltage when rested. Observe and learn and how the battery is discharged for various loads. If it's 12.1V at 2:00 AM it's already 50% discharged and will be dead in the morning for example.

I use the Trimetric battery monitor and I'll let others suggest ones with less cost.

Is your battery a Marine deep cycle type? If so it's not much better that a starting battery and certainly NOT a deep cycle battery. Furnace fans consume a lot of power and you may need more/better batteries in order to use the furnace.

timotb wrote:
What meters are most people installing?

I have this one.

Bluetooth app, so I can check it from anywhere near the coach.