Installing DC Voltmeter

Momentary or on/off switch on meter?

beemerphile1 wrote:

Peg Leg wrote:
I picked up power for mine at the CO2 detector. It was inches from where I wanted to mount it.

Repeat after me, CO detector, CO detector, CO detector. :B

Edited, happy now?

I took the voltage for my voltmeter from the battery and from the line to the CO and propane monitors, using a switch to select which source I wanted.

I selected the monitor line because the current drain is small and constant, and easily accessible, so that gives me a good indication of the converter output.

The battery is wired directly to a 12v socket that is only used for the computer, usually when driving, or for a Battery Minder when being stored over the winter. Usually this socket is unused so it is a good indication of battery voltage.

camperpaul wrote:
If the meter is not self powered (internal battery) you can pick up power almost anywhere.

The dedicated "sense wires" should go directly to the point where you want to measure the Voltage (e.g. the battery).
Measuring at any other point will give erroneous results because of the currents in wires feeding power to electrical devices in the RV.

I suspect we are just looking for ball park readings anyway. If we are actually trouble shooting a problem I'd want to measure voltage in a specific area. Probably with a good voltmeter.

If the meter is not self powered (internal battery) you can pick up power almost anywhere.

The dedicated "sense wires" should go directly to the point where you want to measure the Voltage (e.g. the battery).
Measuring at any other point will give erroneous results because of the currents in wires feeding power to electrical devices in the RV.

Peg Leg wrote:
I picked up power for mine at the CO2 detector. It was inches from where I wanted to mount it.

Repeat after me, CO detector, CO detector, CO detector. :B

The real answer is that accuracy or remote location vs at battery is IT DEPENDS ON LOAD.

If the wires from battery to gauge are not carrying other loads or only light loads, the reading will be accurate.

As load(s) on that wire go up, there will be a bigger and bigger delta between battery reading and the lower reading you get at the gauge.

So, if you can find a circuit that doesn't carry a load when you want to check voltage, it will be fine. The other extreme would be to tap into, say the furnace. With the furnace running, you would see a LARGE difference between voltage at battery and at the meter.

I picked up power for mine at the CO detector. It was inches from where I wanted to mount it.

wa8yxm wrote:
That meter draws flea power. (on the order of less than 0.1 amp)

The pressure (voltage) is pretty much the same everywhere, like water pressure in the house. Amperage, that's a different story, but we're only interested in pressure.

I have two cheap LED meters. The one nearest the battery reads 12.6. The other, 12 feet away and connected with very thin wire, reads 12.7. So the accuracy of the meter is a factor too.

Put the meter across your battery for a reference and then connect it where you want. There will probably be a slight drop but not significant.