Volt Meter/Quick Disconnect

[Kingbiscuit]

I wanted a quick way to see the actual voltage of the batteries on my trailer and I wanted a way to easily connect my Viair Compressor to the trailer batteries. Here's a couple of pics of my idea. It works well for me.



To the left of the bracket, you see the quick disconnect/ protective cover sticking out from under the bracket. This simply unplugs so that I can plug the compressor in. In the middle is the momentary switch and then the volt meter.



Parts List:


Piece of scrap aluminum for the bracket



3 feet of both black and red #10 wire (for the compressor)



3 feet of both black and red #14 wire (for the volt meter)



Digital Volt Meter:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Momentary Push Button Switch:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


2 Each Heavy Duty Battery Quick Disconnects:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Viair Portable Air Compressor:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


NOTE: I ordered 2 of the battery quick disconnects. This allowed me to put a quick disconnect in the storage box, on the end of the compressor cable and another on the "battery clamps". This way, I can use the compressor connected to my trailer or I can connect the clamps to it and connect it to any 12 V battery.




The wiring is simple and straight forward.



NOTE: I have the 2 X 6 Volt Batteries so it is wiring is appropriate for these being wired in series to make 1 each 12 Volt Battery.


The the quick disconnect for the compressor is wired straight to the battery Positive and Negative terminals. The compressor has a fuse wired in line so I didn't need to fuse it.



The Volt Meter is wired directly to the batteries with the momentary switch wired into the positive wire.



All 3 pieces are mounted to the aluminum bracket which is then bolted to the aluminum cross member of the storage box.

[MyronL]

Nice idea. I just bought that same digital volts monitor. Now whenever I open the tongue box can quickly check battery voltage. Probably don't need an on/off switch but I added one anyway.

[Kingbiscuit]

Originally Posted by MyronL

Nice idea. I just bought that same digital volts monitor. Now whenever I open the tongue box can quickly check battery voltage. Probably don't need an on/off switch but I added one anyway.

Nice install. The switch is probably overkill but because the volt meter is wired directly to the battery, it would put a tiny draw on the batteries even when you use the battery disconnect switch. I want to eliminate as much parasitic load as I can.

[MyronL]

True. Pushing buttons is a purely tactile decision and... was thinking, being on 24/7 but rarely checked, without an on/off switch the LED's would have a shorter lifespan.

[MyronL]

Jeepers-no harm intended--- thought it was a harmless joke between toolguys.

[gbaglo]

Beats me. At least it wasn't poutine.

[Jordan]

Originally Posted by Kingbiscuit

Nice install. The switch is probably overkill but because the volt meter is wired directly to the battery, it would put a tiny draw on the batteries even when you use the battery disconnect switch. I want to eliminate as much parasitic load as I can.

Maybe a dumb question, but isn’t there a volt meter inside the trailer? Or is that just if you have the solar set up?

[John in Santa Cruz]

a digital voltmeter has an impedance of 10s of megohms, maybe even higher. your batteries internal leakage is far higher, its not going to do a thing.

12V into 10,000,000 ohms == 1.2 MICRO amps. in a million hours, it will drain 1.2 amp*hours off your battery. that's 115 years.

edit: just checked the impedance of my Fluke and my Craftsman, the Fluke says the Craftsman in DC Volts has 7Mohm impedance, while the Craftsman says the Fluke has 10 MOhms. ok, so the Craftsman would draw 1.7 microamps, or 1.7 amp*hours in a million hours or 115 years.

[Kingbiscuit]

Originally Posted by Jordan

Maybe a dumb question, but isn’t there a volt meter inside the trailer? Or is that just if you have the solar set up?

My unit doesn't have solar. Inside, I only have the standard monitor panel that does battery and tank levels.

My original thought was just to install a quick disconnect for the Visit air compressor. The voltmeter was an add on. The switch, well it's just a little something I did for me! Even if it would take years to drain the batteries or burn out the LEDs, I just like having a switch in the circuit.

[John in Santa Cruz]

you have that switch in series with the LED volt meter ? do you have a digital multimeter handy? could you do a test for us?

disconnect the switch. put the multimeter in milliamp (mA) mode, and connect it to the wires that would otherwise go to the switch. the panel meter should light up and read the voltage, and the multimeter should read the current the panel meter is using. tell us what that current is, I'm guessing 15mA or so. make sure you take the multimeter OUT of milliamp mode as soon as you're done doing this.