Digital Voltmeter Wiring

e vassar · 09-13-2020, 02:08 PM

I ran across a digital voltmeter in a old tool box. I don't remember where it came from. I put the red and black wires across a battery, and it works! Even flashes on and off under 12V. So I think im going to install it in my car.Here's my question. There is also a purple wire on it. What could that be for?

T Ames · 09-13-2020, 02:29 PM

It’s likely lighting.

e vassar · 09-13-2020, 05:30 PM

It IS lighting. But not backlighting since it is digital. So when there is no power on the purple wire, the display is bright . When power is on the purple wire,the display dims.
My car has no master cut off switch and I normally do not disconnect the battery, the gauge will display forever, so I hope the parasitic draw is tiny.

Painter · 09-13-2020, 06:48 PM

If you have msd ignition, they live a lot longer if you disconnect the battery at night and after you leave the track.

e vassar · 09-13-2020, 06:52 PM

Quote:

Originally Posted by Painter

If you have msd ignition, they live a lot longer if you disconnect the battery at night and after you leave the track.

Its Big stuff 3 and coil packs.

Kenny Wigington · 09-13-2020, 09:35 PM

Everett, the purple is to dim it, if I’m remembering the ones I had before, correctly. I just capped them, with a crimp end.

voltdr · 09-14-2020, 01:04 PM

Quote:

Originally Posted by Painter

If you have msd ignition, they live a lot longer if you disconnect the battery at night and after you leave the track.

Huh?????
Dan

09-13-2020, 02:08 PM	#1
e vassar Member Join Date: Jul 2015 Posts: 382 Likes: 67 Liked 271 Times in 107 Posts	Digital Voltmeter Wiring I ran across a digital voltmeter in a old tool box. I don't remember where it came from. I put the red and black wires across a battery, and it works! Even flashes on and off under 12V. So I think im going to install it in my car.Here's my question. There is also a purple wire on it. What could that be for?

09-13-2020, 02:29 PM	#2
T Ames Member Join Date: Jan 2009 Location: the Brazos Valley of TX Posts: 114 Likes: 161 Liked 125 Times in 33 Posts	Re: Digital Voltmeter Wiring It’s likely lighting.

09-13-2020, 05:30 PM	#3
e vassar Member Join Date: Jul 2015 Posts: 382 Likes: 67 Liked 271 Times in 107 Posts	Re: Digital Voltmeter Wiring It IS lighting. But not backlighting since it is digital. So when there is no power on the purple wire, the display is bright . When power is on the purple wire,the display dims. My car has no master cut off switch and I normally do not disconnect the battery, the gauge will display forever, so I hope the parasitic draw is tiny.

09-13-2020, 06:48 PM	#4
Painter Member Join Date: Dec 2012 Posts: 227 Likes: 4 Liked 162 Times in 45 Posts	Re: Digital Voltmeter Wiring If you have msd ignition, they live a lot longer if you disconnect the battery at night and after you leave the track.

09-13-2020, 09:35 PM	#6
Kenny Wigington Senior Member Join Date: Sep 2004 Location: Cumming,Ga. USA Posts: 967 Likes: 36 Liked 60 Times in 12 Posts	Re: Digital Voltmeter Wiring Everett, the purple is to dim it, if I’m remembering the ones I had before, correctly. I just capped them, with a crimp end. __________________ 2894 STK