3 wire hookup led voltmeter

[Furyous]

Having some trouble here. Bought an led voltmeter on EBay. Intentionally got 3 wire hookup so that it could be powered on with the rest of my gauges (accessory voltage, motor temp) via a lit toggle switch. I tested it with the accessory battery by powering it with accessory battery then putting test lead on the positive end if the accessory battery and all looked good. Unfortunately, I installed it into my homemade gauge cluster so it is semi- permanent. I hooked up positive and negative to the 12v through the toggle. Powers in at 0.0 as can be expected with nothing connected to the test lead. However, connecting it to the back of my keyswitch (showing 51.9v on my multimeter), I still get 0.0. If I connect it to a 12v positive like on one of my accessories, it reads correctly. The meter is listed as powered by up to 30v but can test up to 100. I'm only guessing that it works on 12v since it shares a ground, but I am more than hesitant to connect a 48v negative ground to a 30v powered voltmeter. And if that was the case, how can this thing possibly test over its rated supply voltage as in my application?


Sent from my iPad using Tapatalk HD

[Furyous]

Seller was no help... Told me I had it hooked up wrong and that it was burned up several times before admitting they had it listed wrong and the description was incorrect. I had to shave this thing down and ca it into place in the gauge cluster, and now I have to take it back out and do it all over again. Grrrrrrrrr.


Sent from my iPad using Tapatalk HD

[Furyous]

I ordered another one from a different seller, who had the wiring diagram posted like this:

I have the same concern that I had with the other one. If I share the negative for power from my 12v circuit for my accessories with the 48v circuit from my pack, aren't I asking for trouble from both systems? Would hooking it up like this cause any troubles when charging either side? Any input out there? I really want this to work.

Sent from my iPad using Tapatalk HD

[Furyous]

Anyone? I'm going to hook this up as directed tomorrow, regardless. Hope it doesn't fry anything. I'm not an electrical engineer, but do have a good base knowledge of electrical circuits. I think it should be okay as the voltage should not exceed 12v on the negative side since the circuit won't be complete (or shouldn't be complete), so it will only register 12v on the negative side and 48v from the test lead. I hope I'm right.


Sent from my iPad using Tapatalk HD

[98clubcarjax]

which voltmeter did you purchase? if you purchased the MET 4875(48v to 75v) than is reverse polarity protected.

by the way i see you changed the paint on your limo cart.

[Furyous]

Originally Posted by 98clubcarjax

which voltmeter did you purchase? if you purchased the MET 4875(48v to 75v) than is reverse polarity protected.

by the way i see you changed the paint on your limo cart.

Thanks for the response!

I hooked the first voltmeter up, with 12v power and ground shared between the 48v circuit and 12v circuit with no problems to report as yet. I'm still leery to hook up both chargers simultaneously, so I charge them independently for now until I can be here to watch it for a couple of hours.

Yes, it is finally painted. I still have to paint the trunk lid, but it has been a nightmare of aligning it with the body, getting it to close without interfering with anything, and the lid itself was in horrible shape with a ton of work to smooth it out. If it is warm enough tomorrow I will probably get around to laying down he first coats.


Sent from my iPad using Tapatalk HD

[CRK]

Black wire to 48v neg of battery pack

Red wire to 12v pos key/switch

White wire to 48v pos of battery pack


According to the drawing above

[Furyous]

Originally Posted by CRK

Black wire to 48v neg of battery pack

Red wire to 12v pos key/switch

White wire to 48v pos of battery pack


According to the drawing above

Yep- it was the negative that had me concerned- connected to both 48 and 12v circuits.


Sent from my iPad using Tapatalk HD