DIgital Voltmeter install question?

[Larry Backman]

I’m about to install a pair of SMX Digital Voltmeters to a pair of 8Ds.

I’m installing home runs +/- for both but……

Both batteries go to a common ground bus, from which the whole boat is grounded.

Is there any value to having one of the DVMs have a switched negative which goes to the ground bus so I can see the difference between battery egatuve and ground negative? Would that help me in chasing a ground leak if one developed?

Topic

[Larry Backman]

DVMS up and running but…

I discovered this on the charging leads to my battery terminals……

I guess the secret of DVM’s is that they cause you to look at wiring you take for granted and replace it! That was a good find…

[Rob Schepis]

Larry Backman wrote:

Thanks, the confusion is that I can’t See the back of the gauges now that I mounted them….

Understood, that’s why I told you which side each terminal is, so you can reach back and push the spades on. Here’s a pic that “may” help….

[Larry Backman]

Thanks, the confusion is that I can’t See the back of the gauges now that I mounted them. As with all boat projects getting eyes on the work is never easy especially if you are over 60 and wear glasses!

[Rob Schepis]

Where’s the confusion? At the back of the gauge? Looking at the face of the gauges the (+) is to the left and the (-) is to the right..

[Larry Backman]

I knew I should have taken a picture before I mounted them! Going in with mirror and LED light next time at the boat.

bTw and FWIW I did discover yesterday what I once knew. My battery compartment has 2 8Ds, 2 red positive battery cables to separate batteries and one black negative cable wired in series to both batteries negative terminal. Maine built in all its glory 🙁

[Tony Athens]

100% YES–Look at the terminal gauge marking– 100% clear ..

[Larry Backman]

KISS never happens on a boat!

It sounds so simple “just run 2 18/2 ” wires. 🙂

5 hours later…

Serious question – does polarity matter, I installed them on a piece of starboard without looking carefully at the terminals first…

[Rob Schepis]

Larry, ever heard of “KISS” ?

The point of these meters is to be “stand-alone” for your batteries..nothing else. Post some pics of your install.

[Tony Athens]

NO—————Keep it simple without stray grounds

[Larry Backman]

I already pulled the pair of 18/2 home runs back to the batteries. Your wiringof the DVMS is so clean with the big ring terminals that I just installed a spare terminal block I had lying around to connect DVM wires to the home runs.

The block has a couple spare terminals which set me thinking anout running an extra ground wire back to the grounding block.

I do have to say that of all the various electronic gadgets and wires and connections I have installed, this might just be the nicest and cleanest I have seen!

[Tony Athens]

Larry,

What matters is your home run to the battery terminals with a small 1-3 amp fuse on the POS wire near each battery.. All you need is 18-2, 16-2 or 14-2 wire–The DVM’s only draw less than 1 milliamp each.

Battery terminal voltage it what you are after..

Tony

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