A voltmeter is pretty important for monitoring the state of your battery and charging system. After looking around at the various voltmeter installs here and elsewhere, my favorite one was using the empty dash light socket as outlined here:
viewtopic.php?f=14&t=36120
The only thing I didn't like was having visible cutting to the dash in order to fit the meter, I really wanted to find one with a smaller display. I ordered in a few different voltmeters from ebay to play with but would any of them work? Below are the three voltmeters I got. To get to your instrument panel, follow Wingadmin's excellent DIY for replacing your dash lights here:
viewtopic.php?f=14&t=10998
After cracking them open, the one on the left and the one on the right could possibly work, the one in the middle was too big and probably the same size as the other in-dash voltmeter that inspired me.
Looking closer at the two candidates, the one on the left could possibly work, it has two small circuit boards joined together, one board appears to run the USB ports and one appears to run the voltmeter. However even if that were true and they would run independently after separating them, you would still have the non-functional USB ports in the way when mounting the voltmeter.
Let's look at the other one. I think we have a winner! This one has the two functions already completely separated. All we have to do now is verify whether or not it fits.
Here is the difference in size between the two LCD displays:
This USB charger/voltmeter comes with a connector but it looks like it'll be too big to fit through the light bulb opening where it needs to go, JST connectors to the rescue.
After some quick work with the solder iron we are ready to test fit.
Ok, we are going to have to make a very slight non-visible modification, with the Dremel I had to make two small notches in the light bulb socket to accommodate the width of the circuit board.
After making some measurements, using hot glue and a toothpick I mounted it in the opening. I also put a dab of hot glue on either side of the circuit board where it fits in the relief notches.
Checking the alignment, looks good.
Here it is almost completed, testing it using the 12v bus from my bench computer's power supply. I removed a hair too much of the black from the stenciled panel, I've re-painted it on the inside. Also you can see a little of the white plastic surrounding the voltmeter so I grabbed some flat black and a fine paintbrush and went over any visible white plastic.
In the picture it does look really bright. It's not overly bright though, and I want to ensure I can see it ok in bright sunlight. If you want to do this make sure the USB charger/voltmeter looks like below, those will have the two separate circuit boards inside.
Hope you find this useful, I'm glad to be able to give something back to such an excellent forum.
