Blog post 9

Cool 12V electric stuff

Kelvin Smith

1/18/20216 min read

I'm mostly done with the 12V wiring now.  I bought a bunch of stuff from different places over the last few months and I finally got to put it all together.  I really enjoy designing electric systems and have gotten pretty good about diagnosing car wiring issues.  When I was younger I wired a lot of car stereos, and I do quite a bit with 12V on different types of vehicles now.  I save odds and ends like switches, wire, lights, etc. to reuse on other projects and literally have boxes of stuff laying around to pick from.  For this project I didn't want to worry about how much power I was using, so I tried to make the system in such a way that there were multiple power sources available. 

This is how it's setup:  30amp 120v  RV plug powers two 20 amp breakers.  This feeds 5 outlets throughout the van and provides 120V power when plugged in. For the 12V system I completely separated everything "new" I added from the Van's stock 12v system.  Everything new I added so far includes: ceiling exhaust light/fan, 2 usb ports on both sides of van, bathroom exhaust fan and light circuit, water pump (for sink) and associated light circuit, exterior flood lights on both side and rear, light in "utility room", overhead led lighting circuit on a dimmer, usb and 12v socket on switch panel.  I sized the wiring to meet the demand of each circuit, and I collected all the grounds together at the utility room.  I did NOT ground any of these circuits to the van.  All the circuits are ran to a 10 spot fuse block and then to the transfer switch.  The purpose for not grounding any circuit to the van is to have the ability to switch power completely from the Van's auxiliary battery (not installed yet) to a 600w (50a 12V) power converter.  This power converter I have plugged into a surge protector in the utility room. As of writing this, I have all the 12v running off the converter and not tied into the van in any way.  The orange transfer switch is rated for 100amps at 240V and was sourced from Ebay (of course!) and cost about $20.  As cheap as it looks, it is actually very robust and I have no concerns.  The 600w power converter was also about $20. The exact same one is sold on Amazon for $70 and the only difference in the plug is wired in. I simply chopped off an old grounded extension cord and wired it up.

The express van had a non threaded hole in the rear that I threaded with a "self tapper" bolt made with my handy grinder.  If you do this make sure you used at least grade 5 bolt. I used this as the grounding point to switch all the collected grounds when using the auxiliary van battery.

The switch at the bottom of the "control panel" turns on all the usb ports in the van in addition to the ones on the actual panel ( it also has a cool 12v digital gauge).  I have the control wire for this also send power to a 12v relay which in turn sends power to the dimmer control at the very top which will control the main lighting circuit.  I calculated all my ceiling led lights (added later) to be about 160 watts max which along with the usb ports would exceed the switch capability and wire.  The three lighted switches control the exterior flood lights and can be turned on regardless if the main control switch at the bottom is on or not.  Second from the top is an ammeter.  This is a vintage piece and is not mounted how it was originally designed, but I made it work with some aluminum trim and made it match the others (I think).  I may add a small piece of angle aluminum on the sides later.  This ammeter required a shunt due to the amount of power.  It originally came with a shunt, but it read low when I tested it, and didn't look very robust.  I was able to source a new 50a 50Mv shunt from amazon who kindly shipped it to my door in 18hrs (incredible!).  There are many new ammeters that are sold with the corresponding shunt, but they are all made in china and I wanted something accurate (and analog because they look cool).  This one is an Acopian made in the USA.  Apparently most of the old ammeters use a 50a 50Mv shunt, while the new ones I saw use 50a 75Mv shunts.  If you do what I did, make sure you verify what your gauge needs or it will read wrong.  Anyway, the ammeter is cool and I was using about 4amps of power with everything I had on at the time.  

For the exterior flood lights I used some 18w spot lights I bought in bulk. The were 10 for $33 on (you guessed it) Ebay.  I strongly believe that most of these are identical and if you pay more you're just padding someone's pockets.  They are all made in China and I have never had an issue with these.  I ran similar ones on the roof of my Subaru for years.  For the rear lights I ran the wiring inside some 1" aluminum tube and used 1 bolt on either end to affix it through the square tubing of the top.  I sealed everything with butyl sealant.  I wanted to have spot lights tied into the reverse lights of the van and since the van wiring is separate from the "coach" wiring, I used 4 lights.  2 are run by the lighted switch on the control panel and the other two work in reverse through the van.  Since I went through this effort already, I wanted a reverse camera also.  This is how i did the wiring here:

2 center rear flood lights are tied into the existing reverse light circuit (it's the green wire fyi). The reverse camera is turned on by this same circuit.  So now when I put the van in reverse, the center two flood lights turn on, the stock reverse lights turn on, and the camera (and screen that will go up front) all turn on.  I decided to run a 12g power wire from the front to the rear instead of the tiny (probably 30 gauge) wire that the camera came with.  This way I can run a fused toggle switch up front to turn on the camera whenever I want along with the reverse and spot lights.  I decided to replace with stock bulbs with LED bulbs so that I wouldn't overheat the reverse wire circuit for the van.  I believe that by doing so, the stock wires can accommodate the increased load.

So that it so far!