[MRCA] M151 DC Distribution

[W2HX]

I spent considerable time creating a 24VDC distribution system for my 1972 Land Rover Airportable...

First, I put in two 12V batteries, not for use in series, but one as primary starting battery and the other to feed a 30A 12V-24V DC-DC converter (for 100-150W radios).

http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3167.JPG

I use a blue sea systems automatic charging relay. This is a relay that puts the batteries in parallel once the alternator is running so they both get charged. There is a switch to force them in parallel, keep them isolated and connect/disconnect automatically. This system works very well. One of the benefits of this is if I run down my starting battery (which has happened too many times). I can jump the starting battery with the radio battery. Very handy.

I then found a little marine circuit breaker box on ebay and used that to build up the project. Here is what it looked like originally.

http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/original-box.JPG

I cut some holes for a 28V voltmeter and an ammeter, installed some circuit breakers, a pilot light and painted the box.  Pilot light tells me that 24V is on.
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3467.JPG

At the top, I installed a multipole switch to allow me to select various sources of DC power.

1.      Off

2.      12-24V 30A DC-DC converter using the 12V radio battery (not starting battery)

3.      Shore power (a big 24V AC-DC power supply)

4.      A large 100AH 24V lithium battery under the passenger seat in a steel box (I have not set this up)

The DC-DC converter only turns on when that source is selected with the switch. This way I don't run down the radio battery when it is not selected.
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3471.JPG

Here is the assembly for the charging relay switch and the DC-DC converter
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3164.JPG

And here is that assembly installed under the drivers seat in a plastic battery box
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3169.JPG

Here is a (probably out of date) document outlining the system
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/DCSystem.pdf

The insides still in development
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3472.JPG

Installed
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3511.JPG
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3480.JPG
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3514.JPG
http://www.w2hx.com/x/1972LW/Radio-Related/DC-Distibution/IMG_3515.JPG

Fun project. I can run as many radios as I want each with their own breaker. And I can select different sources. I even made one set of banana jacks for testing anything else I might see at a hamfest.

73 Eugene W2HX







From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Ray Fantini
Sent: Monday, June 12, 2017 10:27 AM
To: mrca
Subject: [MRCA] M151 DC Distribution

Spent the weekend installing new slave connector and new ten foot GRC-106 cables that run direct to the battery box in the M151 mutt, just got the slave connector parts, zero gage cables, new long power cables for the GRC-106 and the cable tray that attaches to the floor of the mutt for the cables so decided to remove all the #6 stuff that I installed before and do things all Mill Spec for the installation. Also plan on running external 28 volt MEP-015 and bring that in via the slave connector so I can run everything on board without having to run the engine.
Got the slave connector installed, terminated the cables on that end along with all the clamps for the huge cables that run back to the battery compartment along with all the new power cables that will terminate in the battery compartment and am now looking at five cables that want to terminate in the battery compartment. Two zero gauge power cables, one for the mutt electrical system and the other for the slave connector, two #8 coaxial cables that power the GRC-106 and one power cable that feeds the VRC-12. The next trick will be connecting everything up to the batteries and the auxiliary power stud kit that's feed from a jumper with a 60 amp fuse from the batter terminal. Things are getting tight in that space, anyone have pictures of what the mill spec installation is? I have documentation on the VRC-12 and GRC-106 installation on the M151 but nothing on what is supposed to be in the battery compartment.
Although it makes no practical sense am trying to do everything according to Mill Spec on this project. It's amazing how much time, labor and money can be sunk into such a thing!


Ray F/KA3EKH
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