Re: [MV] 12v CUCV

From: Caleb Pal - MilVeh (m1009@defcon-3.net)
Date: Sun Jul 03 2005 - 12:27:33 PDT


Just to clarify on the CUCV electrical system. I have heard quite a few wild
things about how they are wired in last couple weeks, from people on this
list. MOST CUCV's, IE, M1009, M1008, etc, have 2 Delco 100 amp floating
ground alternators, which really don't do 100 amps, but thats another story.
The CUCV ambulances, etc, are another story also. So IN MOST CUCV's, this is
how it works. Front battery is like a battery in any normal car, 12v, and it
is charged by the drivers side alternator. This is a 12v negative ground
system. I have never heard of a positive gorund system CUCV. The drivers
side alternator is a floating ground alternator, but in the CUCV's I have
seen, it's ground is wired to the block of the engine. Thus, if you have a
blown passenger side alternator (Which REQUIRES a floating ground), you can
put the drivers side ALT. in its place, and get a normal 100 amp non
floating ground alternator for the drivers side, for charging the negative
ground 12v system. Hope everyone is with me up until this point. This system
powers most everything, lights, accesories, Injector Pump fuel solinoid, IP
cold start pusher thingy, etc. The Next battery is the rear battery. it is
WIRED IN SERIES with the first battery, providing 24 volts at the positive
post of the second, or some may call it the rear battery. THERE IS NO RELAY
OR SOLINOID between batteries for starting only! There is ALWAYS 24v at this
point. This battery is charged by the passenger side alternator, which has a
FLOATING GROUND. It must have a floating ground, because it is going to the
hot side of a negative ground system. the floating ground hooks to the
negative of the rear or second battery, which is the positive of the first
or forward battery. This is WHY IT REQUIRES a floating ground alternator.
The positive of this laternator goes to the positvie of the second, or rear
battery. This battery runs the starter, and the glow plug system, and the
slave socket, all which require 24V. Hope this makes sense.

A note on converting to 12v. The Rosco Equip. Page for converting a normal
CUCV like I have described, is bullshit in my opinion. There is a much
easier way that has worked for me. Take the 2nd alternator, passenger side
off. Leave the drivers side alt on the vehicle. Hook both batteries
negatives to ground, and both batteries positives to the positive terminal
block on the firewall. Take off the glow plug resistor, and wires the 2
wires together. Replace the starter with a 12v starter. I prefer autolite.
You are done. If you have a high load situation like a fire truck, you might
want to keep both alts and find a way to wire them both in parrallel to
charge both batteries. This has worked for me, and no starting problems. I
just taped up the pasenger side alt. wires, in case it is ever wanted to be
converted back to 24v, it can be done painlessly. I also disconnected the
slave socket, to prevent it from getting messy if someone tried to jump
start it with out looking under the hood. 24v jump starting a 12v truck
could be messy.

Caleb



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