Electrical and Batteries

Observations from 15 Years of Mog Ownership
All photos, Copyright (C) Bill Caid, 2013. All rights reserved.

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Electrical and Batteries

I was pretty lucky on my truck with respect to electrical issues, with one small exception.  The mog system, assuming you don't change it "much", works fine.  My 1300 had the "torpedo" type fuses which are less than optimal.  The primary issue is contact resistance where the fuze intersects with the mount.  The simple solution is to spin the fuse in the mount to get rid of any corrosion.  Or, you can pop it out and go at it with a wire brush to remove any corrosion.

Ex-mil mogs have circuit breakers, thus removing the problem all together.

In my case, the biggest issue I had with my electrical system was a fire that was caused by some body work that I had done.  The knuckleheads mis-wired my snow plow lights and when they started the truck, it melted the wiring harness under the dash.  And, they attempted to cover up the whole thing (although the burn marks in the rug and the gnarly smell gave it away).  Replacing the harness was a big deal, so I did a cut-and-pasted and got it to work.  But, over the years, it proved to be a source of recurring issues.  Hopefully, this will not happen to you.

My mog was a 12V system, which was relatively rare for mogs in the U.S.  I think most 1300s here are 24V ex-mil type.  If you have a 24V system and you want to run a stereo or radio or "stuff", I strongly suggest that you employ a 24V -> 12V converter with a continuous-duty 24V relay between the batteries and the converter.  This will give you the correct voltage power and will not stress your batteries by doing a "low side pick-off" where only one of the batteries is used for the 12V source.  Eventually, the asymmetry will hose the battery.  The converters come in a number of amperage ratings; choose one that is right for your application.  This will require doing a load estimate which means reading the specs on the equipment that you plan to attach.  You can wire the system so it is only active when the motor is on.  Doing so will require finding the correct wires in your harness and tapping into that line to drive the control relay, so caution is indicated.


The 24V->12V converter is the big box.  The small blue box is a 24V inverter to provide 120VAC power inside the cab.  The relay is visible at the upper left of the photo above.  The small black box is an echo charger that is used to take the 12V and charge my house battery array.  This setup was for Thor, our 1017A expedition camper.

One thing that we did early on was to  get our alternator and starter rebuilt when the motor fried in 1998.  That action headed off any later problems with that system.  I do not know what the expected service life of an alternator is, but it is likely governed by the wear on the bearings.  The starter has other potential issues including whether it has been submerged in water.  If that is the case, then water and silt may have been deposited in the solenoid resulting in corrosion or issues with the solenoid engaging.

In our case, we did a deep-water crossing and some of the muddy water got into the solenoid.  The contamination prevented the starter gear from engaging.  The solution was to rap on the solenoid with a hammer to dislodge it.  Then, later when we were home, we removed it and had it serviced.  And deep-water crossing has the potential of causing issues.

Batteries

My mog had a 12V system and it had 2 "normal" batteries in parallel.  Most ex-mil mogs are 24V where the batteries are in series.  The ex-mil batteries are of a different type than the normal batteries, but normal batteries can be substituted if the ratings are high enough.  I suggest going to Interstate Battery and getting the correct replacement battery to head off issues down the road.

Batteries can be damaged by running them low on fluid.  You should check the battery levels at least once a year or if you have been in very hot weather.  They can be refilled with DISTILLED water which is available at most grocery stores.

If you truck is going to sit for an extended period of time, I suggest that you equip it with a battery maintainer system.  For a 24V system, you will need 2 maintainers, one for each battery.  This allows equal charging of both batteries and if either battery is in worse shape, it will get extra charging.  We recently installed a system on Thor (Thor is 24V) that is  a marine-grade 24V system with 2 12V channels.  The interesting thing about this system is that in addition to just "maintaining" the battery, it also will perform equalization of the batteries at 30 day intervals to keep the batteries from degrading over time.  The unit was about $150 or so but batteries are expensive.  You don't have to head off many failures to pay for this system.  Basically, it is hard-wired to the battery cables and when we see "shore power", the charger is engaged.  This insures that the truck is ready to go when you are.


This is a 2-channel fully sealed system for keeping 2 12V batteries ready to go.  It charges, floats and equalizes automatically.  And it is configurable for wet cell and AGM batteries.  I got mine at West Marine.

You can also purchase a solar charging system for your rig.  To be anal about it, you should install 2 12V systems.  The solar panels must have a charge controller or you will over-charge the batteries and ruin them (which is exactly what you are trying to head off).  There are many of these units out there, check the specification carefully before you purchase.


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Engine  Fuel  Hydraulics  Radiator and Cooling   Air System  Brakes  Wheels  Tires  Electrical and Batteries 

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