From: Neil E. Amrhein (neil@netfox.net)
Date: Sun Apr 13 2003 - 18:18:53 PDT
Ron,
I have not seen a copy of the actual installation MWO, but the Sure
Power DUVAC is designed to operate a single 24V or 12V alternator and charge
2 batteries. The one that supplies the 12V loads is charged in 12V mode,
while the second is charged in 24V mode in series with the first. This is
supposed to keep them charged up. The User's Guide from Sure Power says that
it should be turned on from an ignition source, so it should only be live
when the key is on.
If you can find a copy of issue 432 of PS magazine, it should cover the
M1010 charging system modifications and contained a DUVAC booklet. I have
not seen these materials personally, so I don't know if they would help, but
they sound very much like what you are looking for. I am currently trying to
acquire this issue, myself, to help answer some similar questions about my
truck.
A couple of questions: Do the batteries stay charged up if the truck is
run every day? If not, it sounds as though the unit may not be installed
correctly. If so, it may just be the fact that it is wired "hot" that pulls
the batteries down over time.
Have you checked the voltage at the front battery while the truck is
running? The voltage should be around 14V for at least a small portion of a
60 second period (while the DUVAC is in 12V mode). If it never increases to
that point, then the unit is probably not functioning the way it was meant
to. This could be due to improper installation, or internal fault. I
remember seeing something about DUVAC units that were installed in the
M915A1 (?) tractor had a fault that caused them to malfunction. They were
replaced by the manufacturer for free. I'm not sure if that is relevant,
it's just something I remember reading.
The problem with the M1010's original system was similar to what you
explained. The front (lower) battery received no power to charge from the
"regulator" on the driver's fender. Basically, the front battery supplied
all the 12V loads, but, since the top alternator's output went essentially
nowhere, it only got charged in series with the other battery by the lower
alternator. This allows the rear (upper) battery to receive more charge than
it needs, while the front battery does not receive enough, which will
eventually kill them both.
I believe the original parts (regulator and relay) were also made by
Sure Power, although I have not confirmed this. From what I have been able
to figure out so far, the original equipment (regulator and relay) was
"supposed" to work similar to the DUVAC that was used to replace it. I have
not yet figured out why it did not work properly in the first place, but I
am working on it.
Hope it helps some.
--Neil
----- Original Message -----
From: "Ronzo" <rojoha@attbi.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Sunday, April 13, 2003 11:06 AM
Subject: [MV] M1010 Electrical MWO
> It has been said that the military issued an MWO concerning the Sure Power
> battery maintenance system conversion. Does any one have a copy of this or
> ever even seen one?
>
> My vehicle has had a Sure Power put in and when left for several days,
> the forward battery will be below 11 volts while the upper stays around 12
> volts. This after both had been individually fully charged while in the
> truck 5 days before. The truck will not start because by the time the glow
> plugs get used, the engine will only spin a couple of revs before the
relays
> chatter.
> The upper alternator, which the manual says is supposed to charge the
> forward battery, is disconnected. The lower alternator is the only one
> feeding the system. Since BOTH alternators are rated for 28VDC at 200 Amps
> by themselves, it should do the job. At the point the Sure Power was
> installed is a large "wad" of wires and tape that do not or unknown as to
> what they are connected to anymore. I have not taken the "wad" apart for
> trouble shooting yet. Obviously the old 'whatever' that was there had
more
> places to hook up wires than the Sure Power does.
> It does appear that the Sure Power is 'ALWAYS' on. Thus it is taking
24
> VDC and doing it's wizardry to send 12 volts back to each battery, but you
> don't get something for nothing. Why the lower battery gets drawn down
while
> the upper battery stays up is a mite confusing, but probably something to
do
> with the guts of the Sure Power.
> I am going to look into putting in an normally open, power to close
> relay driven by the ignition switch which will disconnect the ground side
of
> the Sure Power when the ignition is off and establishing the circuit when
> on. Hopefully, this will stop the draw down by shutting down the Sure
Power.
> Comments?
>
> Ronzo
>
>
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