From: Mark J. Blair (ke6myk_mvlist@sbcglobal.net)
Date: Wed Oct 15 2003 - 14:43:32 PDT
Neil E. Amrhein <neil@compu-powr.com> wrote:
> Sure, but the "E" is for electronic, so you have to have a computer
> controlling it. Now, I'm no expert, but my understanding is that you'd
> probably have to go the hard way and get one from a junked GM truck and
> graft it in (running on 12V), or get the controller from a newer HMMWV, I
> guess.
I could be mistaken, but I think that the 4L80E controller in the A2 HMMWVs is
a 12V unit (I don't know whether or how it differs from civvy controllers),
and gets its power from a tap at the lower battery. Doing that generally is
not a good idea, because it can cause the upper battery to get overcharged and
reduce its life. However, those are danged big batteries, and I'd think that
the controller presents a pretty small load, so I suspect that the small
charge imbalance introduced by running the transmission controller from the
12V tap is not a problem in practice.
I still would not recommend running any significant loads (like lighting,
radio transmitters, compressors, etc.) from the 12V tap in 24V electrical
systems which do not charge the lower battery independently. In other words,
it's probably OK in a CUCV, which I think has separate 12V alternators for
each battery, but not advisable in most MVs, which have a single 24V
alternator and thus cannot compensate for a load imbalance between the upper
and lower batteries.
-- Mark J. Blair, NF6X <ke6myk@sbcglobal.net> PGP 2.6.2 public key available from http://www.keyserver.net/ Web page: http://www.qsl.net/ke6myk/
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