Re: Eclair ACL voltage for ACL motor?

[Wade Ramsey <wramsey@bju.edu>]

ACL-ers:

Yes, the single speed English motor can be operated safely on higher
than 12v.  In fact, it is wise to do it.  The CP conversion is the
same old motor with improved electronics (better regulation, variable
speeds) and a flywheel to lessen any tendencies to flicker from speed
variations.  But the motor itself is unchanged.  We used a 14.4v.
battery for it and got more magazines per charge.  To get the most
power from the motor you need to keep the voltage up.

The End-of-Discharge-Voltage for a Nicad is 1v per cell.  A 12v
battery has 10 cells, so its EODV is 10v.  But the ACL motor is going
to struggle (probably fail) trying to pull a 400 ft. mag up to sync
speed on 10v.  You'll probably have change batteries before the first
one is actually technically discharged.  A 14.4v battery's EODV is
12v, since it has 12 cells.  At the end of its charge it is still
giving the motor its rated voltage.  

NiMH cells generally put out twice the Ah of current that a Nicad
will give and that is a big advantage.  However, NiMH doesn't
basically have the ability to give a great amount of current under
heavy load like a Nicad does and this affects its cold weather
performance.  In Minnesota you may be at a disadvantage if you have to
shoot in very cold weather and can't keep the battery warm.  Also,
NiMH cells have a much higher self-discharge rate (running themselves
down on the shelf) than Nicads (which are bad enough already), but
manufacturers seem to be finding a way to correct this.  The ones I
bought recently are dramatically improved in this regard, at least in
the AA size I got for a small flash unit.  Anton-Bauer claims to have
solved all these problems in their Hytron NiMH packs, but warn that
the charging controls have to be much more stringent than for Nicads. 
If you recell your batteries with NiMH you may have much shorter total
life for the battery, due to improper charging with your old charger.

For more info than you probably want to know, see Anton-Bauer's web
site and click on battery handbook.  The specific page is:

www.antonbauer.com/handbook/handbook.html 








Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614

> > > cinesota@yahoo.com 10/9/01 4:05:53 PM >>>
Hi all,
I'm building some onboard battery packs for my ACL and I'm trying to

decide whether I should build them with the standard 12v power or
should 
I up it to 13.2 volts?  I recall a previous posting regarding upping
the 
voltage to the ACL single speed motor helped alleviate some of the 
flickering problems with 400' english mags. Can anyone tell me if
it's 
safe to run the ACL motor at 13 volts? Is there a real improvement
using 
a 13 volt source? My thinking is if I use a fresh, higher voltage 
battery with each 400' magazine it should solve the problem. I found
a 
site that builds 12v packs for cold weather applications and they 
actually spec their 12v batteries with 13 volts. I live in Minnesota.

Anyone have any thoughts on this?
-Ray

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