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Re: [OM] Re: lead/acid in M15V

Subject: Re: [OM] Re: lead/acid in M15V
From: HI100@xxxxxxx
Date: Sun, 29 Oct 2000 03:30:12 EST
In a message dated 10/27/00 6:43:09 AM Pacific Daylight Time, 
wright@xxxxxxxxxxxx writes:

<< I looked around at Digikey, All Electronics and a couple of other places 
and 
 didn't find anything smaller than about a "D" size. I don't know which size 
 the M15V takes, so this may be a waste of time. I also dont' really know 
 which type is best for this application. I did find out that those 6V and 
12V 
 lead/acid packs have a bunch of small sealed cells inside the plastic case. 
 There must be some reason that Quantum uses them, besides cost 
 considerations, since Quantum battery packs have a good reputation.  
>>

The Quantum packs have a variety of cells in them and charger designs 
depending on which model and which vintage you are talking about. 
For example the Bantams have Japanese made "prismatic" (flat plate) sealed 
lead acid cell batterys. 
The Quantum battery 1  often has Hawker (used to be Gates/"Cyclon") D cells.
The Quantum battery 2 sometimes have German Sonnenschein prismatic or 
Hawker/Gates cells. (Overall dimension compatible)
Few vendors make 8V batteries (as used in Quantum 2) with the same physical 
size as the Gates/Sonnenschein. The company I work for ships many thousands 
of these 8V batteries per month in our products.  Lead acid Battery vendors 
seem to go through periods of not being able to control their manufacturing 
process very well.

>>There must be some reason that Quantum uses them <<

Lead acid batteries have much lower self discharge rates are about half the 
cost of NiCd's and are easier to charge. The voltage can be used as a charge 
indicator as is  the case in Quantum packs. The energy density is a bit lower 
but they are easier to recycle not quite as toxic(!) and are "very high rate" 
cells. Example: the Hawker D cells can produce short circuit currents of 
around 180Amps. this is a good characteristic for flash use and ensures 
consistent number of flashes and short recycle times.  The only truly small 
sealed lead acid cells I have ever seen (as might fit in a MD pack) are for 
consumer walkmans etc and have very limited cyle life. The smallest 
cylindrical cells I have seen are made by a company out of Colorado (a 
Hawker/Gates spin off) they make C cells. These are such high rate cells you 
can start your car with a 12V set, with short circuit currents approaching 
1000A.

                  Regards,
                 Tim Hughes
                >>Hi100@xxxxxxx<<

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