I've spent more time than I'd like to admit, looking for the high capacity
4/3-A NIMH cells, and the too-long 67mm length was all I could find.
Yep, battery specs are a bit mystic (intentionally it seems) as there can be
a rated capacity and then a slightly higher average or nominal capacity.
The cells in the pack I opened previously were marked with a somewhat
standard number on the metal shell, NT410LAH.. no brand or other info on the
skins which is typical for commercial/industrial cells, but you knew that.
That number is similar to a GC industrial cell number.
This dead NIMH pack may have had the terminals shorted at one time, it's
used so anything's possible.
I recall seeing a couple of components in images of rechargeable cells
(Duracell, maybe) that are built-in to prevent destruction by shorting
and/or charging at an excessive rate, (although they may not provide
protection on a cells which were aleady partially discharged from normal
use).
I'm thinking those components are a thermistor and a poly-fuse (possibly a
3rd component), and had suspected that these military cells are shorter
because those items were left out, since they absolutely wouldn't be used in
consumer applications, thus liability protection not being needed.. just
speculation.
--
Cheers,
WB
..............
"Jeff Liebermann" wrote in message
news
On Thu, 4 Jul 2013 22:29:23 -0400, "Wild_Bill"
wrote:
Thanks, Jeff.. the packs are marked NIMH and 4.1Ah. There are 12 cells in
each pack. The size of the 4/3-A cells is about 18mm dia x 63.
NICD cells are limited to lower capacities.
That would be an 18630 cell.
I couldn't find anything in NiMH in size 18630 or nearby lengths.
The closest is an A battery at 17x50mm.
https://en.wikipedia.org/wiki/List_of_battery_sizes#Round_single-cell
Random source of NiMH in A battery size:
http://www.batteryspace.com/nimhrechargeablecellasize12v2700mah1pc.aspx
At least it will fit, although it's 13mm short and only 2.7A-hr
instead of 4.1A-hr.
I don't really believe the 4.1A-hr claim. Maybe at extremely low
discharge rates, but not a anything near 1C. For example, the size A
battery above is speced at 2.7A-hr at 1C discharge rate:
http://www.batteryspace.com/prod-spe...%5B1%5D.2V.pdf.
The Wiki write-up states the NiZN are only available as sub-C and common
AA,
AAA etc.
Looks like D cells are also available:
http://image.made-in-china.com/2f0j00wBmTneYqGFol/Ni-Zn-Battery-1-6V2000mAh-SC-Battery-AA-AAA-SC-.jpg
I've only seen a few of them and was rather surprised at the 1.6v
terminal voltage. I didn't believe that I could discharge these
batteries to zero, and not destroy them, so I tried it. No problem
(but I only tested one old cell). Shorting the terminals on a NiMH
cell is guaranteed destruction of the cell.
I dunno what the NiZN capacities are, but it would be interesting to see
greater energy density than NIMH.
And then there would be the need for different chargers.
Yep. Fortunately, they're are chargers for sale on eBay:
http://www.ebay.com/itm/150890715550
I'm tempted to buy some cells and a charger to see how they play.
I've seen NICD packs which had all cells shorted, typically a flea market
item that had probably been sitting around unused for years.
This is my first discovery of DTADN deader-than-a-door-nail NIMH cells.
That agrees with my observations. I think (not sure) that I can make
an NiMH pack hit zero if I short the terminals and leave them shorted.
If I can find some old cells, I'll give it a try. Destroying
batteries is so much fun.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558