The lithium cells have an entirely different seal
structure than do alkaline and nicad/mh cells.
In the NiMH/CD cells, and the alkaline cells, the
positive electrode is part of the seal/gas vent.
The plastic used in the seal is soft and melts well
below soldering temperature.
Because it would be a catastrophe if any moisture
got into a lithium cell (including the moisture in the
air), they have a seal that must never pass anything
in or out, and is quite remote of the exterior
terminals. In the case of consumer grade liION cells
(1650, 1850, ...), there is actually a FET switch and
fuse between the internel cell and the "+" terminal,
put there to protect the cell from conditions that might
cause the cell to detonate.
Lithium cells use plastic in their cell structure,
so heating the whole cell to above 140F can result in
a spectacular display, in the case of the lithium ion
type... not so much for the tadrian primary cells.
From a manufacturing point of view, it would be cheaper,
quicker, and easier to solder the cells. They would
do it for the same reason you want to do it: No desire
to buy/build/maintain an expensive CD welding system.
They don't, and can't, because the cost of making the
cells withstand the soldering operation greatly exceeds
the cost of requiring everyone use a CD welder.
I will again extend my offer. I will gladly weld tabs
on anyone's cell if they send it to me with return
postage. I have the equipment, bought for a government
battery charger research job, but now it mostly sits idle.
One or two cells, is free. If you need something more
extensive, we can talk.
-Chuck Harris
Ancel wrote:
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I have soldered and NOT spot welded on the specialty Tadiran cells to keep the RAM alive in the 2465A....that's since 2013 and 5 years running .....solder with the rust remover flux, applied with a wooden toothpick.
I use a 260 C temperature controlled station and it the 63/37 solder wets almost instantly. The cells were an odd size and were cylindrical. Something like a N cell, but wider diameter. Re-flowed with thin gauge copper to make the connections.
Mounted it with hot glue.
Kester SN63Pb37, type 44, 3.3%, Rosin core, 0.8mm , ANSI J STD 006C is my effective solder.
