Jeff Liebermann wrote:
On Thu, 30 Jul 2009 08:13:41 -0700, D Yuniskis

spamme0 wrote:
D Yuniskis wrote:
Hi,

I'm replacing the battery in a GPS unit. Looks to
be an "A" cell (no, not AA or AAA), 3.7V 1800mAHr.
Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!).
google 18650.
Thanks! Seems to be the right size and capacity;
but I need something with *pigtails*:

Ummm.... Find a picture of a pig. Note the tail. There's no
semblance to a battery tab.

Note the following: ;-)

"Of course, the battery has pigtails soldered to it
so I'll need something with either pigtails or solder
tabs as its replacement (I doubt I could add any
sort of battery holder in this small space!)."

I haven't a clue as to how I could otherwise make the
connection to the battery (without risking explosion/damage).

Ummm.... Google for "18650 tabs". There are also a mess of cells
available on Ebay using the same search key.

Thanks. When I saw these were commonly used in laptop battery
packs, I just fished a couple of laptops out of the trash and
cannabilized the battery packs until I found cells with "decent"
open circuit voltages. Made sure I cut the tabs that connected
them to their neighbors so I would have a fair bit to work
with. Soldered some pigtails on and was able to replace the dead
battery in the GPS unit easily!

Rescued GPS unit: $0
Rescued Li Ion cell: $0
Working GPS unit: priceless

wink

I've also been fairly successful with soldering wires onto the cells.
However, some cells use a stainless can, which won't solder. For
battery pack rebuilds, there's sometime not enough room for the
inevitable "lump" formed when soldering wires. That's not the case
with spot welded tabs, which lie flat.

I've never had luck trying to solder to these cans
(partly out of fear of letting the can get too hot!).

I've a friend who will make me a little welder but I
would have to fetch it from him (out of state) -- its
just not worth the effort for something I do so rarely!

Thanks, all, for the pointers!