Soldering onto NiMH batteries?

D

DeanB

Guest
Hello all,

I've only done a little soldering before, but I want to rebuild a
battery pack for my TI-59 calculator (which is basically 3 AA-sized
batteries soldered together in series).

Can I just solder directly onto the battery terminals? With a copper
wire. Should I use flux? Will this overheat the battery and/or blow it
up?

Thanks for any tips!
 
DeanB wrote:
Hello all,

I've only done a little soldering before, but I want to rebuild a
battery pack for my TI-59 calculator (which is basically 3 AA-sized
batteries soldered together in series).

Can I just solder directly onto the battery terminals? With a copper
wire. Should I use flux? Will this overheat the battery and/or blow it
up?

Battery tabs are spot welded because soldering will overheat the seal,
and possibly damage the battery.

Do a web search on "solder NiCd" or "solder Nicad", and you'll get lots
of opinions on how viable an approach it is and how to do it.

You can get batteries from DigiKey with tabs spot-welded on, then you
can solder the tabs together for your application. You'll dump a lot
less heat into the battery in the process, particularly if you use a
good hot iron that lets you make a good joint quickly.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On Jun 19, 6:48 am, DeanB <deanbrow...@yahoo.com> wrote:
Hello all,

I've only done a little soldering before, but I want to rebuild a
battery pack for my TI-59 calculator (which is basically 3 AA-sized
batteries soldered together in series).

Can I just solder directly onto the battery terminals? With a copper
wire. Should I use flux? Will this overheat the battery and/or blow it
up?

Thanks for any tips!
How did you open the battery pack without damaging it?
 
On Jun 19, 1:28 pm, "jf...@my-deja.com" <jf...@my-deja.com> wrote:
On Jun 19, 6:48 am, DeanB <deanbrow...@yahoo.com> wrote:

Hello all,

I've only done a little soldering before, but I want to rebuild a
battery pack for my TI-59 calculator (which is basically 3 AA-sized
batteries soldered together in series).

Can I just solder directly onto the battery terminals? With a copper
wire. Should I use flux? Will this overheat the battery and/or blow it
up?

Thanks for any tips!

How did you open the battery pack without damaging it?
I had to snap off a cross-piece to get the battery out, but that does
not seem to be an important piece of the construction. I can run the
thing off a recharger ok without the cross pieces.
 
Hi DeanB, you wrote:

I've only done a little soldering before, but I
want to rebuild a battery pack for my TI-59
calculator (which is basically 3 AA-sized
batteries soldered together in series).
Can I just solder directly onto the battery
terminals? With a copper wire. Should I use
flux? Will this overheat the battery and/or blow
it up?
I have opened up surplus NiMH batteries and removed the cells to
rearrange them as a battery supply for a different device. I was able to
solder them and my new battery pack worked. I didn't have any explosions
when soldering but the pack started to leak after about 12 months of use
with regular recharging.
I threw the battery pack away when it started leaking. I don't know for
sure if the resoldering of the cells caused the leaking. The original
cells might have been a problem without the tampering. They were sold as
surplus.

I consider the effort and cost to be worth it. Less than two dollars of
surplus batteries made a working, rechargable pack that would have cost
me nearly sixty dollars!

insula
 
"C. Nick Kruzer" <insula@webtv.net> wrote in message
news:8194-485DBDB6-225@storefull-3257.bay.webtv.net...
Hi DeanB, you wrote:

I've only done a little soldering before, but I
want to rebuild a battery pack for my TI-59
calculator (which is basically 3 AA-sized
batteries soldered together in series).
Can I just solder directly onto the battery
terminals? With a copper wire. Should I use
flux? Will this overheat the battery and/or blow
it up?

I have opened up surplus NiMH batteries and removed the cells to
rearrange them as a battery supply for a different device. I was able to
solder them and my new battery pack worked. I didn't have any explosions
when soldering but the pack started to leak after about 12 months of use
with regular recharging.
I threw the battery pack away when it started leaking. I don't know for
sure if the resoldering of the cells caused the leaking. The original
cells might have been a problem without the tampering. They were sold as
surplus.

I consider the effort and cost to be worth it. Less than two dollars of
surplus batteries made a working, rechargable pack that would have cost
me nearly sixty dollars!

insula

Here is a tip. If you are soldering onto battery terminals, first melt a big
blob of solder onto the end using a very hot iron. Then, remelt the solder
and stick the wire into it. Works quite nicely, and doesn't overheat the
battery too much.

This works well for sets with tabs welded onto them too. Connecting between
welded sets is much easier with 'the blob' technique.

Spot welding is obviously better, but I don't have a spot welder...

I agree about RC pack pricing, way too much for what you get.

Another tip is that you can get shrink-wrap tubes to fit the battery pack
into, which make them very nice looking, and holds them together well, so
there isn't as much stress on the solder joints.

Regards,
Bob Monsen
 

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