# [EVDL] OT soldering tabs on NiMH batteries



## EVDL List (Jul 27, 2007)

I finally got my GP sub c cells but I blew the soldering of the tabs. I should 
have bought pigtailed batteries. I shorted one battery and had to take the pack 
apart quickly. Luckily none of the other solder joints shorted. I shorted one 
cell on the + side with the case. Luckily I finally knocked the offending piece 
of metal or solder away. It was pretty much carbonized. The cell was very hot 
but it's still at 1.27vdc. Amazing as I thought a dead short would croak it. 
Now I'll have to figure a way to charge it so when I put the pack back together 
it won't be the dog. I used a propane torch and got a little carried away. My 
soldering iron with temp control just isn't hot enough to solder the tabs but 
the blow torch works quick but maybe some slag jumped down and when I pushed the 
pack back in plastic housing the short happened. The torch throws flame on the 
insulators and burns them. Is there a better way to quickly heat up the 
joint? I'm already coating the surface of the tab & battery with solder but the 
battery is such a good heat sink my iron is no match. I'm getting bad solder 
joints on the battery part. Maybe I need a new tip. I have the type with 
screw on tips. Lawrence Rhodes......

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## EVDL List (Jul 27, 2007)

Welding the tabs is so much easier, use thin copper strap connections, do
not cover the entire cell terminal, connect a 6 or 12 v lead acid battery
to your jumper cables, clamp a carbon rod in one end of the jumper cable
and clip the other to the copper strap place the strap on the spot where
you want to connect it and use the rod in the other connector to zap the
connection spot, careful wear welders protection as you may see a lit of
sparking. the electric current from the other battery makes a simple
welding rig and the carbon rod tip gets hot and heats the copper and
battery connection to fuse them together (A Weld) *OH Heck this advice is
6 weeks late for an April Fool Joke.* It is not nearly perfect! Perhaps
you can find a quality battery holder for them with several in a stack and
strong spring connections?
Regards,
*Dennis Lee Miles*

++++++++++++++++++++++++++++++++++++++



> Lee Hart <[email protected]> wrote:
> 
> > On 5/15/2012 4:58 AM, Lawrence Rhodes wrote:
> > > I finally got my GP sub c cells but I blew the soldering of the tabs.
> ...


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## EVDL List (Jul 27, 2007)

What are you using this pack for?
Power tool?
I also have a set of sub-C cells to go
in my cordless drill - that was abused
building an EMC chamber, so I bought a
new set of cells, but made sure to buy
the cells with tabs! 
I too will have to solder a pack together
but this only requires soldering the tabs...

I also have several sets of 30Ah NiMH cells
but these are "prismatic" cells of about
4x4x2". Have accidentally shorted a cell by
dropping one of the cell interconnects on
the two cell terminals while doing/undoing
some of the interconnects in the 8 or 9 cell
modules that are used in the Vectrix motorcycle.
The NiMH cells are pretty rugged - there will be
sparks and heating, but as long as the short is
short (not too long in duration) the difference
in charge will be small and the heating will not
have damaged the cell, so you can rely on the usual
way of balancing NiMH: once you have charged the pack
to normal max voltage you can perform a slow
over-charge (make sure temp is low enough or that
may damage the cells!) to make sure all cells are
at 100%.
Normally it is better to stop charging NiMH slightly
before 100% and only occasionally over-charge to bring
the cells back in line.
Experience with NiMH packs such as that in the Vectrix
teach that this will extend the life of the pack
significantly.

Hope this helps,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Lawrence Rhodes
Sent: Tuesday, May 15, 2012 2:58 AM
To: Electric Vehicle Discussion List
Subject: [EVDL] OT soldering tabs on NiMH batteries

I finally got my GP sub c cells but I blew the soldering of the tabs. I
should have bought pigtailed batteries. I shorted one battery and had
to take the pack apart quickly. Luckily none of the other solder joints
shorted. I shorted one cell on the + side with the case. Luckily I
finally knocked the offending piece of metal or solder away. It was
pretty much carbonized. The cell was very hot but it's still at
1.27vdc. Amazing as I thought a dead short would croak it. 
Now I'll have to figure a way to charge it so when I put the pack back
together it won't be the dog. I used a propane torch and got a little
carried away. My soldering iron with temp control just isn't hot enough
to solder the tabs but the blow torch works quick but maybe some slag
jumped down and when I pushed the pack back in plastic housing the short
happened. The torch throws flame on the insulators and burns them. Is
there a better way to quickly heat up the joint? I'm already coating
the surface of the tab & battery with solder but the battery is such a
good heat sink my iron is no match. I'm getting bad solder 
joints on the battery part. Maybe I need a new tip. I have the type
with 
screw on tips. Lawrence Rhodes......

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|
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