Tabbed battery replacements

D

D Yuniskis

Guest
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
 
"D Yuniskis" <not.going.to.be@seen.com> wrote in message
news:hg40gr$sba$1@aioe.org...
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...
Most use a capacitve discharge to spot weld tabs on but if you are not doing
it all the time places like Jaycar have a good range of tabbed cells.


--
Regards .............. Rheilly P
 
In article <hg40gr$sba$1@aioe.org>,
D Yuniskis <not.going.to.be@seen.com> wrote:
Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...
You can buy most cell sizes with tags already welded on - so you can then
solder them together. From most decent electronics suppliers.

--
*A dog's not just for Christmas, it's alright on a Friday night too*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
In article <hg40gr$sba$1@aioe.org>,
D Yuniskis <not.going.to.be@seen.com> wrote:

Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells.
Click to expand...
You can do it easily, IF you use the proper solder and flux. Look for
something that can solder stainless steel.

Isaac
 
D Yuniskis <not.going.to.be@seen.com> wrote in message
news:hg40gr$sba$1@aioe.org...
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...

Cheats "spot weld"

For only one spot weld though, so lowish current purposes. Connect both
parts each to one side of a high current transformer (with a thermal cutout
somewhere) with some cigarette paper separating the two parts of stainless
steel. Press the 2 parts together until current breaks through and
incinerates the paper. Check for integrity and repeat if weak.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
Dave Plowman (News) wrote:
In article <hg40gr$sba$1@aioe.org>,
D Yuniskis <not.going.to.be@seen.com> wrote:
Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?

You can buy most cell sizes with tags already welded on - so you can then
solder them together. From most decent electronics suppliers.
Click to expand...
Yes, that was the "premade packs" option I mentioned.
These are almost always "specials" -- with added cost
and lead times.

You can also buy "single cell packs" (i.e., a cell
with tabs) but assembling these into complete
batteries usually results in a battery pack that
is too large to fit into the space available.
(in addition to being more expensive than
"regular cells")
 
Lee wrote:
On Dec 13, 5:31 pm, D Yuniskis <not.going.to...@seen.com> wrote:
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?

You might try replacing the heating element of a large 120 volt
powered soldering iron with a pair of spot welding points. I'm
thinking of the type with a 1 pound transformer, with a trigger switch
and usually a light to illuminate the work area - they create large
Click to expand...
Understood. The kind used to solder two lengths of 12AWG together :>

amounts of low voltage current. Buy using just the right size area of
contacts, one might get lucky enough to make a one second spot welder
that could be just the ticket for doing this. This is how it's done
in the first place. The end does get hot, but cooler than soldering.
You can solder if you do it very fast.
Click to expand...
The problem with soldering is not knowing how much damage you
have done to the cell. So, you go to all the trouble of building
a battery pack -- only to discover a month later that it is
crap.

How about getting the manufacturers to change all those custom sized
NiCad batteries to standard sized cells so we could just change them
out at a local Radio Shack instead of buying expensive Digi-Key one
off replacements?
Click to expand...
Many of the cells *are* standard sizes. Though often
without the protruding "nubs" (positive end of cell).

One option is to buy the pack at "Bats R Us" place where they spot
weld them as needed. Sometimes a good price can be agreed upon, other
times you are lucky if they take money instead of your first born.
Click to expand...
I'd rather wind a small generator by hand than deal with
their outrageous pricing schedule!

Digikey is a reasonable alternative but that's a week
(at least it seems they have eliminated the minimum
order surcharge -- so, you don't have to delay ordering
that *one* item until you have come up with a list of
other items to purchase at the same time!)
 
On Dec 13, 5:31 pm, D Yuniskis <not.going.to...@seen.com> wrote:
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share.  You can't
"solder" to individual cells.  And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations.  But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries?  Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...
You might try replacing the heating element of a large 120 volt
powered soldering iron with a pair of spot welding points. I'm
thinking of the type with a 1 pound transformer, with a trigger switch
and usually a light to illuminate the work area - they create large
amounts of low voltage current. Buy using just the right size area of
contacts, one might get lucky enough to make a one second spot welder
that could be just the ticket for doing this. This is how it's done
in the first place. The end does get hot, but cooler than soldering.
You can solder if you do it very fast.

How about getting the manufacturers to change all those custom sized
NiCad batteries to standard sized cells so we could just change them
out at a local Radio Shack instead of buying expensive Digi-Key one
off replacements?

One option is to buy the pack at "Bats R Us" place where they spot
weld them as needed. Sometimes a good price can be agreed upon, other
times you are lucky if they take money instead of your first born.
 
In article <isw-09B9A0.20565613122009@[216.168.3.50]>,
isw <isw@witzend.com> wrote:
In article <hg40gr$sba$1@aioe.org>,
D Yuniskis <not.going.to.be@seen.com> wrote:

Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells.

You can do it easily, IF you use the proper solder and flux. Look for
something that can solder stainless steel.
Click to expand...
Ordinary solder works just fine. It's overheating the cell that's the
problem.

--
*Do infants enjoy infancy as much as adults enjoy adultery? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
In article
<043d824c-8727-4587-b813-c11ef3d6f752@b36g2000prf.googlegroups.com>,
Lee <melee5@my-deja.com> wrote:
How about getting the manufacturers to change all those custom sized
NiCad batteries to standard sized cells so we could just change them
out at a local Radio Shack instead of buying expensive Digi-Key one
off replacements?
Click to expand...
In terms of numbers made I'd say sub C is a standard size - pretty well
every cordless tool I have uses them. But supply and demand determines
aftermarket prices for bare cells.

--
*I used up all my sick days so I called in dead

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
Some battery users need to weld lots of cells together on a regular basis,
and they sometimes build their own welding equipment.
I found numerous online examples of home-built welders when I searched for
battery pack welding or some similar terms.

The types of welding processes used are resistance welding, and capacitor
discharge spot welding.
Resistance welding is performed by a low voltage, high current secondary
winding on a large transformer. The winding may be made from large gauge
cable and may only be a few turns. A timer circuit is used to energize the
transformer for very brief periods, some tenths of a second. The high
current passing between the 2 tips creates the spot welds.
Capacitor discharge welding is performed by a large bank of high value
electrolytic capacitors (rated/capable of rapid discharge) which are
charged, then discharged thru the tips applied to the strap. Some commercial
versions are microprocessor controlled with numerous features.

Fixtures are often used to apply pressure to the tips, for more consistent
welds.

Nickel strip is available in coils (McMaster Carr), and straps are cut to
length, then welded to the cells.
Spot welding is typically done as 2 spots at once, with 2 tips pressed
against the strap simultaneously. When the current passes from one tip to
the other, 2 welds are made. This is then repeated, providing 4 spot welds
per cell contact, for very reliable connections.

Cells purchased with tabs already welded to them are fairly easily trimmed,
then joined with solder, which doesn't heat the cell as much as trying to
solder directly to the cell.
Fiberglas tape can be used as an insulating gaurd between straps and cell
cases, and to cover straps after assembly.

I've only encountered one piece of test equipment where the battery
compartment was so tight that a new pack made with tabbed cells almost
didn't fit.

--
Cheers,
WB
..............


"D Yuniskis" <not.going.to.be@seen.com> wrote in message
news:hg40gr$sba$1@aioe.org...
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...
 
On Sun, 13 Dec 2009 17:31:36 -0700, D Yuniskis
<not.going.to.be@seen.com> wrote:

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells.
Click to expand...
Yes, you can if you work fast, prepare the surface, use a very big and
hot iron, and keep the pack cool (water dunking). I've done it with
reasonable success with NiCd and NiMH packs. Total failure with LiIon
which really don't like the heat.

Plan B is a do-it-thyself spot welder:
<http://www.hobbyspotwelders.com/HSBATTERYPEN.php>
Hmmm... broken web site. Anyway, it's just a big fat capacitor and
two electrodes. The trick is to not weld the electrodes to the
battery or terminals. I use TIG welding electrodes but stainless
nails will also work. Plenty of plans on YouTube and Google videos:
<http://video.google.com/videosearch?hl=en&source=hp&q=battery+spot+welder#>
<http://www.youtube.com/results?search_query=battery spot welder>


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
In article <50c97a937bdave@davenoise.co.uk>,
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote:

>,
isw <isw@witzend.com> wrote:
In article <hg40gr$sba$1@aioe.org>,
D Yuniskis <not.going.to.be@seen.com> wrote:

Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells.

You can do it easily, IF you use the proper solder and flux. Look for
something that can solder stainless steel.

Ordinary solder works just fine. It's overheating the cell that's the
problem.
Click to expand...
Yup. And having a better flux allows the joint to be made very rapidly.

ISaac
 
On 14/12/2009 11:36 AM, Dave Plowman (News) wrote:
In article<hg40gr$sba$1@aioe.org>,
D Yuniskis<not.going.to.be@seen.com> wrote:
Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?

You can buy most cell sizes with tags already welded on - so you can then
solder them together. From most decent electronics suppliers.
Click to expand...
Exactly. And they'll probably be significantly cheaper than from a retailer.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
On 14/12/2009 3:56 PM, isw wrote:
In article<hg40gr$sba$1@aioe.org>,
D Yuniskis<not.going.to.be@seen.com> wrote:

Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells.

You can do it easily, IF you use the proper solder and flux. Look for
something that can solder stainless steel.
Click to expand...
IME, standard cells take regular solder easily, if you file off the
plating. You need to use a real soldering iron (ie; a station) & work
fast though.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
D Yuniskis wrote:
Hi,

Replacing rechargeable battery packs in consumer kit
is a bane I suspect most of us share. You can't
"solder" to individual cells. And, you usually can't
slip a battery holder in place to make the connections
for you.

Sure, you can buy premade packs in a wide variety of
configurations. But, these often come at a premium
in price (to pay for the added labor of their fabrication)
*and* you can't just pick them up "off the shelf"
(well, *some* configurations are available like this
but not "in general").

Has anyone come up with a clever way around this problem?
Is there a poor man's approach to welding tabs onto
batteries? Or, some other conductive fastener that
doesn't put the cell at risk in the process?
Click to expand...
I fiddled with this for a decade or so and have some thoughts.

What you want is constant energy into a constant area
of a repeatable material.

Low Voltage Spot Welder

You can replace the secondary of a microwave oven
transformer with two turns of the biggest wire that will fit
the core...don't forget to take out the magnetic shunts.

Couple of issues...you have to build some logic to turn the
transformer on AND OFF at zero crossings of the mains.
You can't just leave the transformer stuck at one corner
of the B-H curve, or you'll eventually be digging bits
of your Solid-state relay out of the ceiling when the
core saturates. The residual magnetism also makes a bad
repeatability problem worse.

This is not an energy welder. The amount of current you
get is critically dependent on the total resistance in the
secondary circuit. The amount of heat depends on the current
and voltage at the weld junction. With careful control of
electrode position and pressure, I was able to get about
50% pretty-good welds. But the other 50% ranged from
no weld at all to blasting the tab completely away.

I never addressed the long-term effects of six cycles of
40-amps on a 15-amp 120VAC primary circuit.

I discovered that .005" brass that you get at the hobby
store is much easier to weld than nickel. I never
examined the electrochemical issues of brass. Resistance
is higher, so probably not viable for high-current applications.

If you're gonna experiment, a good current probe and digital
storage scope are essential. I had been messing with this thing
for months. When a digital storage scope fell into my lap,
I had significant improvement in a matter of hours. There's
no substitute for knowing what's going on.

I was experimenting with ways to stabilize the weld
when a $15 CD spot welder fell into my lap.

A CD welder is discharging the total energy stored in a cap
into the weld. Since the open-circuit voltage is higher,
the resistance of the weld junction is less critical.
Most of the energy gets dumped thru a transformer into the
weld over a wider range of contact resistance. And the leakage
inductance of the transformer softens the initial transient.
Good-weld percentage went way, way up.

Some have suggested you can discharge a cap without a transformer.
My experiments quickly dismissed that possibility. If you can
get repeatable contact resistance, you still need a switch.
Closest I came to a switch was a pair of spring-loaded nails
that blew itself up on every weld...but nails are cheap.
And you need a LOT of caps in parallel on huge copper strap
to get the peak current. My CD welder puts out 7000 AMPS.
If you could reliably get 10A from each cap, that's a lot
of caps in parallel.

A car battery will weld like gangbusters, if you could figure
how to control it accurately.

About the time I figured out how to weld tabs, reality hit.
You can replace the cells in a laptop computer pack, but you
can't make it work. Many either lose their brains completely
when discharged or remember that the cells were dead.
Symptoms range from "still dead in the computer" to
"still has the capacity of the old dead cells." Had one pack with
a pic processor inside that I could look up. Resetting the pic
reinitialized the battery, but that's rare.

Have a heavy metal can with a heavy lid
available for the times when you accidentally create an internal
short in a lithium battery. An old pressure cooker works well.

Wear safety glasses. Hot bits of nickel are not compatible with
clear vision.
I still have nightmares about the time a NiCd blew up in my face
and splattered hot electrolyte all over my glasses.

Are we having fun yet?
mike
 
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