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High drain NiCd - Sub C batteries for power tools (strapping tool)
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PostPosted: Fri Oct 07, 2005 11:46 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

On 7 Oct 2005 11:13:16 -0700, "Hannes" <sventus@gmail.com> wrote:

Quote:
Dears,

At the company I work for we use some powertools (in this special case
a strapping tool) that use 2.4Ah NiCd sub-c type cells. I could not
figure out if they are from Sanyo or some other manufacter.

Here is a picture of this battery

http://www.uline.com/ProductDetail.asp?model=H-956-BATT

It contains 12 - sub-c 2.4Ah cells and a temperature sensor.

(snip)

Actually the term "sub-C" relates to capacity. Such cells are C size but (much)
lower capacity - typically around 1000mAh. 2.4Ah is the norm for C size NiCd
cells. Yours are not sub-C

Quote:
Actually I'm starting to belive that NiCd chemistry is more reliable
for high drain applications than NiMH after I saw this BOSCH report:

NiCd is more suited to high drain applications. That is the key to your
application. Go with the 2.5Ah ones you found.
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browntimdc
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Joined: 06 Feb 2005
Posts: 23

PostPosted: Sat Oct 08, 2005 12:12 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

budgie <me@privacy.net> wrote in
news:f29ek1915f4ir00upnlsv1p1j1ekg6fnm1@4ax.com:

Quote:
Actually the term "sub-C" relates to capacity. Such cells are C size
but (much) lower capacity - typically around 1000mAh.

No, sub-C cells are physically smaller.
23x43mm vs 26x46mm
Here's a table of cylindrical cell sizes:

http://www.batteryspace.com/index.asp?PageAction=Custom&ID=3#Industrial

Tim

--

"The strongest human instinct is to impart information,
and the second strongest is to resist it."

Kenneth Graham
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John Muchow
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Joined: 04 Apr 2005
Posts: 9

PostPosted: Sat Oct 08, 2005 10:08 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Quote:
Where could I find those 2.4Ah cells or similiar ones ? I only found
some 2.5Ah at

http://www.amondotech.com/index.asp?PageAction=Custom&ID=48


Try Steve Hill at Robotic Power Solutions (http://www.battlepack.com)
and tell him I sent you. We've done a LOT of business together. :-)

He does a lot of custom battery packs and carries 2.4AH-3.6AH NiCd
cells for use in his packs. I don't know if those cells are listed in
the Loose Cells section of his web site but his NiCd packs use them
and I'm sure he'll be willing to sell you them loose.

He'd also be a great person to speak to regarding inter-cell
connections too. He does a lot of soldered-battery bar packs for VERY
high current applications but should have some input on those welded
tabs you're using.

Voltage drops (and localized heating) are a real problem with
spot-welded tabs at higher current levels. This robs you of
performance and can cause heat-related damage to the cells. If the
tabs and terminals of your cells are a lot hotter than the cells
themselves (after heavy use), then it might be worth it to double up
on the welded tabs to reduce the inter-cell resistance. Thgis will
keep the connecitons cooler and increase the run-time voltage level of
the pack.

Normally, I'd recommend using NiCd's for your application but there
are some incredible NiMH cells out there now and it might be worth
looking into them too. I have tested the IB3800's at 150A (yup, 150A)
and they didn't overheat until the per-cell voltage dropped under
0.5V. Of course, the run time at 150A was VERY short, but the cells
only get warm if you have a 0.9V/cell cutoff. Steve Hill has done a
few tests on these cells at 80A and they have held up well.

Tell Steve about your application and the discharge current levels,
chargers and the pack maintenance (conditioning, how you store them,
etc.) you perform and I'm sure he can hook you up with cells that will
work well for you.

Call him. He's pretty busy and it can be hard to do something like
this via e-mail. Smile
John Muchow
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Usenet user
science forum Guru Wannabe


Joined: 06 May 2005
Posts: 166

PostPosted: Sun Oct 09, 2005 7:05 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

On Sat, 08 Oct 2005 14:12:16 GMT, browntimdc <tbrown59remove@verizon.net> wrote:

Quote:
budgie <me@privacy.net> wrote in
news:f29ek1915f4ir00upnlsv1p1j1ekg6fnm1@4ax.com:

Actually the term "sub-C" relates to capacity. Such cells are C size
but (much) lower capacity - typically around 1000mAh.

No, sub-C cells are physically smaller.
23x43mm vs 26x46mm
Here's a table of cylindrical cell sizes:

http://www.batteryspace.com/index.asp?PageAction=Custom&ID=3#Industrial

Then you have a different naming regime than our market area. Here if you ask
for a "sub-C 2.4Ah NiCd" you'd be laughed out of the store.
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sventus@gmail.com
science forum beginner


Joined: 28 Sep 2005
Posts: 32

PostPosted: Mon Oct 10, 2005 5:06 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Dear John,

Thanks a lot for your inputs!

I tried the Titanium 3.6Ah sub-C and they did not work :(

Maybe the problem could be on the contact resistance of my cells ? Who
knows... lets see if I can figure that out.

sincerely
Hannes

John wrote:
Quote:
Where could I find those 2.4Ah cells or similiar ones ? I only found
some 2.5Ah at

http://www.amondotech.com/index.asp?PageAction=Custom&ID=48


Try Steve Hill at Robotic Power Solutions (http://www.battlepack.com)
and tell him I sent you. We've done a LOT of business together. :-)

He does a lot of custom battery packs and carries 2.4AH-3.6AH NiCd
cells for use in his packs. I don't know if those cells are listed in
the Loose Cells section of his web site but his NiCd packs use them
and I'm sure he'll be willing to sell you them loose.

He'd also be a great person to speak to regarding inter-cell
connections too. He does a lot of soldered-battery bar packs for VERY
high current applications but should have some input on those welded
tabs you're using.

Voltage drops (and localized heating) are a real problem with
spot-welded tabs at higher current levels. This robs you of
performance and can cause heat-related damage to the cells. If the
tabs and terminals of your cells are a lot hotter than the cells
themselves (after heavy use), then it might be worth it to double up
on the welded tabs to reduce the inter-cell resistance. Thgis will
keep the connecitons cooler and increase the run-time voltage level of
the pack.

Normally, I'd recommend using NiCd's for your application but there
are some incredible NiMH cells out there now and it might be worth
looking into them too. I have tested the IB3800's at 150A (yup, 150A)
and they didn't overheat until the per-cell voltage dropped under
0.5V. Of course, the run time at 150A was VERY short, but the cells
only get warm if you have a 0.9V/cell cutoff. Steve Hill has done a
few tests on these cells at 80A and they have held up well.

Tell Steve about your application and the discharge current levels,
chargers and the pack maintenance (conditioning, how you store them,
etc.) you perform and I'm sure he can hook you up with cells that will
work well for you.

Call him. He's pretty busy and it can be hard to do something like
this via e-mail. Smile
John Muchow
-- remove SPAMMENOT for e-mail responses --
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John Muchow
science forum beginner


Joined: 04 Apr 2005
Posts: 9

PostPosted: Tue Oct 11, 2005 3:14 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Quote:
Dear John,

Thanks a lot for your inputs!

I tried the Titanium 3.6Ah sub-C and they did not work :(

Maybe the problem could be on the contact resistance of my cells ? Who
knows... lets see if I can figure that out.

Do you mean they didn't take a charge? Or they didn't deliver their
expected run time?
John Muchow
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sventus@gmail.com
science forum beginner


Joined: 28 Sep 2005
Posts: 32

PostPosted: Tue Oct 11, 2005 4:23 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

They take a charge, but since the discharge current is so high, the
equipments says that the voltage is too low and it will not work ;( I
should give a look at the tabs and see if they are not heating up too
much melting the plastic housing of the battery. With another pack
3.3Ah NiMH cells, this plastic bag melted and I lost all my cells...
the cells leaked Sad
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John Muchow
science forum beginner


Joined: 04 Apr 2005
Posts: 9

PostPosted: Wed Oct 12, 2005 10:17 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Quote:
They take a charge, but since the discharge current is so high, the
equipments says that the voltage is too low and it will not work ;( I
should give a look at the tabs and see if they are not heating up too
much melting the plastic housing of the battery. With another pack
3.3Ah NiMH cells, this plastic bag melted and I lost all my cells...
the cells leaked Sad

Did you get those Titamium 3.6AH cells from Steve Hill at Robotic
Power Solutions? If not, where? I want to find out how these cells
are rated for different discharge current levels. For your
application, this is critical.

A lot of cells (particularly the lower cost ones) have very high
capacities but the voltage-under-load drops very low at high discharge
current levels due to the high internal resistance of the cell. You
need cells specifically designed for such high discharge current
levels.

Checking the tabs is a good idea too. You could be dropping a lot of
voltage across them at that high a current level. In fact, I
recommend soldered cells, not spot welded. Try measuring the voltage
across both ends of a tab at full current and see what you're losing
there.
John Muchow
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sventus@gmail.com
science forum beginner


Joined: 28 Sep 2005
Posts: 32

PostPosted: Thu Oct 13, 2005 11:12 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Hi John!!

I was using the Titanium 3600MAh that I bought from amondotech, see

http://www.amondotech.com/index.asp?PageAction=Custom&ID=48

but I also used other 3.3Ah cells and .... nothing...

I will check the tabs then Smile Hope not to melt the cells Smile) The
original cells are spott welded so I was thinking I could manage that
too!!

Which welder machine would you recomend me ?

sincerely,
Hannes
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Backup Error
science forum beginner


Joined: 23 May 2005
Posts: 26

PostPosted: Fri Oct 14, 2005 2:10 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Budgie, I think you have a non-standard naming regime. If someone told
me "Sub-C" reffered to the capacity I would try hard not to laugh at
them while I reffered them to a battery size guide, as Tim did above.
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wlb
science forum beginner


Joined: 14 Oct 2005
Posts: 1

PostPosted: Fri Oct 14, 2005 12:24 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

On Sun, 09 Oct 2005 17:05:43 +0800, budgie <me@privacy.net> wrote:

Quote:
On Sat, 08 Oct 2005 14:12:16 GMT, browntimdc <tbrown59remove@verizon.net> wrote:

budgie <me@privacy.net> wrote in
news:f29ek1915f4ir00upnlsv1p1j1ekg6fnm1@4ax.com:

Actually the term "sub-C" relates to capacity. Such cells are C size
but (much) lower capacity - typically around 1000mAh.

No, sub-C cells are physically smaller.
23x43mm vs 26x46mm
Here's a table of cylindrical cell sizes:

http://www.batteryspace.com/index.asp?PageAction=Custom&ID=3#Industrial

Then you have a different naming regime than our market area. Here if you ask
for a "sub-C 2.4Ah NiCd" you'd be laughed out of the store.

Stop shopping at Radio Shack..
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John Muchow
science forum beginner


Joined: 04 Apr 2005
Posts: 9

PostPosted: Fri Oct 14, 2005 4:35 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Quote:
I was using the Titanium 3600MAh that I bought from amondotech, see

http://www.amondotech.com/index.asp?PageAction=Custom&ID=48

but I also used other 3.3Ah cells and .... nothing...

I will check the tabs then Smile Hope not to melt the cells Smile) The
original cells are spott welded so I was thinking I could manage that
too!!

Which welder machine would you recomend me ?

I spoke to Steve Hill at Robotic Power Solutions (who knows a LOT
about which NiCd/NiMH cells can handle high current levels best) and
he's never heard of the Titanium cells and suspects that they have a
very high internal resistance compared to cells like the Intellect
IB3600 (which he recommeds for your application).

He does not recommend using spot-welded tabls at the 30A your
application needs, the resistance is too high and your
voltage-under-load will suffer and the cells mightbe damaged from the
heat (depends on how long the current is at that 30A max level). He
recommends (carefully) soldered battery bars.

Steve is amazing at making custom packs (been doing it for years) and
might be worth talking to. He can give you a quote for soldered packs
that will easily handle your application. Or, at least, source those
IB3600's for you. Smile
John Muchow
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Usenet user
science forum Guru Wannabe


Joined: 06 May 2005
Posts: 166

PostPosted: Sat Oct 15, 2005 11:49 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

On Fri, 14 Oct 2005 08:24:00 -0400, wlb <nottelling@thistime.com> wrote:

Quote:
On Sun, 09 Oct 2005 17:05:43 +0800, budgie <me@privacy.net> wrote:

On Sat, 08 Oct 2005 14:12:16 GMT, browntimdc <tbrown59remove@verizon.net> wrote:

budgie <me@privacy.net> wrote in
news:f29ek1915f4ir00upnlsv1p1j1ekg6fnm1@4ax.com:

Actually the term "sub-C" relates to capacity. Such cells are C size
but (much) lower capacity - typically around 1000mAh.

No, sub-C cells are physically smaller.
23x43mm vs 26x46mm
Here's a table of cylindrical cell sizes:

http://www.batteryspace.com/index.asp?PageAction=Custom&ID=3#Industrial

Then you have a different naming regime than our market area. Here if you ask
for a "sub-C 2.4Ah NiCd" you'd be laughed out of the store.

Stop shopping at Radio Shack..

nice one ;-)

Fortunately they have all but disappeared on our part of the planet.
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sventus@gmail.com
science forum beginner


Joined: 28 Sep 2005
Posts: 32

PostPosted: Mon Oct 17, 2005 4:49 pm    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Dear John,

thank you very much, I will substitute the stainless steel strips
(70microOhm.cm) and use nickel strips (much lower resistivity ~
8-10microOhm.cm) and see if this helps, if not, I will try soldering
them with Tin and will keep you updated :)

What is the internal resistance of this IB3600 cells ? The ones I use
are around 7-8 mOhm

Sincerely,
Hannes
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John Muchow
science forum beginner


Joined: 04 Apr 2005
Posts: 9

PostPosted: Tue Oct 18, 2005 9:39 am    Post subject: Re: High drain NiCd - Sub C batteries for power tools (strapping tool) Reply with quote

Quote:
thank you very much, I will substitute the stainless steel strips
(70microOhm.cm) and use nickel strips (much lower resistivity ~
8-10microOhm.cm) and see if this helps, if not, I will try soldering
them with Tin and will keep you updated Smile

Double-up on the strips. Every little bit helps. Smile
If you end up soldering the cells, be careful. It's very hard to do
right without damaging the cell. Lots of instruction on the Web
though. Use "battery bars" instead of the strips. They're thick
copper or silver-plated copper bars and when soldered on significantly
reduce the inter-cell resistances compared to spot-welded strips.

Quote:
What is the internal resistance of this IB3600 cells ? The ones I use
are around 7-8 mOhm
Around 2mOhm. But, if the Titanium cells are truly 7-8mOhm cells at

30A discharge over the entire useful discharge curve, then the problem
is definitely the tabs you're using for inter-cell connections.

John Muchow
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