# Pouch Cell Tab Connection Methods



## LithiumaniacsEVRacing (Oct 9, 2010)

I am looking for input from all on this issue. Most pouch cells are designed with one tab copper (negative) and the other aluminum (positive). I have read there are issues when connecting aluminum to copper, so what about using copper blocks for the copper tabs and aluminum blocks for the aluminum tabs?


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## etischer (Jun 16, 2008)

At some point, copper needs to connect to aluminum if you're going to connect cells in series. I would use tin plated aluminum blocks. That seems to be the standard for electrical connectors that are compatible with both aluminum and copper wire.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Yes, you have a very good point, but we have 10 cells in parallel all using blocks to connect. 9 blocks of aluminum would sure save some weight.

Tin plated aluminum sounds interesting. 



etischer said:


> At some point, copper needs to connect to aluminum if you're going to connect cells in series. I would use tin plated aluminum blocks. That seems to be the standard for electrical connectors that are compatible with both aluminum and copper wire.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Found this info researching copper to aluminum connections:

The answer is that as the metal wires heat and cool, they expand and contract. Copper and aluminum expand and contract at different rates, so when you put them together under 1 termination point (as in a wire nut), it tends to loosen that splice up over time. This is where potential problems can occur. So one of the biggest differences about the AlumiConn is in its unique patented design. Using an AlumiConn connector keeps the dissimilar wires separated, but connected through a tin-plated aluminum block inside the connector. The tin-plating of the internal aluminum block, along with a secure mechanical connection, provides a much cooler, safer splice – completely and permanently repairing the problem.


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## LithiumaniacsEVRacing (Oct 9, 2010)

One way to secure the connection might be to use a lock washer on your bolt connecting the tabs, when the expansion and contraction happens this will maintain a tight fit. 



LithiumaniacsEVRacing said:


> Found this info researching copper to aluminum connections:
> 
> The answer is that as the metal wires heat and cool, they expand and contract. Copper and aluminum expand and contract at different rates, so when you put them together under 1 termination point (as in a wire nut), it tends to loosen that splice up over time. This is where potential problems can occur. So one of the biggest differences about the AlumiConn is in its unique patented design. Using an AlumiConn connector keeps the dissimilar wires separated, but connected through a tin-plated aluminum block inside the connector. The tin-plating of the internal aluminum block, along with a secure mechanical connection, provides a much cooler, safer splice – completely and permanently repairing the problem.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Another issue that I keep reading is the amount of current aluminum can carry compared to copper is much different. It seems the blocks would need to be much larger if I went with aluminum. 



etischer said:


> At some point, copper needs to connect to aluminum if you're going to connect cells in series. I would use tin plated aluminum blocks. That seems to be the standard for electrical connectors that are compatible with both aluminum and copper wire.


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## steven4601 (Nov 11, 2010)

The amount of current you can pass through a conductor depends also how long you wish to do that at which duty-cycle. Drag strip duty cycle is small and the duration is also.

Even though im about a megawatt short of what you are doing, I calculated the energy dissipated in my cell interconnects. I chose 100 seconds max for full power and used that as my thermal time limit for the interconnects to heat up a certain amount of Fahrenheit/Kelvins. This output from the calculation allowed me to use very thin copper interconnects. 0.5mm thick strips of 20mm wide @ 100Amp per cell. Length doesn't matter as volume & powerloss goes up linear with length.


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## rwaudio (May 22, 2008)

LithiumaniacsEVRacing said:


> Another issue that I keep reading is the amount of current aluminum can carry compared to copper is much different. It seems the blocks would need to be much larger if I went with aluminum.


Don't get too caught up in this, since one of your cell tabs is already a thin aluminium strip. There are plenty of online calculators that will give you a voltage drop for a certain cross section at a given current. You can compare copper to aluminium easily.

One thing that I have learned from my connection method is that I have slightly higher than expected/wanted connection resistance due to the simple quantity of connections in series.

Using my method you would have the tab of the 1st cell connected to a block, connected to the tab of the 2nd cell, connected to a block, connected to the 3rd cell etc. Cell one and Cell ten would be many connections apart (I only have a 3P set up and at 1000A I can measure a small voltage difference between the cell one tab and cell three tab) 

In short if you can devise a method where tab one, two....ten are all connected to a single electrical point then I think you would have lower loses and less sag in the pack.

I have my pack apart anyway for capacity measurements I'll be putting it back together a different way to avoid/reduce this problem.


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## EVfun (Mar 14, 2010)

rwaudio said:


> Don't get too caught up in this, since one of your cell tabs is already a thin aluminium strip. There are plenty of online calculators that will give you a voltage drop for a certain cross section at a given current. You can compare copper to aluminium easily.


I just wanted to point out that not all aluminum is equal. The conductivity of aluminum alloys varies widely from that of electrical grade aluminum. 6061 has about 70% of the conductivity of pure aluminum, 5052 only about 60% of the conductivity of pure aluminum, and 7075 only about 50% of the conductivity of pure aluminum. It isn't hard to get electrical grade copper but more difficult to get electrical grade aluminum. I think all the 1xxx series alloys are pretty close to the conductivity of pure aluminum. They are often harder to find.


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## PhantomPholly (Aug 20, 2008)

rwaudio said:


> I have my pack apart anyway for capacity measurements I'll be putting it back together a different way to avoid/reduce this problem.


Yikes!!! - are you using stereo speaker wire? No connectors? Look at all the frayed strands where the wire was stripped!!! I hope this is just a temporary test lash-up....

Although these are cars rather than airplanes, for those unfamiliar with good wiring techniques I would highly recommend reading up on the practice and theory of all things electric you are likely to deal with in an EV from over 30 years of experience in aircraft electronics. Bob Nuckolls is renowned in the aviation world as "the man;" his primary book is called "Aeroelectric Connection." It is cheap for the knowledge it contains.


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## rwaudio (May 22, 2008)

PhantomPholly said:


> Yikes!!! - are you using stereo speaker wire? No connectors? Look at all the frayed strands where the wire was stripped!!! I hope this is just a temporary test lash-up....
> 
> Although these are cars rather than airplanes, for those unfamiliar with good wiring techniques I would highly recommend reading up on the practice and theory of all things electric you are likely to deal with in an EV from over 30 years of experience in aircraft electronics. Bob Nuckolls is renowned in the aviation world as "the man;" his primary book is called "Aeroelectric Connection." It is cheap for the knowledge it contains.


Nope that's the final product.... a 6.6v Porsche


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## LithiumaniacsEVRacing (Oct 9, 2010)

Wow, thanks for the picture. My pack will look similar, but with 10P / 90+S 

The resistance using aluminum is one problem I might have since my pack requires many more connections. 



rwaudio said:


> One thing that I have learned from my connection method is that I have slightly higher than expected/wanted connection resistance due to the simple quantity of connections in series.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I have found two grades of aluminum in bus bars that are very conductive:

Grade 6101
Grade 1350

It seems the 1350 is more conductive, anyone know the difference in these two alloys?



EVfun said:


> I just wanted to point out that not all aluminum is equal. The conductivity of aluminum alloys varies widely from that of electrical grade aluminum. 6061 has about 70% of the conductivity of pure aluminum, 5052 only about 60% of the conductivity of pure aluminum, and 7075 only about 50% of the conductivity of pure aluminum. It isn't hard to get electrical grade copper but more difficult to get electrical grade aluminum. I think all the 1xxx series alloys are pretty close to the conductivity of pure aluminum. They are often harder to find.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Testing equipment needed to test 4000amps @ 3.7volts, is that possible? or 400amps @ 3.7volts?


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## LithiumaniacsEVRacing (Oct 9, 2010)

Great information:

http://www.geindustrial.com/Newsletter/Aluminum_vs_Copper.pdf


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## EVfun (Mar 14, 2010)

LithiumaniacsEVRacing said:


> I have found two grades of aluminum in bus bars that are very conductive:
> 
> Grade 6101
> Grade 1350
> ...


Both of those alloys are used for electrical conductors. 6101 is more machinable but somewhat less conductive than 1350. 

Here is data from Alcoa on 1350.
Here is data from Alcoa on 6101.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I have placed an order for the aluminum bus bars. I can cut and drill myself, but not sure about the tin coating process? Is there a way to dip or spray the bus bars with a home process? Or do I need to send them to a facility?


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## LithiumaniacsEVRacing (Oct 9, 2010)

I have found a home kit process, anyone ever try this method?

http://www.caswellplating.com/kits/tin_plate.htm

Merry Christmas!  Currently watching:
The Greatest Story Ever Told (Old School Flick)


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## EVfun (Mar 14, 2010)

I looked at that but it won't plate directly over aluminum. Actually, little will because of how quickly it makes a thin oxide layer. For the home plater it looks like you need to do this first. Then you could nickel plate. I believe the zinc coating on the aluminum is removed by the nickel plating process. 

I don't know if nickel is suitable. It is the main component of stainless steel which is often used for fasteners with aluminum terminals. It is also commonly seen on the bus bars for NiCad battery packs.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Thank you for reviewing the website, I just posted the link after a quick look. Can I just leave the blocks coated with Zinc? 



EVfun said:


> I looked at that but it won't plate directly over aluminum. Actually, little will because of how quickly it makes a thin oxide layer. For the home plater it looks like you need to do this first. Then you could nickel plate. I believe the zinc coating on the aluminum is removed by the nickel plating process.
> 
> I don't know if nickel is suitable. It is the main component of stainless steel which is often used for fasteners with aluminum terminals. It is also commonly seen on the bus bars for NiCad battery packs.


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## LithiumaniacsEVRacing (Oct 9, 2010)

*This is my Aluminum source:*

https://www.onlinemetals.com/merchant.cfm?pid=18142&step=4&id=1282&top_cat=60

*Grade 6101 T61* 

T61 and T64 are more conductive than T6, T63, and T65


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## LithiumaniacsEVRacing (Oct 9, 2010)

I am going to build two 12 volt batteries with my cells, one with copper bus bars, the other with aluminum. I will make each pack 3P (1200 amps) at 3S (12 volts).

Then I want to pull 1000 amps with this baby:

http://standardus.com/stdshop/associated-6-12v-carbon-pile-load-tester-1000-amps-aso-6036b.html

I will monitor temperature and voltage drop. Will this work? 

I really need a 4000 amp carbon pile load tester?


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## LithiumaniacsEVRacing (Oct 9, 2010)

Anyone ever heard of this material? Can it be used as is?

http://www.cupal.de/engl_seiten/frame_engl.html

*Properties*

CUPAL sums up the advantages of light metals – low specific weight (hence lesser deadweight) – easy forming, etc. together with the advantages of copper in corrosion-proof, galvanizing and tinning abilities, electrical properties, etc.

Chemically and mechanically, the copper and aluminium surfaces react as pure copper and pure aluminium respectively. CUPAL permits a corrosion-proof bond between heavy and light metal conductors.

CUPAL has specially good heat conductivity. The electrical conductivity of CUPAL is excellent and compares in high frequency with pure copper. The contact values are even better than in the case of pure copper.

CUPAL sheets can easily stand cold drawing, light an d deep stamping, bending, folding, riveting, etc. and also can be galvanised or tinned as pure copper, with a special and simple process to protact the cross-cuts against corrosion


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## LithiumaniacsEVRacing (Oct 9, 2010)

*I would love to coat all the bus bars in silver, that would guarantee a solid connection! 
*
*
*
*Material IACS % Conductivity *
*Silver *
*105% *
*Copper *
*100% *
*Gold *
* 70% *
*Aluminum *
*61% *
*Nickel *
*22 % *
*Zinc *
* 27% *
*Brass *
*28% *
*Iron *
*17% *
*Tin *
*15% *
*Phosphor Bronze *
*15% *
*Lead *
* 7% *
*Nickel Alum. Bronze *
* 7% *
*Steel *
*3 to 15%*


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## LithiumaniacsEVRacing (Oct 9, 2010)

_*BINGO!*_

*Bus Bar Plating:
Aluminum & Copper With Silver Or Tin Finishes Up To 12' Lengths*

 Nobert offers silver or tin plating on aluminum or copper base metal. Aluminum base metal is pretreated with the Alstan® surface preparation process to enhance adhesion strength of the coating metal. Our tanks can accommodate up to 12-foot lengths of material. Plated material is held within dimensions set forth by ASTM B-317 for aluminum and ASTM B-187 for copper or tighter. Nobert Plating also distributes all sizes of aluminum and copper bar, rods and tubes internationally.
 ® Alstan is a registered trademark of Atotech USA, Inc.
*Bus Bar Available:
Silver Or Tin Finishes
Up to 12' Lengths*


http://www.nobertplating.com/busbar.htm


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## rwaudio (May 22, 2008)

LithiumaniacsEVRacing said:


> _*BINGO!*_
> 
> *Bus Bar Plating:
> Aluminum & Copper With Silver Or Tin Finishes Up To 12' Lengths*
> ...


That's interesting..... but what would it cost for the hundreds if not thousands of pieces you are going to need?????


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## NabilAhmad (Feb 26, 2011)

rwaudio said:


> That's interesting..... but what would it cost for the hundreds if not thousands of pieces you are going to need?????


Depending on its machinability after coating, which should be pretty good, it may be most cost effective to plate full sticks, then cut them down. Don't care about the conductivity of the ends


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## rwaudio (May 22, 2008)

NabilAhmad said:


> Depending on its machinability after coating, which should be pretty good, it may be most cost effective to plate full sticks, then cut them down. Don't care about the conductivity of the ends


yes but how long will that plating last with chopped ends and full of holes? (no idea myself, just asking)


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## NabilAhmad (Feb 26, 2011)

rwaudio said:


> yes but how long will that plating last with chopped ends and full of holes? (no idea myself, just asking)


That is a very good and crucial question. Id imagine there are a number of factors at play. However, if it would be anything like the plating on most copper connectors, I'd think pretty well. I've never had the coating on a crimp connector flake off. But this may be a whole different animal.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Very good questions guys! 

If the pack was built 10P 90S I would be looking at around 1800" (estimated) 150' of bar. I have placed a request for an estimate.

I would really like to plate the bus bars with a "home process", but I am looking at all options at the moment. Silver coating would increase the conductivity of the aluminum blocks. 

The reasoning is based on some pack designs will weld the tabs together, but because of the "space" between each of my cells and the amount of cells in a parallel "block", I just need some type of "fillers" that conduct very well.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I know some battery pack builders coat their copper in Nickel, Zinc or Tin wouldn't this reduce the conductivity?



LithiumaniacsEVRacing said:


> *I would love to coat all the bus bars in silver, that would guarantee a solid connection!
> *
> *Material IACS % Conductivity *
> *Silver **105% *
> ...


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## LithiumaniacsEVRacing (Oct 9, 2010)

First response from Nobert:

Dear President,
Nobert only offers plating on customers goods. We do not sell aluminum bar. You need to contact supply house for the metal. We can quote you for the silver plating of your bar. If you give me the thickness of the silver required and the exact size of the aluminum, I can quote you a price.
Regards,
Pete Smith
Nobert Plating 

I have sent him the info, 1800 pieces pre-cut and drilled. Waiting for estimate?


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## LithiumaniacsEVRacing (Oct 9, 2010)

My quote to silver plate 1800 pieces of aluminum:

$0.78 each plus shipping. 

This is at the current silver price. I am happy with this quote and will be sending them the aluminum bus bars.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I have received additional info, which is bring me back to copper instead of aluminum. I really need to make a decision soon, any more advice?


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## EVfun (Mar 14, 2010)

I am not racing EVs, but I have had the privilege to turn a wrench on a couple. I have not seen any signs of skimping on the conductor. Bill Dube talks about correctly sizing conductors for racing (and I'm sure practices what he preaches), but he is in the motorcycle side of the house where weight is even more important. The thing is, resistance is lost performance at the far end of the quarter (resistive losses are voltage drops.) 

I would lean toward copper, especially since racing will get things hot and hasten the loosening of fasteners. The thermal expansion of Aluminum is at least 30% greater than that of Copper. 304 and 316 Stainless steel have almost the same thermal expansion as copper. Should the fasteners expand 35% less or 5% less?


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## LithiumaniacsEVRacing (Oct 9, 2010)

I agree, but need another solutions to fill the 1/4" space between tabs. I next thought is copper U channels, I am researching now. 



EVfun said:


> I am not racing EVs, but I have had the privilege to turn a wrench on a couple. I have not seen any signs of skimping on the conductor. Bill Dube talks about correctly sizing conductors for racing (and I'm sure practices what he preaches), but he is in the motorcycle side of the house where weight is even more important. The thing is, resistance is lost performance at the far end of the quarter (resistive losses are voltage drops.)
> 
> I would lean toward copper, especially since racing will get things hot and hasten the loosening of fasteners. The thermal expansion of Aluminum is at least 30% greater than that of Copper. 304 and 316 Stainless steel have almost the same thermal expansion as copper. Should the fasteners expand 35% less or 5% less?


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## LithiumaniacsEVRacing (Oct 9, 2010)

Good info:

. Electroplated Tin vs. Nickel One of our vendors is planning to start plating the copper bus bars in their assemblies, to which we connect our busbars, with nickel. We are unfamiliar with the properties of nickel, and are considering whether we should change from Tin plating to Nickel plating for any reason. Can you advise me on any concerns about long term effects between nickel and tin plated materials clamped together, and any significant differences in cost between the 2 methods?
*Tin vs. Nickel*
Nickel is not Solderable, so any items that may need to be soldered to the buss bar wouldn’t stick to electroplated nickel. Forming, nickel is not as ductile as tin would be and therefore may crack under stress if bent. Tin is better than nickel as far as conductivity is concerned. Nickel can and will grow a thick oxide that may prevent conductivity over time as the oxide is more difficult to break through than tin.


http://ppc1904.com/resources/faq


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## NabilAhmad (Feb 26, 2011)

LithiumaniacsEVRacing said:


> Good info:
> 
> . Electroplated Tin vs. Nickel One of our vendors is planning to start plating the copper bus bars in their assemblies, to which we connect our busbars, with nickel. We are unfamiliar with the properties of nickel, and are considering whether we should change from Tin plating to Nickel plating for any reason. Can you advise me on any concerns about long term effects between nickel and tin plated materials clamped together, and any significant differences in cost between the 2 methods?
> *Tin vs. Nickel*
> ...


Ron, it sounds to me like the only way to avoid second guessing will be prototyping a couple dozen in each combination you are currently most confident in. This thread has many good questions and little consensus and you are stirring the pot the most! 

Generally, in racing situations, I'd imagine expansion and long term galvanic corrosion will be mitigated with routine checks. However- this does put great emphasis on serviceability of connector design. 

What I haven't seen much of is real numbers. So again, if you are asking for advice or recommendations, opinions don't win races. Test it yourself and trust that the forums will look over your shoulder and point out things you didn't even think to question and quantify.


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## aeroscott (Jan 5, 2008)

silver plating on copper , 10% better conducting by volume 3 or 4% by weight then copper , if I remember . silver oxide is conductive .Mercedes uses it for there connectors and switches , some aircraft wire will be silver plated if Teflon coated , Tin would melt at Teflon extrusion temps .


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## GizmoEV (Nov 28, 2009)

Ron,

For your tab connection setup what about a bar with V grooves cut into it. The V would not come to a point but more in a keystone shape where there would be room for two screws to go through the bar into the center of the keystone opening. Then have a matching V or key stone shape that has tapped holes for the screws. The tab of a cell could be put into each side of this keystone opening and the screws tightened to secure the tabs. This would then connect all the tabs in a set of cells to the same bus bar and not have all those separate connections that a stack of blocks would like mentioned earlier. The angle of the sides of the grooves could be tapered such that a small tension of the screws holding the keystone piece in place would translate to a large force against the cell tabs. Something like this viewed from the edge...


```
[FONT=Courier New]===============================
           /---\   bus bar material
__________/     \______________

           /===\  <---- key stone
          /_____\       
[/FONT]
```
Hopefully it shows up ok and makes sense.


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## rwaudio (May 22, 2008)

GizmoEV said:


> Ron,
> 
> For your tab connection setup what about a bar with V grooves cut into it. The V would not come to a point but more in a keystone shape where there would be room for two screws to go through the bar into the center of the keystone opening. Then have a matching V or key stone shape that has tapped holes for the screws. The tab of a cell could be put into each side of this keystone opening and the screws tightened to secure the tabs. This would then connect all the tabs in a set of cells to the same bus bar and not have all those separate connections that a stack of blocks would like mentioned earlier. The angle of the sides of the grooves could be tapered such that a small tension of the screws holding the keystone piece in place would translate to a large force against the cell tabs. Something like this viewed from the edge...
> 
> ...



I think that's a cool idea, I built my first test pack using the stacked block method and at 1000A I can measure a voltage difference between cell 1 and cell 3 in a parallel grouping. Although it's pretty small it is wasted power. The voltage drop over 90S or more would turn into something significant.

The basic idea could be tested using a flat bus bar and rectangular blocks just to see if the solid bus bar makes a difference over stacked blocks.


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## aeroscott (Jan 5, 2008)

Google brush plating , no epa problems doe to small amounts , it's done with a swab or foam brush in small plastic tray . better adhesion 3x then tank plating , you can plate the bolts , nuts ,wire or redo anything needed in shop .


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## LithiumaniacsEVRacing (Oct 9, 2010)

Thanks guys for the input. After spinning my brain in circles for a few days I have decided to build with the copper bus bars 30mm wide coated with Nickel or tin. I will channel the sides to remove some copper and weight and keep the mating area completely untouched.


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## NabilAhmad (Feb 26, 2011)

rwaudio said:


> I think that's a cool idea, I built my first test pack using the stacked block method and at 1000A I can measure a voltage difference between cell 1 and cell 3 in a parallel grouping. Although it's pretty small it is wasted power. The voltage drop over 90S or more would turn into something significant.
> 
> The basic idea could be tested using a flat bus bar and rectangular blocks just to see if the solid bus bar makes a difference over stacked blocks.


Just curious, what is the drop across the same distance in your final cables? My question is, without quantification and comparison with the rest of the system, I'm not hearing from you any real evidence of anything. Does you observation imply any significant avoidable loss, or is it just a matter of shoving 1,000a through a conductor?


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## sdcellpack (Jan 3, 2012)

We sell complete battery packaging solution for 40 amp kokams.
www.sdcellpack.com


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## NabilAhmad (Feb 26, 2011)

sdcellpack said:


> We sell complete battery packaging solution for 40 amp kokams.
> https://www.sdcellpack.com


 Your link doesn't work.


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## sdcellpack (Jan 3, 2012)

I fixed it
sorry


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## DIYguy (Sep 18, 2008)

How do you get 33 volts out of 8 cells?


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## sdcellpack (Jan 3, 2012)

4v each...that's 32v, the bms boards are set @ 4.125v


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## DIYguy (Sep 18, 2008)

sdcellpack said:


> 4v each...that's 32v, the bms boards are set @ 4.125v


You probably shouldn't advertise a battery based on an arbitrary voltage. They are typically rated by "Nominal" voltage and for lithium polymer Kokam cells that is 3.7 volts. This pack should really be described as a 29.6 volt battery.


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## sdcellpack (Jan 3, 2012)

Sure.
Thanks for your concern.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I would like to see the inside connection method of your Dow Kokam packs?

Also, a word of advice. Customers need to trust who they deal with, you should add additional info on company, name of owner? Address? Phone? It assures customers they are dealing with a legit company. Good luck! 
Look forward to the pics.


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## sdcellpack (Jan 3, 2012)

We don't sell to retail customers. If you want our packaging products you have to contact manzanitamicro.

Thanks!


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## LithiumaniacsEVRacing (Oct 9, 2010)

sdcellpack said:


> We don't sell to retail customers. If you want our packaging products you have to contact manzanitamicro.
> 
> Thanks!


Pictures of connection method and info?


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## palmer_md (Jul 22, 2011)

sdcellpack said:


> We don't sell to retail customers. If you want our packaging products you have to contact manzanitamicro.
> 
> Thanks!


I don't want to sound combative, but why then did you send all the retail viewers to your site instead of manzanita micro? Just asking.


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## Genius Pooh (Dec 23, 2011)

Hi..

I worry it high voltage high peak ampare. If it short or connected your body..

Your body part is explode.....

I worry so I decide not making my own battery pack..


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## LithiumaniacsEVRacing (Oct 9, 2010)

Lexan is the best material for battery boxes. Designing a basic 1000amp 300+volt box is very easy and leaves much room for cooling options etc..

Building my boxes are more difficult because of the amount in parallel. All parallel connections are sealed in the first level of lexan. The series connections along with BMS will be sealed in the second level of lexan. Cooling is not needed in drag racing, time is very short. Lithium polymer works better when warm. If you want lithium cells for continuous use, you will need some type of cooling, water channels work best, but air can be used on smaller packs.


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## Theredone51 (Oct 15, 2011)

Ronald, how thick is the lexan you use? And do you glue or screw the walls together?


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## barron (Dec 10, 2011)

On this thread, Luke (liveforphysics) is building your pack for you.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=31687&hilit=luke&start=60

Since you are asking about connection methods now on this forum it sounds like he is no longer building the pack/ providing construction advice to you. 

Is that correct?


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## LithiumaniacsEVRacing (Oct 9, 2010)

barron said:


> On this thread, Luke (liveforphysics) is building your pack for you.
> 
> http://endless-sphere.com/forums/viewtopic.php?f=14&t=31687&hilit=luke&start=60
> 
> ...


Yes, Luke gave me very helpful advice along with others from the Endless-Sphere forum. The pack was very difficult to build because my cells were pre-assembled in series packs of 5S. The main concern was how to balance the pack without a BMS.

The current pack is much easier to build with single cells built into parallel blocks then connected into series strings. I needed some opinions on bus bar materials, I have decided to stick with copper and remove some material on each bus bar slab. I am way past that now, already designing series connections on the second level with BMS.


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## Theredone51 (Oct 15, 2011)

Hello Ron,

Maybe you didn't see my post, but how thick is the Lexan you are using for the stacks and the casing?


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## LithiumaniacsEVRacing (Oct 9, 2010)

Theredone51 said:


> Hello Ron,
> 
> Maybe you didn't see my post, but how thick is the Lexan you are using for the stacks and the casing?


Sorry I missed it. The rear battery modules are 24" long and 4.5" wide. Each box has 3/8 lexan botton and ends. The sides are thinner 1/8 thick. The compression is secure, each 10P battery is doubled taped together and then wrapped with plastic to reduce the chances of any swelling. Each 10P battery has a very thin slice of G10 fiberglass between the series connections.


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## LithiumaniacsEVRacing (Oct 9, 2010)

I have ordered 2000 (parallel connections) copper bus bar pieces cut with hole and silver plated. I also ordered 200 (series) copper bus bar pieces cut with holes and silver plated. Copper adds about 150lbs to the light pack, but I want assurance the tabs will not run hot pulling 4000+ amps! 

The price was under $3000.00 
3 weeks lead time.


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## LithiumaniacsEVRacing (Oct 9, 2010)

LithiumaniacsEVRacing said:


> I have ordered 2000 (parallel connections) copper bus bar pieces cut with hole and silver plated. I also ordered 200 (series) copper bus bar pieces cut with holes and silver plated. Copper adds about 150lbs to the light pack, but I want assurance the tabs will not run hot pulling 4000+ amps!
> 
> The price was under $3000.00
> 3 weeks lead time.


I have been informed my silver coated copper bus bar connectors will be shipped out Feb 12, 2012 

I guess its time to order the BMS.


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## powerhouse (Apr 1, 2011)

LithiumaniacsEVRacing said:


> I have been informed my silver coated copper bus bar connectors will be shipped out Feb 12, 2012
> 
> I guess its time to order the BMS.



What BMS are you going with? Orion? Lithiumate?


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## LithiumaniacsEVRacing (Oct 9, 2010)

powerhouse said:


> What BMS are you going with? Orion? Lithiumate?


I am leaning towards EMUS.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Update on pack build. The silver coated copper bus bars have been completed. They shipped out of Tenn. today, I should have them in a few days! 

Now the real work starts! 

I never thought about what type of nut and bolt I will be using? 
The size is 1/4", but not sure what I should buy? 
Hmmmm, will galvanized work? or is stainless steel better?


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## steven4601 (Nov 11, 2010)

From my limited knowledge about metals, stainless steel in/with aluminium is asking for trouble. There a rather large potential difference. The Stainless steel is very noble, the aluminium not so noble and will sacrifice itself.


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## Jan (Oct 5, 2009)

steven4601 said:


> From my limited knowledge about metals, stainless steel in/with aluminium is asking for trouble. There a rather large potential difference. The Stainless steel is very noble, the aluminium not so noble and will sacrifice itself.


In my project a previous owner combined the two: Stainless steal plate and alluminum nuts. More 'rusted' together than just plain steal.


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## steven4601 (Nov 11, 2010)

Stainless like Aluminium comes in many grades. Some combo's sort of workout okay ish, most really do not.
A2 (304) and A4 (316) grades which are faily common for bolts on this side of the pond are not such a good combo with aluminium.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Thanks guys!

I know the nuts and bolts must be coated, I think galvanized is my best choice. The lock washers look great.


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## GizmoEV (Nov 28, 2009)

Here is a picture of what I was talking about in my post #40 except that this only hooks two tabs/cells together. My idea was for several wedges in parallel to match the number of parallel cells all on one buss bar to minimize the number of connections between paralleled cells.


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> Here is a picture of what I was talking about in my post #40 except that this only hooks two tabs/cells together. My idea was for several wedges in parallel to match the number of parallel cells all on one buss bar to minimize the number of connections between paralleled cells.


It looks good, but you still end up with the same amount of material. Say you use one of these for 2P, you still need to connect to the next 2P, in my case 10P.


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## steven4601 (Nov 11, 2010)

What about the mechanical stress onto the tabs.

If the Tabs are dead solid connected to a piece of aluminium which can vibrate back and forth referenced from the cell tab begin points, it may introduce cracks / leaks. 

A123 uses cassetes on which the cell tabs are pressed, the cassetes are directly glued/attached to the pouch. No 'sliding'/vibration likely there.


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## GizmoEV (Nov 28, 2009)

LithiumaniacsEVRacing said:


> It looks good, but you still end up with the same amount of material. Say you use one of these for 2P, you still need to connect to the next 2P, in my case 10P.


I was thinking of a solid piece for the 10P to eliminate a joint which might add to the resistance of the connection in the parallel set.



steven4601 said:


> What about the mechanical stress onto the tabs.
> 
> If the Tabs are dead solid connected to a piece of aluminium which can vibrate back and forth referenced from the cell tab begin points, it may introduce cracks / leaks.
> 
> A123 uses cassetes on which the cell tabs are pressed, the cassetes are directly glued/attached to the pouch. No 'sliding'/vibration likely there.


Even in the Mac battery packs I've disassembled which use pouch cells they have a very strong adhesive between parallel cells and then to the case. Vibration is definitely something which has to be looked at.


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## LithiumaniacsEVRacing (Oct 9, 2010)

steven4601 said:


> What about the mechanical stress onto the tabs.
> 
> If the Tabs are dead solid connected to a piece of aluminium which can vibrate back and forth referenced from the cell tab begin points, it may introduce cracks / leaks.
> 
> A123 uses cassetes on which the cell tabs are pressed, the cassetes are directly glued/attached to the pouch. No 'sliding'/vibration likely there.


RC packs go through hell and back and never rip at the tab, unles the cell is abused it will push from the inside out. Most glue or double tape the cells together to prevent cell chaving. Then wrap in heat shrink or tape, once in the battery box they seat tight and compressed.


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## steven4601 (Nov 11, 2010)

Not that I am expert in 'aerial mining', but I have dug out some LiPo's in the recent history  Packs usually became 'shorter' in length after such events.

Small packs with soldered tabs vs Large packs with many pounds of interconnects is something quite different don't you think.

You will be fixating the cell pouches relative to the busbars/interconnects?


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## LithiumaniacsEVRacing (Oct 9, 2010)

My silver coated copper bus bars have arrived! 










































Will be building modules for a few weeks!


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## rwaudio (May 22, 2008)

Very nice, I hope this gives you much lower connection resistance than I was seeing with raw aluminium.

When will you have a finished module/pack to show off?


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## LithiumaniacsEVRacing (Oct 9, 2010)

rwaudio said:


> Very nice, I hope this gives you much lower connection resistance than I was seeing with raw aluminium.
> 
> When will you have a finished module/pack to show off?


I will start tomorrow after my first cup of coffee! 

Everything is ready, lexan boxes complete, 10P packs built, zinc nuts bolts and lock washers, etc....I will build all the modules with parallel connections covered and sealed, the series bus bars pop through the first layer. The final connections will be all the series with BMS boards.


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## drgrieve (Apr 14, 2011)

rwaudio said:


> Very nice, I hope this gives you much lower connection resistance than I was seeing with raw aluminium.


What sort of additional sag did you measure?


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## GizmoEV (Nov 28, 2009)

LithiumaniacsEVRacing said:


> My silver coated copper bus bars have arrived!


Awesome!

BTW, I may have missed it but why did you go with silver coating rather than nickel? Is it because you don't have the acid mist from lead batteries to contend with? Silver does oxidize but I don't know what effect that has on the resistance.


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## LithiumaniacsEVRacing (Oct 9, 2010)

*The work has started!* 

































*Need to trip some off the lexan boxes!*
























*The lexan boxes have been screwed together, I add the duck tape as extra sealant from water, remember we do huge burnouts in a water pit before we race!* *The BMS will be added before final cover is added.*


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> Awesome!
> 
> BTW, I may have missed it but why did you go with silver coating rather than nickel? Is it because you don't have the acid mist from lead batteries to contend with? Silver does oxidize but I don't know what effect that has on the resistance.


This is why I used Silver:

http://en.wikipedia.org/wiki/Silver


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## GizmoEV (Nov 28, 2009)

LithiumaniacsEVRacing said:


> This is why I used Silver:
> 
> http://en.wikipedia.org/wiki/Silver


" it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal."

"Silver also has the lowest contact resistance of any metal."

The only question is how conductive are the oxides which could form? Given how you are assembling your packs I doubt that will be a problem.

BTW, it appears that the tabs at each end of your parallel set have minimal contact area as they are only pressed against the blocks with the washer under the bolt head/nut. If you pull 3000A out of the battery that is 300A/tab. Can it handle that without issues?

Edit: I think your setup is definitely smaller than the multiple wedge method of attaching cells. There also won't be any issues with getting enough contact pressure at the terminals since you don't have to worry about threads stripping out of aluminum or copper. Thanks for sharing.


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> " it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal."
> 
> "Silver also has the lowest contact resistance of any metal."
> 
> ...


Yes, I am not to happy with using washers on the ends, I do have some flat stock steel zinc plated, it would work perfect, but drilling a 1/4 hole will expose remove some zinc. Not sure if I should try it, the flat part connecting to the tabs will be covered in zinc, but the hole will not?


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## GizmoEV (Nov 28, 2009)

LithiumaniacsEVRacing said:


> Yes, I am not to happy with using washers on the ends, I do have some flat stock steel zinc plated, it would work perfect, but drilling a 1/4 hole will expose remove some zinc. Not sure if I should try it, the flat part connecting to the tabs will be covered in zinc, but the hole will not?


I see that McMaster-Carr has High-Strength Corrosion-Resistant Washers with a 5/16" hole and ~3/4" in diameter. They also have some large diameter and extra thick washers.

Another option is that since the hole won't be rubbed against you could just paint the holes in the zinc coated plate after drilling and deburing.


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## palmer_md (Jul 22, 2011)

gottdi said:


> Ron,
> 
> After looking again at your cell packs and tab layout and connection method I see an issue you might want to think about. The end tabs on the end cells are connected on the outside of the blocks you had made and are only held against those blocks with the washer


That is what GizmoEV already pointed out, and you discounted it saying "The bolt and washer is only holding it together. Nothing to do with the ability to carry mega amps."

Instead of saying "I see and issue", would it not be more appropriate to say, that you now agree with GizmoEV once you took a second look.

I'm not trying to be argumentative, just seems like credit should be given when it is due.

I also agree that some sort of plate on the outside should be considered. Also, do you have a silver block to go between the modules to put them in series? The spacing seems large between the tabs, and it looks like it might be a big chunk of metal. How are you doing the interconnections?


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## Nathan219 (May 18, 2010)

Polish off the oxidation make the connection then keep oxygen from being able to reach the silver to cause corrosion. You could pressurize the battery box with nitrogen, to avoid any possible oxidation and loss of power. Pure Aluminum will give better conductivity per weight.


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## LithiumaniacsEVRacing (Oct 9, 2010)

*I cut zinc plated flat stock drilled a 1/4" hole, then sprayed with high heat engine enamel.*


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## LithiumaniacsEVRacing (Oct 9, 2010)




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## LithiumaniacsEVRacing (Oct 9, 2010)

*The BMS board will connect by a copper L bracket on one side and the loop the the other side.*


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## LithiumaniacsEVRacing (Oct 9, 2010)

gottdi said:


> Not what I was expecting for a fix but it works. Should be just fine that way too. I like your small packs. Nice work Ron.
> 
> 
> Pete


Thanks, each module will hold 10P 7S. Easy to move, strong and safe. Any 10P block is easy to replace without dismantling the whole pack.


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## GizmoEV (Nov 28, 2009)

LithiumaniacsEVRacing said:


> *The BMS board will connect by a copper L bracket on one side and the loop the the other side.*


Those look great, Ron. Using the L bracket will also allow you to tighten the connections between cells without worry about crushing the BMS board.


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> Those look great, Ron. Using the L bracket will also allow you to tighten the connections between cells without worry about crushing the BMS board.


Thanks! Having fun while learning.


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## LithiumaniacsEVRacing (Oct 9, 2010)




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## LithiumaniacsEVRacing (Oct 9, 2010)

Each 10P pack is separated by G10 Fiberglass, this gives an additional safety barrier between cell packs. The series connections are above the first layer of lexan, this allows easy disconnects if any 10P pack goes bad. The 10P pack will lift up out of our battery modules, once the series connection has been removed.


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## LithiumaniacsEVRacing (Oct 9, 2010)

*28 Volt 4000+ Amp Battery Module.*


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## kerrymann (Feb 17, 2011)

Cool! Nice looking set-up. The checkerboard motif isn't my style but it's obvious you have got victory one your mind.  I am curious how/where you will be fuse protecting the packs?


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## LithiumaniacsEVRacing (Oct 9, 2010)

kerrymann said:


> Cool! Nice looking set-up. The checkerboard motif isn't my style but it's obvious you have got victory one your mind.  I am curious how/where you will be fuse protecting the packs?


What you are looking at is one pack module, the rear pack modules will connect as one pack then be fused, same for the front.


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## GizmoEV (Nov 28, 2009)

Love those cell-to-cell interconnects. On the first 4000A draw they should weld right on nicely.

What is the red stuff which can be seen between the tabs?


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> Love those cell-to-cell interconnects. On the first 4000A draw they should weld right on nicely.
> 
> What is the red stuff which can be seen between the tabs?


High Temp Silicone. I wanted to give structure support to the cell tops and tabs, the silicone fills in nicely, once cured it gives a solid hold. Lithium Polymer cells do not need cooling for 7 second runs, they work better warm.


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## rwaudio (May 22, 2008)

Nice work Ron, now is there any way to load test it (other than in the car?).

You could always try some magic and make a wrench disappear!


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## LithiumaniacsEVRacing (Oct 9, 2010)

rwaudio said:


> Nice work Ron, now is there any way to load test it (other than in the car?).
> 
> You could always try some magic and make a wrench disappear!


After I pay some huge bills on the table, I will buy 4 pile testers (1000 amps each) and test 4000 amps from a 10P pack, I will video tape the demonstration. 

Or I could just drop a butter knife on the pack.


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## LithiumaniacsEVRacing (Oct 9, 2010)

GizmoEV said:


> Love those cell-to-cell interconnects. On the first 4000A draw they should weld right on nicely.
> 
> What is the red stuff which can be seen between the tabs?


The red silicone also secures the bus bars from moving and touching the cell edge, most pouch cells conduct voltage on the cell edges, if one of the bus bars were to move and touch we would have a short.


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## LithiumaniacsEVRacing (Oct 9, 2010)

*As the building continues...*


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## LithiumaniacsEVRacing (Oct 9, 2010)

I know this has happened on Dow Kokam pouch cells, now I had my first issue with cell ends conducting electricity. I noticed on a few of my cells the glue did not pass or was even with the cell pouch edge, where the tab seals. This caused a short when the pouch wrapping touched the tab. 99% are okay, but a few I had to trim the pouch aluminum below the tab glue to prevent the pouch wrapping from touching the tab. My idea of adding high temp silicone between the tabs creates the needed support and sealant to prevent this from happening. Remember on most pouch cells the cut edges of the aluminum wrapping conducts electricity.


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## LithiumaniacsEVRacing (Oct 9, 2010)

gottdi said:


> Ron,
> 
> Thanks a whole bunch for that information. It is good to know that we need to keep those edges from touching. Maybe shrink-wrapping the cells would be a good idea if you use a shrink wrap that is pretty sturdy. So good shrink tubing could be a benefit.
> 
> Pete


I double stick tape each pouch together, then wrap in plastic tape. The sides seem to be okay, but the top edge was the issue where the tabs are sealed, if the edge touches the tab she will short. When using pouch cells I recommend careful examination of each cell when building pack.


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## jr dragster (Oct 11, 2010)

how did you make up the lexan boxes screws or glue of some kind?? I may steal your box idea for the jr dragster.Im only using 24 cells so it will be alot smaller than yours.


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## LithiumaniacsEVRacing (Oct 9, 2010)

jr dragster said:


> how did you make up the lexan boxes screws or glue of some kind?? I may steal your box idea for the jr dragster.Im only using 24 cells so it will be alot smaller than yours.


The lexan boxes used #6 screws, I drilled and tapped each hole. Use 3/8 lexan for the bottom and ends, the sides and top can be thinner lexan to save weight.


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## LithiumaniacsEVRacing (Oct 9, 2010)

Battery modules will be completed by next week. EMUS BMS on the way!


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## rwaudio (May 22, 2008)

LithiumaniacsEVRacing said:


> Battery modules will be completed by next week. EMUS BMS on the way!


Well done Ron, I know what it takes to put these together. When is the maiden voyage? (if you can call 8-10 seconds a voyage)


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## LithiumaniacsEVRacing (Oct 9, 2010)

rwaudio said:


> Well done Ron, I know what it takes to put these together. When is the maiden voyage? (if you can call 8-10 seconds a voyage)


Thanks! You got that right, building 10P 100+S battery packs is a pain in the azz. Almost complete, waiting for EMUS BMS before installing in car.

First trip down drag car lane will be May 5th, 2012 at Lebanon Valley Dragway. Many will be there, including Jeff Disinger, and the el moto guys. We should have a ball! They have an all night party planned after the race. May 5th, 2012 is also my twin sons birthday!


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## LithiumaniacsEVRacing (Oct 9, 2010)




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## marc02228 (Jan 15, 2011)

Could you tell what made you choose the EMUS over the Orion or lithiumate?


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## marc02228 (Jan 15, 2011)

Just found these Patents... 
especially that one with the tab connecting method should be very interesting. I Think I'm gonna try it that way.

Connecting Tabs
Batterypack Idea


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## copyfiles26 (Dec 1, 2013)

what is the metal you suggest for connecting cells in series if i use 40 Ah Lipo pouch cell with 40s1p configuration.??


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## nikita (Aug 24, 2013)

how can we connect 2 lipo poch cells? i mean how to make holes in their terminals? any specific tool?


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## Theredone51 (Oct 15, 2011)

nikita said:


> how can we connect 2 lipo poch cells? i mean how to make holes in their terminals? any specific tool?


An easy way to make the holes is to use a paper hole punch:
https://www.google.be/search?q=hole...&biw=1536&bih=777#q=paper+hole+punch&tbm=isch

Just make sure that if you have cells with both tabs on the top side that you don't shortcircuit the tabs with the paper hole punch.


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## davidmillin (Dec 14, 2013)

> An easy way to make the holes is to use a paper hole punch:


Great idea Theredone. I was going to drill them.


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## major (Apr 4, 2008)

nikita said:


> how can we connect 2 lipo poch cells? i mean how to make holes in their terminals? any specific tool?


Like I said on the other thread: Use a paper punch. You said the hole would not be big enough. My paper punch made for 3 ring binder types punches a 7mm hole. That is over 1/4 inch. How big do you need? Typically a M5 or smaller fastener is used to clamp the tabs. On the EnerDel cell tabs a slot is needed so I used the punch (a single punch can be removed from the 3 hole unit) and made the hole using pliers to squeeze the punch. Then scissors cut the slots.

The tabs are thin copper and aluminum. You can use paper punching/cutting tools or sheet metal tools. I got a handheld sheet metal punch with various sized dies from Harbor Freight. But they don't appear to carry it anymore. It would be overkill for cell tabs anyway. I don't see why you need larger than 7mm. Show us what you have planned.


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## Jan (Oct 5, 2009)

Thanks for the tip, Major.

I wonder why in all pouch cell applications there is metal placed between the tabs to make a connection. I can imagine you need some hard material to clamp them firm together, but anything between them doesn't make sense to me.


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## major (Apr 4, 2008)

Jan said:


> I wonder why in all pouch cell applications there is metal placed between the tabs to make a connection. I can imagine you need some hard material to clamp them firm together, but anything between them doesn't make sense to me.


It appears to me that OEM batteries clamp 2 tabs directly against each other but if the module requires more, then a jumper bus plate is used to connect cell pairs to adjacent pairs. Personally I have clamped 4 tabs. That was kind of tricky. I can see why from a QC point of view only doing 2.


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## Jan (Oct 5, 2009)

Thanks Major. So there is no other reason than what's physically possible with the length of the tabs. As long as you get enough surface connected.


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## copyfiles26 (Dec 1, 2013)

nikita said:


> how can we connect 2 lipo poch cells? i mean how to make holes in their terminals? any specific tool?


 Go for the specified punching bit or specified paper punch.If u need 12mm go for a 12mm paper punch. But i dont think you can get the desired dimension for the hole.


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## nikita (Aug 24, 2013)

major said:


> Like I said on the other thread: Use a paper punch. You said the hole would not be big enough. My paper punch made for 3 ring binder types punches a 7mm hole. That is over 1/4 inch. How big do you need? Typically a M5 or smaller fastener is used to clamp the tabs. On the EnerDel cell tabs a slot is needed so I used the punch (a single punch can be removed from the 3 hole unit) and made the hole using pliers to squeeze the punch. Then scissors cut the slots.
> 
> The tabs are thin copper and aluminum. You can use paper punching/cutting tools or sheet metal tools. I got a handheld sheet metal punch with various sized dies from Harbor Freight. But they don't appear to carry it anymore. It would be overkill for cell tabs anyway. I don't see why you need larger than 7mm. Show us what you have planned.


thanks for your reply on making holes, but i got one more doubt: i.e which tab is better copper or aluminium for making tab connection? ( as we know copper is a good conductor while on the other hand aluminium is a light weight material)


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## major (Apr 4, 2008)

nikita said:


> thanks for your reply on making holes, but i got one more doubt: i.e which tab is better copper or aluminium for making tab connection? ( as we know copper is a good conductor while on the other hand aluminium is a light weight material)


The pouch cell has copper for the anode tab and aluminum for the cathode tab, both nickel plated, typically. Cell to cell connections should compress the tabs together directly if possible. If a conductor is needed from tab to tab, it is your choice. It is best to use a non reactive metal and non ferrous metal. Nickel plated copper or aluminum sheet stock is good, or even just nickel sheet. The higher resistivity metal needs to be of adequate thickness and width to provide the proper contact area and conduction.


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## copyfiles26 (Dec 1, 2013)

Hello,
I heard that cell terminals are made up of Nickel an nickel alloy particularly in lipo cells.Can you tell me a good process by which we can easily make holes through the battery terminals?
I came through some suggestions like..... " Use a Paper punch" ? what do u suggest guyz ?


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## major (Apr 4, 2008)

copyfiles26 said:


> Hello,
> I heard that cell terminals are made up of Nickel an nickel alloy particularly in lipo cells.Can you tell me a good process by which we can easily make holes through the battery terminals?
> I came through some suggestions like..... " Use a Paper punch" ? what do u suggest guyz ?


I use a paper punch.


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## nikita (Aug 24, 2013)

major said:


> The pouch cell has copper for the anode tab and aluminum for the cathode tab, both nickel plated, typically. Cell to cell connections should compress the tabs together directly if possible. If a conductor is needed from tab to tab, it is your choice. It is best to use a non reactive metal and non ferrous metal. Nickel plated copper or aluminum sheet stock is good, or even just nickel sheet. The higher resistivity metal needs to be of adequate thickness and width to provide the proper contact area and conduction.


 how can a high resitivity material can increase conduction? 
what we are doing is using copper plates with silver plating to increase conductivity.


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## nikita (Aug 24, 2013)

copyfiles26 said:


> Hello,
> I heard that cell terminals are made up of Nickel an nickel alloy particularly in lipo cells.Can you tell me a good process by which we can easily make holes through the battery terminals?
> I came through some suggestions like..... " Use a Paper punch" ? what do u suggest guyz ?


yea,you can use paper punch. they are good only,even i have used paper punch fro making holes in my pouch cells


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## major (Apr 4, 2008)

nikita said:


> how can a high resitivity material can increase conduction?
> what we are doing is using copper plates with silver plating to increase conductivity.


I explained that a while ago here:



major said:


> Hi cop,
> 
> The silver plating would typically be so thin as not to affect the resistance of the connector between the terminals. It would aid in the conduction at the contact area but again not so much in resistance compared to bare copper, but in the fact that it reduces or eliminates contact contamination due to oxides or corrosion on the surface of the copper mating contact. Gold plating is considered the best for this purpose and its conductivity is less than silver or copper. To those ends, nickel or tin plating can be almost as effective and a lot more affordable.
> 
> major


You can use silver plating but it is overkill IMO.


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## nikita (Aug 24, 2013)

ohaky! 
thanks for the information major!


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## Nomma (Dec 3, 2014)

The pouch cells that I have appear to have an aluminum tab and a tin plated copper tab. So why do you need to have the aluminum block between the connected tabs? Can't you just clamp the two tabs together between two aluminum blocks thus eliminating current through a middle block?


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## major (Apr 4, 2008)

Nomma said:


> The pouch cells that I have appear to have an aluminum tab and a tin plated copper tab. So why do you need to have the aluminum block between the connected tabs? Can't you just clamp the two tabs together between two aluminum blocks thus eliminating current through a middle block?


Hi Nomma,

Sure. We touched on that. Read through the thread. Example from the previous page: 


major said:


> It appears to me that OEM batteries clamp 2 tabs directly against each other but if the module requires more, then a jumper bus plate is used to connect cell pairs to adjacent pairs. Personally I have clamped 4 tabs. That was kind of tricky. I can see why from a QC point of view only doing 2.


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## andreaguerra (Jul 19, 2017)

Hi,

very interesting discussion. Do you have any update on the matter, especially regarding tox joint like in this schema?


Thanks


----------

