Pouch Cell Tab Connection Methods

[EVDragRacer]

I have received some good input from the DIY Forum, but you guys always add excellent feedback.

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. I have been reading the positives and negatives.

My original plan was to use copper bus bars, but I would like to use aluminum. I have found two grades of aluminum in bus bars that are very conductive:

Grade 6101
Grade 1350

https://www.onlinemetals.com/merchan...282&top_cat=60
Grade 6101 T61
T61 and T64 are more conductive than T6, T63, and T65

I will plate the copper or aluminum, what ever I decide to use, so my main issue is heat, resistance, voltage loss.

I am going with a 10P cell modules each connected with a 30mm wide block, 19mm tall, and 6.5mm thick between each tab. This seems like enough "meat" between each tab to use aluminum, I am looking for some advice?

Each 10P module will deliver 4000 battery amps+

 

[dnmun]

why do you have to use aluminum for the buss bar?

 

[EVDragRacer]

why do you have to use aluminum for the buss bar?

Trying to save weight.

 

[EVDragRacer]

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/associ...aso-6036b.html

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

I really need a 4000 amp carbon pile load tester?

 

[EVDragRacer]

I am getting an estimate for silver plating of 1800+ aluminum bus bar pieces.

 

[jonescg]

The solution appears to be finding a good way to spot weld a copper tab to the aluminium tab. Once you have two copper tabs, you can solder them together, or to an appropriate copper sheet. Aluminium is a satisfactory conductor for it's density, but unless you triple the cross sectional area you'd normally use for copper, it's going to get hot mighty fast. Corrosion is another factor worth considering too.

I gather you are still bolting them together using stainless steel bolts and washers? Maybe you can get away with aluminium spacers for paralleled cells, and only use copper for joining series connections?

 

[dnmun]

i thought the aluminum tabs always had nickel steel tabs bonded to the ends by that roller spot welder machine.

 

[EVDragRacer]

The way I see it is the space between each tab is 0.25", that is a large space. The tab itself is 30mm wide and the tabs are .2mm thick, so adding a silver plated aluminum block between each tab is plenty of "meat". The aluminum I am using is about 69% conductive, 6101-T61 is very good conductor, and with a plate of silver even better. 0.25" bus bars are equal to 32.5 tabs at each connection..I am not worried about any corrosion etc....copper tabs to aluminum because the aluminum will be silver plated.

The solution appears to be finding a good way to spot weld a copper tab to the aluminium tab. Once you have two copper tabs, you can solder them together, or to an appropriate copper sheet. Aluminium is a satisfactory conductor for it's density, but unless you triple the cross sectional area you'd normally use for copper, it's going to get hot mighty fast. Corrosion is another factor worth considering too.

I gather you are still bolting them together using stainless steel bolts and washers? Maybe you can get away with aluminium spacers for paralleled cells, and only use copper for joining series connections?

 

[bigmoose]

Do the math on the silver plate. It is great oxidation prevention, once you do the calculation you will see the minimal effect of flash silver (typically 0.00001" to 0.00002") over aluminum with respect to DC conductivity. It makes sense for gigHz RF if it's thick enough to match the skin depth. Also if you did not specify "high conductivity silver plate" you will likely get decorative silver plate, which has a conductivity worse than copper. Just FYI.

 

[parabellum]

I am getting an estimate for silver plating of 1800+ aluminum bus bar pieces.

Considering higher electrical resistivity and lower thermal conductivity, Aluminum is opposite step from getting performance in your application. Saved weight will not be worth lost performance and hidden complications you will confront in near future.
All your setup is really based and depending on conductivity and electrical performance of your setup, it is the worst place to save weight.

 

[EVDragRacer]

Thank you guys. I am back to considering copper. :x