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Thinking of using copper strip vs supplied bus bars for parallel connections and battery wire clamp  

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davedude
(@davedude)
Street cred = 10 mAh
Joined:2 weeks  ago
Posts: 6
13/02/2018 8:14 pm  

Hi Micah (or anyone else who can answer): I bought some 1.5mm pure copper strips.  I'm thinking of drilling holes exactly to fit over the caps, then using one continuous  strip to go over all 6 of my cell caps in my 2 parallel groups forming the +/- terminals of the pack in lieu of using the standard bus bars and wire clamps.  I plan to make the strips long enough to bend over the edge of the pack, then either crimp or solder my BMS/discharge wires onto that tab bending over the edge.  I figure that will give me good current flow between all cells in the parallel groups but also keep the top and bottom of the pack clean and right at the 3.5 inch thickness the pack will be once all cells and caps are assembled.  I'll use the supplied bus bars for all the other serial connections (pack is 13s6p).  My strong desire is to keep the pack thickness at the minimum since I will be carrying it between my knees in a triangle frame bag.  If I use the regular method with the bus bars and wire clamps I will have that extra thickness on both sides of the battery.  If there is a flaw in my logic anyone please feel free to comment - I will not be offended.  Thanks in advance -

 

David


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zoama
(@zoama)
Street cred = 500 mAh
Joined:8 months  ago
Posts: 65
13/02/2018 11:16 pm  

That should work great. I never found a reasonably priced source for copper buss bar so I use 1/4" soft copper tubing made for plumbing.

I flatten it which makes it 3/8"(9.38mm x 1.08mm) wide and use the ss buss bars as a template for drilling. Costs $26 US for 50 feet at Lowes.

MG Chemicals makes a product called "Liquid Tin" intended to tin copper circuit boards but you can soak the copper buss bar in it for a few minutes to tin plate the copper and prevent corrosion. It's not cheap but it is easy.


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davedude
(@davedude)
Street cred = 10 mAh
Joined:2 weeks  ago
Posts: 6
15/02/2018 11:43 am  

Hi Zoama - thank you for the reply.  I found some strips on Ebay HERE for $10.79  4 strips  1.5 x 10 x 250mm so should be good for a couple of batteries.  I wasn't sure if there would be a resistance mis-match factor with pure copper vs the kit bus bars but it didn't seem like it would be any worse than adding the clamps on top of the bus bars with the normal kit setup.  Do you think there will be a corrosion issue if I leave the strips untreated?  I plan to seal the battery in shrink wrap and it will be carried in a triangle bag.  I don't want to have to take it apart and deal with it later if there is going to be a corrosion issue.  Thanks again -


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zoama
(@zoama)
Street cred = 500 mAh
Joined:8 months  ago
Posts: 65
15/02/2018 8:02 pm  
Posted by: davedude

Hi Zoama - thank you for the reply.  I found some strips on Ebay HERE for $10.79  4 strips  1.5 x 10 x 250mm so should be good for a couple of batteries.  I wasn't sure if there would be a resistance mis-match factor with pure copper vs the kit bus bars but it didn't seem like it would be any worse than adding the clamps on top of the bus bars with the normal kit setup.  Do you think there will be a corrosion issue if I leave the strips untreated?  I plan to seal the battery in shrink wrap and it will be carried in a triangle bag.  I don't want to have to take it apart and deal with it later if there is going to be a corrosion issue.  Thanks again -

It should be fine with bare copper. I was just sharing an option.


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davedude
(@davedude)
Street cred = 10 mAh
Joined:2 weeks  ago
Posts: 6
16/02/2018 12:24 pm  

Thanks again zoama.  I went ahead and ordered some of the liquid tin since at this point I would rather be safe than sorry.  Have you just attached your battery wire at the end of your copper bus bar or have you attached it in multiple spots like you would if one uses the supplied wire clamps?  I plan to just use the end "tab" that I will have bent down toward the edge of the battery pack.   


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zoama
(@zoama)
Street cred = 500 mAh
Joined:8 months  ago
Posts: 65
16/02/2018 3:52 pm  

I have one 6ga wire attached to each of the two main buss bars. My battery pack is 200 MJ1 cells that power a 36v trolling motor on my boat. Maximum amp draw is about 60 amps.


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