solar bus wire

Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#1
Hi am just wondering if anyone has used solar bus wire when making a battery for their ebike? been looking at some and seems to be perfect stuff 5mm width 0.2mm thick and is copper covered with a solder layer but i can`t find any info on what is the max amps/watts this could carry, I am going to build 2 new batteries soon and wondered if it was any good
 

vfr400

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Jun 12, 2011
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#2
You won't be able to weld it because it's tinned, and you shouldn't solder directly to 18650s because the heat can damage them.
 
Oct 26, 2018
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#3
You won't be able to weld it because it's tinned, and you shouldn't solder directly to 18650s because the heat can damage them.
Interesting, that would be a worry, unless there are spot welders that already weld tinned copper to steel maybe for the solar cells? Technically thats probably not true welding as several different metals are involved....
Does anyone know how wiring is attached to cells in the Solar business?
I had a quick look on the IOT and it appears to be soldering, which is unacceptable heat wise of course.
Can anyone clear that up, maybe test a spot welder on a few defective cells?
regards
Andy
 

vfr400

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#4
Solar panels have tinned pads to which you solder the tinned bus wire. It's a completely diferent system and won't work for 18650s. For 18650s in an ebike battery you need pure nickel strips, which you weld to them.
 

Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#5
Solar panels have tinned pads to which you solder the tinned bus wire. It's a completely diferent system and won't work for 18650s. For 18650s in an ebike battery you need pure nickel strips, which you weld to them.
not entirely true, copper works even better on 18650`s than nickle with less heat/wasted energy and the bus wire has copper inside 5mm x1.6mm and 0.4mm of solder on outside. Also with the right solder Iron soldering 18650`s is not a issue, The problem i think is that the bus wire maybe won`t be able to take the amps i want to push through it. I can`t find any info on what it can actually take. There are a couple of vids on youtube who have used bus wire for smaller packs than i would build but am still dubious on what the max amps etc it can take.
 

vfr400

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#6
It seems that you know a lot about making ebike batteries then. I can't understand why you're asking if you know all the answers. Have you tried welding with copper? If you think it's so good try it and tell us all about it, then go and get the nickel wire. The same applies to soldering the 18650s. If you think it's going to work, try it. It's your money!
 
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Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#7
Have you tried wrlding with copper? If you think it's so good try it and tell us all about it, then go and get the nickel wire. The same applies to soldering the 18650s. If you think it's going to work, try it. It's your money!
Yeah have soldered copper wire to the first 4 or 5 battery packs i made, I used the core from twin and earth and tinned the spots to connect to the 18650s on bench before putting on the batteries 800F solder iron is key though. i Then made last 10-15 batteries with a homebrew spot welder, am always looking for a different way though so was hoping someone would have the info on the specs of the buswire i don`t have the tools to find out max amps/watts i can put through it so was hoping someone had maybe tested it before. I would honestly prefer to have copper on my battery packs than nickle
 

Derrick Lewis

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Jul 20, 2018
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Redditch
#8
there is also another reason why i want to be able to build a battery of this type, i plan to try a very long distance ebike tour and would be good to have a easily repairable battery that i only need extra wire and a gas solder iron to repair
 

vfr400

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#9
To me, it just doesn’t make sense. You can't spotweld it because the tin/lead coating has no mechanical srength and very low fatigue resistance, so is very likely to break from vibration. Copper is the same. Also, it has to be coated to stop it from corroding, but that's not a problem if you used the tinned stuff.

It's a great idea to be able to resolder all your soldered joints that fail due to vibration, but wouldn't it be better to use the right stuff so that they don't fail? Sure, in the past, we used to hear of the odd bad spotwelds on batteries, but that's extremely rare these days, and whenyou do it yourself,you can check the quality as you go.

Then you add the risk of compromising a cell by overheating when you solder them. How do you know how much you damaged them? Are you going to test the capacity of every cell group after soldering? Is it 99% or 95% of what it should be? How have you affected their life? Are they only going to live half as long? It's all very well saying how great a pack looks after you soldered it up, but how great is it compared with a spot-welded one?

Surely, if you're going to make a few batteries, it makes sense to get the proper stuff and do it properly.

You can buy really good ready-made batteries for less than you can make them, so I find it fairly questionable why anybody would want to make one these days unless you need something special. I still make a few batteries every year, but they're always because I can't buy what I need, like special size or shape, but by the time I've bought everything to do it properly, they never work out cheap.
 

Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#10
my batteries are 20s 8p on my bike so not readily available. every battery i have built for friends are awkward shapes to fit frames,I also have a good 18650 battery source. Anyway is not the question i was originally asking, Just wanted to know if anyone knows the max amp/watts the solar bus wire can take to see if it is even possible, If not i will go ahead and nickle spot weld
 

Nealh

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#11
5mm x 0.16 copper is 0.8mm2/12.8a, typical rating for copper is 16a/1mm2.
How much a tinned coating adds I wouldn't know, possibly tinning may even reduce the ampacity.

Pure nickel optimally is 4.459a/1mm2 or 6.619a/1mm2 is acceptable.


For my HE2 140a 17.5ah pack 7s7p, Swizzbee will peak at between 60-80a so I have used 122mm x 25mm x 0.15mm /18.3mm2 pure nickel which will allow for 121a acceptable draw. More then that is needed.
 
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Nealh

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#12
Any direct prolonged heat on the neg end of the can is potentially heat damaging, avoiding the very centre of the can is important. Contact for soldering needs to be very short 1 sec or less.
 

Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#13
5mm x 0.16 copper is 0.8mm2/12.8a, typical rating for copper is 16a/1mm2.
How much a tinned coating adds I wouldn't know, possibly tinning may even reduce the ampacity.

Pure nickel optimally is 4.459a/1mm2 or 6.619a/1mm2 is acceptable.


For my HE2 140a 17.5ah pack 7s7p, Swizzbee will peak at between 60-80a so I have used 122mm x 25mm x 0.15mm /18.3mm2 pure nickel which will allow for 121a acceptable draw. More then that is needed.
Thats good to know, i have found some bus tape at 8mmx0.2mm advertised has carrying 30amp but it is so much cheaper than nickle strip that i could double up and still save £40 on a battery.i may build one from recycled cells and see if it lasts some banging around, am sure it may help others building their packs if it does because it would be the easier way of soldering.
 

Nealh

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#14
Soldering copper is like trying to weld copper to cells, it requires a lot of instant heat as conductivity of copper absorbs heat better.

That is why pure nickel is still favourite amongst hobby builders and professional builders. Unless you have a state of the art machine 0.1mm copper is about the limit for welding.
 

vfr400

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Jun 12, 2011
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#17
I'm totally confused now. You'd rather spend £14 per meter to buy nickel strip than the £1.50 a meter that I use, but you don't mind running the risk of compromising your battery completely by using unsuitable tinned copper strip because it's cheaper. Did I misunderstand something?

In case it helps, here's nickel strip from a supplier that has a proven reputation.

https://eu.nkon.nl/accessories/battery-solder-strip.html
 
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Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#18
no what i meen if i was going to go the spot welding route i would want propper nickle strip not plated stuff. the clue is in the title of that ebay link, it can say what it wants after
 

Nealh

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#19
The nickel which vfr has linked to although uses the word plate in the title doesn't mean it is plated nickel. China uses some strange descriptions and plate just refers to a flat thin strip. Further down the page it does give purity as 9.96%.

I buy my pure nickel off Ann/Ann Battery on Aliexp and they often use the word 'plate' in the description, all the nickel I get I test/cut a piece grind the surface and let it sit in saline for a day or two. Have yet to get any plated rubbish
 

Derrick Lewis

Finding my (electric) wheels
Jul 20, 2018
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Redditch
#20
The nickel which vfr has linked to although uses the word plate in the title doesn't mean it is plated nickel. China uses some strange descriptions and plate just refers to a flat thin strip. Further down the page it does give purity as 9.96%.

I buy my pure nickel off Ann/Ann Battery on Aliexp and they often use the word 'plate' in the description, all the nickel I get I test/cut a piece grind the surface and let it sit in saline for a day or two. Have yet to get any plated rubbish
would be nice to get some cheaper, Am going to try the tinned copper route anyway and maybe put some probes on it and try real world testing as can program controller on amp draw etc . found some 1.2mm round core copper that is tinned meant to take 45amp so in theory it should be able to work. will see anyway
 

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