What’s the issue? I can poke around in it if you’re willing to send it my way. 
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I would hate to ship a suspect battery…
it was not charging.
would plug in and light on charger stayed green.
opened up the board
main lead is at 36 volts.
on the charger lead it reads 31 volts.
I suspect there was a short on the charge port.
I put a different battery In there and hooked up to the same charge port and it popped the fuse I had on the positive charge cable.
I replaced the fuse and the charger port lead (jst to 5mm barrel)
and the new battery charges fine…
I tried a new port to charge the Bkb pack and the charger stayed green…
so I expect the little charge only BMS is fried…
I have not peeled off the shrink for close inspection…
Hey yall,
I need to make a fuckload of 1.0mm x 10mm x 100mm copper bus bars. So far the cheapest two options I have been able to find are these:
Link
($0.59 per bus bar, for those bad at math)
(14mm wide is the cheapest this shape goes on sendcutsend, anything wider costs more, anything narrower costs the same)
Since I need to make so many (hundreds at least), I dont want to buy sheet metal and cut it all to size myself, even though that would be cheapest. I either want to get pre-cut bus bars or get 10mm wide copper so it’s a one-cut operation.
Does anyone know of places I should look to find good pricing on this kind of thing? Alternatively, can any of you talk me into spending nearly double buying pre-cut bars from SendCutSend vs AliExpress? 
Thanks!
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Try https://www.bigbluesaw.com/ as well. They have an instant quote engine for waterjet. They’re likely slightly more expensive than SCS, but worth a shot.
Honestly those are pretty fucking cheap already though. I’d be surprised if you can find a shop to make a ‘custom’ part for cheaper. Off-the-shelf is the only way you may get lower. Ebay?
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Could you use thinner copper? I think 1mm x 10mm is about the equivalent of three 12AWG wires (about 7AWG).
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I’ll check them out, thanks!
Yeah, nearly
I could probably get away with thinner copper, yeah. That Aliexpress listing I posted above has 0.8mm x 10mm, which is about equal to 8AWG, and probably plenty for my needs. ($0.48/piece)
There seems to be a gap in the market for copper of this thickness. There’s tons of options at 0.3mm or less (spot welding foil), and lots of options at 3mm thick and above (construction sheet metal), but the 0.5mm to 1.0mm range is pretty sparse, from what I have seen so far.
Maybe I should just settle for the 0.8mm x 10mm, I dont think I would want to go a whole lot thinner than that anyway. 8AWG equivalent is probably good for my application (as I’m sure you know already John 
)
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I have ~26 samsung 35E that were salvaged from a pack with low cycles that I’d like to use in in a pack for a low power board for a friend’s child. Would you recommend any budget cell in particular to compliment?
EVE 33V are $3-4 3200mAh and 10A
Yay? Nay?
Thank you!
I’ll be posting my 33V test report in a day or so (my patrons saw the results a while ago). Otherwise the NCR18650GA is a decent cell. Both of these perform a lot better than the 35E but you have a low power application so no worries.
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Question.
Is tinned copper wire preferred for pack building?
In what sense? Do you mean the tinned braids? Or just standard silicon tinned wire?
We pretty much always use tinned silicon wire for discharge leads and series connections, and then usually the PVC or whatever standard balance leads are
I would tend to stick away from silicon balance leads just because, although flexible, I tend to find the small insulation less durable than on the standard PVC ones
Example:
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First time working with copper braid, does this joint look okay?
I’ve got a 200w iron so it did flow through all the way.
Should’ve gone for the tinned braid though.
Looks a bit cold if you ask me. Its probably fine though. This is a non-flex pack right?
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it’s Flux at2, very little flex.
If you must use braid, it’s likely better to use it in a configuration like this…
It keeps the braid longer so that there is less chance of the solder wicking all the way through the braid. @TheRef has some good examples of this.
Personally I’d recommend silicone wire like this
Give it as much length/curve as you can to mitigate solder wicking.
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Thanks.
Do these look alright?
.2mm, p42a, kweld on 5500mah 3s lipos in parallel
That’s 40j on the positive, 35 on the negative
ok, my first post.
I’m building my first ESK8 battery, 12S4P out of Molicel P42 (21700).
I’ll be running 2x 6376 160kv Trampa motors, open belt drive with 14T/76T gearing, 8inch offroad wheels.
reading the forum I’m still not 100% certain what specs nickel strips I need to use to join the 4P groups and to make fold-over tabs and then to join all 12 groups in series.
I note some people double up (double stack) nickel strips, is this necessary ?
Can I use just single nickel strip 0.2mm thick for the job ?
atm. I have at home 5m of 0.2mm x 8mm nickel strip, 2m of 0.2mm x 18mm nickel strip, AWG14 and AWG12 wires ( I’m unable to get a different nickel strips for another 2-3 weeks so I don’t want to wait unless absolutely necessary).
My plan is to run single 0.2mm x 8mm nickel strip across 4 cells in each parallel group and then create 2 tabs out of 0.2mm x 18mm nickel strip (one between cells 1 & 2, second between cells 3 & 4) and fold them over on top of the 4P group (both for + and -) and finally use 2x AWG14 to join all 12 groups in series (where the tabs were created).
would this satisfy the current flow requirements when I’m planning to limit my VESC to 60A per motor ?
Motor current has basically nothing to do with battery current. If you mean you plan to limit yourself to 60 battery amps per side, then no, two 0.2x18mm strips is not sufficient for that.
two 0.2x18mm strips would be good for ~100A at most, and I probably wouldn’t push them past 70 or so myself.
It would be significantly less hassle to just get some 0.15 or 0.2x30mm strip and do it all in one go rather than having to weld three strips for each end of each group.
Not with proper pack design.
Yes, if it’s wide enough. It’s all about cross sectional area. Doesn’t matter if it’s 1mm thick and 10mm wide, or 0.1mm thick and 100mm wide, either will have the same cross sectional area. If you’ve got the width for it (and you do, with 4 cells side by side you have over 80mm of width to work on) I might even suggest going down to 0.15mm thick strip because it’s easier to bend and weld.
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That doesn’t look so good at all to me. What iron are you using? Wattage tends to matter much less than most folks think it does.
I’m also new here, but this plan sounds poor to me. 21700s on the positive side you have about a 9mm diameter positive terminal surrounded by a ~6 mm ring you don’t want to weld to. That means you’ll have 12 mm of your 18 mm strip over an area where you don’t want to weld and on 3 mm on each side to weld to if I’m understanding your plan correctly and you’re planning to have the 18mm strips run perpendicular to the 8 mm one creating the p group. If it’s the other way then you won’t really have much of a tab.
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thanks
my bad, sorry. on my existing eBoard with 12S3P battery made out of same cells I limit battery max current to 37.5A per side so with same spec battery (except 4P) I should be limiting it to 50A
yes I have some 0.2x25mm on order from Fogstar in UK but they don’t ship to Australia so I had it shipped to a friend in Europe and once he gets it he’ll ship it to me, we just don’t live in an ideal World and I have to work with what I have at home. it’s 2-3 weeks wait but ordering from China is currently even slower.
I’ve seen that conductor rating table in this thread above but the numbers were significantly lower,
I would post it here but for some reason this forum doesn’t allow me to post images.