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Friend’s exway flex ER battery only charges to 48.1v, there’s no warranty anymore so he says he’ll open it up. Could somebody already guess what’s wrong with it? 
Parallel group is out of balance because a cell went bad, run it down till it dies before opening it and check all the group voltages, then charge it (don’t need the board back together just make sure nothing shorts out and note CF is conductive) and verify everything is balanced again, if it is then either the cell is toast or it’s connection is
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It could also be broken welds leading to an imbalanced group. The group or groups in question would charge/discharge more quickly than the other groups causing the bms to shut down the charge when the group(s) reach to overvoltage cuttoff.
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I was going to try something like that, wasn’t 100% sure so thank you a lot for your advice 
I doubt there’ll be CF around. Thank you!
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two places should be enough.
Step 1. Plug the spot welder into a standard 120v outlet.
Step 2. Wait for voltage display to reach 5.3v. When you initially power up the spot welder it will take about 15 minutes to fully charge the capacitors. After the initial charge the power supply will normally keep up with your spot welding speed.
Step 3. Adjust the power setting from 005-080.
Step 4. Spot weld batteries
@Battery_Mooch
This sounds really interesting
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This is quite interesting. Wall powered with a small power supply, welder isn’t too huge. Seems compelling if its consistent
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LoL: “Don’t eat the spot welder.”
Even says it can do copper. Hmm. Kind of hard to believe. I suppose super thin copper might be possible.
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Bodged together with custom and China modules but for the price that is expected. What counts are the results and I’m not sure how the pulse is handled…varying just power it seems?
If consistent and powerful enough then perhaps worth trying out (not by me, love my kWeld).
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Maybe someone here can help our friend
Sooo… I bought a lot of cells from nkon.nl. I bought 50 for my pack (haven’t measured those yet) and 10 reclaimed of another model for test welding etc.
Their product page says:
These batteries come from battery packs in which welding errors have been found. The batteries have never been charged or discharged.
The cells we offer have:
- Minimal damage to cell
- Never charged during production (from the box) (each cell is tested)
- Resistance is according to datasheet, never worse (every cell is tested)
5 out of 10 cells are lower completely dead or lower than 1 V. What a load of bullshit.
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You should try and get your money back. Perhaps make a short video showing the voltages, and send it to customer service. It’s nonsense.
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Shoot them an email, I got a partial refund for my clearly-previously-welded cells that they sold me as new. It’s the second fuck up that we know of in a short period of time, but they make it right
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Yeah, it’s not at all about the money because I literally bought those 10 cells cheap just to have as tests or to do some random side project with but still, claiming they are tested and never discharged… Can I trust anything they say now?
The 50 new cells that I’m actually gonna use were all good though 
Send halp pls!
So a while back I got this kit:
I know it might have its limitations and what not but since I have never built a pack or spot welded before I thought it would make a nice first project. So during the weekend I started to assemble things, got the spot welder (maelectrics.eu) running etc. Did a few tests on dead cells with some 0.2mm nickel strips from nkon.nl. All good. Strong welds at 20 ms. Happy times. Did some pull of tests and those tore holes in the nickel. (The electrodes tends to get a bit stuck to the nickel though, suggestions?)
So I start to assemble the real deal. The kit has exactly 20 nickel strips (yes, the exact amount I need, should have predicted what happens next).
I get a few good welds to begin with but things get more and more problematic.Eventually I realize that this nickel is actually 0.3mm. Anyhow… for reasons I can not explain I get holes torn where one of the electrodes are (top is one weld, and bottom is another, ignore the one at the edge…). I get this also at ~20 ms weld time, the same weld time that got me nice welds on the battery above with 0.2mm nickel. The nickel have passed 24 hours in salt water.
It’s now all a mess. I can not get the provided nickel strips to weld properly and even if I figure out I’m an idiot and did something wrong I only have 17/20 left.
So now the question is
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What am I doing wrong with the provided nickel strips? Or are they simply too thick?
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I would like to still use the PCB, could I do something like this with 0.2mm x 10mm nickel (preferably with one wider strip rather than 2)?
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Other suggestions?
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It is very hard to get good welds with 0.3mm nickel. I would recommend getting some more strips that are 0.2. I’m not sure where in Europe sells them but I’d just recommend getting new pre-cut pieces. I have provided a picture example.
I would also recommend getting some 30mmx.0.2mm nickel and folding it over in a way similar to the kit that you got. I’m pretty sure there are a few EU suppliers.
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I actually found those strips when looking online but the shipping was quite steep to EU. And then extra fees on top of that for import handling etc 
By 30mm x 0.2mm you mean get wide strip and then cut out my own tab to fit in the ~17mm slot of the PCB? 30mm seems doable as the length of the tabs I have is about 27-28mm.
The product description said 0.2mm and also recommended the same spot welder, but measuring its actually 0.3mm… Looking at the product images they actually say 0.3mm nickel (in chinsese)… I was hoping for a stressless care free assembly but there’s always something…
You would just have to cut the notches to the size of the holes in the pcb. You might not even have to cut notches at all. I would just be sure to round the corners but this can be done with common scissors.
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Rouding the corners for the sake of my fingers not getting sliced in half or theres other reasons? Thanks for replying, I think the 30mm nickel is a better idea than any idea I managed to figure out during the day. Seems to be available at nkon.nl as well. If anyone has more suggestions I’m all ears!
That, it looks nicer, and you don’t want a bunch of nickel sticking out at the bottom of the cells once you weld. If you accidentally get anything in there, stuff will be less likely to make contact if the nickel does not stick out beyond the profile of the cell.
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