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  1. V

    Are EV grade battery and solar grade battery manufactured differently?

    Hello I've been looking to buy 32650 size cylindrical LFP cells and the most common attribute I'm being asked is whether I want an EV grade cell 3C discharge rating, or Solar grade cell 1c discharge rating (sometimes 0.5c). As far as I know, the cell manufacturing process remains the same, and...
  2. V

    kWeld - "Next level" DIY battery spot welder

    Update: The ksupply current adjust trimmer seems to be broken. And it either giving out 0.198A @ 8.7V or 0a if I turn it too much. There is no option or way right now to get out of the menu settings on the kweld. Talking with Frank and figuring out a solution, he's really helpful and answers all...
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    kWeld - "Next level" DIY battery spot welder

    Update: Kweld is still able to weld. BUT, it is stuck in auto mode. Whenever I try to click on the MODE in the menu, it shows "Manual" and then goes onto show some values that used to be shown after a weld was done. like "Spot R, =000004, R=7825.4, t= 0.40m, I= 0A, T= 36.3C," in cycle. And there...
  4. V

    kWeld - "Next level" DIY battery spot welder

    Thanks for your reply! I increased the voltage to 8.7v and the kcaps right led came on, meaning "module is fully charged". I haven't kept the system going for 10min total though! The kweld has a problem now, I clicked the CAL for calibration, and since then the screen has been stuck on "offs=...
  5. V

    kWeld - "Next level" DIY battery spot welder

    Hello guys! I bought a kweld last year, but didn't get a chance to use it properly. I was using a cheapo lipo battery with insufficient power output. I was getting 750a max output from it and the weld were decent, but nothing good or promising. So I bought a Kcap and Ksupply to power the kweld...
  6. V

    8C and 12C cells with same IR

    Thanks for your reply! I'll try to find that from someone who will ship to my location. :thumb:
  7. V

    8C and 12C cells with same IR

    What internal resistance tester do you use? I'm looking for one, but can't seem to find a good one that lasts.
  8. V

    kWeld - "Next level" DIY battery spot welder

    I'm about to order the Kcap and Ksupply. I'm having difficulty in selecting the correct power supply for the Kcap, can someone help me with the correct part number? Or confirm that this is the model I would need...
  9. V

    Large Charger for 21700 cells, 50-100 cells simultaneously

    Is there an example of this done by someone on the forum? I don't think I have skills enough for doing all that, but might be able to follow along. I was under the impression that for NCM chemistry, lower voltages don't have much energy. Can you explain this a bit? Yeah, I got in touch with...
  10. V

    Sourcing 21700 cells from Korea, Japan or China, 10,000 cells

    I broke my phone while in a new city, got back today and got it fixed. I'll send you a PM about now.
  11. V

    Sourcing 21700 cells from Korea, Japan or China, 10,000 cells

    2000kg @ 70g cells is like 28-29,000 cells. I need 1/3 of his total supply! Can you send me his information, I'll try my luck with him as well.
  12. V

    Sourcing 21700 cells from Korea, Japan or China, 10,000 cells

    I thought tesla used 4.8a 21700 cells :shock: And this will get expensive SOO fast haha Edit: Pack of 100 is reasonable though. I have sent them a mail, lets see how they respond. I dont see any other brands other than tesla. Out of stock probably.
  13. V

    Sourcing 21700 cells from Korea, Japan or China, 10,000 cells

    I live in India. Cell chemistry preferred is NMC, but if other chemistry's are fulfilling the power requirements, then I am fine with anything. And yes, I'd prefer a wholesale seller so I can buy at a cheaper rate and pay shipping etc once.
  14. V

    Large Charger for 21700 cells, 50-100 cells simultaneously

    hey thanks for the reply, my mistake for not providing enough info. I'll do that below. I need charger for 1S. I will be charging and discharging the cells independently to see the capacity of each. I am planning to do a couple builds for me and my friends, and dont want bad cells to be added...
  15. V

    Large Charger for 21700 cells, 50-100 cells simultaneously

    Hello I am looking for a charger that can charge 50-100 cells at a time individually. I have not been able to find any good options or reliable company's. Is there a solution that I can follow through for my requirement? If there is an option of discharging like in the Cell aging machines big...
  16. V

    Sourcing 21700 cells from Korea, Japan or China, 10,000 cells

    Hello I am looking to buy 10,000 cells 21700 size, 4-4.5A 3C. I am having a tough time differentiating between legitimate sellers and shady businesses. Anybody bought large quantity at wholesale rates from a reputed seller? I would prefer a Korean or Japanese seller if possible. China would be...
  17. V

    Copper strips versus nickel strips on battery packs?

    Hello How were these connections made though? Copper is still hard to spot weld and protect against corroding. What is this welding technique? Also, if I am able to find someone with laser welding machine, can that be used to weld copper to lithium batteries? Anyone known to do so, copper bus...
  18. V

    Discharge circuit to stress test 18650 cells

    Hello I am new to the forum, but I have been a lurker for about an year. Me and my brother are looking to start my first EV project and I bought 18650 cells from a nearby seller. These are 2900mah 3c cells. I want to stress test these cells and see what sort of temps do these cells work at. We...
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