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  1. B

    One BMS to rule them all

    Please elaborate on balance fusing! Yeah, harness is not going to be JST... we need something reliable. I am thinking if we leave the connector port unpopulated, then people can either solder on the port, or solder quality silicone leads directly from the board if they prefer that. Not sure...
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    One BMS to rule them all

    Yeah this won't go up to the high voltages. The reference design is from FTEX who made this BMS for an e-bike company in montreal because they were tired of the DOA BMS rate they had with their import batteries. From there I saw a potential for something more versatile if we had access to the...
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    One BMS to rule them all

    Yes, ideally we will be able to push the same design up to 24s, but FETs operate best in certain ranges, so it might have to be split into two products, one for higher voltages, one for lower voltages. Bluetooth was the next addition, but now I'm wondering if WiFi should be the priority. Either...
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    One BMS to rule them all

    Excellent point, I did not know marine was 60v nominal. I think the 14s is just because that's where our reference design started (the OEM BMS he produces for some ebike companies), I'll see what we can do about increasing. I'd like to see it go up to a higher s count for sure.
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    One BMS to rule them all

    Hello everyone, my buddy owns FTEX and he's agreed to work with me on a versatile BMS (4s-14s, ~300A) that will be fully programmable (cutoffs, chemistry, etc.). The goal is to have a made in North-America option in the high-end spec range, at a mid-to-high end price (say $200-$300). We have...
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    Gear for logging C-rate vs Temperature, also capacity

    Doesn't hit all the points, but for 10$ of parts I log charge / discharge cycles at up to 20A discharge, 5A charge, and accuracy is pretty good, reliability is excellent. I'm not quite done yet, but the latest version is far more robust and quick to assemble. I still need to figure out how to...
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    JP spot welder

    And once I've screwed that up, what do I do?.... Asking for umm.. For a friend [emoji849] Sent from my CLT-L04 using Tapatalk
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    JP spot welder

    I'll be putting in copper bars where the aluminum bars currently are. Maybe with some slots in there too. Sent from my CLT-L04 using Tapatalk
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    JP spot welder

    I'll be putting in copper bars where the aluminum bars currently are. Sent from my CLT-L04 using Tapatalk
  10. B

    Testing large amounts of cells quickly

    If you're going to use it, the SSD1306ASCII library is amazingly small and efficient. Sent from my CLT-L04 using Tapatalk
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    JP spot welder

    Yup, I bought the last 2 diy kits and I'll upgrade those heatsinks... I'll get amazing duty cycle :D Sent from my CLT-L04 using Tapatalk
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    Testing large amounts of cells quickly

    Oled 0.91" display Sent from my CLT-L04 using Tapatalk
  13. B

    Testing large amounts of cells quickly

    Battery cycler prototype built! Now custom pcb coming to clean it all up. Ps since there was a comment about the resistor board, it's super simple but here I the design anyways. I use jumpers to make any combination from 1 - 15 p resistors to get a bunch of different values. It's based on...
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    Testing large amounts of cells quickly

    I just confirmed, the a123 data sheet specifies ac testing at 1khz... I'll have to compare usefulness! Sent from my CLT-L04 using Tapatalk
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    Testing large amounts of cells quickly

    Ummmm I went about it back wards, I though they used 1khz impedence for the spec sheets and I was trying to compare to nominal. Making a high current tester with arduino is a piece of cake... Darn. Sent from my CLT-L04 using Tapatalk
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    Testing large amounts of cells quickly

    Thanks :) I'm not super happy with the reliability of those b6 but no surprise there. They are still very helpful for bulk processing to ready everything for the precision tests or for regular use though. V1 of the arduino prototype will be tested today when I get my high current 22650 holder in...
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    Testing large amounts of cells quickly

    So to get the correlations down I'll be doing some endurance testing on some sacrificial cells (1000 cycles). The issue I'll have is it takes around a month to run a single cell. That means I need to test with many cheap testing rigs, so I've designed one from jellybean components and modules...
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    Testing large amounts of cells quickly

    I settled on a methodology not that far off from that + a little bit. I'll stay quiet on that until I can test a few hypotheses as there I no point in spreading misinformation... Just some hunches I want to explore for now. I got some 3500 cells XD Sent from my CLT-L04 using Tapatalk
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    Testing large amounts of cells quickly

    I don't know if I'm misunderstanding, but it seems like they are talking about testing impedence. Sent from my CLT-L04 using Tapatalk
  20. B

    JP spot welder

    Pmed you Sent from my CLT-L04 using Tapatalk
  21. B

    Lower capacity at lower discharge current

    Would the charge wh or ah be more reliable than the discharge on a b6ac ? Sent from my CLT-L04 using Tapatalk
  22. B

    Lower capacity at lower discharge current

    Huge thanks, and noted for the CC! You've been great help... Time for more troubleshooting! Sent from my CLT-L04 using Tapatalk
  23. B

    Lower capacity at lower discharge current

    Thanks, I was going with constant load (resistors) Do you have a device with constant watts you can recommend? Sent from my CLT-L04 using Tapatalk
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    Lower capacity at lower discharge current

    Oh wait you mean constant current or coulomb counter? Sent from my CLT-L04 using Tapatalk
  25. B

    Lower capacity at lower discharge current

    I'm using a load tester for the higher discharge, it's the lower discharge rate (0.025c) that I did with the b6ac in a charge (0.25c) discharge (0.025c) cycle. However some packs get much closer to their nominal capacity at the 0.025c discharge rate, even if they are still 20-30% off... Still...
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