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  1. S

    Questions about shipping large quantities of laptop batteries - 18650

    So I've got hundreds of lbs of batteries from retired laptops (cells have not been removed from the battery packs) from a local business, maybe somewhere between 50-100kwh worth. I built an awesome ebike battery with some which looks like it will last me a decade, but I have an insane amount...
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    Video of ebike collision - be safe out there!

    Completely agree, I can only hope others can learn from my mistakes.
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    Video of ebike collision - be safe out there!

    https://www.youtube.com/watch?v=5WA974Csaus I'm sharing this video of an accident I was involved in a bit over a year ago to hopefully help others avoid similar situations. Thankfully the driver stopped and my injuries where minor, cold temperatures meant I was wearing several layers, the road...
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    Uses for a giant transformer?

    Crap sorry, just made the images public.
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    Uses for a giant transformer?

    Probably not applicable to ebikes so much, but this seems like the right place to get some direction. I acquired this massive transformer from a new (but sitting on a shelf for years) 5KV battery backup supply that was being thrown out. It probably weighs close to 30lbs. My electronics...
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    Dirt Cheap DIY eBike

    Nice build! My ebike is similar, large pack of used laptop cells. 14s20p total made up of two bricks of 7s20p, one for each pannier. This solved the 14s problem as well as my charger could support 7s, I would just put the two bricks in parallel and then charge both at the same time. I did not...
  7. S

    How do I figure out shunt value for my CA?

    I have a Thunder 1220 charger and it does not have a "foam cut" feature that the iCharger does. Is there some other way to do this?
  8. S

    How do I figure out shunt value for my CA?

    I recently got a CA v3 for my bike (DP type even though the controller doesn't have a plug, not a big deal, just made the connections myself). I need to input the controller shunt value so I can get an accurate amp draw reading, but I don't know what that value is and my googling on figuring...
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    Finished bike - 2KwH 18650 battery with pics

    Bike: Diamondback Response SE Motor: Yescomusa 48v 1000w Controller: Stock controller (I remember someone mentioned these are 30a) Battery: Used laptop 18650's - 20p14s total (2 20p7s packs) Top speed: 34mph / 55kmph So this has been a work in progress for a couple years. I started out loading...
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    RC Brushless DC motor 90A pair with 18650 cells?..

    Question about this and laptop cells. Is it better to have more in parallel or shift a bit more towards a higher series count? For example a 48v 1kw motor with a large recycled 18650 pack, better to have 12s20p or 14s17p? Or is it just a matter of trade off's (power vs range)?
  11. S

    Solderless 18650 pack - looking for feedback

    This is a simplified design based off the other solderless packs I've seen here, similar to the one Snath posted here a few years back. The block shown will be 24p3s, going to hopefully build 4 of these which fit flat in my panniers for a 48v motor. The brackets are sandwiched between 1/4" PVC...
  12. S

    Homemade Battery Build 48V 20Ah Finished

    What BMS did you use?
  13. S

    18650 charging/discharging system - share yours!

    That's correct, doesn't matter which way it's wired up. Yes, just cut the cord, I used an old bathroom light fixture. Or if you have a spare AC outlet you could just wire it up to that and plug your lamp right into that if you don't want to cut the cord.
  14. S

    18650 charging/discharging system - share yours!

    Dang Matt! That is one polished system, nicely done!
  15. S

    18650 charging/discharging system - share yours!

    As someone who wanted to go with the "used laptop battery" route due to having a good source of batteries I recognized how tedious it is individually test the hundreds of cells I have, in fact if I did have to do them one at a time I would have given up a long time ago. So here are some jigs I...
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    Proper voltage for 18650 battery build?

    Thanks for the clarification, that makes more sense! I think I may just go with the 15P, I guess if I really want a little more speed I can make a separate little booster pack. 9.3kg doesn't sound too bad considering I was using 23kg of lead acid batteries initially. I'd like to charge on the...
  17. S

    Proper voltage for 18650 battery build?

    I'm in the process of building an 18650 battery pack for my 48v 1000w hub motor. The batteries are used laptop batteries, I've tested them all and I'm working on the final configuration of the pack. I built a triangle that can fit a max of 185 batteries so my question is this... I can either...
  18. S

    18650 spot welding -how to- ULTIMATE REPOSITORY

    Nice! Thanks for sharing the nickle strip deal, just bought some. Anyone know how to add a timer to a welder? I recently made my own spot welder with a microwave transformer. I used one of the door switches to make a foot switch to turn on the welder, however my results are very inconsistent...
  19. S

    Charging question - not reading voltage correctly?

    Found the problem and all is well! I've been using some extra alligator clips that had some fairly thin wire to reach the ends of my batteries (the ones that came with the charger are so short they are almost worthless). When I took these extra wires out of the equation the voltages read by the...
  20. S

    Charging question - not reading voltage correctly?

    Just a little background, I'm using a Thunder 1220 charger and I'm working with used 18650 laptop cells (in this example, working with a single cell), I'm also using a Fluke 117 multimeter to monitor the cell. When I first turn the charger on the voltage read by the charger is 3.71v and the...
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    Recommendations on voltmater/ammeter for daytime riding?

    Yes, I know the cycle analyst is the way to go, but I'd like to hear about other options available that aren't $150. I'm just getting started and all I want to see is volts/amps at the moment and I figure that can be done at 1/10th the cost. I'm going to be running a 1kw yescom...
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    18650/charger questions

    Yup, definitely not new and many are likely not great. I don't have a sense of a what a good cell and a bad cell look like when charging, how do you tell? Will the voltage on a good cell increase only a small amount when charging? If so, what is "a small amount"? I'm trying to figure out how I...
  23. S

    18650/charger questions

    So I'm starting to charge 18650 cells that I've scavenged and need some feedback. I purchased a Thunder 1220 charger to use, I set the cell voltage to 4.2 (cells are in the 3.7 range). I put 10 cells in parallel to speed things along and apply only .5 amps, which is what... .05c? However the...
  24. S

    18650 battery Kit development and discussion[testing done]

    Great project! I'm definitely watching your progress on this. Curious why you decided on 10s (41v when cells are charged to 4.1v each) and 14s (57.4v total). Why not 12s which would be 49.2v? I'm still pretty new at all this, but I see a lot of kits that are 48v. How will the end user...
  25. S

    yet another solderless DIY battery pack via NIB's

    Guess I'm not completely understanding yet. How would you balance such a pack?
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