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  1. W

    better resistor, method for testing 12v lithium/lifepo4 batteries?

    Yup, 4.6 Ohm is what I got too. I can't find 4.5 Ohm resistors readily available, so I'm just going to grab some 5 Ohm, 50 watt resistors off Amazon. Thanks!
  2. W

    better resistor, method for testing 12v lithium/lifepo4 batteries?

    That single handedly cleared all the confusion for me. Thanks!
  3. W

    better resistor, method for testing 12v lithium/lifepo4 batteries?

    Dummy load resistors appear to start at 100W. Will a dummy load resistor try to pull 100W out of this tester even though it's only capable of 45W max (though I'd think it's best to keep it under 35W to help prolong the life of the tester)?
  4. W

    better resistor, method for testing 12v lithium/lifepo4 batteries?

    I'm using a ZB2L3 battery capacity tester (all I have on hand at the moment) to test some 12v LiFePO4 batteries (4s8p A123 cells). First I used the included ceramic 5 watt 7.5 ohm resistor; it pulled ~1.5 A, got very hot (temp gun says 350 to 400+ F (177 to 204 C)), had a very unpleasant smell...
  5. W

    time of use -ish system?

    THIS. IS. GOLD!!! Thank you!
  6. W

    time of use -ish system?

    Rats! 50%!!? Inverter is rated at 90% efficiency (probably really 85% since it's not a solid brand, Powerjack) and utility's off-peak and peak rates are $0.0999 and $0.1326 cents, respectively. Sounds like this project is not worth it. Guess I'll re-use these parts to make an emergency power/UPS...
  7. W

    Powerjack inverter and charging board

    I have a Powerjack 15kw 48V to 120/240vinverter. I purchased thebattery charger board (both the 120v and 240v boards... not sure which one I willneed), but it doesn't come with instructions and I can't find anything onlineon how to install it. Anyone happen to know how to install it?
  8. W

    time of use -ish system?

    I picked up a 12kW automatic transfer switch (ATS) just because it was so cheap. I figured I could put it to use asI also have a 12 kW 48V inverter and a ton of 18650's (so I could make a DIY powerwall). How can I set it up so I can charge the battery bank from the grid/utilityduring off-peak...
  9. W

    better bins for organizing and storage during harvesting

    I'llbe processing a couplethousand of harvested 18650 cells. I started using the AkroBins to sort and store cells during processing (the 11 x 5 x 5 version, photo attached),but they only hold about 80 cells per bin and waste a lot of space if I want to store them safely. Any recommendation on a...
  10. W

    charge up to 8300 mAh, but get 6400 mAh in capacity test

    The cell never gets warm during charge or discharge. The charger is a HTRC branded hobby charger and the discharger/capacity tester is a ZB2L3. I'm going to discharge/capacity test now with the HTRC hobby charger (has a discharger too)instead of switching to the ZB2L3(I forget why I was doing...
  11. W

    charge up to 8300 mAh, but get 6400 mAh in capacity test

    I'm capacity testing a Headway LiFePO4 38120 cell - charging puts 8300 mAh in, but capacity testing/discharging it only gives me6400 mAh (cut off is 2.5 volts). I've ran this test multiple times and get essentially the same resulting mAh's even after tryingdifferent charging current (12 A, 6 A...
  12. W

    I messed up, big spark, but not sure how

    Yup! This is what I did wrong - connect the positive of the first battery to the negative of the second battery causing a short. Wow, that's embarrassing. Chalk it up to rushing and cockiness. Thanks everyone!
  13. W

    I messed up, big spark, but not sure how

    Yes, I connected Neg->Pos then Pos->Neg then spark! This is just the first two batteries, to make the 24v leg of the series (the last 2 batteries weren't connected yet).
  14. W

    I messed up, big spark, but not sure how

    I needed to quickly test a 48v inverter just to make sure it actually works, so I grabbed four (4) 12v batteries to put them in series. The first battery is aAGM car starter battery (automotive post terminal), the second one is a solar AGM battery (1/4" inserted screw terminal) and the last...
  15. W

    18650 for 48v powerwall - charging, discharging and currents?

    The project is a 48v 24-ish kWh 14s245p powerwall where I'm using harvested 18650 cells with around 2000 mAh. Based on my house's average energy consumption, I'm looking at roughly 215 mA of continuous current per cell. The 48v inverter I plan to get has shut down voltages at 42v (~3.0v per...
  16. W

    calculating current per cell for powerwall

    Okay, I think I see my issue - I'm confusing A and Ah... to run the house for an hour I need 2500 Wh of energy and EACH of the 3.x strings has to have 53 Ah capacity. But, if I need 2500 W of power at any given moment then the WHOLE battery has to be able to put out 53 A and NOT EACH 3.x string...??
  17. W

    calculating current per cell for powerwall

    I'm losing my math somewhere and can't figure out where. I'm planning the battery config for my DIY 48 V powerwall using harvested 18650 cells. Let's say my baseline power usage is 2500 watts/2.5 kW, so 2500 W / 48 V isroughly 53 amps of current I need to pull from the battery/inverter (let's...
  18. W

    big DIY power supply

    I already have the 6 spares on hand. Plus I want to be able to get up to 72 V andI can't stuff 6 x HP DPS1200's in a small/medium enclosure. Plus the 6 I have add up to 1920 watts which is exactly 80% of a common 20 A (120 V) AC circuit (I would only be able to useone DPS1200 on a given AC...
  19. W

    big DIY power supply

    I dabble in all types of DIY projects, butfind my 60V, 5 Abench power supply to be limiting. I do have six (6)12 V, 27 A(325 watts)server power supplies and it would be great to combine them all to get up to 72 V or162 A (1950total watts) for testing scenarios and components. I already...
  20. W

    use Li-on BMS on LiFePO4?

    I'm looking for a 16s BMS for LiFePO4 batteries, but the only ones in stock are from China anddelivery time is 30+ days. 16s BMS's for Li-on are in stock here in the states... I know there's a charging voltage difference (4.2 vs 3.6), butis there a way to use Li-on BMS's on LiFePO4, maybe in...
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