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StirCrazy's avatar
StirCrazy
Moderator
Mar 30, 2024

New Camper battery build

so as of today, I don't have a Battery in my camper.  I gave my 280Ah home built one to a friend for his camper.  this isn't an issue as I bought 4 new cells in september to build a new battery, I have just been working so much overtime at work I havent had time to do it yet.  

I went with the eve 304AH cells that have the new two bolt termanals and a few other advantages including increased cycle life, lower operating temprature and so one..   since I have bouhgt them the price has droped from 134.00 US per cell to 109.00 and thats buying from a US based store, if you want to buy direct from china they are down to 84ish bucks a cell.  the price of LiFePO4 cells has been steadily driping and expected to drop more in the next little while.  

anyways on to the build.  I dusted off the cells this morning, conected them all in parallel and set them on the charger at 3.55V to start the balancing.  the cell voltage was 3.245V on all cells after sitting since september when they arived at 3.278V.  once the cells are at 3.55V and 0A I change it to 3.65V and sit and watch so I can disconect it when the amprage hits 0.  

    • 1995brave's avatar
      1995brave
      Nomad
      Apr 01, 2024

      Where do you buy your cells from?  I want to build my own battery pack and need to know where to get the parts. 

      • StirCrazy's avatar
        StirCrazy
        Moderator
        Apr 02, 2024

        I got these ones from 18650batterystore.com for some one based in the US it is a great place to buy from.  for canada, it ends up being a bit expensive with the shipping and exchange and duty at the boarder, but I had gotten ripped off a few times and luckily got my money back and wanted a north amaerican sourse.  there is a chinese source that I am going to order from next time, I just have to look them up yet, but lots of people have had good luck with them for a while now but the shipping is obviously a lot longer.  18650 did treat me good though, I had one cell that was dammaged some where before it was shipped (just a slight dint and scratch) but when I stated I paid premuim money (at the time) for grade A undammaged cells, they agreed and sent me another cell to replace it.  thats why there is 5 cells balancing.  

        you can order pretty much everything, the cells, bms, seperators, klapton tape and the case if they are in stock yet from 18650.

         

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Apr 01, 2024

    due to my new power supplys low output, not sure if somthing is wrong with it or I am missing something, but it has been charging for 24 hours so far and back on this morning... hopefully I'll have it close to full today...  Should have just installed it in the camper and set the charge controler to 3.50V to bulk charge it in hindsight.  

    • StirCrazy's avatar
      StirCrazy
      Moderator
      Apr 02, 2024

      well after 40 hours of charging I am at 75%.  back to work today so next days off I'll finish charging I guess.  

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Apr 08, 2024

    not a lot happening right now, Im working 6 on 2 off shifts right now and my bentch top power supply is only putting out 3.4amps at 3.65V getting close to top ballanced though.  I think the 5 cells were close to 3.34V when I unhooked the charger to go to work.  

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Apr 16, 2024

    well, the cells are up to 3.36V now.  getting closer..  when I did some thinking on why its taking so long, I am putting over 1100AH into the cells at a 4 amp charge rate....  

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Apr 27, 2024

    well after almost 200 hours of top balancing I am there.  the first battery I did I just put it togeather in a 12v config and let the BMS balance it.  I wanted to try a proper top balance this time to see if it makes a difference.  so I atarted to put it togeather in a 12V configuration and grabed the BMS but quickly realized that I don't have any ring termanals for 24AWG wire, so now I am stalled to find thoes

    • 1995brave's avatar
      1995brave
      Nomad
      May 29, 2024

      Use uninsulated terminals and solder your leads in them. 

      • StirCrazy's avatar
        StirCrazy
        Moderator
        May 29, 2024

        I got some proper crimp ones.  I avoid solder for delicate stuff, it tends to work harder with vibration, but I did think about that.  

  • MNtundraRet's avatar
    MNtundraRet
    Navigator
    May 28, 2024

    My head was spinning trying to make sense of your battery install. It looked like you were trickle charging batteries needing a heavy charge rate. Did you finally get the system charging correctly?

    🤔

     

    • StirCrazy's avatar
      StirCrazy
      Moderator
      May 29, 2024

      I was trickel charging them in a sence.  I was doing a top ballance to set all the cells at the same point when they are full, problem was I didn't realy think about it and 314AH average, (the cells all tested above the 304Ah rating) so 314 x 5 is 1570AH so at 3.7amps it would be aproximatly 424 hours to get them all to exactly 3.65V which I did and they are.  I started to put them togeather and realized this BMS uses smaller wires so I had to order some new ring termanals, and now I am working a bunch of OT so I will be finishing this soon.  

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