I just got this assembled last weekend.

printables, complete with F3D file.

This is a battery adapter that will allow you to insert D cell batteries into a LiitoKala Engineer Lii-500. I included the Fusion 360 file, so you can customize it to fit other applications, but odds are it will fit most 4+ 18650 based chargers that are also compatible with Ni-MH.

It prints in two halves that I simply hot glued together around their perimeter. It’s not like this part is going to see very high loads… The parts are designed to print without supports. My copies are 20% infill (you could easily go with less) and 3 walls for an overall wall thickness of 1.16. Wall thickness is something I wouldn’t change, at least for the battery side so the battery terminals don’t eventual fail. The batteries are a very slight interference fit to ensure a robust electrical connection.

For terminals, I used 8mm wide nickle strip. I’m sure you could use something else, but I had some on hand and it seemed like an obvious application. Connections between the two halves were made via wires and solder.

  • marcos@lemmy.worldEnglish
    17·
    3 years ago

    There’s supposed to be a heat sensor on the positive contact that you are rendering useless. That said, given the lack of longevity of every nickel battery I’ve tried on the past couple of decades, I don’t think the charger manufacturers take this guideline seriously.

    • IMALlama@lemmy.worldOPEnglish
      8·
      3 years ago

      This is true, but at the default 500 mAh charge rate it seems unlikely that much heat will be generated? Worst case of 100% of input voltage getting converted to heat would be 700mW or so of energy needing to get dissipated per cell.

      • ChaoticNeutralCzech@feddit.deEnglish
        8·
        3 years ago

        Yeah, the big cells can handle that just fine. The charger would overheat first unless a cell is shorted, which only possible with NiMH/NiCd if the charger malfunctions or the battery is physically damaged.

        • IMALlama@lemmy.worldOPEnglish
          4·
          3 years ago

          If “10,000 mAh” (if they’re half that I’ll be happy) batteries are heating while charging at 500mA odds are they’re not in great shape to begin with.

    • partial_accumen@lemmy.worldEnglish
      5·
      3 years ago

      given the lack of longevity of every nickel battery I’ve tried on the past couple of decades

      Early Ni-CADs and NIMHs I agree with that assessment. However for low duty cycle applications the 3rd and 4th gen Eneloop type technology NIMHs perform very well for me. I’ve got about 20 operational cells I purchased in 2011 from an original batch of 30.

      This isn’t my data, but my anecdotal experience matches this:

    • lysdexic@programming.devEnglish
      1·
      3 years ago

      I love the idea of being able to fit 4 big D’s

      I’m more interested in knowing whether the charger actually supports that type of usage.

      • IMALlama@lemmy.worldOPEnglish
        5·
        3 years ago

        This is a four bay charger that supports the chemistry already. The only thing it didn’t support was the battery from factor, so adapter to the rescue.

      • warmaster@lemmy.worldEnglish
        1·
        3 years ago

        The chargers typically support 3 sockets, you could adapt one to fit two big D’s for Double Power.

  • dual_sport_dork 🐧🗡️@lemmy.worldEnglish
    3·
    3 years ago

    I did something similar back in the day, but I did it in a much more boring fashion by getting a 4 D cell holder from Radio Shack and wiring a Deans plug to it, so I could plug it into my R/C battery pack charger. Your solution is a bit more elegant, in a way.

  • ramenshaman@lemmy.worldEnglish
    41·
    3 years ago

    What do you D batteries for?

    I hadn’t used them in many years but then my gf got me the hot wheels set I asked for at Christmas 30 years ago and never got and it uses D batteries. I’m planning to make a wall adapter for it.

    The hot wheels set is Criss Cross Crash and it’s probably the best toy ever made. They haven’t changed it in the last 30 years.

    • IMALlama@lemmy.worldOPEnglish
      6·
      3 years ago

      Amusingly, this is almost exactly the reason why we have D sized batteries. The batteries are for a Criss Cross Crash, which I also never owned for a kid. But we got it for our kids (one of the perks of being a parent - you can buy the toys you wanted as a kid but didn’t get).

      I initially purchased a pair of these chargers to charge 18650s for… high power flashlights. Yes, that’s a thing, go check out !flashlight@lemmy.world. Then I started tearing down older laptop batteries to harvest 18650s for a DIY electric scooter. Then we had kids and now these chargers see a lot of use for Mi-MH

  • RememberTheApollo_@lemmy.worldEnglish
    3·
    3 years ago

    FWIW I bought similar AA and triple-A of this brand to replace regular alkaline batteries my kids use in their VR controllers. It was getting expensive with the disposables, so I decided to try rechargeable batteries even though I’ve had poor luck with them in the past. This brand is doing really well and has paid for themselves handily in saved disposable batteries. Worth it not throwing more crap in the landfill, too.

      • mvirts@lemmy.worldEnglish
        1·
        3 years ago

        I think my preference would be to cover the parts that would short on the bottom, but that’s because I’m a messy person that would probably discharge the batteries accidentally 😹

    • Contend6248@feddit.deEnglish
      6·
      3 years ago

      Because you don’t have to with the right tools and the right mind.

      The less e-trash the better.

      The only difference is literally the case itself, which can be solved with this print and some contacts.

      Anyone with some electrical knowledge can tell you that this solution is totally fine.