The Best NiMh Charger?

[Paul Allen] has been working on the latest iteration of his NiMh battery charger and it looks amazing!

We’ve covered [Paul Allen]s awesome hacks and tutorials before, but never this project. What makes his charger so special is it’s ability to monitor and log every aspect of the charging process. Not only does it have a SD card for data logging, but it also interfaces with a Windows application for real-time monitoring as well as analysis and visualization of the charging process (Linux users don’t fret it has a serial interface too).

[Paul] doesn’t say if he plans to open hardware or kickstart the charger, but some of his older posts give us a quick peak at the gerbers. Let’s hope this awesome project makes its way into the wild soon, and hopefully we’ll be able to try it for ourselves and see if it lives up to its name.

32 thoughts on “The Best NiMh Charger?

  1. It’s already been kickstarted. More than a year ago. Paul has kept us very much in the loop as he keeps iterating and pushing the boundaries of this charger. I am more than happy to wait for his masterpiece. It’s been a most kickstartery of kickstarters.

    1. Maybe read the comments Mark Griffiths – “I’m sorry that it has been so long since either Paul or myself have posted an update. Unfortunately we ran into some problems with programming the boards that Paul has recently built and due to work commitments and recent family illnesses for both of us, we haven’t been able to coordinate a time to work through the problem”

      It is a normal KS project, it will be ready when it is ready.

      1. No need to read the comments, I’m a backer and have followed this project through from the start. I bought the one with an LCD that it turns out will not be created. It was to be delivered August 2013 (2 years ago)… I didn’t see the “will be ready when it is ready” disclaimer when I backed, lol. At this point I really dont care, and I actually doubt I’ll ever see a real product, just thought I’d add a bit of reality to all the gushing here…

          1. As an aside, 20k isn’t a lot of money – certainly not enough to develop a product.

            It is enough to get an existing design produced though.

            One-man-shop + limited capital + “almost finished” + “next revision is awesome” = fail.

            You almost feel sorry for these guys; they low ball to get the Kickstarter over the line (“we did it!’) and they they realise they’ve been working for 10 cents an hour. Ah well, it’s not his day job.

    2. Yes, I was definitely naive when I posted it on Kickstarter a long time ago. It has been a very hard lesson for me to go through. I cringe when I think back to right before I posted it and how I thought I was 90% done. I had no idea what I was getting into. I have learned through experience how much I didn’t know about what it takes to try and move something from proof of concept and/or prototype, to a finished product. That being said I am glad I did it. Somethings you really just can’t learn until you go through them.

      Delivering to backers has and is taking forever, but slowly I have been chipping away and have now delivered over one hundred chargers. If I could go back in time and do it all over, I would have waited until this stage (past development) to post it on Kickstarter. I know Kickstarter isn’t a store, but I would never put another project up again unless it was 100% done, figured out and everything was lined up so that all I needed kickstarter for was to make the big order.

      Having my charger featured on Hackaday reminded me that I needed to update the files so I did and for those who care you can find them here:

      Also Mark, a kind backer who pretty much saved my life with software, maintains his own for Forum for the charger here:

      1. Paul if you ever find time to do a writeup of what went wrong I would be eternally grateful. I want to do a Kickstarter but as you and most people who run a Kickstarter have learned the devil truly is in the “to production” part. I would very much like to learn from your experiences before I embark on my KS journey.

        1. He already did – read the updates page.

          In short, he offered something he didn’t have. Look at the promo video, can you see the LCD? No? “Well, might add a screen, that’ll attract a few people and will be a really simple thing to do!”.

          He also redesigned the product (eg SD to MicroSD); which might not be too hard compared to adding the LCD but it’s still a 2 month delay while you respin the board, get parts etc and COSTS MONEY.

          If your Kickstarter is only for a few 10k of cash, you don’t have enough for design. That’s enough for tooling & production of your existing product and a few months wages at best. The money vanishes faster than you can imagine. If you raise a million then hey, go wild.

          Most importantly – if you’re asking the question, you’re not ready.

          1. …and if you’re not asking the question, you’re an idiot. Damned if you do, damned if you don’t. There’s got to be a middle ground there somewhere, Tony.

          2. It’s the wrong question to ask.

            The question should be “Can I produce the product I’m selling?”, and in the case of this Kickstarter, the answer was “No”.

            What went wrong is simple – current product not finished and sold the next version anyway.

            Most Kickstarters go off the rails for exactly the same reason – getting a product built is hard, even if everything goes right.

            What they should have done is finished what they had (maybe a couple more months on the firmware) as v1, and launch with that.

            A year later launch v2, the one with the LCD.

  2. The best charger is under active control. I would hope for 8 analog ports (cells) that are fully programmable. Perhaps a multiplexer so you could run 4 lots of 8 cells simultaneously. Since it is software driven it charges NiCd and Lithium as well. My 2 cents.

  3. looks interesting, have not heard of this one before.

    btw, why such a narrow depth of field (photo)? this is not art, this is tech and we want to *see it*, dammit ;)

  4. It seems to me that the iMAX B6 chargers that are all over ebay do this. Not the SD card part, but you can monitor them via a serial interface. They also have a nice LCD for monitoring, and can charge any common battery chemistries.

    1. Or one of these,

      I think the Accucel and the iMAX are closely related, I have an older model and they work great. FYI the old ones use an old IBM laptop charger plugs right into the Power Jack, no modification needed (IBM T30 or similar, they made them for years). The new ones use standard XT60 plugs.

      Tons of information:

  5. It sounds nice…but what use case is there to NiMh compared to a Lithium chemistry? I definitively remember some beautiful NiMh chargers back in the day though, hobby-designed stuff like some DeltaQ charger or whatnot that I had [forget exact name but it was superbly designed and purchased from some coordinated mailing listserv].

    1. NiMh is cheaper and tends not to catch on fire.

      Also, rechargeable lithium cells that output ~1.5v in the AA size your stuff uses are somewhat rare.

      (They do exist, but they’re just 3.7v lithiums with a regulator. And they’re expensive. And the capacity is about the same as NiMh. And this charger won’t work with them anyway.)

  6. Since I’m not into chargers much a quick q to you guys: Am I right in assuming you can charge any Lithium ion battery of similar specs with any charger that is designed for it? I mean you can use say a motorola phone battery charger for say a digital camera battery if they are both let’s say 3.7v and 1100 mAh for instance right? (After modifying the contacts to match that is of course.) Or is there a difference in temperature and charge current capabilities that prohibits it?

    1. Not quite bust mostly. Now and days most batteries are 3.7V nominal and 4.2V charge termination, but some older lithium batteries would want 4.1V charge termination and die quicker at 4.2V. The other difference is the charge rate. Don’t charge a tiny lithium battery (like a 250mAh RC helicopter battery) with a fast charger (a safe bet it 0.5-1X the capacity rating. So don’t charge a 250mAh RC battery with more than 125-250mA unless you know it can tolerate more.)

      The other big-big thing is that most battery chargers for lithium products aren’t battery chargers, and they’re just power supplies. So for your phone it’s mostly just a 5V 1A power source, and internally your phone regulates that power to the battery. So if you directly connected a battery to the 5V 1A little dongle, it would overcharge and possibly light on fire.

      1. By the way, the place to find chargers suitable for direct charging lithium would probably be to dissect a cheap “EGO” or “510” ecig charger. Those are typically USB powered and regulate charging to 4.2V.

      2. My bad of using a phone as an example, obviously those don’t come with chargers as you say. Although I guess you could use an old phone and use its internal connectors wired to an external box of sorts to charge a battery of similar specs.
        Anyway, thanks for the reply, it’s useful to know since it’s easy to find batteries for various devices and also easy to find chargers, but harder and more expensive to find a specific charger and battery combination. And often it’s just a case of making the 3 contacts fit correctly then it seems.

        1. Yup! Cool, glad to hear it. It’s always good to re-purpose when it’s suitable.

          I wanted to mention two minor sidenotes:
          There is one wild type of battery that you will very rarely see- LiFepO4, which has a very different charging voltage termination than LiPo/Lico. You’re very unlikely to see it but it might be in some power tools and usually will be marked. Can’t use a LiCo charger on those.
          Also, you can get some decent 1s 18650 chargers on ebay which will also be suitable for the charging that you’ve described.

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