Cross-Brand Adapter Makes For Blended Battery Family

Even though he’s a faithful DeWalt cordless tool guy, [Richard Day] admits to a wandering eye in the tool aisle, looking at the Ryobi offerings with impure thoughts. Could he stay true to his brand and stick with his huge stock of yellow tools and batteries, or would he succumb to temptation and add another set of batteries and chargers so he could have access to a few specialty lime green tools?

Luckily, we live in the future, so there’s a third way — building a cross-brand battery adapter that lets him power Ryobi tools with his DeWalt batteries. [Richard]’s solution is a pure hack, as in physically hacking battery packs and forcing them to work and play well together. Mechanically, this was pretty easy — a dead Ryobi pack from the recycling bin at Home Depot was stripped down for its case, which was glued to a Dewalt 20-v to 18-v battery adapter. The tricky part came from dealing with the battery control electronics. Luckily, the donor DeWalt line has that circuitry in the adapter, while Ryobi puts it in the battery. That meant simply transplanting the PCB from the adapter to the Ryobi battery shell would be enough. The video below shows the process and the results — Ryobi tools happily clicking away on DeWalt batteries.

While [Richard] took a somewhat brute-force approach here, we imagine 3D-printed parts might make for a more elegant solution and offer other brand permutations. After all, printing an adapter should be easier than whipping up a cordless battery pack de novo.

26 thoughts on “Cross-Brand Adapter Makes For Blended Battery Family

      1. More so, the “20v” tools max out at 20v as 5x 18650’s fully charged with no load will read over 4v.

        Personally I like the distinction as it allows for easily communicating whether you are referring to the older “18v” line or the new “20v” line.

        But people are going to get bent out of shape over anything, no point trying to correct/explain.

      2. *Looks at his DeWalt drill with its 18v lithium battery pack*
        Nope, 20v is pure marketing BS. They’re sold as 18v in the UK (and probably europe) because that’s the packs nominal voltage. You can bet if they sold them as “20v” instead of “20v MAX” in the US there’d be a slew of false advertising claims.

        1. From what I have heard, the 20V is the actual static voltage rating, 18V is the working voltage, so they are 18V tools, but the 20V lithiums do hold more power and referring to them as 20V does clarify they are a new line. Having used both, the 20V are decidedly superior and noticeably lighter as well (no nickel or toxic cadmium, lithium is the lightest solid possible, although I would not think they have 18650 cells in them, 18mm x 650mm cells would never fit in the 2Ah battery for starters, but I don’t know what is inside one).

          1. 18650 means 18mm x 65.0mm, not 650mm. Other than some Bosch batteries running bigger 21700 cells, pretty much every li-ion power tool battery is made up of 18650 cells.

        2. The Bosch rep explained it to me thusly: All the tools are 20 volt but are actually 18 “working” volts. Its just that deWalt elected to market there line as 20 volt. At first I thought, “Aw BS”. Then when reading the manual inside the deWalt tool box it actually states that they are 18 working volts. Deceptive maybe but the tools starts out as 20 volt until you trigger it and they do say so in the paperwork .

  1. I like the 20V better since they have the meter built into the battery. Dewalt has great customer service with the adapters also as I called in when one of mine stopped working within the warranty period and I wound up calling a couple months later because I was off the grid on the farm and on the road and they still mailed me a free replacement.

    This is interesting and neat. Great article and video.

    Now to look into Ryobi tools if need, as I was looking at Milwaukee at one time to hack an adapter and found the discrepancy between the battery logic circuit being internal versus external with the Dewalt and looks like Ryobi. Wound up working on the 120V 9A Portland Harbor Freight Electric Chainsaw portable inverter deep cycle battery pack. Sweet and great find on the wife.

  2. This is yet another useless article. There are, BTW, dozens of 3D printed models in thingiverse to adapt almost any battery to almost any device (if voltages are compatible, and yes… 20 V DeWalts are really the same as 18 V everyone else’s).

  3. …Made a couple of these a year or so ago to run Black & Decker tools ..Nothing fancy ..Works Great ..EZ fix for any tool.
    ..Seems to be a lot of taking about this and that’s not rocket science.

  4. Thanks for the inspiration in this article and 42Fab!

    Finally got around to completing the repair of the adapter I had with one of two 20V Dewalt trigger assemblies I found on eBay at a great price, since I figured those adapter components to interface the 20V Dewalt batteries are present from researching before.

    Decided I’d make the adapter to the Ryobi 18V ONE+ since I was wanting the tire inflator, glue gun seems handy, an air compressor for cleaning hard to reach places and Peter Schripol may have corrupted me also for an antenna launcher system make. Seemed like better portable off the grid kit (with electric).

    Found out there are LED 20V connectors and trigger assemblies as well as some other wires in the trigger assemblies. Here is the middle video of a three video presentation I did to document what was done:

    1. Heads up regarding the pressure gauge on the Ryobi P737 Inflator. Mine is reading 6 psi higher than should be.

      I just realized after using to inflate one of my Prius tires, that no one has been able to find the slow leak, since January and not using the regular psi gauge.

      Went to rotate the tires and found some crazy wear on the tires that I guess was increased going across country and riding on 6 psi less in that tire for the last 3 months. Had to get a new set of tires.

    1. “Can i get an Li Ion adaptor for an 18V BOSCH tool ( previously Ni Cad)?”

      Looks like there is for a Bosch 18V NiCd to Li Ion here:

      I’d ask about this one and maybe like above if you can just buy the design files and promise not to sell since for “personal use”:

      This one looks like there is for a Makita battery to a 18V Bosch in the files, though no photos of yet so probably worth verifying the battery style interface:

      This one is different as I guess there are different that style packs:

  5. Here is the explanation and solution I’ve come up with. The third tab is both a thermistor and a comms* tab. This can be fooled with an adapter from an old battery which could in turn be attached to a homegrown mount. And just as you would harvest out the internal Samsung (or whatever brand) individual cell units by snipping away the solder joints when attaching an 120v ac – 24v dc unit, you could use the post harvested kobalt battery top for your mount with a double spade +- conventional battery of your choice within reason. I would only recommend (at your own risk) using like volt with like volt.

    *This is a comms tab but not in the way you would think.

    Because you are dealing with a brushless motor you have three leads where the – tab, the + tab, and the T tab are operating in a forward sequence where upon rotation of motor stator the signal for say the current – tab moves forward to become the + tab and then on the next rotation becomes the T tab and so on and so forth. This is consistent with all three wires exiting motor. However, on the newer Kobalt tools their is also comms with the battery to insure the battery does not drop below minimum charge parameters and thus cannot then be identified by the charger.

    As for bypassing the T tab, I believe the only way to safely accomplish this is in the aforementioned explanation. HOWEVER, finding the proper thermistor resistance (generally anywhere between 4.7 and 10 ohms soldered between T and – tool tab should work.) however this is only in the older Kobalt tools as the newer Kobalt have the additional tool to battery comms. IMPORTANT: You’d damn well better make certain your power source is independently protected at all levels as you are disabling your low charge protection with this method and for me the thought “ABANDON HOPE ALL YE WHO ENTER” comes to mind. Their is however a third solution I recently stumbled across. Their is a company that makes the majority of Battery Management Systems for the majority of the proprietary Li-ion brands. In fact these go for about $3-$4 each. You can pick up one of these, drip it in your DIY adapter and you’d be set to have all your safeguards in place and for pennies on the dollar. This would bypass the sketchy adapters advertised on various sketchy websites. Should you desire the company name please dm me and I’ll get that to you.

    Good luck

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