Ryobi Battery Hack Keeps CPAP Running Quietly

When it comes to cordless power tools, color is an important brand selection criterion. There’s Milwaukee red, for the rich people, the black and yellow of DeWalt, and Makita has a sort of teal thing going on. But when you see that painful shade of fluorescent green, you know you’ve got one of the wide range of bargain tools and accessories that only Ryobi can offer.

Like many of us, Redditor [Grunthos503] had a few junked Ryobi tools lying about, and managed to cobble together this battery-powered inverter for light-duty applications. The build started with a broken Ryobi charger, whose main feature was a fairly large case once relieved of its defunct guts, plus an existing socket for 18-volt battery packs. Added to that was a small Ryobi inverter, which normally plugs into the Ryobi battery pack and converts the 18 VDC to 120 VAC. Sadly, though, the inverter fan is loud, and the battery socket is sketchy. But with a little case modding and a liberal amount of hot glue, the inverter found a new home inside the charger case, with a new, quieter fan and even an XT60 connector for non-brand batteries.

It’s a simple hack, but one that [Grunthos503] may really need someday, as it’s intended to run a CPAP machine in case of a power outage — hence the need for a fan that’s quiet enough to sleep with. And it’s a pretty good hack — we honestly had to look twice to see what was done here. Maybe it was just the green plastic dazzling us. Although maybe we’re too hard on Ryobi — after all, they are pretty hackable.

Thanks to [Risu no Kairu] for the tip on this one.

34 thoughts on “Ryobi Battery Hack Keeps CPAP Running Quietly

  1. Props to the builder for taking existing parts and making something that works better for them – looks almost OEM, retains safety components (though I’d consider fusing the XT60 connector), and only required basic tools and skills. No fully 3D printed enclosures or laser-cut panels, just the standard tools most hobbyists have.

    The [newer style](https://www.ryobitools.com/products/details/46396026750) inverter is an improved design similar to this hack, though I don’t know if it has a fan or how loud it gets.

    Side note, thank you for linking to old Reddit instead of the abomination that is their “new” design.

  2. >Although maybe we’re too hard on Ryobi
    Indeed such a vibrant green may not be to everyone’s taste (though I like it as it stands out against the mostly red airline tools and steel/black of hand tools really nicely), but it is hard to bash Ryobi for much – they have stuck with compatible battery in their cordless range for a very very long time and make tools that are pretty damn durable and cheap..

    Damn slick execution here, and very much like a project I was talking over with my parents only recently – having that portable reliable backup battery for anything seems like a great idea, and if you have cordless powertools using that same easily exchangable battery is great, as you need plenty of the darn things anyway so can extend the runtime or have one on charge and on in use…

    1. When we were stuck without power for five days in the 2021 Texas Snowpocalypse, my collection of 2Ah and 3Ah 18V Ryobi packs and a buck converter came in handy to charge our phones and other gadgets. Last year I got a Ryobi lantern with USB ports so I don’t have to rig a connection with rubber bands and alligator clips.

    2. Most tools outlive the battery these days. Home Depot also has such good deals on batteries (every couple months you’ll see buy 1 or 2 and get a free tool), it’s difficult to pass up. And now I have such a library, and so many batteries, that as a weekend warrior, there’s no reason to switch.

      They do sell an inverter if you don’t want to DIY. Picked one up after the last power outage.

      1. The hack uses the off the shelf inverter, they just hacked the side of the charger to insert this in to have a more reliable battery connection.

        Of course he could have also used a RYi150BG that has the latching battery connection built in.

    1. And the blue tools are still compatible with the latest batteries. I’ve picked up some amazing deals at garage sales. I don’t think a lot of people know the blue tools are forward compatible.

      1. I still have a couple of the old tools in the ‘blue and yellow’ scheme, and I haven’t been able to kill them yet. Those ran off the original ni-cad packs and are almost old enough to vote and drink. :)

        Ryobi also has a 40 volt system designed for their lawn and outdoor tools, but they have both a single pack inverter and a ‘generator’ that will allow one to gang four batteries and is moderately capable as an emergency power supply or as a replacement for a small gas powered generator.

        I will state that if one opts to use one of the inverters to get some electrical tape to cover up the power light partly- that green indicator is really bright in the middle of the night…

        And finally: TTI owns both the Ryobi and Milwaukee brands; you can see some of the Milwaukee genetics in some of the specialty ryobi tools (like the PEX crimper). I can also recommend the hot glue gun (the old ‘we started with a drill as a base’ model, not necessarily the newer ‘phaser’ style) enthusiastically- good ergonomics, heats up fast, and is a pleasure to use. They also make a dremel clone which is passable, but tends to trip out if you push it too hard. The soldering iron (also the first rev and not the dinky one) is no Hakko or any of the other nice brands, but it works well enough to get by.

        1. My company used all kinds of gas and battery soldering solutions, but none of them worked outdoors in sub-freezing temps. I suggested a Ryobi station since I had one. Now every job gets a solder station and two batteries. We’ve also started using their heat gun for heat shrinking in the field.

    2. Here in Japan the older ones are black and red, and I think the newer ones might be orange. I’d prefer that nice screaming lime color, though. I like tools that are easy to pick out of a pile of wires.

    1. Same here, although I was recently prescribed a CPAP and have to take a visit in a week or so. We may have been used for too much time to associate the word crap with tech items.

      1. I moved from Craftsman tools to Milwaukee as my old batteries died, but after four drills and none of them could hold a 1/16″ bit without wobbling, I tried Ryobi. Have a whole shop full of their stuff now, and for tools I seldom use, I can buy the blue ones used and they work with all the new batteries.

        1. I have two Ryobi ONE+ drills. An old blue 1/2″ and a new green 3/8″. The keyless chucks on both are garbage. They won’t hang onto anything. Put a hex shank screwdriver bit in and after a couple of cam-out bumps the chuck just lets go. I’ve cranked down on the chucks as hard as I can and they’ll still spin on bits in soft pine. The 3/8″ drill did that fresh out of the box. I *can* get them to hold by using two pairs of channel lock pliers to really tighten the chucks, then they have to be released with the pliers.

          I have a 1/2″ and 3/8″ Jacobs keyless chucks that are excellent and will screw onto the Ryobi spindles, if I could get the chucks off the drills. I removed the left hand threaded screws from inside the chucks and I’ve tried every trick I can find but they will not break loose and unscrew. Ryobi used some insanely strong thread lock or glue on these.
          Supposed to unscrew with normal right hand thread so the way to remove a drill chuck is to use the largest hex key the chuck fits, put the short arm in it, then smack the long end with a big hammer to turn the chuck backwards. No bueno. Not even with a 4lb sledge. It just turns the drill motor. I’ve even tried running the drill in reverse and letting the end of the hex key smack into my bench vise. Nope. No lefty-loosey. The way these drills are assembled, if anything inside needs repair, the chucks have to come off first.

          I have a Skil 1/2″ corded drill that also came with a garbage keyed chuck that wouldn’t hold anything. That chuck came off easily and I put a Jacobs keyless on it. Hand tighten until *click*click* and it will not pop loose, nor will it spin on a bit shank. Releasing it is just as easy. One odd thing about this drill is its spindle used the thread size commonly used for 3/8″ chucks and the Jacobs chuck I put on is a model they make for upgrading 3/8″ drills to 1/2″, just their keyless 1/2″ chuck drilled and tapped for the common 3/8″ spindle size.

          1. I struggled like hell to get an old keyed chuck off my drill, to replace it with a new keyless chuck. Turned out there is a screw at the bottom of the chuck (accessed from the front) that needed to be undone first! :facepalm:

            Once I removed that screw, it came out easy as pie!

    1. Have you priced the “cheap” 12v model of Milwaukee PEX A expander kit? $438.90 from Home Depot. Some places price it at almost $500. The 18v kit is nearly $1000 and the bare 18v tool $213.53 from Faucet Depot, higher through other sellers.

      I replaced all the galvanized plumbing in a house with PEX A and had to buy the 12v Milwaukee kit because nobody in this area has any kind of PEX A expander for rental. I did the whole job on one charge of one battery. The only reason I could see for needing the 18v version is on large commercial / industrial jobs where one is going to be doing hundreds of connections without any break for battery swaps.

      It would be nice if Ryobi could produce a much lower cost PEX A ONE+ tool.

  3. I’m surprised an inverter is necessary – the CPAP machines I’ve seen all use an external power brick, albeit a hefty one where a humidifier is in use. e.g. Philips One takes 18V DC @60W+ iirc. A worthwhile project though, partial suffocation in a power outage thanks to the restricted airflow in a power failure situation is a particularly unpleasant way to wake up.

      1. Possible it uses an AC motor? I mean if its never been designed to have a battery unit variation, just to be a quiet reliable home unit AC motor is cheap and effective for those goals.

        Though in that case if you need one through power outages does seem like sourcing one that can take DC is going to be the best idea – inverter losses can be avoided and the battery lasts longer, seems like a worthwhile investment.

    1. As is mine.

      Reddit says it was a “Resmed Airsense 11” which after googling suggests its’ DC too.
      Not only is there the OEM overpriced battery system but plenty of people making Li Ion “middleman” packs which function as inverter/chargers and are designed for cellphones tablets etc.
      Might take a look at one of those.

  4. Personally, for running my CPAP, I’d go for a simple UPS, though, I don’t know if anyone makes any that are quiet. Still, if it’s just replacing a fan and maybe gutting the beeper, that seems safer/more reliable than hacking your own UPS from junk. If it is for something less important, I applaud their work, I just wouldn’t use it for a CPAP.

    1. I’ve thought about a UPS, but the problem is that if you need it to be running off the UPS, you can’t stay asleep with the beeping, and I don’t want to go mucking with the internals of critical infrastructure to disable that. The lithium ion power station type batteries are the way to go, since they’ll be quiet when you’re trying to sleep, naturally, and you can get ones that have pass through charging so you don’t need to fiddle with cables before going to sleep.

      I have a DC/DC converter for the CPAP, so it’s only 120V until it hits the charging brick for battery, and it’s DC from there on. This also improves the efficiency of the setup. One night with using the AC output brought it down by 67% of the charge, while all DC kept it at less than 50% used.

  5. My biggest concern is the inverter. Many CPAP machines require both high wattage (300) and pure sine waves. Many inverters run on the cheap and use modified sine waves and/or run lower watts. Lower watts may not be a killer but the modified sine wave = broken CPAP and no way I am going to destroy a lifesaving expensive equipment on that gamble. Using Ryobi’s inverters, the 18v one is modified sine and cannot be used with my CPAP, the 40v one does though. But for 8 hours of sleep, it takes me two 40v batteries. Those 18v ones are not going to last long at all and not worth having to wake up 4+ times during the night to change them out. I do use high pressure though so someone who doesn’t have extremely severe apnea like I do might get longer battery times. To me, a thousand dollar machine that keeps me alive every night, I can splurge on getting something that I can 100% trust will work with my machine; that isn’t something I am willing to skimp on – ever.

    Also, I have a lot of love for Ryobi tools. They were the first to go hard into li-ion when the other brands just lagged behind and when they finally did, didn’t bother to cover the depth that Ryobi already had. I would have waiting years to get an good electric lawn equipment and less common electric tools on the other systems. No thanks. I feel like they didn’t want to take any risk and just waited, to the detriment of their customers. It feels like an apple move (wait way long time to get new tech and to justify it say we just waited to do it better, when it usually wasn’t always better or just marginally).

  6. Hi guys! This is my project. Thanks for the questions and suggestions.

    Quick summary: the CPAP has a switch mode DC power supply; it is happy to run on square wave inverter. No, it does not have a single-voltage barrel connector; it looks like a DisplayPort connector with wider pins. Yes, there are commercial battery packs available for $300, or DC-DC converters for $90, while this inverter was $10. This inverter is 100% silent, running for 7 hours overnight.

    And, well, uh… yes, all of the questions/comments here were already asked and answered in the linked reddit thread :)

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