I think the companies that wouldn’t like the proprietary are ones trying to make a new entry into the market, since you have to convince someone your tool is worth adding a new battery/charger to the garage while knowing there’s not a full system of everything that could use it.
If there were a standard battery it’d be easier to say “we’re a company that only makes a circular saw.”
It's also the broadest system, with everything from drills and saws, to lights and fans, to soldering irons and dremel-like tools. Some of their stuff isn't as compact or as full-featured as Milwaukee, and this is shitty artificial segmentation on the part of their shared parent company, but for the most part it's all I've needed. (The new HP drill with the metal chuck and anti-backdriving clutch finally answers my chief complaint about all Ryobi drills before that.)
But, NOBODY, on any battery platform, or even all of them put together, makes EVERYTHING I want, and I end up doing a fair amount of hacking. Ryobi 18v is a forgiving system, with the BMS integrated into the batteries, so you can just draw power and do whatever. I made my own soldering iron long before Ryobi released their own. I've had USB outputs since long before Ryobi released their own. I've cobbled together a 100W USB-C one now, while the official ones top out at 45W. I've been using those batteries to drive an electric cooler/freezer since long before Ryobi released their own.
If I hypothetically had universal batteries that would fit any tool from any brand, would that make it better? Not significantly, I don't think. Other brands don't seem to offer significantly more, or significantly earlier. If I want a lot more or a lot earlier, I have to do it myself.
A universal battery would've given me an anti-backdriving drill earlier, and I could have the Makita microwave, that's legitimately cool but it's also ungodly expensive and I wouldn't buy one even if I was already on the Makita battery platform. DeWalt's radio is probably nicer but I don't even use the Ryobi radio I've got, so I don't think that matters.
A universal battery WOULD be great, just for competition's sake, but in practice I don't think it would change much for me. I'm already basically there, through a combination of a very versatile base platform that goes most places, and the ability to chop things up and make new stuff when I want to go even further.
A little over the top sometimes, like do they really need 20 different cordless leaf blowers? Or is that just so they can brag about how many tools the ONE+ system has?
Should I get a P21110? Or a P21140? Or maybe a RY40412VNM or PBLLB01K?
I don't count that crap when I say broadest, though. I mean, there's a battery-powered pump which is great for draining or loading medium-sized vessels, where you don't want to suck-start a siphon or maybe gravity goes the wrong way. Milwaukee makes one too, but I don't think anyone else does -- there's a third-party one that takes Makita batteries and a different third-party one that takes DeWalt batteries, but that's it. Or there's a heatgun now, I think a few brands have those now too. There's hot-melt glue guns, only Ryobi has first-party, everyone else is using adapters and stuff.
That's what I mean when I say broadest, there's just a ridiculous variety of stuff on those batteries, like the overlap of all other brands combined, and a lot of it is really useful. I can't count how many times a corded hot-glue gun launched itself into my lap because I snagged the cord while moving around, and that simply can't happen with the cordless one.
I don't own anything toooo unusual, the weirdest is probably the hot glue gun that you mentioned. It's great as a cordless tool because the cord on a hot glue gun is always trying to tip it over and burn your arm or pull it off the table.
And of course they do have two different hot glue guns. One where the battery locks into the handle, and one where the battery goes into a base station and the gun is a smaller unpowered piece that you pick up with some thermal mass to stay hot until it goes back on the base to heat up again.
Nobody really cares about the Makita coffee maker or microwave or whatever, but Ryobi has some interesting things.
Lowe's Kobalt had a kids drivable toy car that took their batteries, that was kind of nice. I just added an adapter to take M18 for my daughter's toy jeep, now it can flip itself over.
People what think these companies are selling batteries; they're really just selling motors with different plastic.
Obviously Bosch DIY tools ("green") are in another alliance [2]. Much sharing, big convincing.
I've always needed to buy first-party batteries to replace worn out ones, and if I'm doing that it doesn't make any difference to me if their interface is proprietary or standard.
Sell me batteries worth a damn, then we can talk about standards.
Once you have two battery types, you might as well have a few. People seem to be quite fine with M12 and M18, which are only compatible on the charger itself.
It is much less important to have access to multiple brands now compared to 20 years ago, as most of the brands have acceptable tools across the line even if they're not all the "best in class".
But that doesn’t matter! If, say, Makita, Bosch and Hilti started using standard, interchangeable batteries, you could use Makita, Bosch, or Hilti batteries in tools by any of the three brands. No need for third party batteries.
https://www.protoolreviews.com/power-tool-manufacturers-who-... <--these include all power tools, not just cordless. Kind of interesting to see who's actually related to who.
The company was responsive to support before ordering to ensure compatibility.
The interfaces can be adapted... it's just voltage and all you have to do is step up or down.
It isn't quite that easy. The high-output 18v batteries can dump over 100 Amps for short durations. Stepping that kind of power up or down isn't really possible in any consumer device.
The good news is that Dewalt 20V and Milwaukee 18V are actually the same: they are both 5 li-ion cells. The no-load voltage of a li-ion cell is ~4V, the voltage under load is 3.6V. This is why you can use Milwaukee batteries on Dewalt devices and vice-versa.
So some batteries protect themselves from being overdrawn, others do not.
M18 batteries, for example, are dumb and will let you discharge them way too low where they won't take a charge anymore.