[, Music ] so no really grinds my gears every tool manufacturer having their own proprietary battery system, no, it's great for them and their sales, but it sucks for us and our wallets and we've all been there. You'Re out, you see a particular tool. That'S on sale and be a great addition to your collection, but it's not from the brand that maybe you're loyal to, and so you don't already have the battery and the charger for that new tool. As you have two options, you put the tool back on the shelf and you don't buy it or you do buy it and you invest in another battery and another charger. It might cost you 100 or $ 150, and the other scenario is that you stick to one particular brand and then all of a sudden, I don't know where they decide that they're gon na change the shape of their battery, and it goes from a slide in To a pop in or whatever you want to call it, but it changes and it's no longer compatible. Now you have a legacy tool system with legacy batteries that aren't compatible with the new tools or vice versa, and so what I'm gon na show you here today is the solution that you can interchange batteries between brands or even within the same brand. You can make your legacy batteries work with your new tools and it's usually pretty simple. So why don't you just follow along so for this particular video? We'Re going to be looking at this Makita, 3 and 3/8 inch mini circular saw which runs off their 12 volts. The XD battery system and we're gon na be interfacing that with a Milwaukee m12 battery, and the key thing here is that the battery and the tool operate at the same voltage. Because you don't want to be using a higher voltage battery on your lower voltage tool and burning it out now, if you are looking for this particular combination of parts, you can find those design files in the description down below, but this process should work for pretty Much any combination and manufacturers out there so now we're looking at the bottom of the makita tool where you'll find the battery receptacle and we're gon na take a pair of digital calipers and we're going to start measuring all of the critical dimensions to interface. With that receptacle, so things like the depth, the width, the length height, the distance between the terminals, the thickness of the terminals, pretty much any critical dimension that you're going to need in order to design a part that will slip into place. https://felixfurniture.com/best-bathroom-exhaust-fans-with-light-and-heater/ going to take all those dimensions and you're going to put them on a piece of papers to keep track of them all and create a 3d model from your drawing. Now, if you don't have 3d modeling software, you can find some free software from Autodesk I'll, put a link in the description down below and then, of course, with the prevalence of 3d printing. These days, you will be 3d printing. Your design, just like I have here. If you don't personally, have a 3d printer, maybe a friend, a colleague or even your place of work has one where you can do some free prototyping. So I've designed mine here with a little locking tab, we're gon na test, fit that into the bottom of the makita tool. You can see that it slides and locks into place. So we've done this successfully and from here we can take a look at the terminals. We'Re going to be using for this adapter, so I have these little spring terminals that are meant for regular 18 650 battery holders. I'Ve designed slots in my part to press these terminals into place, so it's just a light press fit and then, when you flip, the adapter on its side, you'll see that there is a hole in the model that lines up with a hole in the little spring. Connector there and we're gon na be using some m2 hardware to secure those into place. I'Ll show you guys that a little bit later right now, I just have a random piece of stainless steel. Here that happens to be about the same thickness as my Makita. The terminals on the bottom of the tool - and you can see that it slides into place and makes contact with those battery contacts, so that looks like it should be successful in making a electrical connection. Now we're gon na address the Milwaukee m12 battery side of things, and I've done the same process of taking a set of digital, calipers and measured things out. This is a little more complicated than the key side, since it has more curves and it's more of an organic shape, but luckily, for you, I've done the hard work for you and I've made those design files available to you in the description down below. So you don't have to do that now on the top of the adapter. There are some recesses which fit in some right: angled blade connectors, so those blade connectors will just pop into place through those little slotted holes and the blade connectors will complete the electrical connection to the Milwaukee battery. Now, in the top side of the model, there are some holes in there that will fit more em to socket head cap screws, so the exact same length as we used on Nikita side be 10 millimeters long and we're just going to be using some jumper cables. Here, with some number 6 ring terminals crimp to the ends to make the connection using the ring terminal jumpers that I've crimped we're going to be making those connections. First, on the back of the Milwaukee adapter, and these ring terminals are number 6 ring terminals, and so we are gon na be using an M 2 by 10 socket head cap screw em to washing them to nylock nut to secure these ring terminals down then we're Gon na start by taking our m2 socket head cap, screw we're gon na be flipping over to the receptacle side of the battery. There'S a little channel that you can see with a hole on the end and that's where this bolt is going to slide into so we're gon na run that down with our little P here to that hole and we're gon na fit it through the hole and Through the blade connector and it should be a nice snug fit so it'll actually hold itself into place. While we work on the topside now, you can also see that I've marked the terminals positive and negative, and the battery itself has those marked on them. So you can obviously just transfer those over to the 3d printed part, so we don't forget which is which and we're gon na just tighten things down. So the ring terminal goes on. First, then, the washer and then the nylon, locking nut and on the top side. Here we can just use some small pliers or something to hold that nut for making our connections to the makita side of our adapter. We have a intermediate piece here that we have to pass our ring terminals through. Otherwise, if we don't do that, first, we're not going to be able to do it after and so we're going to pass our contacts through and then we're gon na secure this piece down to the Milwaukee side of the adapter and we're just gon na be using Some flathead self tapping screws for this, and these are number four and anywhere from 3/8 inch to a half-inch long. We'Ll do you can see those in place there from here? We can make our connections on the makita side of the adapter and the ring terminal slips in through the bottom and the hole in the ring term lines up the hole in the battery contact. And then, of course, you can slide in your m2 socket head cap. Screw with the washer and on the other side, your nylon locknut, which, of course you will tighten all down and retain that battery contact with the electrical connections complete, we can take our green, locking tab and fit that into place, and this locking tab works in a Similar sort of way as it would on a regular Makita battery and it just retains the battery adapter from falling out of the receptacle and I've secured that down with another flat head screw number four self tapping and this one's only a quarter inch long now. Finally, we can take all of our pieces, we can tuck the wires into place and we can grab some more self tapping screws. These are again number fours. These are a half-inch, long, there's, four of them, and this just sandwiches all of the pieces together and secures them in place very rigidly after that's complete. We can go ahead and test our connection onto the makita tool itself and you can see that there's a nice snug fit in the battery receptacle and the locking tab should lock into place and keep that from falling out and then, of course, on the other end, We can slip in our Milwaukee m12 battery and that should also snap into place, and so now you're, probably thinking great we're done fire this tool up, but here's we were wrong, at least for this Makita tool and many tool. Manufacturers out there that monitor the temperature of the battery to make sure that you don't damage it. And so here's where this one weird trick kind of comes into play and if you guys noticed when you're looking at the bottom of the makita battery receptacle. There' https://felixfurniture.com/best-brake-pads-for-towing/ is a positive and negative and there's a connector in the middle, and that terminal is a temperature terminal. Now these tool manufacturers monitor the temperature of the batteries with using, what's called a thermistor, which is just a fancy resistor that changes resistance with temperature. Now I've taken a regular resistor that I'm showing you guys here and I've soldered it between the temperature pin, which is the yellow wire and the negative terminal at the black wire. And this is a 10k resistor and this just simulates, the thermistor being at its regular. At room temperature, so 25 degrees Celsius. Now how I determined to use a 10k resistor was just by doing a little bit of research online. I found a website that sells Makita replacement parts and one of those replacement parts is a thermistor for their battery packs and it lists that thermistor at a 10k value. What this means is that at 25 degrees Celsius, that thermistor resistance is 10 K, and so essentially, what we're doing here is just tricking that tool into thinking that the battery pack remains at a constant, 25 degrees Celsius. For you guys really paying attention, you might be wondering, then, why I didn't just connect the temperature terminal on the Milwaukee battery to the temperature terminal on the makita tool, and the reason for that is that some manufacturers use different values for the thermistor and so again By doing a little bit of research, I found a Milwaukee replacement, thermistor and those come in at 6.8 K and so that 6800 home value is too low for the makita tool and it likely won't run properly. And now I have the tool handle reassembled and we're. Finally, ready to test everything out, so we can take the adapter that we've made pop it into the tool lock it into place. Take our Milwaukee m12 battery slide that into our adapter pop that into place and fire up the tool, and not surprisingly, it should run as it would with a Makita battery in it. That'S that's it for this video guys in this particular video. I use a Makita tool with a Milwaukee battery as an example, but across the board there's a lot of the same things going on between all the different tool manufacturers and despite their different claims in their ads, there's pretty much just a sensor inside monitoring the temperature. The battery making sure that thing doesn't overheat, and so, if you're gon na do something like this there's only two things to really keep in mind. One of them try to maintain, obviously the same voltage, because you don't want to burn out your motor by putting a higher voltage battery in there. And the second thing is that if you do defeat the thermistor with the resistor modification that I showed you guys just keep in mind that you shouldn't be running these tools all day. If your professional trades person, or something like that who's using this on the job 24/7, then you're probably going to damage your battery pack, it could even explode seeing as how it's a lithium ion battery, and so, if you're, a more of a hobbyist like myself, who Uses these things and frequently, then the risk is very low, as you're not likely to overheat that battery pack, so just keep those things in mind. Stay safe and I hope this inspires you guys to build one of your own [, Music, ]