[005] How M18 batteries communicate with tools 

Scumbags unite!

scumbag wave generator amazing

The activation pulse seems unnecessarily complicated, though. Don't see why it needs to be a pulse of a certain time, rather than just J1 high brings J2 high. The consequences of J2 accidentally being activated are just that the battery consumes a few microamps for ~3min. There's some nice things you can do with a full digital protocol, like having the battery transmit its max current, continuous current, max temp, et cetera. Then tools that can control the load (blowers, vacuums, pumps, lights), can adjust to avoid overheating the battery. I know that Makita XGT has the batteries communicate digitally with the tools, and the tool won't run without this communication, which does make them less robust. It will be interesting to see if they're doing useful things with it, or if it's just there to make it harder for 3rd party makers to copy their batteries and tools.

I have 2x M18 batteries that give those flash codes, although I haven't had time to look at it yet. Someone posted a fairly good guess of what they were in a forum or reddit (something like manufacture year, week of manufacture, etc). They're both 2013 batteries, whereas all my other batteries are 2015+ and don''t give any flashing led codes. Good thinking on the one-key tools. I was going to try and send queries to the battery based on what seemed logical from the charger messages, but a one-key tool could save a lot of effort there.

@rossradford5767 that is interesting. Can you put a quick vid of the sequence on youtube? You should be able to post youtube links in the comments here, but any external link will block your comment without telling you. If you can't post the link, post the title so I can search for it.

@@rossradford5767 I've saved it. Haven't had a chance to view it yet.

Got one more project before XGT packs. From what Malvineous posted, XGT is about 20x more complicated than M18, so could take a while.

@@toolscientist yeah I bet it will be a doozy but I believe in you 👍😁

@@toolscientist I want to see Flexvolt batteries too please!

Thanks! I enjoy your tool videos, too.

The algorithm giveth, and algorithm taketh. All hail our algorithm overlord!

It is sorta funny how little seems to be actually going on in the communication protocol though lol especially when these companies really play up the secret sauce in these batteries

Yeah, I should do a written version of all my tests. Video is not the best format for a lot of this stuff, but it has much better reach.

No wuckers!

What shenanigans are you trying to do with M18 batteries?

@@toolscientist nothing special just fixed an impact wrench but it didn't have any batteries to test it only my bench power supply. And using the finger to j2 trick managed to prove it working.

Hopefully there'll be some standardisation in the future. It'll probably require the Brussels Banhammer to make it happen, though

I'm not using the IRFZ44, I'm using IRLZ44N. In the datasheet, Fig 1 & 3 show that it is rated to just under 20A at Vgs = 3V, hence why I said 10A for that simple circuit. My high-powered circuit (which I blurred to avoid inexperienced people from building) is using a booster setup to drive my 2x IRLB3813 at Vgs = 17V (dropping to around 10V as the battery depletes)

@@toolscientist Oops on the part number. I note you can't quite trust Fig 1 and 3, Vgs(th) is defined as varying by a volt maximum, typical is undefined. Id can be as low as 250uA at 2V Vgs, if Vgs(th) is worst-case at 2V. The Rds(on) spec @4V/21A anchors this@0.035R .735V. I am surprised! This is the first datasheet I have checked on which typical seems close to worst case, as Fig 1 seems very close to .735 at 21A/4V. This has unfortunately bitten me before.Expecting 10A easily due to Fig 1 on a different datasheet, and finding 10mA due to the part having a worst case Vgs(th) spec. Great work.

All good. You are right, though. The IRLZ44n isn't intended to be used at Vgs = 3V, it just happens to work decently there. So yeah, variance could be quite high between samples.

Interesting. I'll have to watch your video. I'm happy for you to direct link any of your videos. Don't think I'll be getting any Ego anytime soon. I do have some Makita XGT and my initial tests show that the tool won't even run without digital communication. A user called Malvineous on github has figured out some of the XGT protocol between battery and charger. Will be interesting to see what it's saying to the tool. As with you, it's a matter of finding the time!

Here's the video for anyone else: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-H-hggUXgYlU.html Search showed me the T-terminal video first, so I watched that thinking you made a typo!

@@toolscientist Thanks man!

Don't have any Dewalt's yet. Powerstack is the only one that cuts power. It's most likely some simple connection on ID or Th pin, otherwise powerstack wouldn't work with older tools.

@@toolscientist Would love to see a video if/when you do!

Greenworks have low-voltage cutoff inside the battery packs? That's interesting. Never even seen a greenworks tool in person, so I have no knowledge of them. Only ever seen them in a few comparison reviews.

I think they have a voltage signal cutoff inside the pack. There is 3 relatively beefy mosfets and an aluminium heat sink. If you measure the + and - terminals you get 0v when the battery isn't connected to a tool/charger. You can short the pack and nothing happens. One of mine got put on a charger wrong and discharged to 9.8v....thats a 10s pack.

I was wrong. The pack was 9.8v last time I checked....the cells are all now between 4.11 and 4.13v and the whole pack is 41.2v. There is 3.6v across the main power terminals of the pack. This is really low current stuff so some shenanigans are happening but there is 35.2v between the - output on the board and the B- into the board. The resistance is not equal in both directions either

J2 is a safety feature for the battery to tell the tool that it has overheated or reached its low voltage cutoff. The anti-kickback that you're talking about is only in a few tools and is only in the tool. The tool has no need to tell the battery that it wants to stop, the tool just stops. You can somewhat see this when I stall the grinder. The grinder just stops with no change on J2

You should be able to get an M18 tool to work with any resistor (from 0 to whatever my fingers are [I think 3+MOhm]) between + and J2. Shouldn't need anything on J1.

Haven't tried repairing batteries yet. There's a few good repair channels on YT that might have good info.

Yeah, I've got 2 batteries from 2013 that have standard Redlink and not Redlink PLUS. They use basic pulses with the charger rather than serial data. Maybe it's just the one-key tools that communicate? The 12ah has a large mosfet that might be able to throttle power, but I didn't see any different behaviour between tool and the 12ah.

Just curious about how you're talking shop to Milwaukee engineers. Do you sub-contract for them? I understand if you're not allowed to say anything. If you can talk, I'd love to hear any inside gossip :-)

@@toolscientist Haha no I do not subcontract with them, but I have a couple friends and coworkers who work/have worked with Milwaukee. I'll poke one of them for which batteries have the power reduction on them, my guess is it's the HO batteries with 21700 cells. Also some fun gossip is they had a hell of a time getting pouch cells working, they were having issues with them puffing from extreme loading so they were late to release. Dewalt beat them to it and they get a little upset if you mention it.

​@jackphilp7057 yeah, it's hard to beat a cylinder as a pressure vessel. Whatever weight you save from going to pouch cells, you have to put back on the enclosure. I think the best use of them is making sizes that aren't achievable with 18650s and 21700s. The Dewalt 1.7ah seems like the only one so far that offers anything over cylindricals.

I could see them at least doing a basic handshake, and if that fails, the tool uses a lower overload current. In the grinder tests at 4:39, I'm pretty sure the 12ah and 6ah are the tool cutting out when it hits ~160A, or maybe overheating the ESC. So if they did have even basic comms, I could see the tool lowering its stall current for weaker batteries. The batteries should be pulling J2 low when they detect that they've exceeded their current limit, but it seems Milwaukee relies on the batteries tripping low voltage or overtemp rather than looking for overcurrent.

@@toolscientist That’s my finding as well. The 2Ah will droop voltage and overheat in a blower before it ever cuts. Tragic lol.

Opposite sides of the planet, unfortunately. He's welcome to use any of this info to power M18 impacts with a custom battery.

Thanks! Hope you enjoy it. It's a different video to my last one, so not sure how it will go.

​@@toolscientist I can't speak for other people, but this was exactly what I was hoping for. Thanks for the staggering amount of effort you put into this. That whole aspect of different batteries having different thresholds for things must have been a fairly irritating complication.

Definitely! I said a few hours, but I think that aspect was closer to 10 hours of testing time for something that isn't super important to most people. I was pretty thorough with the 2ah, so I'm pretty sure 700mA is its threshold. I got bored on the 5ah and left it at 2amps, when it's threshold is probably around 1.5 amps. 1 amp kept it awake for 10m40s. The testing time just becomes exponential as each increment in current increases the time that it keeps the battery awake. I nearly had a heart attack when the 12ah behaved completely different, but luckily it was the only one. I was also really dumb and did a lot of testing with resistors before I realised that I had a battery tester that is essentially a programmable load!

There's an instructable by Noloxs on Makita LXT that covers the gist of it. The 3rd pin is similar to the J2 pin on the M18, except instead of being 3V, it's 0.5V below pack voltage and cuts to zero when a fault is detected. This makes driving a mosfet with it very easy - there's no need to boost the signal like I had to do to get the M18 to drive a high-powered mosfet. There's presumably digital communication on the yellow connector as Makita sells a tool that lets you read battery temp, charge cycles, et cetera.

There's a couple of those "15-40V to 12V" buck converters in an aluminium heatsink that claim to do 30A, and lots that claim to do 10A. You may be able to run them in parallel to get even more current. Ideally you'd look at the output on a scope to make sure there's no craziness. If you've only got a multimeter, then you can check the Hz and ripple voltage of a single unit, then compare those results to putting two in parallel. If you don't get crazy frequencies or large ripple voltage, then it's prob ok.

@@toolscientist Thank you for the info, I'll take a look into those and check them with my meter. So many uses I can come up with for a portable 12 volt source, I am surprixed they don't offer something off the shelf. Gtanted, that is old school, a lead acid will do that, but oz to oz.... tool packs are easier to move around.

The M12 batteries are 12V at full charge. Their average voltage is 10.8V. Milwaukee cuts power when voltage goes below 8.2V and refuses to start if voltage is below 9.6V. Depending on the pack, they'll be good for 15-20A for the compact and 30-40A for the XC packs. So just make sure you're not putting too much current on them and that you're not dropping the voltage too low.

You can't get much power from J2. I think 10uA drops it to 2V. Around the halfway point of the video, I show my plot of voltage vs current for J2.

I've got some Makita and Dewalt that I'll eventually get to. I don't think Porter Cable and Craftsman are available in AU, so I'm unlikely to test them. I've heard that you can cut part of the battery off and it will work across Porter Cable, Craftsman and Dewalt, so likely using the same system.

Definitely no wireless chips in any of my batteries. My newest battery is a 5ah from 2021, though. Newest high output battery is from 2019.

0.3V is fairly imbalanced. Not enough to prevent charging, but enough to suggest that cells are failing. The Samsung 40T in the 8ah and 12ah had fairly high failure rates. You could try measuring voltage of each bank of cells under load to see if one is dropping voltage more than the others. When you put the battery on the charger, does it make a hum that gets higher pitched in about 4 steps? It might even repeat this 2 or 3 times before giving the flashing green and red. If so, I think that's the charger detecting too much resistance. Only other thing to try is buying a logic analyser and recording the signalling between battery and charger, then compare your data to what I get in my [004] video.

Not at the same time. You could make a system that detected when one battery had finished and switched to the next one

12ah is 5s3p Samsung 40T. 6ah is 5s2p Samsung 30T. 5ah is 5s2p Samsung 25R. 2ah is 5s1p Samsung 20R. 12ah and 6ah have a physical fuse. Project Farm short circuited an M18 6ah a few weeks ago and got a few hundred amps for a few seconds before the fuse melted. Theoretical continuous draw for 6ah and 12ah is ~70A, but I'm pretty sure it would overheat due to cells being tightly packed and enclosed in plastic.

Don't have any OneKey. Someone else mentioned OneKey and I can't believe I didn't think of it. There could be useful info being transmitted and it would be fairly easy to intercept it. Might have to get my hands on a OneKey tool

I haven't managed to reset one yet. Only way I've heard is with the genuine charger.

I don't have any One-key. Other people mentioned it and I looked into it. From what I can see, it's tool only. The only thing I saw that might be battery is a screenshot showing battery capacity, but they could be getting that from pack voltage. If you can see battery temperature, manufacture date, charge cycles, or similar in one-key, then that would indicate that there is digital comms between battery and one-key tools.

I don't think we can get Einhell in AU, but apparently Ozito is just relabelled Einhell. I'm currently doing Makita, and then Dewalt. Might get to Ozito/Einhell next year.

I have a Ryobi 36/40V mower and battery, so I'll be doing something with that. Don't have any Ryobi 18V, though. My suspicion is that the extra contacts on HP tools/batteries allow them to bypass the low-voltage cutoff mosfets in the battery.

@@toolscientist Ryobi made the same claims that those extra pins enable communication. In my limited testing, it seems those pins enable the brushless tool to draw more power than a battery without them. So perhaps the tool normally operates with an amperage limit, but with the extra pins that enables a higher amp limit or perhaps a constant power mode. I'm really surprised nobody has looked at this tool communication stuff before, good work.

Yeah, Makita will be interesting. Also a lot more effort to crack...

@@toolscientist yeah, their tools are way more picky about their "meals"

No, the tool stops when voltage goes below 8.2V or when the voltage across the thermistor ("Th" pin) goes below a threshold (which indicates overheat). The batteries have no disconnect whatsoever. Original M12 batteries only had resistors in them. One from ~2019 onwards have a chip in them, but I'll need to desolder one to see what it does.

@@toolscientist This is great! Thanks for the info. Looking forward to another video when you tear into one of the newer M12 batteries!

@@stevenmullin3616 i should just sacrifice one of mine to the science gods. Maybe I can find a cheap/dead one on a 2nd hand site. There looks to be an i2c interface on the PCB, so if I can find out what chip it is, I might be able to talk to the chip on a live one, which will be fun.

Definitely. Any M18 tool can run off external power. All you have to do is put > 0.72 volts on the J2 pin, but you can use 3V, 5V, 12V, etc. The highest voltage I put on J2 was I think 25V, but not sure if it would cause problems if left like that. The J2 pin on the tool is the one closest to the ground pin, and the ground pin is the longest pin. Easiest way is a 100kOhm (or more, my fingers are something like 3 MegaOhm) resistor from the positive pin to J2. Just be mindful that running at reduced voltage could burn it out as the slower RPM will mean the cooling fan isn't running as fast. It shouldn't be terrible as 18650 based M18 batteries run down to 10V (although they fall off pretty quickly and only spend around 30sec under 12.5V with a 18A load)

@@toolscientist this was far and above what I expected in response. I think the only thing you could've done more for me would be building the wiring harness and shipping it to my door! 🤣 Thank you so much! I certainly hadn't thought about the cooling fan, that's a very good point. I'll make note to consider it's duty cycle halved when running on 12v. Just gotta go out and build the adapter now hah! This will be a huge boon for not having to store a second compressor while offroading! Thank you again!

I'm always interested in people hacking their tools. This one was also a fairly simple answer, too!

@@toolscientist you rock. I'm so glad I'm subscribed haha The first Milwaukee video with the charger is what I saw first and instantly subscribed, specifically hoping for a video like this. :D

I don't think we can get Parkside in AU. We get Ozito, which is identical to Einhell. I see that Parkside is owned by Einhell so are they compatible with either of those?

The charging side is a bit more complicated. But you could design your DIY batteries to have a JST balance connector and then just use a hobby charger.

Yes, but very unlikely. The tool will keep going as long as it receives > 0.725V on J2. Using a power supply, I've run these tools as low as 5V (although they barely run at that voltage). However, a connection issue on J2 will just make J2 at the tool 0V, and the tool will stop. The only way it could happen would be a short circuit between + and J2. J2 is closest to the ground pin, so it is very unlikely that this could happen.

@@toolscientist Ok, thanks!!

Not a clue. Maybe the lights turn on randomly, but you obviously only notice when you're near. You'll have to setup a camera to see if they're going full Toy Story on you and getting up to mischief when you're not watching.

This post might get you excited. Still a few weeks away, though. www.patreon.com/posts/expanding-92383338

Looks like their previous gen was licensed M18. Their website even says they partnered with TTI. M-Cube looks to have same pinout as M18, but different physical interface. Do you have these tools?

I have Würth brushless angle grinder but i don't have M-Cube battery.

Yeah, they're the most basic of the major brands. They're interesting to me as you have direct access to the thermistor and cell voltages, so lots of scope to make DIY adapters that don't overheat or overdischarge

It's doable. I think I'd prefer a sandwich press, though. They're 1000W, so you'd only get about 10min runtime on a 12ah.

Soon ;-)

I think I know that subreddit, and that mod. Is it the smaller subreddit - MilwaukeePowerTools? Until I did this test, I thought there was at least some communication, even if it wasn't as fancy as Milwaukee tried to claim. I was fairly surprised that it didn't even differentiate between batteries as it's common for people to claim that the tools can detect high-output batteries.

Yep! That's the one...lol. It was weird because he was claiming the charger was doing stuff I've never seen it do and I monitor the voltage and current of every battery I charge. I simply said he was wrong (didn't know he was even a mod at the time) Immediate permanent ban.

Yeah, I've seen him make some very strange claims in a few subreddits. If you've seen my power testing video, he's the guy I got into an internet argument about the drill being 1500W. I think he has some issues, so I just leave him alone. Interesting on your charging tests. Have you got a jig, or do you wire the terminals up each time and measure current/voltage from the leads? Any interesting discoveries?

​@@toolscientist I use a non Milwaukee charger that displays that info now. Before that I built a little jig from an old dead battery pack I cut out the terminal section (connected to charger) and the bottom of a dead drill (I put the battery to be charged in) connected with wires I would have access to. It's not really necessary for legit Milwaukee batteries, but I like to buy the knockoffs just out of curiosity a lot so like to keep an eye on what's actually happening. The only real useful information I've seen is that charging at the rapid charger rate very often leaves the cells unbalanced sometimes...but you have to open up the pack to check that after anyway.

Microsoft (the African Americans of software thanks to them having more oxygen and blood flowing to their aggression sector than the rest of their brains) are the same way. They've practically dominated Mojang and corrupted them in more was than one, and their horrible design tactics are quite literally killing Minecraft in thousands of screwed up ways.

SoC can easily be estimated from voltage. Every M12 tool shows SoC and they definitely don't communicate. As I said, I haven't tested every tool. I'll be very interested to hear if anyone can show battery/tool communication, but so far no one has.

@@toolscientist When it exactly matches the on-battery display that uses coulomb counting? Fat chance. Again, you tested only the cheapest tools, no ONE-KEY and no dual-battery and made a faulty conclusion.

@straightpipediesel they don't use coulomb counting. Put a 5Ah on a blower, hold trigger, push button, and it'll show 2-3 LEDs. Let go of the trigger and It'll instantly go back to 4 LEDs. It's purely voltage based. I've looked at one-key app images and videos and never seen battery info. Not battery type, charge cycles, days since first charge, or anything. I'd be happy to be wrong as it would make reverse engineering their diagnostics very easy. If you can show me something that shows there is communication, then I'd be very keen to hear it, but battery SoC is not proof.

@@toolscientist I'm sorry, but you don't know anything about Li-Ion if you think this thing is voltage based. Put a dead battery on the charger for 10 minutes and check the status, it doesn't read full. There's 0 science here and 100% guesses.

@@toolscientist I just did that and it didn't drop 2-3 at all. I have never seen that behavior except near empty. Maybe the batteries for APAC are cheaper.

I should be getting to Makita soon. Makita will be hard as they like to brick their batteries. I might have to start with the knock-offs first to avoid bricking too many batteries.

@@toolscientist what do you mean brick? If they are messed they no longer work anymore?

@eduardoramiro4846 I'm going off what I've heard, but apparently if a LXT battery is put on a charger and gives an error, it records it. If you get 3 errors in a row, the battery bricks itself and won't charge ever again and can't be repaired. So doing crazy stuff like I've done to my M18 packs (undervolting and overtemp) might trigger the battery to brick itself.

Yeah, Dewalt is the best battery for the apocalypse! Dewalt tools are slightly harder to trick as you need to trick the ID pin and Th pin, M18 just needs 3V on J2. Dewalt is obviously much easier to charge.

@@toolscientistYou sure that Ryobi isn’t the best for the apocalypse? NiCd compatibility, low voltage cutoff in the battery…much less communication than most other brands.

I do go a bit too fast sometimes. Feel free to ask any questions.

All of my high-output ones do, and most of my 18650 packs, too. Seems any battery newer than 2016 has it. Do you have any one-key tools? Can it tell you any information about the battery? Best I can find is the radius light will tell you remaining capacity of the batteries, but they can just guess that from the voltage.

Do it! 😅

The 12ah does have mosfets on the ground rail. @ThriftyToolShed showed them in a video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TphIrEWvW68.html It's possible that they could throttle the power with this mosfet. PWM would likely play havoc with the tools, unless Milwaukee knows that all their tools have sufficient input capacitors. They could also run the mosfet in the ohmic region, but that would make a lot of heat, although they do have a sizeable heatsink on it. They'd need to add ~20mOhm to make the 12ah look like a 5ah, which would create 50W of heat at 50A. Doable, but seems unlikely. The 6ah high-output is similar resistance to the 12ah and it doesn't have any power mosfets. I think it's most likely a power cutoff. I'm hoping I can get some probes on the gate pin and see what it's doing.

Probably going to do the big 3 first (Milwaukee, Dewalt, Makita), then get on to others. Bosch has a pretty small presence in AU, so might be hard to find 2nd hand stuff.

@@toolscientist Okay, looking forward to watch those videos as well :) In Europe the three brands you mentioned + Boch are the most common. For a suggestion for future videos it had been awesome with some videos on the DIY battery kits that are sold, to see if the bms used in those kits are ok etc. A video making your own kit had also been awesome ;) I have made my own power tool batteries for a couple of years now and im really happy with them. Way better performance (because of better cells) and a much lower price is making it well worth it.

Here it's probably Hikoki, then Bosch. I think Metabo might be below Bosch - they probably do better in EU. In the future I can hopefully get people to loan me their tools for a week, otherwise I'm going to end up with a very expensive and barely used tool collection! Yeah, I'd like to test some of the 3rd party batteries and DIY kits to see if they've implemented the same charge/discharge/temp limits as the manufacturer. Problem is they can change fairly regularly.

​@@toolscientistOkay, looking forward to new content :)

Still working on vids. Things just got slowed down a lot over Xmas. Hoping to have my Makita LXT vid finished this week. I'll probably stick to tool related tests. If I had an escooter I'd definitely look at modding it to work with power tool batteries. Although I think that's been done, and I want to avoid rehashing stuff. High powered circuit was mostly not shown because it's a bad circuit that can lock on are cause pulsing. I'm working on a better circuit which I will make public.

Yeah, I originally had a section of the vid discussing the noise in J1 and J2 during operation and saying that was the reason for no digital comms. I left it out as I'm not sure if that noise could be filtered, so didn't want to categorically rule it out. I know that Makita XGT tools use digital communication and the tool won't run unless it receives that communication. I'm pretty sure they have a separate isolated ground for comms to get around the noise issue. I have heard from one person of having problems with their XGT tools and having a rep come and clean out the batteries for him multiple times. In the end they gave up and went back to the older LXT system.

M12 tools don't have any digital communication. It's all done with analog pins. The tool is just reading temperature directly from the T-pin, which is a thermistor. I've done a few rundown tests with the blower, but that's a brushed tool that's not likely to have anything fancy in it. Can't say I've ever heard any sudden changes in motor speed from the backpack vac, but maybe there is something.

@@toolscientist ty gl

Ok mate just checked and nothing there. You may allready be on this one i dont know. But buy a new Makita battery and a duff one. Work out the terminal address lines and monitor as i can see that you are well capable of doing. Now change one or maybe two duff cells in the bad battery, you will get the battery monitor blinking from side to side. Balance ( manually ) all of the cell pairs to 4.1 or 2 and and try charging on a makita charger...it will still say NO whatever you do the BMS locks out and the only thing you can do is chuck it in the bin and fit a new one then you are good to go again. They have the nerve to sell a £300 tester that tells you that you have charged your battery 97 times, or that you charged it once when it was really cold or even three times when it was really hot, it even will tell you what is wrong with your battery ? Maybe or say oh sorry computer says No. There is a memory chip on the Makita BMS that is like no other and when it locks you out thats it ! All the best and good luck Kev

I am currently working on LXT. They even have fuses that the BMS can burn and physically disconnect the B+ pin. I'm about to get to the part where I start overheating it to see its response. I bet there's a limit where if I overheat it too many times, it'll lock itself.

Keep us all in the loop mate !

555s are 1970s tech, we prefer 1870s tech on this channel - just ignore the scope, multimeters, and mosfets :-) Happy for you to link a video. If you've got a circuit on stackexchange or similar, you'll have to give me a search query so I can find it, then I can post a link. You won't be able to post any external links.

Lets hope BMW doesn't start making power tools!

I’m pretty sure that the Hilti Nuron battery chargers have at least WiFi if not cellular radios inside. The tools store data in the batteries and then they get uploaded from the chargers. Haven’t dug into the details. Too $$$.

@@gf2e would they need wifi? Seems like that can all be done wired. Just read that charging the battery uploads data to the cloud. Maybe they've got a cellular chip in the charger? Edit: Sorry, I can't read. You said charger, haha

@@toolscientist Now I’m imagining a PoE wired Ethernet charger. RJ45 jacks would be pretty terrible on a construction site. Max power on PoE is probably not very good either.

Worthy of your morning poo? That's the highest praise that my videos have received!

I can describe it to you. I just don't want my nasty circuit being copy-pasted across the internet and getting put together by people that don't understand it.

@@toolscientist I'm going to do it anyway, so you might as well explain what to watch out for. Feel free to get as technical as you want.

Main danger is the bounce in J2. My circuit has LEDs on it so I can at least see if it's bouncing. Depending on what you're intending to drive, you may need capacitors to stop this bouncing from creating voltage spikes. You should only get this bounce at high currents (~50A with a 2ah, ~80A with a 5ah, haven't tested the others) 2nd danger is that my circuit is using mosfets, so if the pull-up or pull-down resistors fail or get disconnected (which they often did on my breadboard), then the mosfets can stay on even if J2 is saying "OMG stop". Start with the simple circuit, but replace the LED resistor with 2 resistors so that you have a voltage divider. Use this voltage to drive a high-side p-channel mosfet. On the low side of the p-channel, make another voltage divider, and use that voltage to drive the high-powered mosfet. You should end up with ~18V at full charge (and ~10V at empty) driving the gate of your high-powered mosfet. When J2 goes low (or you manually disconnect it), then you should get 0V at the high-powered mosfet. If you're familiar with transistor circuits, then that should make sense. If not, let me know, and I'll give more info.

@@toolscientist cheers!

I'm unfamiliar with Jacob's Law. Is it similar to Thevinin Max Power Theorem? I've previously estimated the 12ah at 40mOhm, so max power would be R_load = 40mOhm, 20V/80mOhm = 250A. But of course the battery will heat up and increase in resistance, plus other effects. You can see at 10:15 that at 75A I'm "only" losing ~2.6V across the battery. The tools are typically only in the 20-50A range. They need to be used in unusual ways to get over 100A.

@@toolscientist pretty well much, yes. same as the 1/2mv^2, or 1/2I^2L, or 1/2V^2/C equations... hit equal resistance, its pretty logical that as per kirchoff, equal currents, equal resistance, equal heat, equal power. go back to the basic of a generator as the magnet in a copper ring showing lenz reactions. wheres the volts? wheres the current? cut a slot in the ring... wheres the volts, wheres the current? keep the load well above the source resistance, and its "efficient". my analogy is watering a pot plant with a wee hose hooked up to the snowy hydro. real efficient, yes? very precise and controlled with little waste or effect upon the dam... whereas a wee little bucket on the dam wall instead is going to drain rapidly and the height and pressure and flow will be dramatically affected. we call that inefficient... lots of parallel batteries... low internal resistance, better efficiency than single cells, if that all makes sense. pretty straightforward. its like watching the attempts at charging batteries from wind turbines. forget the erratic source , the generator itself may deliver its max power at a load where its held at say, 12v/25A for 300W. but as the SLA batteries only start charging at 14.4V, the load must be higher in resistance for the same voltage. but that load will not draw 25A anymore. it may be limiting the current to say, 10A... less... and as batteries are not obeying ohms law... it hits 14.4v, attempts to pull more current than the source can deliver as the internal resistance is far lower... and the voltage sags below the charging threshold, and attempts to find some sort of equilibrium, a midway point... they end up getting figures like 25W, etc... no matter how hard the wind blows. the load is unmatched. in that area, im of the opinion that using wind power to generate heat, thermal storage... its the only logical method. use the heat to make the electricity somewhere else, just like a coal or nuke already does. making power directly from the wind is ...effin stupid? unless its heat. heat is power. definitely not convenient on a power tool though, batteries are fine there... i give them that. "efficiency" is this marvellous term that can be used in so many ways... 100% efficient may very well mean its still throwing half the potential away. it HAS to! oh. its also newtons law of action and reaction. all related. push something, youre gunna go backwards as well... it all depends on who is bigger!

I'm sure other brands are doing lazy/stupid stuff, too. Milwaukee is just the first to go under my microscope. Letting the battery disable and enable the tool every 50ms is pretty high on the stupid scale, though. I hope none of the other brands are doing stuff like that.

I do wish there was a bit more to the signal. Like a dual analogue/digital signal so that you could also tell the battery's temperature. The on/off signal is perfectly good for cutting power, but I always want more, haha!

Haha, thanks!