[006] Do Makita LXT batteries have low-voltage protection?

[@doctorlefthandthread]

Question:Do Makita LXT batteries cutoff at low voltage ? Answer: it's complicated Great video thanks

[@toolscientist]

Answer: it's complicated...and we don't even have the full picture yet

[@thatguythatdoesstuff5899]

I feel like makita should have this information publicly available. I was under the impression all star batteries had the same protection due to their marketing. Also one of my oldest batteries is acting weird, seems like it lost its low voltage cutoff. Instead of the tool stopping it just gets slower and slower. Thank you for doing this and showing no one was wrong.

[@toolscientist]

I think star protection refers to the stop/go signal on the 3rd-pin. All star batteries have this, it's just that the 5 & 6ah then have another layer of protection with the internal mosfet. The weird thing is it seemingly never gets used as Makita tools will always cutout before the mosfet does. The 3ah will sound sad as they're running it down to much lower voltages (3ah goes down to 9V, 5ah cuts out at 12.5V). Lower voltage = lower RPM, so you'll hear it fading.

[@toolscientist]

I might have misread your comment. Can you measure voltages on 3rd pin? Shallowest should be same as +, and deepest should be 0.6V lower. If they're both the same then somethings gone funky. You could have dirt buildup that's making those pins always in contact. Could be worth taking it apart and giving them a clean. If no luck, then try measuring the voltages of these pins as you run it. If + goes below 9V and D-pin doesn't drop to zero, then it's buggered.

[@thatguythatdoesstuff5899]

@@toolscientist That I can do, I already had the battery open once to see if there is anything obviously wrong.

[@ThriftyToolShed]

This video is very helpful for the EGO battery guys as well. The newer 3rd Gen packs have a very similar fuse type now as shown around 1:00. Usually more than one 60A version. The older packs has a trace fuse and that's it. These are more advanced as mentioned in this video. Very helpful. Thanks for sharing!

[@toolscientist]

Can they be burnt by the BMS? Have you seen many that have popped? There's a few vids of older Makita batteries that were using white package fuses and I'm not sure if they could be burnt by the BMS. Those videos had people soldering a bypass wire around them.

[@ThriftyToolShed]

@@toolscientist I am just starting to see these, but I think EGO started putting these in around 2020 in what I call the 3rd Gen packs. I was getting questions around that time about fuses on the viewers board and I kept mentioning it was simply a Trace fuse on these and I had seen a few pop over the years working with EGO packs. I then received a couple of photos from viewers and you could tell something has changed and I noticed the black SMD devices with 60A on them and I was very surprised they had added fuse. I am just now realizing it is also an additional wire on the BMS for what seemed to be a monitor, but now that you share this info I am thinking it may be a way for the BMS to disconnect in emergency situations? I have not personally seen any of these blow myself. I am just starting to work more and learn the 3rd Gen packs. I have had over a dozen viewers ask questions about these and find them faulty. At first I was no help as I did not even realize they were there. So I am trying to find out more on these and don't know if the viewers that had the blown fuses were a typical overload fuse blow or if it's a way the BMS on these will do it. It is very possible since the newer packs also have that extra wire from that area going to the BMS board.

[@ThriftyToolShed]

At the beginning of the video I was screaming they are all three correct! Glad you have the sane conclusion. I knew the smaller older batteries had no mosfets and thw newer 5Ah packs did. I did not know some if the newer ones the same 1.5 and 3Ah do have them now. Thanks for sharing.

[@toolscientist]

I wanted to give a bit more credit to each of them, but I was getting bored and wanted to publish. Even though Noloxs was more wrong than the other 2 (due to only having older batteries), he understood how they work a lot better than the other 2. Do you have a vid on Makita LXT batteries or is this just your unpublished testing. I thought I searched fairly thoroughly for any testing or teardowns of LXT packs as I was trying to fill in my table.

[@ThriftyToolShed]

@@toolscientist I don't have a video on the Makita packs cut off directly as I knew from past experiences with my older 1.5 and 3Ah packs that they have no cutoff protection on those tiny boards. I don't have the newer packs, but noticed the Project Farm video and realized then that (wow) they have added cut off Mosfets. I did not know that the newer packs would cutoff that much lower below 5A drain, that was strange. I have a video putting an after market board on my older Makita pack and a video testing some aftermarket packs. I so respect Makita tools and how they hold up, but they have been needing to improve the battery line for nearly a decade. Hopefully they are at least working on Lipo stack packs and some larger 8 or 10Ah packs. Your video was very thorough I really enjoyed it.

[@toolscientist]

Going into the test I thought that maybe PF and Sauron Makes had done something weird with their battery testers. It didn't seem like there was enough space or heatsinking to have a mosfet in there. Seems Makita just threw money at the problem and bought a super high-end mosfet. What's really strange is why did they add protection. And why did they only add protection to the batteries that aren't compatible with pre-Star tools. The 3Ah is the only one compatible with pre-Star tools, but it has no stand-alone protection. Instead they've only put it on their newer batteries, and it only seems to get used to put them in storage mode, which could be achieved with yellow-connector digital interface. Need to find a disgruntled ex-Makita employee to spill the beans. Given Japanese culture, there probably aren't any.

[@ThriftyToolShed]

@@toolscientist Exactly!

[@riba2233]

another awesome video, thanks and can't wait to see the same done for XGT packs :)

[@nesertema4583]

excellent content! I have few newer 3.0ah packs (maybe even some 1,5ah) at my summer house. might take a while, but I will open them as soon I will get there.

[@murdo_mck]

Thank you for this video which explains a lot. Of the three BL1830 3.0 Ah batteries I bought 10 years ago, two are still in great shape. (DIY use not trade). One was 'bricked' early on, I suspect because my impact driver is a 2 pin tool which discharged the battery too far and I waited too long to charge it. The cells were fine and I could charge it with a non-Makita charger. A second battery died recently - some of the cells died - but I managed to avoid 'bricking' the BMC. I swapped the cells from the 'bricked' battery so I still have two batteries which work with the Makita fast charger. Not bad after 10 years.

[@toolscientist]

How did you avoid bricking BMS? Did you do a "live" swap of the cells? I.e. kept voltage on the balance leads whilst removing the old cells and connecting the new ones.

[@murdo_mck]

@@toolscientist I thought about tacking a resistive divider and bench supply across the board during the swap, but did not. I unsoldered it from the faulty cell pack and soldered it to the good one, end lead first then balance wires (flying leads in this case). Then I found the third (split) connector was no longer working. Shorting both parts of the connector to battery positive got it working with the Makita charger and with the 3 pin tool but without low voltage protection. Do you know if a "dead" swap can brick the BMS so it is rejected by the Makita charger or damage the third (split) connector circuitry? I would not be at all surprised if that was built in to newer BMS chips. One thing I will not do is buy third party BMS boards without balance wires. Why risk a house fire for the convenience of fast charging with the safety rails removed?

[@toolscientist]

@murdo_mck this vid is my first foray into taking Makita packs apart so you probably know more than me. I'd say it's very likely that disconnecting a balance lead on a new pack will brick the BMS.

[@murdo_mck]

@@toolscientist A couple of other observations: 1) my experience is consistent with claims by others that if a battery is rejected by a Makita charger 3 times in a row due to low voltage the BMS is bricked and 2) If a battery is rejected by the Makita charger due to low voltage (once), it can be recovered by part charging on a non-Makita charger then the Makita charger will accept it again.

[@Jeff-rk8hq]

This comment section is where the party’s at this is the kinda stuff I came for great info boys

[@DavidScheiber]

Thanks for making these videos, last year I was tinkering with fixing and using makita and other batteries and as I couldn't find a definitive answer on if makita batteries had undervoltage protection so I ended up adding an amazon relay module to cut off the power. The main downside being Is I would have to disconnect is after as the module draws power from the battery. Now I know I can just use a Beefy mosfet connected to the signal pin.

[@toolscientist]

Just make sure you use the deepest of the 2 pins. The outer pin stays at pack voltage (although I never monitored what it did on low-voltage/over-temp)

[@BingoBongoMan]

Just to set the record straight: I have zero affiliation with Noloxs, and this wasn’t an argument-more like a friendly tech talk! Still love your video, and yep, you’re the reigning champion. You went above, beyond, and then some! really great work 👏👏👏 Now we just need someone to design an open source, top-notch PCB with some quality SMDs based on your findings-minus all of Makita’s built-in “booby traps”-and start selling it online! Battery cases are a dime a dozen from China and some of them come with electronics, but trusting their PCB design? Not even with my morning coffee-let alone with those energy-packed cylindrical beasts! Any takers?

[@toolscientist]

Oh wow, I was sure you were Noloxs, and SauronMakes did, too. Don't worry, internet arguments (or friendly tech talks) are the foundation of my channel. There's some fairly well made 3rd party boards, but the problem will always be reliability (who knows if they'll swap to cheaper components) and they're programming is a black box. We don't know what their cutoff limits are. A guy made a Makita battery reset tool, which is helpful for unbricking Makita batteries. Doesn't work on all types, unfortunately. I linked his vid in my community feed if you want to look it up.

[@oinktron8053]

Thabk you for doing a video on this subject! I’ve been planning a lighting project and trying to figure out the answer to this very question!

[@toolscientist]

Just beware that under 5A on the 5 & 6Ah will drain down to 8V. It's very easy to add your own mosfet, but if the current goes below 510mA, the D-pin signal will go to sleep after 60s

[@TranTek]

Would love to see if you can get your hands on Hilti batteries to see if they balance their batteries when charging

[@AlyonaFar]

I have a lot of Makita batteries the charger don't accept them but when i charge them with my power supply they take fully charge.... How can i use the on Makita tool that have 3 pin ?? They work on Makita tool with 2 pin ( positive and negative only) perfectly but the don't work on the 3 pin tools any help please

[@toolscientist]

You might be able to reset them with this tool. Requires some knowledge of Arduino. kzbin.info/www/bejne/imebmqZ7nLyqrM0

[@BoltahDownunder]

Great stuff! Recently i thought my little Makita fan had bricked my new 6Ah battery after i let it run to dead. Fan only has 2 pins so no temp/voltage monitoring. Battery had no lights, but charged up fine. I wish I'd checked its voltage!

[@toolscientist]

Interesting that it's a 2-pin tool. Was it genuine Makita? Was it a really old one from before star protection? Only other reason would be if it draws less than 1.1A. Under that and the 1.5 & 3Ah go to sleep. I would have thought a fan would pull at least 3A

[@toolscientist]

I'm well off. The 235mm fan gets 7h on a 6Ah, so

[@BoltahDownunder]

@@toolscientist DCF 102, built 2020 bought from total tools, yet no Star on it. It's really small (180mm) so low current I guess

[@kristianszviedris1580]

Thanks, great video!

[@earl3358]

Interesting stuff. I have 3 older 3AH Makita i haven't gotten around to rebuilding. They all have totally different bms. I got a few different aftermarket bms if the original brick. The aftermarket 3rd rails are one piece. Maybe just thermister. Makita batteries are a fustercluck, be nice if you can sort some of it out

[@toolscientist]

I think very old LXT (before star protection) had a switching PTC thermistor between + and 3rd pin. At least that's the only thing that makes sense for the

[@crazyphil1336]

Careful, many of the aftermarket BMS don't monitor all the cells, even if they have connections for them. I had one where the trace that leads to a cell connection lead under the yellow connector. After removing it (for repairing an original board) I noticed it's a dead end - which means that at least that pair of cells isn't properly monitored and I'm now really sceptical whether the other cells (some were connected to resistors and transistors) or even the thermistor are monitored properly or just bluff too. However there are legit working boards that include cutoff mosfets for charging and discharging and they do monitor the cells and thermistor correctly. The third pin is a whole piece too so that's not a telltale sign sadly.

[@MattsAwesomeStuff]

Magnificently thorough as always. Well done. Everyone, buck up and toss a dollar in the guy's *Patreon* hat so he can afford to spend more time making content.

[@toolscientist]

Thanks! Are you the guy that made vids about rewiring microwave transformers? I think I got into an internet argument with you once 🤣

[@MattsAwesomeStuff]

@toolscientist I did! At least, I was one of the first 12 years ago. An argument, on the internet? Well gee that doesn't sound like me, I'd be too busy with your mother to have time for that. What was the nature of our dispute?

[@toolscientist]

I think it was in r/skookum on a discussion about powering 18V tools from AC power. You said "use my sketchy transformer and a rectifier" and I said that would be too inefficient and that 18V tools are often pulling over 60A (and up to 150A). Good times :-)

[@MattsAwesomeStuff]

@toolscientist I don't recall this specifically, but thats exactly what I would've said, yeah. And I do hang out on Skookum.

[@Jeff-rk8hq]

I would love to see you do a dive like this on the hikoki multivolt batteries and I bet you can even get the Bluetooth enabled version in your country

[@toolscientist]

I just got a hold of a Hikoki Multivolt battery. Will need to find a charger and tool. Should have it done by Apr-Jun, depending on available time.

[@Jeff-rk8hq]

@@toolscientist I got a spare charger but I’m in the states idk what shipping would be but I can get a quote if I have the country and city let me know I’ll look into it

[@toolscientist]

@@Jeff-rk8hq all good, mate. Chargers can usually be found 2nd hand for fairly cheap.

[@Jeff-rk8hq]

@@toolscientist nice I look forward to seeing the testing you do, I appreciate your vids, the thorough and detail oriented methods of testing a category of tools that are very common in many folks daily life but no one really tests them like this…Now If driving lags with drills akimbo just letting them rip to determine a winner was considered scientific testing we’d have all we could ever need lmao

[@JT-lq4yd]

Will you be doing this test to other brands? I am interested in Dewalt's, as I purchased an adapter with leads and a fuse to "extract" electrons out of batteries, but the 5 ah powerstack refuses to contribute. The 9 ah flexvolt will work though.

[@toolscientist]

Prob in the next 2-3 months. I have a Dewalt tool and a 2Ah battery. Need to find a cheap charger and a few more batteries.

[@WaynesWorld999]

@@toolscientist I have a heap of dewalt batteries

[@franta2545]

Hi . I have several old Makita pcb at home. When I disconnected them from the cells, do you think they are blocked? so I can't use them for new cells?

[@toolscientist]

Most likely bricked. Very old ones might work. Can't hurt to try.

[@franta2545]

@@toolscientist very thank you . I tried one of them and it doesn't work (pcb bl1830 rev:3.1 2014.03 08) cells +-0,1V I will try the others as well

[@dkhuber1]

@ToolScientist - When using the battery capacity tester (heatsink and fan) what settings did you use for low voltage cutoff and amp draw? What would proper settings be to accurately determine amp hour capacity of battery?

[@toolscientist]

Low voltage cutoff was always 0V as I was testing to see what the battery's cutoff was. I would stop the test if it went below 6V. Amp draw was usually 7A to make the tests faster, but I did several tests to examine the weird lower cutoff that occurs below 5A. Proper settings according to most datasheets is 2.5V/cell and 0.2C discharge. So that would be 12.5V for an 18V battery. Discharge is 0.2*capacity, so 0.2*5Ah would be 1A. For a 3Ah it would be 0.6A. These are quite low and very few power tools would go this low, but that's the industry standard for capacity testing and what most manufacturers (Samsung, LG, Murata, Panasonic) use to rate their cells

[@tyronevonchadley]

I still have 2 old 3.0A makita lxt batteries that work(although they do not last as long from full charge as when new). These had teal color lettering on the side of battery compared to white later. During this 19 year period I have used up at least 3 of the newer batteries to the point of broken/will not charge. Does anyone know if they use lesser cells on the newer styles? Just curious.

[@toolscientist]

Older Makita batteries were very basic. Newer ones have a lot more intelligence, so they're more prone to bricking themselves when they detect a fault.

[@saiiiiiii1]

I'm looking to replace cells on a BL1820B. I've heard that the BMS locks up of you disconnect them from the cells. Any ideas if this is true? Would need to hook up an external power source I guess 🤔

[@toolscientist]

Yep, the BMS will brick itself. You can look into Martin Jansson's tool to unlock it, or try and keep the cell pins powered during the transplant. kzbin.info/www/bejne/imebmqZ7nLyqrM0

[@user-2uf2kr2c]

Hi i have one of these batteries the cells have almost 21 volts, but there is no voltage on the outgoing connectors. Any solution? The board is BL1840B rev:V0.4. date 2015.03.07. Regards

[@toolscientist]

Fuse could be blown. Check continuity between B+ and P+. Otherwise the BMS is locked, so try this unlock method (needs a UNO R3 microcontroller) kzbin.info/www/bejne/imebmqZ7nLyqrM0

[@crazyphil1336]

Great video! I believe the more recent 4Ah packs do have a mosfet similar to the 5Ah. My BL1840B from 2018 once cut out by itself while it was used to power a DIY light. It would also be interesting to see the differences in newer style batteries (the logo on the sides) but with no charge indicator (BL1850 without the B). Do those also cut off like their B counterparts?

[@toolscientist]

Awesome. Would you be willing to post a video of your 4ah running down on your DIY led. Ideally with a multimeter measuring the pack voltage. Pack voltage going negative at cutoff is a sure sign of a cutoff mosfet on the negative terminal. Some pics of the PCB too, if you're willing to take it apart. Do you mean older batteries? I thought all batteries were now the B variant.

[@crazyphil1336]

​@@toolscientist I discharged the 4Ah today via 3 10 ohm resistors in parallel and logged both pack and signal pin voltages. The mosfet turned off at 9.2 volts, the signal pin cut off 20 seconds earlier and before that it stayed very consistently 0.5v below the pack voltage. I'll take the battery apart and try to post some photos of the board. Yeah, the current batteries are all the B variant except the 1.5Ah. Makita seem to have had a lot of different but similar styles of battery casings making them difficult to tell apart. I meant the generation just before the B variant, I think they were exclusively 4 and 5Ah. They have the Ah marking in a different spot than the current batteries. I think they also lack the mosfet - I have one that I'll take apart together with the B one and include pictures of it too. Fun fact, I completely desoldered the PCB from the older 4Ah to swap the yellow connector. It didn't brick the battery, however it did need a "reset" charge to activate. Even older batteries (3Ah) have a smaller PCB with less of a coating and a flex PCB to monitor cell voltages.

[@toolscientist]

@crazyphil1336 so is that a 2018 4Ah with mosfet cutoff? You won't be able to post links here, only channel owners can. Can you post board shots in this thread: www.reddit.com/r/Makita/comments/19609zt/partially_solved_some_lxt_batteries_definitely/

[@crazyphil1336]

@@toolscientist Done! I also included a BL1450 (2015) that has four mosfets and a BL1830B (2018) in case it might be interesting.

[@m1stertim]

i have 4ah and 5ah pre-2019, but i have over 20 5ah batteries and haven't serialized them - how do i find the date? I don't see any date code on the outside of the battery

[@toolscientist]

First 2 digits of the serial number is the year. Serial number is near yellow connector

[@Schrankenposten]

Do you have a good protection board for these 18v batteries I can use for DIY Projects that you can recommend? I have some German Bosch 18V 5Ah Li Ion batteries but unfortunately they have nothing for protection in it.

[@toolscientist]

Search for "low voltage protection", "low voltage disconnect", "low voltage cutoff" modules. They can be found on ebay, etc. They're all unbranded stuff, so I can't really recommend any in particular. Most will only do 30A, but if you go beyond that, you'll potentially be overheating the battery anyway. Just make sure that they have an adjustable cutoff voltage. For an 18V battery, 14-15V is a fairly safe cutoff voltage.

[@AlexKall]

Very interesting video, thanks!

[@v3nato]

Hey Tool Scientist. Amazing video as always. I have both aa 3rd party and a bricked makita 5ah battery that I can make work with my tool DTW700Z by putting a 10kOhm resistor between the positive and third pin. Could you explain what is happening to fool both the battery and the tool to work?

[@toolscientist]

Bricking the battery doesn't seem to turn off the mosfet, so you can still draw power from it. The 10k resistor from + to the 3rd pin on the tool brings the voltage of the 3rd pin high (i.e. within 2V of +), which gives the tool its go signal. Anything below 12kOhm between + and 3rd pin will make it work.

[@v3nato]

I see, thanks for the information. I charge the bricked battery via a balanced lipo-battery charger with a modded 5S jst connector, thus ensuring safe and balanced charging. And 10kOhm resistor to be able to draw power from the battery. How could I additionally protect the bricked battery ? Will the N-type Mosfet(IRFP3006) protect a bricked battery from undervoltage? Again thank you for you for taking your knowledge, time , tools to make and share the information. It will save money and the environment. @@toolscientist

[@toolscientist]

@v3nato unfortunately not. To drive the mosfet's gate, you need the D-pin to be high when the BMS says voltage and temp are good, and then pull it low if the voltage or temp are bad. A bricked battery is going to keep the D-pin low all the time.

[@v3nato]

Damn, there goes that plan :P. Would love more makita videos. Maybe one where you give some tips on how we can reuse old bricked batteries? Don't really trust those cheap bms replacement units you can find on a A-xprs. If they even have all the protections features they promise. @@toolscientist

[@alekpop1625]

My makita 2019 cut of over 30amps maybe 35 on another tool with 2 phase A after wont work. Neesd reset on charger shortley

[@toolscientist]

Which battery and how old? If it's a small or old battery, there's a good chance it cut out from low voltage. High currents cause voltage drop from cell resistance. A new 5Ah can do 100A before hitting low voltage, but after several years it will only do 60-80A

[@alekpop1625]

@@toolscientist ITS BL1850 4 YEARS OLD. STILL HAVE PUNCH. J DONT BELIEVE IT CAN HANDLE 100 AMPS. MAYBE 60 SHORT. ITS USED OUTSIDE THE TOOL WITH OUT 3 TERMINAL. TERMISTOR OR ELSE. AFTER OVERLOAD WONT WORK PERMANETLEY.

[@SuperHondaFitDriver]

Hey do you work with any rigid batteries? I was wondering if I connect a AC to DC transformer to a battery, could I use that as a source of power in case all my batteries die?

[@toolscientist]

We get AEG in Australia, which is identical to Ridgid. Don't have any of their stuff yet, maybe next year. Check out Harrison Hobbies who has the best example of an AC-DC adapter. Short version is that it's expensive and still underpowered for some tools.

[@SuperHondaFitDriver]

@@toolscientist Is it more expensive than buy multiple batteries I would just like something that could get me at least 6 amps of output. Just for a backup you know? But thank you for the response I really appreciate it! I'll go check out Harrison Hobbies now!

[@toolscientist]

@@SuperHondaFitDriver most 18V tools are typically 20-40A (400-800W), and some will go over 80A (1,600W)

[@SuperHondaFitDriver]

@@toolscientist oh I Guess 6 amp and 6 amp hours is very different 😅😅

[@woltergrant]

Would love this kind of diagnosis on the specs/features of Bosch batteries! If you need to have one sent to you in order to make it happen I’d be willing…

[@toolscientist]

Bosch is definitely on the todo list. Are you in Australia?

[@woltergrant]

Sorry I’m in the US. I have loads of their 8ah power core bats to spare though. Would shipping be more than 40 USD or can these bats be shipped internationally to you? I’m also curious about using adapters and wondering if you can explain your findings more. Most cheap Chinese tools are compatible with Makita bats and the majority are two pin. So on two pin makita tools it’s up to the tool to signal for low voltage cut off? Then three pin rely on the battery and that’s why they aren’t safe with adapters? I know there is no guarantee but assuming the Chinese two pin tool replicates this cut off it would be okay to use with an adapter with these Bosh batteries I suppose.

[@wilvandendoel4289]

This is usefull info, thanks. Don’t you think that the 3Ah switches off so late , just to kill them sooner, so that you update to 5ah? I can also imagine that 3ah is more often used at home and 5ah at work, so they would never sell a new battery to home users without this low voltage drop. So the old two pin tools are better for the 3ah, or chinese clone tools for that matter, they are two pin and shut down in time, at least, the ones I have.

[@toolscientist]

I think it was just because those cheap cells in the 3Ah have high resistance, so their voltage sags a lot under moderate loads. It's still bad design, though. They have accurate current sensing so they could adjust the cutoff voltage based on the current.

[@OtherWorldExplorers]

Love seeing goofy's trial at this is fine.

[@michaelsauer5726]

Hi. I have ordered several BL1820B and all were delivered with 7-9 V. Can I measure the current on the pins, or is this current faulty because of some shipping mode? Is there even something like a shipping mode, or is this just marketing to sell deep discharged batteries?

[@toolscientist]

From what I've heard, nearly every Makita battery is shipped with very low voltage. Li-ion doesn't like being stored at high voltage. Damage doesn't occur until you go below 1V/cell (5V/pack)

[@saiiiiiii1]

​​@@toolscientist below 2.5V is already harmful to the cell iirc. 7V for the whole pack is plain crazy. That being said I thought this is some sort of shipping mode and not the actual charging state the pack is in. I've noticed this on a new 1850 as well.

[@toolscientist]

@saiiiiiii1 at high currents, the voltage drop on the cells is "true voltage" - current*cell_resistance. So even when you discharge to 1.7V/cell (like Makita does for 1.5Ah and 3Ah packs) it pretty much instantly rebounds to 13-14V. I'm guessing the big companies have tested this and found the degradation is minimal.

[@saiiiiiii1]

@@toolscientist but we're talking shipping charge state of 7v-9v. This can't be for real...

[@toolscientist]

@saiiiiiii1 it's very real. At 5:10 I show the 1.5Ah and 3Ah cutting out at 9V (~1.8V/cell). The next scene is running it on a tool to confirm it. Yellow multimeter is pack voltage, red is 3rd pin voltage. It's only the 1.5Ah and 3Ah - the 5Ah and 6Ah cut out at 2.5V/cell

[@Кто-тоТам-ъ5н]

Hello thanks for the video I am watching your channel from Russia and I need to use a translator to write this comment I would like to say that I have a battery Makita and I know their big problem the batteries are charged more than the nominal voltage calculated by the manufacturer, they go into protection and I can assume that this can only be corrected by resetting the controller memory, the whole problem is that this error can be obtained not only by charging the batteries yourself, but also on the original charger if several times in a row If you put the batteries on charge, their voltage will increase slightly even if they are charged, so using the original makita charger can damage the batteries

[@toolscientist]

Спасибо за просмотр! Это тоже перевод. Значит, подлинная Makita может заряжать аккумулятор выше 4,2 В? А только если поставить на зарядное устройство полный аккумулятор? Мне придется это посмотреть. --------- Thanks for watching! This is also a translation. So genuine Makita can charge above 4.2V per cell? But only if you put a full battery on the charger? I'll have to look at that.

[@Кто-тоТам-ъ5н]

@@toolscientist perhaps, I’m not sure, the whole problem is that the battery goes into eternal protection before the voltage limit of 4.2V is exceeded on one cell, I charged the battery with a homemade charger with voltage control and the voltage did not exceed 20.8V, but the battery went into protection and after forcibly discharging each cell to a lower value, the battery did not come to life

[@Кто-тоТам-ъ5н]

@@toolscientist regarding your question, makita charging can add a small voltage to the battery even if it is already charged, my friend had a case when he forgot which batteries were already charging which ones were not, he put the same battery on charge several times and after that he had the battery has recharged and gone into protection

[@techtastisch7569]

I think the reason makita switches the data signal first and only uses the internal mosfet as a backup is to still allow the tool to do some things. Like my DML809 work light, turns the main light off when the battery runs flat, but keeps a single LED on

[@toolscientist]

Yeah. Cutting the negative rail can also be bad for some circuits. What I don't understand is why they added it. It adds significant cost, but doesn't seem to change anything as Makita tools always switch off first. It could help with pre-star tools that didn't have any protection, but only the 3ah works with those tools, and it has no mosfet.

[@uhjyuff2095]

@@toolscientist Makita must have had a new internal policy to add more safety within their battery packs.

[@toolscientist]

@uhjyuff2095 or external (Japanese laws?), I doubt we'll know ynless someone knows a Makita engineer in Japan. I nedd to get hold of newer 3Ah packs to see if they have it. If they don't, then it's really confusing

[@BikerWildRat]

@@toolscientist There are such types of tools as, for example, work lights, fans, power bank attachments that can use any batteries (models with and without a star), even 14 and 18 volt ones, and they only have 2 contacts.

[@toolscientist]

@BikerWildRat yeah, but they seem to have their own cutoff. The light in this video only has 2 pins and it cuts out at 13V

[@tomhaba2109]

Interesting, but how can some tell what production year it is? Most of sellers have no clue what they are selling and they have very old stocks... battery does not have any production year identificator, only model number and maybe some identificator where it will be hard to define what production year that particular product is.

[@toolscientist]

There's a serial number near the yellow connector. There are 2 numbers next to a QR code. The top/longer number has the year as its first 2 digits.

[@toolscientist]

Also, production year doesn't seem to matter. I've had 2 people give me PCB photos of 4Ah batteries. There was a 2018 with cutoff mosfets and then 2014, 2015, and 2021 without cutoff mosfets. If there is a pattern as to which 4Ah have mosfets, it's going to be hard to figure out. So far all 5Ah and 6Ah have cutoff mosfets.

[@michaelseitz8938]

Your research is as interesting as the results are infuriating.

[@toolscientist]

😄 which part is infuriating?

[@michaelseitz8938]

@@toolscientist The part where you point out how much money Makita invests in fancy silicon ... and the battery management is still crap? 😁

[@toolscientist]

Yeah, the electrical design is quite high end, but they've made some strange choices in the programming. The weird 8.4V cutoff I'll ignore as something that I don't really understand - it'll never happen in normal use anyway. The only thing I dont like about the 5Ah is the seeming lack of overcurrent. They've probably tested it and found that the low-voltage protection will kick in first, and therefore there's no need for overcurrent. I couldn't find detailed info on the fuse. Obviously it won't instantly combust at 30A (90A total), but how long can they handle 35-40A (105-120A total) Letting the 1.5Ah and 3Ah go down to 9V is just trash though. I don't think that's defensible. Especially as they have such accurate current sensing it would be very easy for them to scale the cutoff voltage with current.

[@michaelseitz8938]

@@toolscientist Without knowing the company, but having worked for a big company myself, I suspect it is a wild mixture of "someone trying to do the right thing", "someone higher up trying to save a few cents, after too many dollars were spent", and "someone very high up the food chain saying: F it, folks will buy it anyways, and broken batteries will make us more profit in the end".

[@gf2e]

@@michaelseitz8938I wonder if there was some weird glitching where it would sometimes cut off prematurely? Or maybe someone in management was testing tools and seeing them cut out with non-empty batteries and said “be less conservative!!!”

[@dazaspc]

I have been using LXT since 2009 pre star. I have never gutted and tested a battery but my experience is this. Pre star battery's could be used so hard that you couldn't hold them in your hand comfortably. If cooked in this way you had three chances before the charger would reject them. I know all Star battery's log their use, Times charged, times overheated and the cell condition can be read. Here is a video on the unit. kzbin.info/www/bejne/q6bQqJybgdpreac Most of my Makita tools are star with a couple of motor driven units that are not. Things like the radio will cut off at a decent voltage that will allow the battery's to recharge but certain tools wont like the old brushed multi tool, the very first 3 speed gearbox drill and the very first impact driver they sold with a LXT. Newer brushed and brush less I have dont seem like they will do this. Also a little known thing with them is the interlock on the plastic guides. When the 14 volt platform was a consumer thing there was LXT battery's that had different plastic guides on the top to prevent them from being fitted to a 14 volt and vice versa. Later tools also used a slightly different guide. For example a very early non star battery wouldn't fit the brushed angle grinder 1.5 and 3 amp yet a later one did and it also fitted the older tools. The problem with Makita battery's is the amount of fakes out there. Far to many are faked very well right down to the decals and print on the cases let alone the packaging. The only way to tell without opening them up is the charge time. I have had a few "Borrowed from me" and replaced with fakes and can tell you the Boards are different as well as the cells. I have tried new fakes and they are no bargain price usually being about 25%~50% more expensive than the actual capacity equivalent genuine OEM. For the home player if you decide to use Makita dont bother with the copy's as you will only be disappointed. I just got a LXT lawn mower and bought more batteries to power it as a matched set. I got 8off 5 amp LXT for $900AUS so they are not that expensive.

[@toolscientist]

I think LXT has had a lot of changes over the years, even before Star Protection and definitely a few major ones after Star, too. From what I can gather, the very early LXTs where one of the worst Li-ion designs, then they've shoe-horned fixes in over the years to the point where they've now got probably the most advanced design (although maybe over-engineered). Would be a big effort to figure out the whole history of them. The thing that I find strangest, is that they've added stand-alone protection to at least the 5Ah and 6Ah, but not made them compatible with pre-star tools. Yet the 3Ah, which is the only battery compatible with pre-star tools, has no standalone protection and they seem happy to just let it get overdischarged or overheated. The fakes seem pretty rampant with Milwaukee and Dewalt, too. Virtually indistinguishable from the outside.

[@dazaspc]

@@toolscientist The not compatible is a remnant of the 14 volt tooling using the same basic pattern. You can doctor the old tool guides easily and the new batteries work just fine with no issues I have noticed. The star modification appeared very early in the line, 6 months from when I got my first Makita cordless drill and honestly I got my first set cheap so it was probably end of the line run out.Great video BTW.

[@uhjyuff2095]

Yep, I remember that the 1.5ah packs would not fit in larger tools to prevent them from overheating. The 3.0ah packs would fit in small and big tools.

[@Josh-b3c]

I have been using rigid batteries they have MOSFET controlled shut off on their 18 volt I haven't had any problems on those

[@toolscientist]

I'll have to test those at some point. They're called AEG in Australia, but common enough that I should be able to pick one up 2nd hand.

[@gf2e]

@@toolscientist Just like the Ryobi, they kept compatibility with NiCd packs. I have a ~20 year old reciprocating saw. Its NiCd pack still works on a Ridgid tire inflator I bought last year. The saw, though, draws a bit more power. It barely moves with the battery. I’ve since gotten a Makita adapter, since I don’t have any other Ridgid tools and don’t want to buy more batteries. Both tools work well with the adapter.

[@TradeWorks_Construction]

Who’s the winner of the Makita Battery LV Cutoff argument? “It’s me!” Cuz I did more accurate/repeatable testing than the rest those internet hacks, now applaud my work as I stand triumphant over their corpses (loosely paraphrased) Me: 👏 🥳 👏 “ I love it “

[@toolscientist]

"It's me. Cuz I stole their work and spent 10x longer answering a question that nobody cares about"

[@TranTek]

The only way i can see why people said Makita batteries are better is they use Murata VTC 6 on their 5Ah batteries 3Ah they use the same low quality cells as others including Ryobi i have a older Makita 4Ah but not sure what year it is, i can send you a pic of the board it doesn’t have the big chip instead it has two smaller one

[@toolscientist]

2x mosfets? The 4Ah seem to be mixed - some have them, some don't. Doesn't seem related to build date.

[@queazocotal]

I wonder how the nice 12.5V/... shutoffs vary with cell assymetry. If one cell is 0.2V low, is it simply 13.3 (2.5+2.7*4). Overvoltage behaviour and normal charging protocol also may be enlightening, though possibly less people care. Thinking of the 65W in and out USB 'Battery Charger Converter for Makita/Bosch/Milwaukee/Dewalt 20V 18V Li-ion Battery USB Type-C Input Output Replacement Charger' from ali.

[@toolscientist]

They're almost certainly monitoring for any cell below 2.5V. I did do a test where I measured the cells individually while draining to look for that, but it didn't make it to the final vid. I'm pretty sure it's in the RAW vid that'll be out in a few weeks. I didn't do any crazy stuff like intentionally pulling a cell low as Makita BMS is notorious for bricking itself.

[@toolscientist]

I'll def be looking at the charging protocol, but that'll probably be a long one. Someone's started on the XGT protocol and it's very verbose!

[@WaynesWorld999]

I may have some of what you're looking for.

[@toolscientist]

You've got some LXT batts? Have you got a battery tester? Otherwise I think taking it apart and looking for big mosfets will help, but the mosfets could be on the underside. This will void your warranty as you have to drill out the white plug.

[@WaynesWorld999]

@@toolscientist no warranty on the many batteries I have.

[@toolscientist]

@Hagar76a haha ok, this sounds like a rabbit hole, but I'll dive in!

[@WaynesWorld999]

@@toolscientist no rabbit hole I promise. I just can't think of any other way to reach out to you

[@toolscientist]

@Hagar76a I've found your post. waiting on admin approval

[@koputai]

Thanks for the video Mr Scientist. BTW I did a Makita fast charger test to see what rate it charges the batteries at, see it here, kzbin.info/www/bejne/b5Tao6mgl7iGiMksi=PXDZyG4fOulWKm0T It shows the different rates of charge over the charge cycle. It’s in real time, but you can FF through the middle bit.

[@aaa-oy3vl]

厉害！

[@zoeyzhang9866]

EPIC! What a treasure channel I've just found! I'm thinking if any custom PCBs may help for any upcoming content? If so, we'd love to supply and reach any collab together if there 's chance! (PCBWay zoey)

[@toolscientist]

Thanks! Glad you enjoy them. I do have a few ideas that could use PCBs. Those projects are probably several months away, but happy to talk. I've put a contact email in my channel's about page

[@zoeyzhang9866]

@@toolscientist Thank you for the email! I'd just sent one, looking forward to hearing from you!

[@Marvv89]

Maybe a redesign of the original BMS board, adding some extra features. When faulty cells have been replaced to create a working battery again. The main problem is most likely the communication with the charger, if you want to keep using the Makita charger.

[@Scrogan]

It’s probably not a storage mode, but a disposal mode. A battery drained down to 9V is probably safe for landfills or even trash compactors without producing heat in the event of a short.

[@toolscientist]

There was a recent reddit post on r/Makita where someone posted their bramd new battery as being at 8-9V. I'll see if I can post a link

[@toolscientist]

This person got 8V on a brand new battery. www.reddit.com/r/Makita/comments/18uq8c1/low_voltage_on_new_batteries/

[@uhjyuff2095]

I think so too. I believe the heater circuit that is activated to pop the fuses can also discharge the battery cells to empty for safe disposal.

[@mohgujai]

Ryobi when? :D

[@toolscientist]

Hopefully this year. Dewalt and then XGT are in the pipeline, but I want to branch out a bit and not focus entirely on battery communication. Standard Ryobi looks pretty straight-forward (every time I say that it ends up being way more complicated, though). I might try and get hold of Ryobi HP to see what the extra pins do.

[@r0000g]

5:48 😂

[@gf2e]

I’ve been thinking to use Ryobi batteries for my projects. I’ve seen their low voltage cutoff in person on my own batteries. Seems much easier than trying to find a good circuit. (I’ve got 5 of them so I’m in good shape for what I need.)

[@toolscientist]

True. I'd bet good money that Ryobi's BMS is not watching how many times you trigger its protection as I think that's how they normally operate.

[@gf2e]

The two things I like about Ryobi batteries: They have maintained compatibility with NiCd batteries from 1995. And they added random pins to random parts of the battery to add more pins. I have a Ryobi high torque that came bundled with a high power battery. It has pins on the back of the battery. Normal batteries literally have no pins there.

[@Andrew-xd9fg]

Trying to get my head around what a bat-tree is?

[@toolscientist]

It's Australian for batt-er-eeeee. Just like char-juh is Australian for char-jeeerrrrrr

[@Andrew-xd9fg]

I’m Australian, I’ve always said battery, not bat-tree

[@toolscientist]

@@Andrew-xd9fg sounds like some posh Adelaide settler talk, not real scumbag convict talk

[@Andrew-xd9fg]

I’ve never been to SA, I wouldn’t know

[@Якобсъ]

Странная постановка вопроса. Макита предпреждает: работать с родным инструментом, только вместе батарея будет защищена от переразряда. Зачем выдумывать проблему, если ее нет! Strange formulation of the question. Makita predicts: work with a native tool, only together the battery will be protected from overdischarging. Why invent a problem if it is not!

[@toolscientist]

Yes, that confuses me, too. The mosfet is expensive and wastes power, but the 1.5Ah and 3Ah batteries show that it is not needed.

[@MrArcticPOWER]

I never understood why people say Makita has the best batteries and after watching this video, I'd say it's either ignorance or brand bias.

[@toolscientist]

I'd rate the Makita 5Ah ahead of the Milwaukee 5Ah. Better physical design (less slop, internal cooling vents that the charger blows air through). Definitely a more sophisticated electrical design as it uses precision fuses, precision shunts, and a cutoff mosfet. There's a good argument to be made that the LXT is over-engineered, though. It's almost certainly more expensive to make than the M18. I really don't like the 1.5Ah and 3Ah. Taking them down to 9V just seems reckless.

[@riba2233]

because others are worse (at least other major brands that are worth talking about), and they have XGT ones that are even better than this

[@MrArcticPOWER]

@@riba2233 Please tell me why you think Makita has better batteries than Metabo HPT, Bosch heck even the non flexvolt Dewalt. All that over-complicated design yet they let you discharge it to 1.8v per cell and the charger will brick your battery if it sense anything wrong with it.

[@gf2e]

@@MrArcticPOWERBricking your battery if something goes wrong seems like a good feature, though. Mistreated cells can emit magic smoke.

[@toolscientist]

The 9V (1.8V/cell) is only on the 1.5Ah and 3Ah, which are their cheaper batteries. The 5Ah is 12.5V (2.5V/cell). It seems to be something that a lot of the early power tools did, and then later they switched to the standard 2.5V/cell. But then for some reason they've kept their legacy programming on their older batteries, even if they're manufactured more recently. It still seems crazy to me, but Milwaukee and Makita would have good data on how they hold up. You can always find someone that has a 10+ year old LXT or M18 battery that's still going. I have a few.

[@KeijonAutoVuokra]

I think @toolsandstuff has a Makita battery tester and a shit ton of batteries, he could perhaps offer some information

[@toolscientist]

It'd be interesting to see what his tester shows for my bricked battery. I'll have to convince him to brick one of his batteries to see what the tester says 😄