Inside an Aldi Ferrex 20/40V battery (with schematic)

[@vatterger]

As a young electronic engineer: Really love your reverse engineering videos! You've explained/shown so so many creative and low cost circuit designs over the years, it's really educational! Thanks for that!

[@whatilearnttoday5295]

Better than the tradition of forums where everyone new is screamed at about how dumb they are.

[@tniemi]

Totally agree. I really like that someone opens up these circuits so that even an amateur like me can see how things in the modern life work. Information on this level is unfortunately rare. Thank you Clive for NOT simplifying things for us! (Also my wife falls into a blissful sleep when I watch your videos at the evening. :D Good stuff.)

[@chrislloyd9619]

Your video saved two of my batteries . I let them go flat in the garage and the button showed 2 lights and would not charge. After watching your video i jumped the second side off a good battery b2 +and the b2- and after half an hour it charged a treat on the charger. Now i have 4 good batteries. Thanks for the in-depth review and saving my batteries.

[@bigclivedotcom]

If a battery has dropped in voltage too low it's better to gently bring them back with a low trickle current.

[@andytaylor8802]

I have a battery pack that is fully charged but won't allow a power tool to run. Is it totally different now or could it be fixed? Problem we have now is that these batteries are as hard to get as rocking horse manure. I don't suppose you know if replacement boards are being sold anywhere?

[@dcallan812]

When you look at the board and software it's amazing, they can get something this clever for the price. When you think back just 10 - 15 years. Very interesting video 2x👍

[@ChoppingtonOtter]

Makes you wonder what we will have in another 10-15 years!

[@dcallan812]

@@Okurka. I click the 👍 button once but if I appreciate the video I like to say 2x👍 up in the comments. Have a Merry Christmas and Happy New Year 2x👍

[@dcallan812]

@@ChoppingtonOtter Yes and everything is getting smaller too. (well not my waist 🤣) Merry Christmas 🎅🎅

[@dcallan812]

@@Okurka. Im not?? I like using the thumbs up button AND I add 2x thumbs up because I really lime the video

[@dcallan812]

@candyman I thought he was a bit simple, not quite retarded but still.

[@TopEndSpoonie]

Wow, so much involved in that one. Thank you for your efforts 👍

[@williamromine5715]

Those of you who have been around for a while, know that I know nothing about he is talking about, but this one might have been in Greek and I wouldn't have been any more lost. On the other hand, I enjoyed the video as always. His voice is so calming, that the stress of the day goes away. This is the only website that I am subscribed to that I don't understand a word that he says, but that I open as soon as I see a new episode available. Merry Christmas to all, and to all, goodnight.

[@Derek_Garnham]

Don't be too surprised if something starts to make sense, you may be learning subconsciously.

[@rogerhargreaves2272]

Your honest. I’ve learned a lot from Clives channel. Happy Christmas anyway. 😊

[@williamromine5715]

@@Derek_Garnham Possible, but at the age of 80, it's not important that I understand what he is saying. His knowledge of his subject comes thru, and I am always attracted to a person who has knowledge and enjoys passing that knowledge to others. In addition, his subscribers are courteous with each other, something not common on other websites.

[@Derek_Garnham]

@@williamromine5715 Quite so, particularly what you say about the subscribers. All I'm saying is be ready for the day you wake up to the odour of solder flux and find out that you've converted your alarm clock in your sleep to run on vape batteries (charged from a pound-shop solar garden light).

[@williamromine5715]

@@Derek_Garnham That would be neat , although I'm not sure I know what you said. Thanks for the encouragement.

[@jkobain]

Well, I didn't hope to behold the times when microcomputers are cheap as dirt and exist in multitude in EVERYTHING. I can't express how I was amazed when I discovered they made a specialized chip to replace a huge mess of discrete components with a single dedicated unit. So much efforts went into engineering this, simple from the outside, thing; so much efforts you put in reverse-engineering them. That's a lot, thank you very much!

[@jasonkmec1589]

The microcontrollers look to be from Fremont Micro Devices, from their line of very cheap 8 bit PIC clones. Looking at the datasheet for the FT64F0A5 for instance, shows a matching pinout to the power, gnd, and reset signals from the schematic. Many of the parts from this product family also have a 10 or 12 bit ADC.

[@mevk1]

My 10 year old, ten cell 18V weedwacker stopped working so I desoldered the beast and found 3 corroded cells. Rather than tossing the whole thing,I turned it into a 5 cell pack and pieced it back together. Amazingly the battery still has 70% capacity but with half the cells, theoretically last half the time. The electronics still kinda work but the cut-off voltage strangely went from presumed 2.5V to measured 3.5V so time between charges is greatly reduced. OK though since a full charge is still enough wacking for my yard. BTW, the number of SMD components on these double sided boards is mind blowing and alien to me - you deserve at least two pints after reverse engineering -cheers!

[@nec3f]

In an entirely unrelated example I can think of, two thermistors are placed next to each other for redundancy. That way, even if they're both reading 'normal' temperatures, the controller knows there's a problem if they drift too far apart. People have problems with false positives when they don't read the instructions and place them away from each other thinking they'll get better coverage.

[@matthewbaker6827]

Or perhaps, and I'm a mechanical engineer so please be kind, the schematic called for two thermistors i.e. one per battery but the intent got lost when the job was thrown over the office cubicle wall and the layout and mechanical engineers made an assumption. However, I think that the your rational is more likely, mine being the flip side of yours:-) PS edited for typographical error.

[@andymouse]

Makes sense.

[@Eddiecurrent2000]

I thought the same, the thermistors are probably important to stop runaway and not just charging temps, so having two would mean the uC definitely has the correct temps.

[@Handlebar-MustDash]

I just recently bought the Ferrex 20v Combi Drill/Driver/Hammer (WWS-ASBS20-SP for £18 Bare Unit. Unbeatable value for money, solid construction and takes this Active Energy 20/40v battery. If it lasts me only 6 months then it has earned its keep but it has a 3 year warranty so.... absolute bonus. Don't know how they manufacture these units for the cost, crazy. I couldn't buy just the motor for much less than the price of the whole unit. Having mostly DeWalt and Makita (refuse to jump on the Milwaukee hype train), just had to get one of these for the fun of trying out the quality available at this price. Plus, if anyone needs to borrow a drill, I needn't panic about my Makita/DeWalt XRP being abused by a novice family member, I just lend them this 😊 Ferrex. Always found it incredibly annoying when family/friends expect to borrow a professional, expensive tool and inevitably abuse it because they didn't pay for it, only to return it covered in crap, bashed up and wobbly bearings that were fine when they took it. Lent out an 8 month old DeWalt Cross Pull Mitre Saw some time back to an idiot neighbour who put down some Laminate Flooring, only to get it back with the noisiest bearing I have ever heard. How you damage a main bearing on a large mitre saw cutting just thin laminate flooring is beyond me. You expect lost Carbide teeth on the blades where they stupidly cut something with nails in, but a whole bearing wrecked 😮. Cost me £80 in repairs for a fool to floor his downstairs. As for warranty - DeWalt would not have believed the bearing on the main drive shaft had failed just 8 to 9 months in due to proper usage. A 180lb Gorilla swinging on the handle maybe, a routine failure, absolutely not. I also bought the Ferrex 18v nailer which this far in, 4 to 5 months, is very good, no nail jams, smooth operation and effortless power as a 2nd fix nailer shooting brads upto 50mm into hardwood, softwood and even plastered walls for fixing architrave, dado rails etc. Always used a gas, then pneumatic nailer before this. The Paslode is great, as is my air nailer hooked to the compressor but the Ferrex works just as well for anything upto 2" brads, anything longer, I use the Paslode. I always swerved Aldi's WorkZone products because they were crap, similar to B&Q's Performance Pro range which were also complete crap but Ferrex in comparison seem really good value for money. Tempted to buy some Ferrex Pro tools, maybe the Brushless Impact Driver if I can find one. They appear to have an all metal gearbox housing as well as a fully metal gearbox. The Parkside Pro range looks to be well constructed too. Never been a better time for buying powertools at the cheaper end of the market to see how much value for money you can squeeze out of them and also to test how much better the high-end tools we pay a fortune for actually are or are not. Keeps the big manufacturers on their toes 😂 which is never a bad thing.

[@aarondavies8486]

I have the ferrex Pro impact driver with 20/40v battery it cost me 35 quid its brushless and will undo wheel nuts at 200nm I have the grinder and hammer drill Pro version they are brilliant missed out on the shop vac last week 35 quid wet and dry vac I don't know why people seem to think big brands are best the 20/40v battery 5 years ago was better than a few big brands batteries all I hope for is a impact wrench ferrex Pro

[@Handlebar-MustDash]

@@aarondavies8486 An impact wrench would be a fantastic addition to the toolset, would also buy one myself. Great to hear that you are having a really good experience with Ferrex too. They are extremely good tools, particularly for the price. Mine are still running perfectly these 2 to 3 years later. I absolutely recommend them to everyone I know and none of my friends have regretted their purchase. Best value for money in power tools of all of the brands available.

[@amorphuc]

Good Grief! & WOW! I'm blown away by your reverse engineering of this thing. Very complicated and couldn't help but think of the corresponding charger that talks to it. I think you mentioned the deal you got this at and it seems like you scored! I mean, the battery alone right? Way over my head but I think I learn a little something each time. Thanks!

[@BTW...]

Despite the dual battery (and so, voltage) circuit, this appears to be A LOT simpler than what's inside the dreaded Milwaukee M18 battery packs. The same in depth circuit analysis (for Milwaukee M18) would be a significant benefit for the users of those tools who suffer the mystery of those 'battery management' boards and big $$$ cost of replacements.

[@Rx7man]

Yeah, same with Makitas!

[@Handlebar-MustDash]

Milwaukee tools are becoming less reliable with each iteration of the range. The hype was big at 1st here in the UK, but inevitably in the name of even bigger profits, standards suffer and Milwaukee seem to be cashing in with a very short-term view. There is a channel - Dean Doherty here on KZbin, a guy who repairs powertools as his business. He points out regularly the failings of Milwaukee and falling reliability standards. A very interesting channel with honest opinions. Makita still make the best grinders, Hikoki (formerly Hitachi) the best Nailguns along with Paslode, Bosch the best Concrete Breakers, etc. Not always best to have brand loyalty with powertools even though it is financially beneficial to have one battery eco-sysyem. That is how they hook us in with Bare Tools being far cheaper when you already have the batteries/charger, often the most expensive parts. When you add the interlocking case systems like T-Stak II for instance, they sort of have us by the b0llocks. The EU if they want to do something useful, would standardise Batteries, Chargers, Cases, etc. They are attempting this with phone chargers insisting that any new phones sold within the EU henceforth will have to be the Type C charging interface. Something which Apple are not very happy about 😂.

[@aarondavies8486]

These were 15 quid a battery only 5 years ago they are 25 quid now for the 20/40v

[@youdontknowme5969]

Happy Winter Solstice ❄🌌🌙🕯

[@Derek_Garnham]

Sherlock Holmes would have been proud with your recovery of the chip ID. Nice forensic technique.

[@AintBigAintClever]

The resistor ratios in the monitoring schematic at 6:27 may help it make sense, they may not:- E: 6:1 D: 5:1 C: 4:1 B: 2:1 A: 1:1 Interesting that a 3:1 ratio was skipped.

[@3niknicholson]

01:25 ..and for those of you with low patience...made me chuckle.. how did you know i was watching..I am a tech, and really appreciate your Scots intelligence, clarity and style, sir.

[@paulharvey1624]

Thanks for this amazing video! I can confirm that having tried to revive a battery with a trickle charge and failed . Tried the force reset and boom 💥 it’s now charging!

[@sundog486]

Things just get more and more complex as we try to get more and more out of less. Well done on this one!

[@PhilippaGordon-z2b]

Thanks for this really helpful breakdown. I had a battery that just flashed red on the charger. Using your info I tried shorting the reset caps but noticed one didn't have +5V across it. There looked like an OC between B1+ through to the next door B1+ shorted with a link and now fixed.

[@ALAPINO]

I live in Canada, and I am always surprise how much Aldi house brands make it over here. Ferrex tools that have made it over have been fantastic and were cheap as chips. Particularly the bit sets, excellent value.

[@aarondavies8486]

If you ever see ferrex Pro brushless range it's brilliant the impact driver will undo 200nm its tiny was 22 pound

[@devttyUSB0]

Awesome reverse engineering. That circuitry is amazingly complicated. Does look like you're getting bang for your buck though. :)

[@lint2023]

Hey. Merry Christmas and Happy New Year! Thanks for another year and all the good cheer.

[@leotoro51]

Thank You mate :) Have a nice day !

[@andrewwmacfadyen6958]

I use various power hungry cordless from different brands including Mac Tools, Macalister, DeWalt and Keilder but I have been seriously impressed by Ferrex 20/40v tools. The 20/40v batteries give seriously impressive performance in my chain saw as a result I have bought other Ferrex tools.

[@SinterBronze]

Timestamp 13:20 This pins are possibly for programming each processor in circuit.

[@nialldaly7108]

Excellent teardown and Rev Engeneering not only of the circut but the rational behind it. Thanks Clive, keep up the good work. Would be interesting to do a comparrison between the Aldi Ferrex and its compatriot the Lidl Parkside. Amazing how on the surface all these look the same, Riobi, Ferrex, Parkside Black and Decker and none fit each other, I know there are adaptors., buy not redaily available in a pinch. Another interesting fact to know is how the cells in these batterys compare, ie no of mA they are and rated and actually good for. Some of the cheaper chneese 2200mA dont even come close to stated ratings. Hence why people buy Riobi used battery packs to build their own Powerwall.

[@franktuckwell196]

I do not understand 90% of what you are talking about, but i relish your opinions as to wether an item is actually, good value for the money?, or worth avoiding at all costs. Happy Christmas to you and great new year, cheers.

[@sparkyprojects]

The ntc connection must connect with the charger so the battery doesn't overheat Maybe that 3rd mosfet in the chain also signals the charger

[@RobWVideo]

It's interesting that Aldi sell Ferrex tools in Australia as well, but with what appears to be an incompatible "Xfinity Plus" 20V battery standard. The pins are in different locations and the actual physical shape of the slide-in battery connector is different. I guess there might be a patent issue or maybe it's just to stop parallel import of cheaper equipment from overseas. Kind of like how Soda Stream use different gas cylinder threads in different countries.

[@iaov]

I really enjoy these videos and your excellent explanations. Thanks!

[@PaulSteMarie]

Those gate resistors are actually a third leg of the voltage divider. I suspect they are doing some level shifting to bring it within range of the ADC.

[@Wpjgdmtu]

Thanks Clive, was looking forward to the battery breakdown! Cheers

I recently bought a few to power my rovers, they use 36V hoverboard wheels (I got a lot of motors cheap but no batteries and controller). The batteries are great I 3D-printed a socket so they are easy to change. Quite a good source for decent standard battery packs for a budget. ALDI also claimed to support the battery system for the next years. One is used in 20V mode to power a DC-DC converter and the jetson Nano.

[@bigclivedotcom]

Keep in mind that these do not have onboard ability to shut off power when a cell gets low.

@@bigclivedotcom good point I wonder if the ID or Temp Pin has an error state for this case. For the rover it is no problem since you want to monitor the input voltage anyways.

[@shaunmorrissey7313]

Excellent, these batteries fascinate me, that's not how i thought it was going to work, it is a tad more complicated.

[@Farmelle]

5:00 that looks like a long form D2A circuit. Similar is used on the old 80s/90s home computers to produce video signals.

[@SeanBZA]

PCB looks like it has ICSP header, so the reset is needed to allow the processor to be reset, and then on coming out of reset you can enable programming mode, likely to allow writing into the data storage area of the EEPROM for things like allowed capacity of that batch of cells, and also set the ADC calibration, plus a serial number for the pack. No balancing, so the weakest cell determines capacity, and the dual thermistors, along with the transistors, also allows use with tools that have "dumb" monitoring controllers, simply using the packs as supply with a thermal sensor, or an intelligent pack (likely the 40V tools) that use the comms to read things like capacity and allowed current, and to thus extend battery run time considerably. Probably uses the tool being connected, and thus pulling up the NTC line to 5V, as a wake up, using an internal comparator to interrupt the micro, and starting a routine that first attempts to communicate by disabling the thermistors, then looking for a communication down the NTC line, signalling via the ID line. Nothing coming in within a second it then assumes a dumb tool and switches the thermistors on, and then also sends an IR pulse to the high side to wake it. high side then simply feeds battery state voltage down slowly, and likely the method for dumb tools is to switch off the thermistor drive, and let the tool think the battery is very hot, shutting off the tool. smart tools likely get a rough battery capacity gauge sent periodically, with the microcontroller probably running every 5 seconds in a loop to read, so thatit can spend most of the time asleep.

[@bexpi7100]

If they had chosen lower value resistors for the voltage dividers used for sensing, not only would they get less risk of noise on the dividers by increasing the current flow, but they could also use the measurement resistors for balancing. I suppose they could still be using the measurement resistors for balancing, but it might take a while to significantly influence the state of charge of an 18650 with just 1 µA of current.

[@tonfleuren3536]

That would have been a lot smarter; however it may be impossible to discharge one of the higher cells in the pack, without also discharging the cells below it. Maybe there is a clever arrangement (possibly with more MOSFETs) that would allow this. I was wondering about how those MOSFETs would be driven, considering the microcontroller can only output up to 5V. Consider the gate of the top MOSFET; the gate does not need to go higher than the pack voltage, the gate needs to only be higher than the voltage drop across that bottom resistor. The 2N7002 needs about 3V Vgs to turn on fully, so as long as the voltage across that bottom resistor is less than 2V, it can be turned on. The whole arrangement is rather complicated to analyse logically, because all of those gate-source resistors become part of large voltage divider is the outputs that are not being used are driven low instead of high-Z, and the output driven high sources some current to the bottom resistor. When it's turned off, the Vgs should not go below -20V, which is violated, since 5x 4.2V = 21V.

[@stevenspmd]

Well done! You continue to up your reverse engineering game. Chineisum vendors beware!

[@strongandco]

congratulations on the reverse engineering, that's impressive!! Also Happy Christmas Clive 🎉🎄🥳

[@wherami]

this was very complicated. amazing considering how cheaply the part costs but it supplies a lot of power.

[@kevtris]

Trying to figure out how the battery voltage monitoring part works and I think I figured it out. The Vgs for those FETs is around 2V, so the voltage at the drain needs to be 5V-2V so 3V or less. The large series resistors would accomplish this I think. In regular operation, I suspect the micro is tristating those gates, so the G-S resistors are closing all the FETs off and the 1M is ensuring they stay near ground. It would then pull one of them high which will turn one FET on, and its series resistor with the battery limits the voltage going into the drain to around 2.5V or less I'd think. The G-S resistor would act like a pullup too, injecting some current into it. that part is pretty strange still. I would expect the resistors to get larger as you go up the ladder but the schematic shows otherwise.

[@simonwatson2399]

Once the MOSFET is on, the gate capacitor voltage is going to be summed with the voltage on the high side of the 1M sense resistor. It looks like the ratio of the gate resistor and battery resistor has been tuned to ensure that the boosted capacitor voltage is never high enough to damage the MOSFET or the microcontroller. I assume the specific values were chosen as the cheapest for that ratio.

[@Steve_Wardley_G6JEF]

Great video as ever Clive. I usually like to let the adverts run if it benefits the channel but the one following your vid was 49 mins long. Just had to chop that one.

[@bigclivedotcom]

Only watch the adverts if they interest you.

[@DatBoiOrly]

my guess just from looking at it in bits is that it's 10 18650's pushing around 40v's with a battery protection circuit then thats split into four terminals 2 going to a buck converter dropping it to 20v's in two prongs then 2 connectors thats direct from the battery that gives 40v's then the final pin being earth

[@EMS.Fire.Welder]

Thanks so much for your videos! It helps me get a better understanding than just school theory

[@jschwenker1]

the values of each bank are a ratio. bank one is 1:1, bank two is 1:2 and so on up to a 1:6 ratio for the sense resistors. so that must make it ez for the software to know it has the correct bank. im a complete novice but thats my take on it :)

[@labiadh_chokri]

thanks for the schematic I get the value of the thermistor and used a 10k resistor to get the 20w led projector np-rwd-20r working with 18v erbauer battery . they said compatible only with active energy battery :-)

[@d.t.4523]

All that design time. All that buildout, and all that reverse engineering. Just to hear the sound it makes when it hits the trash bin, when it dies. It's not like you can replace cell 4 when it goes bad, they just shut off the whole pack. Keep working. Good luck! 👍

[@johndododoe1411]

Unless the microcontroller refuses. This should happily recover after cell replacement.

[@gregorythomas333]

Damn...that was very complicated!

[@dougle03]

A multiplexing ADC into those binary IO's currently used for mosfet switching (i2c) would have been a simpler option, and whilst still two IC's would be required, one would have been cheaper than two MCU's. This looks like an exercise in hardware design snobbery, rather than getting the job done in the simplest and most efficient way. Equally, to go to all that trouble without adding any balancing does seem a very odd choice, especially when capacitor active balancing is super cheap to implement with minimal passive components. And what's with that NTC connection pulling double duty? Why does the battery and device need access to the NTC's when the battery 'almost' has its own BMS (Sans juicy MosFet switching) with comms to the device. A very odd design indeed; thanks for doing this Clive.

[@rpavlik1]

Some of the tool batteries that have "communication" use it to allow the tool to exceed what would normally be an over current limit.

[@johndododoe1411]

I see very little snobbery. To allow the tool to run the batteries in series or parallel requires some way to run the two half circuits either isolated or with a clever circuit to reconfigure its own operation for P, S or other load config. A serial port with optos makes efficient use of the most common on chip communication feature. As designed, this leaves the main BMS job to the separately sold chargers and tools. The controllers basically multiplex all the battery status data onto a single pin to keep connector price down.

[@abitofabitofabit4404]

Speaking of efficiency, voltge dividers with a 1Mohm output impedance would impose an uneven 1-5µA continuous draw on the cells. A user or stockist would have to charge the pack frequently. With switches embedded in the voltage divider, it is possible to disconnect all the cells' dividers, reducing the BMS's parasitic current consumption by orders of magnitude depending on how often they are sampled. An idle battery isn't very exciting, so hourly sampling might do.

[@dougle03]

@@rpavlik1 Would an over current damage the cells? An over current situation would presumably only lead to damage, thus allowing the tool to over load the cells surely should be avoided... unless selling more battery packs is a marketing goal of course...

[@rpavlik1]

@@dougle03 an overcurrent without a tool attached is called a short circuit and could cause a fire.

[@ericblenner-hassett3945]

Interesting that they would use a " reverse resistor ladder/voltage divider " to ensure that the FETs are off except the cell they are checking. Also of note that they used opto-isolators for a form of low speed COM ports to each other. The thermistor issue could be a way of not having either MPU have some complex way of both reading the temperature as well as the charger reading it.

[@stevenfaber3896]

Great series, but there is still that question out there of if there's comms between during charging. If you have or can access it, after the holidays when the returns come in stock, maybe finish off the trilogy?

[@bigclivedotcom]

Spoilers, the charger uses both signal connections, and can switch current to each section independently.

[@youcandoit8615]

I have that 20/40 battery,i used to read the voltage each terminal on the battery and i confirmed that there's two separate 20v reading,(b1-and b1+=20v),(b2-and b2+=20v) this is completely separate no contact to each other,my theory is that the key how it change its voltage to 20v or 40v was inside of the power tools terminal, if it design for 20v or 40v..l,if your tools is 20v the terminal inside of the tools have jumper to b1-b2- and the b1+b2+ jumper too,this will result to parallel connection (20v) and if your tool is 40v there's a jumper to b2- b1+ this will result to series connection 40v.i hope you understand 😊

[@robertadsett5273]

Hmmm, the 2N7002 has a 5V gate with typical threshold of 2V1 (max 2V5). I wonder how much of that divider work is keeping the gate drive within acceptable range.

[@keithking1985]

Thanks Clive, merry Xmas 🎄

[@pa4tim]

I think to see what it exactly does, you need to calculate all voltages and currents. But you need Vg for that. The current from Vg through the gate resistor and the 1 M at the bottom adds to that flowing via the drain resistor and the 1M. If the output of A,B etc can sink current you need to count that too. It is also possible Vg is not a fixed value (via an opamp ? ) but different for each mosfet to get enough Vgs to switch it on. And the voltage over the 1M resistor needs to stay within the range of the ADC.

[@nicholashacking381]

I was in Aldi, today, and they had an angle grinder reduced to £9.99 ... amazing. At that price I couldn't afford to leave it on the shelf. Now, I've always tried to avoid buying rechargeable tools other than the brand that I normally buy, so that I don't end up with a load of incompatible batteries and tools. But an angle grinder for £9.99 is not to be sniffed at, so a 20/40 V battery and a charger went into the basket too. When I got home and unpacked my shopping... I realized that I'd bought a corded 240V angle grinder, (still a bargain at £9.99) and a battery and charger that I really don't need. Ah well, now I can buy Aldi battery powered tools, when they are on special offer.

[@handlesarefeckinstupid]

I've somerimes bought a lidle tool, perfectly fine if you use one very rarely for a job. Still using a corded lidl angle grinder after 6 years as i rarely use it and it would be pointless spending a lot on one. Let's be honest the ecoensive brands aren't much better sometimes.

[@SeanBZA]

@@handlesarefeckinstupid Still using an angle grinder I got in the 1990's, Black and Decker. Not used much, but still does a few jobs a year for me. There were 2, one was killed by a builder who burnt it out in 5 minutes by pressing so hard the motor dropped to around 800 RPM, and running it till the smoke billowed out. The Bosch one of around the same vintage is also still in good order, and each has typically only one type of disk on them, one grinding, one cutting. Had a few cheap Ryobi ones that were bought, used a few times then either given away or failed.

[@aarondavies8486]

I have the ferrex Pro grinder impact driver hammer drill all brushless grinder was 15 the drill and driver 10er each but its been batteries I couldn't get but last few weeks 20/40v back in so have 3 of them now the impact will undo 200nm bolts the pro stuff is unreal how good it is the brushless motor to but is more that what I paid for the tool

[@MrDbone75]

A very merry Christmas to you all from Wellington Somerset

[@adammorris3082]

Woah- A bit more in there than I thought there would be- These are actually looking like they are worth the £19.99 for the whole drill- I'm tempted to get a few just for the 18650 cells alone - I could knock up some decent 10/13s 10ah packs for the scooter if you get a decent amount of charge cycles. Thanks for another good vid. ATB :)

[@wich1]

Yeah, was wondering what the quality of those 18650s is like

[@aarondavies8486]

​@@wich1samsung or LG cells

[@Farm_fab]

Clive, apparently workzone tool batteries are interchangeable with the Aldi Ferrex tools.

[@bigclivedotcom]

I wonder if it's just the physical shape or if they have the correct communication too.

[@Farm_fab]

@@bigclivedotcom there's a yt vid that asks about "Aldi/Ferrex/Workzone. Is the build quality getting worse?"

[@ThriftyToolShed]

Great video Big Clive. I did not know that Ferrex had the dual voltage packs. I have an older video looking inside the DeWalt FlexVolt and I was amazed and a little bit scared of how complicated the switching contacts were on it to put the 3 sets in either series or parallel. I did not see a microprocessor on the board for it. DeWalt usually don't have one. Unfortunately the whole board is covered in thick coating making troubleshooting difficult. Thanks for the look and Merry Christmas!

[@johnrhodes3350]

I have a Parkside drill that made a loud clack sound when releasing the trigger. I loaned it to a friend and it came back worse. It would stop or cut out if turned on its side or not operated with a particu5 orientation. I took the gear box apart only to discover one of the orbital gears was missing. Not damaged or fragmented, but totally missing. It was evident that one had never been in place. I could tell this by the distribution of grease, and clean bare patch where the gear should have been. I've got a photo if any one is interested. Put it back together and it still sort of works but cuts out if you don't orientate it exactly, which is not convenient. I have another smaller Makita which is doing double duty.

[@Z-Ack]

Pin 4 is the set output regulation for overcurrent draw from the battery which is always too low for the tool you plug it in to. Ive had to remove that cap all together on every battery ive made using those diy boards..

[@Gazereths1234]

Beer and tinkering with circuit boards, sounds like my kind of night!

[@mikeselectricstuff]

Odd that it can monitor individual cell voltage but not balance them

[@bigclivedotcom]

Yeah. The Ryobi clone I looked at had a similar system, but also a balancing chip per cell. I think it may have added too much circuitry to this pack though, as it would have required around 50 more components. (chip, RC filter, MOSFET and shunt resistor per cell.)

[@mattmoreira210]

Wow! How convoluted of a design. Loved it! 😂

[@Mike-H_UK]

I think that the pull down resistors for the MOSFETS' gates could have been connected to 0V thereby removing the through current causing an error for the ADC. NMOS devices do not mind if the gate is lower voltage than the source - it just depletes the channel a bit more.

[@robertadsett5273]

Some N channel MOSFETs are only rated to -1V or so but the 2N7002 isn’t one being rated to -20V. I’d be more worried about low gate voltage. You might get significant Rds on variation. That might explain the divider variation

[@billhall1983]

I have a lawn mower that runs on the 40V. When I use that battery in a drill (20V) it does seem to last much longer so I think that they do go in parallel. Really good video. 🙂

[@bigclivedotcom]

They do. I've tested it.

[@anythingyouwanttvmr.anonym959]

That circuit Is like a passive balancer. The temperature, over charge voltage etc.. of Each battery cell is monitored and control on MCU.

[@paulwright8378]

I use a solder sucker on those terminals when I'm refurbishing a battery an after I put new cells in I solder wires to the connections so I don't have to fiddle about getting the old terminals inline with the circuit board

[@AUATUWVSH]

nice charge level indicator with the Zener diodes, ive seen one on a Ryobi pack that used a TL431 per LED

[@jimsvideos7201]

You wonder how many hours of forward engineering went into this.

[@opjose]

I would love to see you do a video on the small Lithium powered car jump starters. Most tout 24000mAh battery packs or larger, yet there is no possible space for any battery that large in those devices. The max power draw values are also ridiculous.

[@bigclivedotcom]

I've looked at a few and shorted one out to measure the current. They use parallel stacked plates in their lithium cells and can put out hundreds of amps for brief periods.

[@BrianG61UK]

Re the possible RC reset circuit. It could also be for a clock oscillator. Knowing the R & C values would help decide which is most likely. I hear the dislike of using processor to monitor safety critical voltage and temperature but maybe the processors have a watchdog timer built in.

[@AdityaMehendale]

In the 4:06 schematic diagram, they could have pulled-down all gates to 0V (instead of to Vss for each MOSFET) - MOSFETS are fine with negative gate-potentials, and the "leakage into the sensing-resistor" issue would have been a non-issue. Let's attribute this to "mental straight-jackets".

[@daveroche6522]

Thank you and Happy Christmas Big C (plus Ralphie & the Max Beard Club [mine grows white with flecks of dark brown/black for some reason - very timely!]).

[@bigclivedotcom]

A salt and pepper beard?

[@frankowalker4662]

That's a very complex circuit. :)

[@SusanAmberBruce]

£27 divided by 10 £2.70 per 2500ma cell seems like good value for money

[@bigclivedotcom]

That's probably why the batteries sell out so fast.

[@enoz.j3506]

Interesting Clive,the talking to both MCU,s via optos could have a benefit of allowing lock up to be monitored,1 checks the other etc.Most if not all MCU's have the brownout ability,the strange divider battery monitoring might be so the A/D converter (8 or pos 10 bit) is working at max resolution,i had a similar problem on my 8 channel designe.Good and detailed job you did there. Thank you.

[@kevinmartin7760]

That is a pretty wacky circuit for the a/b/c/d/e sampling. The ratios of the gate pulldown resistors and the corresponding battery resistors sort of follow a pattern: A 1:1 B 2:1 C 4:1 D 5:1 E 6:1 but that jump skipping 3:1 is strange. The battery resistors themselves seem to follow a pattern at first, for A, B, and C they are all around 3M, but then on D it jumps way up to 7.5M and on E plummets to 1.8M. Actually, that value for E seems almost implausible since (I assume) the output across the 1M resistor should be perhaps 2-4V, wouldn't you need the battery resistor at E to be perhaps 4-9M? Is the E output of the MCU capable of sinking current to pull the voltage down? Actually, that can't work that way because it would just cause the MOSFET to cut off... Maybe the A/D input of the MCU can take voltages higher than its supply voltage? Whether this makes sense at all depends on how the 5 outputs from the MCU are used (+5 active/Hi-Z inactive?)

[@McTroyd]

Thank you for stepping through the reverse engineering, even if it was a posterior pain. Seems a bit overkill to me to have a microcontroller in a battery pack, but I guess that's just the world we live in now.

[@trueriver1950]

If there wasn't a microprocessor in there how would the CIA/PRC/Iran/DPRK (*) monitor your DIY and steal your skills? (*) _select to suit prejudices_

[@McTroyd]

@@trueriver1950 Forgot the FBI and GCHQ.

[@wegmandan]

Merry Christmas Clive

[@tniemi]

I love the schematics!

[@fiveleafcloverfpv4445]

Be aware sometimes after desoldering the BMS (battery monitor system) for example changing the cells the circuits stops working. First put it on the charger. Most of the times it's comes back alive then. Probably the cell cutoff that needs to reset first. Btw they just should call it nominal voltage as it should be. So X*3.6V. This is weird

[@JustinHunnicutt]

I'm not sure if it means anything but the ratio of the resistors for each cell are 1:1,1:2,1:4,1:5,1:6. Seems like it might explain something? Maybe something with adc range? As seen at 4:16.

[@ConstantlyDamaged]

The battery indicator is surprisingly simple, stupid, and effective. Exactly what most electronics should be, really.

[@Youtronics]

They seem to have changed the board design at some point; mine has a date code 20181015 on it, so maybe one of the erliest. I've disassembled it because it didn't charge anymore (didn't find the fault, so maybe broken MCU), and it had the more typical multi cell monitoring circuitry with a resistor in series with each cell and a capacitor to the next cell connection below; 2 times of course. Used some sort of protection/MCU combo chip it seems, and it doesn't have any optocouplers, don't know how it communicates with the other MCU then. Also no fuses on the PCB itself, but the nickel strips for both packs were slotted to reduce cross section to form a fuse. I still have the PCB in my electronics scrap bin and could make some pictures if interested.

[@dozer1642]

As a hobbyist, this battery pack reminds me that I’m just a hobbyist. 😳

[@WesternAustraliaNowAndThen]

Had one of these fail to charge. It still had useable internal power but once that was gone, it was useless. Took it to bits to see if there was anything I could fix and after looking at how it was assembled I gave up.

[@johannglaser]

I'm confused with those NMOS for the voltage monitoring (around 6:02). How can a 5V MCU output turn them on, if voltage on their source is higher than, say, 3V (i.e., the gate sees only 2V, compare 2N7002 VGS(th) min. 1V, typ. 2.1V, max. 2.5V, and with the goal that RDS is negligible to those MOhm resistors)? Also, if A..E 0V except for the one selected channel, then all gate resistors would be in parallel with the bottom 1M resistor. Except if the MCU would let the output float, which might also work.

[@kimchristensen2175]

ooohhhh! Now it makes sense to me. I didn't think about the gate resistors effectively being in parallel with the 1M when their associated output was low. Hmmm... With the correct combo of high, low & Hi-Z on the A,B,C,D & E lines from the MCU, it should be possible to put the ADC voltage in the sweet spot (2.5V or a bit less) for each tap on the battery pack.

[@snakezdewiggle6084]

All of that to nurse Li Batteries ! NiMh are looking better and better every day. ;)

[@robert_g_fbg]

The T terminal may be for Telemetry

[@Orxenhorf]

I'd think you'd want to connect the pull down resistors to their own path to ground separated from the ADC line by a diode perhaps.

[@lmwlmw4468]

Great work.

[@crazygeorgelincoln]

Good to know about the reset procedure, wonder if it bricks itself like the Ryobi clone packs .

[@curtishoffmann6956]

"This is the case. This is what's inside the case. It's all case-by-case."

[@dauerwerbesendung7045]

I love it! Can you recharge the battery using a DC-DC power supply? I have a 24V solar setup and want to cut out the losses from inverter and battery chargers. Is there a save way to do that? Looking forward to the next part of the series! 🤩

[@bigclivedotcom]

It's better to use the official charger. It might be viable to adapt one to low voltage use.

[@ChoppingtonOtter]

Love how you foxed their sttempt to hide the processor serial

[@richardkaz2336]

I have long suspected communications between the Aldi Ferrex brushless drill and the 20V battery. I have a battery that displays 95% charged and when I checked each cell they were 4.1-4.2V each. If I put a test load across the 20V battery terminals there is plenty of current on hand, 20A. However when the faulty battery is plugged in and the trigger squeezed it bumps and stops immediatly. If I plug a different batteryin and squeeze the trigger the drill runs and has full torque. There is no stopping it unless you apply enough force to stall the drill. However if I hook up a 15A power (peak 25A) supply set to 20V to the drill the dril runs drawing 2.2A @20Vdc, but as soon as you apply a slight load to the chuck (holding it) the drill stops, it has no torque. You can only run it up to ~70% of full speed with no load at all. If you go to 100% of the trigger speed it immediately stops. If I connect a good battery with some wires to the drill it works fine. I suspect some sort of communications on the + terminal that communicated back to the battery micro controller that must respond back to the drill's brushless motor controller. I assume that because my power supply does nothing with any communication on the + terminal and does not respond with any signal on the + terminal back to the battery. The drills motor controller shuts down. Anyone else seen this type of behaviour, I'll have to hook up my CRO and see if I can see any activity one the + terminal. I suspect this is a way of only allowing propriaty batteries to be used and ensuring a revenue stream.

[@Darieee]

would be very chocolaty to see a scope view of how those MCUs chat during their time alive ❤️