eBay finger-chopping pocket chainsaw

lithium electric tool mini cordless electric chainsaw let me get this out of the box and describe well what's inside let me show you that it's like an unboxing that's nice i don't do many unboxings instructions uh written in english very odd instructions it's like someone deleted all the spaces and then added them in random positions what we have in here is an unusually light charger i tried opening this already on a live stream recently it's very hard to open it's unusually light it's really bizarre we have a spare chain and it says it's an expert chain but it also says angel of chain angle of chain and angel of filling angle of filing it comes with two rechargeable lithium batteries which are apparently possibly makita type clones uh rated 21 volts they say it comes with a pair of gloves to stop you chopping your hands off that's not going to work and it comes with the handheld chainsaw right too let's get this out i have just knocked over some bottles of flux and stuff like that but i also have a bottle here i had a bottle here i've misplaced it of chainsaw oil because i'm going to uh oil this thing and then i'm going to take it out and we're going to chop something up but let me just show you initially let me just focus down on here that's better let me just show you i'm going to connect this but i'm going to be very careful because this thing has no safety interlocks there's nothing it only as soon as you pull this trigger this chainsaw blade is going to start running so let me connect a battery to it and give it a quick zap there we go perfect right today what i'm going to take the battery off now for safety reasons and i'm going to take it outside oil it and uh chop some wood and we'll see how well it cuts wood old dry wood cuts okay fresh greenwood also cuts okay not bad right let's explore so the only thing that wasn't supplied with this you've got some basic tools and a replacement chain the only thing that wasn't supplied was chain oil for chainsaws and this oil is a very sticky gooey oil it's designed to actually cling onto the blades and not get sort of thrown off or or basically spread onto them ultimately it does but it doesn't have an oil feeder so you're going to have to oil it i don't know if they recommend that i didn't read the instructions well there we go the chain yep right i'm not really sure how you'd specify i'm not really used to changing chainsaw blades i usually just buy them for specific models i shall investigate this but it's a nice sharp chain and as usual with these things you can sharpen them if you have the correct tools which is kind of essential for chainsaws the batteries are quite heavy the batteries weigh about 310 grams each the charger weighs 69 grams the unit weighs 743 grams when you add the battery on it comes up to just over a kilogram at 1053 grams this is a safety guard you've got two screws on the front here one is for adjusting the blade tension one is for the safety guard now i'm guessing the safety guard is for two things i guess really it's an anti-kickback guard to try and stop it carving up your face is the first thing that comes to mind i should have put that on before i used it but i didn't let's uh take something to bits i shall take this apart first so let's go into this you undo the cover over the chain mechanism and if you undo this screw here this is a double-edged double-sided screwdriver it supplies i know this because it popped apart when i was taking it initially there is a screw down here and when you're actually set setting this up this moves this pin to actually slide this bar back so forwards it tensions the chain the chain should be tight enough that it's not taut but just tight enough that you can just pull it and it's got a little bit of slack coming out there too tightened it puts excess wear on this and the chain too loose and it may actually skip right out of the actual chamber that gets adjusted by this little screw here which i shall loosen off now and when i loosen it off that should loosen it enough that i can then lift the chain bar off and the chain the chain is just driven round by this sprocket there is the mechanism slight that slides backwards and forwards very simple don't do what i didn't tighten that one thinking that was a tensioning system it's not let's go into this a bit deeper i think i was going to drop out here probably it is held together by torx screws which i've already pre-measured so to get the correct screwdriver not sure if all the screws are going to be the same length it'd be really nice if it was it's always a good good thing when the screws are all identical length but sometimes they're not that's a good start so far the lack of safety is a concern in this if you have one of these i strongly recommend taking expectations wearing gloves to at least provide some protection thick gloves but making sure that when you're not using it take the batteries out of it if you had this in a toolbox and you reached and pressed that button down even though it's got a fair decent mount spring tip if it started off the blade would make short work of your of your hand which is not good so far all the screws have been the correct eye the same size this is good this one is recessed deeply which is a bit annoying but that's all right i have the i have my deep torques to get that out and this should be the last one it mentions in some listings that this is a brushless motor kind of skeptical about that but you know what let's find out oh does it come apart easily i got more screws to take out let's loosen this off is there anything i'm missing here have i missed a screw i don't think i've missed a screw i think it's just tight fit which it should be maybe i should pick that up no there it goes it is not it is not an electronically commutated motor it's a plastic gearbox it's got a standard variable speed control system with a little heatsink on the outside it'll be super mass produced uh can i get this out for that gonna need another screwdriver bit to get this out is it gonna reveal much other than the fact that this is a plastic gearbox i suppose really in the spirit of eve i should be going deeper oh it's actually the same the same bit that's nice again i looked when i saw this online i was very skeptical about it i looked at reviews on youtube people had bought these and they were all raving about how much stuff it cut i think ultimately that uh the plastic gearbox does allude to certain disposability it's going to come out anything else holding it in i don't see anything else holding it in is it latched in somewhere is it some spring-loaded mechanism i shall push in the front or has all this has been added afterwards and i don't think there's a grub screw i think this has been pressed on i don't know if this is going to come out then it looks as though this wheel has been right give me one moment i'm just going to actually you know let's not pause let's just try and grip that let's see if that's gonna unscrew no it's just rotating the whole thing hmm it's just a gearbox but you know i feel the need to take it out at one moment please and the secret is apparently this little circlip that was around that which is now off letting this lift off and now the gearbox drops out oh really that's it not much gearing it is this little direct drive from the motor shaft onto this which is going through a fairly deep bearing to the back of the unit for extra uh stability there's really not much in here ave would be analyzing all the metals and things like that i'm not going to analyze all the metals i'll animal analyze the electronic stuff the speed control will be a standard speed control right what's next to open up now i've taken that into bits all right tell you what i'm just going to uh i'm going to pause when i put this together just so i don't mix all the hardware up and then we'll go into the battery packs one moment please right battery time but before i go into the battery things worth i mentioned there's a 100 degrees celsius thermal cutout on the side of this so that's quite interesting wonderful i hope it's a self-resetting one i think it is but it's just if you've got one of these and you're using excess in the garden it cuts out it may be that also a potential point of failure i'm going to put this down the ground now and make sure i don't smash my feet into it let's take one of the batteries apart it feels hefty this doesn't always mean anything it might be full of metal hopefully it is full of metal battery metal it's interesting to know that you can get 21 volt ones you can get at four to eight volt ones 56 and well this uh charger actually says it goes from uh output 21 volt to 98 vf one amp dc by 9 to 8 vf it means fake because this is just a 18 volt charger effectively this probably has five cells in it because that's what you'd typically find an 18 volt battery pack with five cells and a charge control circuit board well a protection circuit board right at one moment please i'm just going to take a picture of this and explore it try and find what the chip is and we'll analyze the battery at this point in the battery says uh inr or 18650p 2000 milliamp hour that would be quite respectable actually if it was two thousand milliamp hour interesting stuff one moment please and resume uh very interesting the chip it's using is a cm 105 one which is a five cell protection pack there is the output to the actual tool because the charging port is in the back here you basically plug into this little charge port but the output for protection of the mosfets it has a back emf diode wired across those two pins i wonder what that was initially the mosfet here is the discharge mosfet that's used to basically shut the battery pack off when the voltage is too low or potentially a monitor for an overload situation as well where the voltage it measures the voltage across this mosfet and if it gets too high it detects that as high current overload and the chip will switch off there is the option for putting two mosfets in parallel i was thinking so where's the charge protection well the charge protection is this tiny little mosfet here because the charge current is somewhere between 500 milliamps to one amp so from the charge port we've got uh a connection via a diode and then over to the negative connection via the mosfet so the chip schematic it gives a couple of options for the wiring it gives one where you've got the inverse uh series mosfets for controlling charge and discharge but this is the circuit they've used down here which is where there's two separate mosfets used so the only the big mosfet is needed to switch the current out and the charge mosfet is that tiny little one but everything else is more or less textbook there is the facility in that chip for a temperature sensor which is bypassed by this little resistor that's been sorted across that position so they're not monitoring for a temperature situation in the pack anything else worth mentioning here not really it pretty much fulfills the thing each each cell is monitored via its own resistor and capacitor just forming a sort of like a simple decoupling circuit so that you get a fairly smooth consistent input where it monitors that voltage there's no balancing at all as there is an even posh battery packs all it does is if say for instance that something had happened a packet got wet this seems to be a common thing and it caused a pool of water had caused this battery to go low this lithium cell to go low if these ones are say fully charged 4.2 volt and that one was way down low it was almost the point of cutting off then it won't balance them again if you put that on to charge uh it will terminate on the batteries that are already full but if you plug it into the tool it will terminate on the one that was almost discharged already so you'll end up the battery pack just doesn't have much capacity the answer there is if it's not damaged if it's not got a bad cell is to measure the voltage across all the cells individually find the one that was rogue that there was low and just uh gently bring it up to the same vultures other ones and equalize the voltage accurately to the 10th of a vote across the mall and that will restore the battery pack if it loses capacity again suspect that one of the batteries is damaged and it's time to dispose of a controlled manner discharging all the cells completely before disposing of it in a suitable place the in the contents of lithium cells it's actually a mixture of copper and aluminium and graphite and lithium iron cobalt i think it is all fairly inert materials it's the energy they store that is the danger this is a one of the things the battery manufacturers all distance themselves i should have i should make a video about that they distance themselves from people using these cells out with things like packs 18650s are designed for use in packs and they basically put a bulk disclaimer out all together it must have been the battery manufacturers association organized it to basically say if you use these individually we are not responsible if they blow up your pocket when you short them out in your keys because that's what's happening with the vapors uh so that's it really not much this little tiny uh mosfet for charging this big one for switching the output with the option to boost it up and add a thermal sensor it's a typical battery pack to be honest right how am i going to get into this little thing because this i'm going to have to use brute force i have sponged this unsuccessfully to the point i actually bent the spudger a bit i can get the spudger in like that i can slide it along but uh there's no obvious screws i i rank there's glued pillars in here so i'm going to have to get destructive i may have to get eve's hammer out and just give it a little tappy tap tap and see if i can get into this one moment please the eve hammer of ultimate knowledge did free the truth the truth is now free for us to explore interesting case the case was kind of held together with pillars in reality it's got a clips here here here and here but with supporting pillars to actually make those clips hard to part so once you force this together it's actually extremely hard to get apart for reference the case is called an xy 207 not sure who makes that it's quite a good case it's very very robust stuff ricocheted out i think it was just an insulation plate there was also bits of foam holding this circuit board in place the circuit board has the main voltage switch mode circuitry on this side driving this transformer what looks like a class by capacitor but isn't its part of the snubbing network there is no class wise capacitor and then the output side it's really just um a voltage monitor an lm358 to monitor the voltage to actually light this led to show it's charged it doesn't the current regulation is simply the energy capacity of this inductor when fully charged from the primary side the flyback circuitry and then when this side turns off and that dumps it puts out a portion of energy so the current limiting is ultimately in the transformer let's take a look at the circuit board we have the incoming supply which has a fusible resistor 4.7 ohm leading to a bridge rectifier and then there's a smoothing capacitor we've got the fm three seven eight three ga chip and it just has a support components it has a snubber network it has a the current sense circuitry it's got feedback circuitry and it's also bootstrap i'll show you this on the drawing the bootstrap is consisting of this diode here and this little electrolytic capacitor here on the output we have the rectifier diode and smoothing capacitor not very big uh and then we've got the lm358 to actually monitor the voltage and just switch the led that's all it does not too much to say about that horrible contrast of circuit board this is much better let's take a closer look i didn't draw the op-amp and maybe i should have but i didn't incoming supply 4.7 ohm resistor there's the bridge rectifier it's a discrete single package project far there's capacitor 6.8 microfarad a few components missing a few components added uh the bootstrap circuit for this chip the way it powers itself is initially current flows from the positive supply rail through this one mega ohm resistor to this capacitor charges it up once it's charged up to suitable level this then starts once it's started if everything is working if the output is not short-circuited uh it also as well as powering the output also powers via this diode it keeps that capacitor charged up and that's how this chip powers itself if something goes wrong if this gets shorted or it can't actually make up that power supply if this purse play goes wrong as well this capacitor it will do that bring blink blink hiccup thing because it's repeatedly trying to start and failing to start when it turns on there's a mosfet inside that the current flows in the positive through the primary uh down through the chip and then through these current sense resistors there's one ohm in parallel with 9.10 which means it will just be the total volume will be just slightly less than one ohm the lowest value takes a precedence here and that measures that basically regulates the amount of energy put into the transformer there's a feedback circuitry to show that things are good basically they've set a resistive divider here 15k and 7.5 k going to the feedback which also lets it monitor what's going on the transformer that is about it so this thing just blindly just pumps energize the transformer and then when it turns off the field collapses and that's when the current goes through that diode to the output so it puts control portions uh with magnetic isolation of energy through that the one other thing worthy of note here is this 100k in parallel with a one nanofarad capacitor and this diode from the primary what that does is when the transistor turns off in here there's initial quite high spike before this diode can start conducting it basically just nips off the peak of the emf the back emf that could otherwise the high voltage can damage this mosfet so it diverts it to this capacitor and this little resistor here just keeps trickle discharging that capacitor uh just to basically take a control chunk of that uh back emf spike but without actually shunting too much energy it's needed going through here after that it basically has an op amp uh driving the led i'll just draw this in roughly uh and the op amp monitors the voltage across a resistor going to the output is that resisting the positive negative it's actually i think it's in the negative so it actually uh monitors the voltage drop across that resistor and if it sees a significant voltage drop it knows that this battery is still charging but if it sees the voltage equaling our side it will signal to this op-amp that that there's no charge current going out and that's just when it says charged and it does that trick there are two leds let me bring the drain in again there are two leds in this package one is powered continually and the other one uh probably the green one and the other one the red one is switched by the lm358 and instead of turning the green off all it does is it switches the red one on it swamps the green out to show that it is charging and when it has charged it turns that red led off and the green light shows even though it was lit all the time in the background so what my thoughts on this thing in general the batteries are typical of a battery pack for a tool it's not bad good decent springy contacts good solid contacts i guess it is based on another brand's battery uh interesting the charging port is built onto it it does have the protection as the option for you to upgrade that protection with another mosfet or they'd probably have to be matched and it does have both discharge protection it has charge protection with full monitoring i should brighten this image of a wheat head there we go it's not bad it's a generic package um the case that for the power supply snaps together very tightly to the point it was very hard to get apart um the tool itself it has a plastic gearbox that's no great deal because the main components here are steel that the bearing here uh presumably a sleeve bearing uh the motor looks beefy you can't really tell how well it's going to last the little regulator will instantly disintegrate it'll be full if i try opening it will have a minimum number of components just for the variable control using positive modulation and a little battery connector that slides in you know it's worth almost worth actually getting something like this just for the batteries the charger and this sort of bit down here the connector because then you can tap into the battery and you could just make a little power supply it uses these it's very it's surprisingly good i shall say how long would it last in continuous use i'm not really sure but the construction in general um looks pretty typical i guess that's just what happens you mass produce things the batteries look acceptable the construction of the unit looks acceptable it just seems like a fairly decent generic unit just lacking that safety that is kind of essential just that little double function that you know uh you have to press make a concerted effort to push that button that's the biggest weakness it's a fairly stiff springy plunger but there's still that risk that you know particularly if this got into the hands of kids or something like that that you could hurt yourself because chainsaws are ruthless they they are they're not very friendly to hands and faces and body parts at all but other than those uh those things that safety issue it seems okay

Channel: bigclivedotcom

Views: 221,205

Keywords: 18v, 21v, cordless, rechargeable, pocket, chainsaw, gardening, branch, trimming, dangerous, safety, interlock

Id: tgNGHehIsSw

Length: 24min 11sec (1451 seconds)

Published: Sun Sep 05 2021

Reddit Comments

[u/stivo]

Finally someone taking tools apart. I long for the good old days when ave put out good content. Now it's just filler bs about chickens and clutches or cement mixing or some bull shit. He's milking the system.

[u/FBAHobo]

Time!