Thank you Luca for the additional advice to make this BK11 mini spot welder to work reliably. I had bought a BL01-2K mini spot welder and was worry about some of these design/manufacturing problems and not dare to use it until it is mature enough over time. Thank you for the in-depth explanation on this product. Brilliant, priceless and appreciated. Thank you Luca.
Hi, Luca I just did mod. This time I was lucky so diode wasn't burned. Now with 3 FETs I am getting even stronger weld. Thanks a lot. Your work with this is great.
I Luca, Thanks a lot for all these videos. I began using this welder as a basic customer (plug it and play with). I did not ran into problems with this welder but I was worried by the spark seen when I connected it to the battery. I have to precise that I use a booster/starter portable battery that can deliver 1000A (peek 2000A). So I started to look into the box and was astonished by this huge capacitor: 10000 µF are quite unusual. So I quickly find the diode (which was burned/shorted) and noticed the lack of drop resistance in serial between. Get rid of the SMD (dead) diode and put two 10 ohm in parallel followed by two 1N4xxx in parallel - not the best choice but I had them in stock). Bingo no more sparks and my diode are still alive. Then I think to google on it and find your videos. So I congratulate you for these analysis and for sharing it. The fact I used a powerful booster battery probably explain why I didn't ran into more trouble. I'm myself an electronic engineer for more than 30 years and I agree with the poor manufacturing quality (I re-flux many soldering). But the product is cheap (less expensive than the MOS) so I am not surprised. Again, very nice video, excellent analysis and congratulation. Best regards. Michel
Hi Luca!!! BINGO!! You have found my first board BL01-2K failure!! The diode in the my board is short circuited!!! I have blown 3 power mosfet!! Now I am waiting the 10 x 4N04R8 I have purchased...
Luca, THANK YOU SO VERY MUCH for all of your videos! I am so happy I found them as the “capacitor” videos of others didn’t make sense. Your video for my CR04-2K was perfect and so very helpful!!! As an engineer, I really liked your freestyle analysis.
I want to say thank you. I received one of these and opened it up when I first got it and noticed a resister stuck (not soldered) to the controller board and noticed the missing resister. Well I put it back on thinking it was a defect from the factory. As we now know it is not. Well powered it up and tried to use it and it powered up seem to work fine sensed and acted like it was welding but nothing. Well did the 470ohm controller mod and the 15ohm mod from the battery. Turned out the diode was bad. Lucky for me I had a few parts and a soldering iron. It's not pretty as it was repaired with thru hole parts but for the first time it works.
Good job diagnosing that and coming up with a fix. My original welder never had any spark when connecting the battery and never had any output, even a low one, from the probes so I'm assuming the diode wasn't the problem. If I hadn't sent it back already I'd test it, but too late now. When the Wise Maple unit I ordered arrives I'll definitely be adding an inrush resistor, even if the smaller cap works around the problem there should be inrush protection. Thanks for the great work and the informative video!
I suspect your first one had a short between some Gate pin and the source or something similar - if you got no activity with a good battery there was surely no Gate pulse present. The Wise Maple will surely work.
Hey Luca, Kai here from reddit. Nice to see my schematic in your video :) Thank you for the investigation. Unbelivable - how many flaws can you design into such a simple circuit? I will check my board and add the resistor. I think I got lucky because I used a very old and weak battery, this might have saved the diode.
Hey Kai! Yeah that came in handy and saved me some time;) Yes I'm sure that with weaker batteries the diode may live a bit longer but it's prone to definitely fail (plus with a weaker battery u risk killing your FETs if it has failed;). Let's hope that this is the last flaw!.
These new welders have a few changes. I'm not tech enough to spot all of them, but they use alloy bus bars along the long solder traces. The diode that he put a resistor around is no longer there (or moved). I'd be curious how the units made today have improved over what is reviewed here.
@@Luca_Techy I've been working my way through your videos. (I just bought a new welder last month and have been looking at the differences. Welded together a 14s5p pack off a 38 ah AGM with the welder stock out of the box. I had to use "45" setting (ms?) to get good welds (.006" nickel) but then again I lengthened the battery leads 18" with 8 ga. wire. I'm sure that doesn't help performance. Thanks!
I was hoping someone would actually watch them as I was contacted by a Chinese company to review products but when I asked for a mini spot welder they had I never heard back!
It can work and has been done but it's in *no way* precise (a relay can't be as fast and precise in the sub 20 ms range as electronically driven FETs). There are videos showing many using a timer driving a 100Amp power relay and it does work though the spots are an overkill - plus they all use a modified MOT with the secondary removed and wound with 2 turns of AWG6 or less (not realy portable). It's all really too overkill plus it can even trip your household circuit breaker.
if it the inrush current from connecting to the battery cant you use an xt90 anti spark connector? the anti spark xt90 connector has a built in resistor to stop capacitors from causing sparks
Can the boards be modified to a separate power supply on the control board thus eliminating the voltage drop.Has any one used headway cells to power the board.
It is certainly possible but not really convenient as with the decoupling cap and the inrush current limit resistor you don't need to seperate the power lines - it would defeat the portability of the device. Just be sure to apply the correct mods and it will work fine within it's operation limits.
I hawe this second eddition of spot welder. With p7 diode and 4 resistors near. Connect this to 70Ah 12V car battery with good quality screw terminals. Try to make first weld with 20ms time. And one fet blew inmidiatly.
You need to apply 2 mods before using these welders safely - modify R4 with a 470 Ohm and add inrush current limiting resistor as explained in my videos.
@@primoziskra6394 If you apply the mods (swap R4 resistor with 470 Omhs, check Cap diode if not shorted and add 20 Ohm resistor in series) and check all the solderings it will work fine - just start your weld tests from 5ms value upwards, don't jump to 20 directly without testing.
Thanks for this video Luca; excellent work. I reckon that resistor will sort out most failures but the 20uS turn on time is very long indeed IMHO. (It would be interesting to see (on your Tek) if those gates are actually ringing.) I would have expected to design for around 200 - 500nS max? - but that would mean major mods. I shall leave you to do the hard work and wait a few more days before trying out my Bk11-1k. Thanks again for your hard work.
So who is selling the BJ-07. All the ones I have seen are earlier versions. (the one I got in January from an Amazon seller is the style with the driving transistors on the CPU board.) Searched ebay, and aliexpress for bj-07 bj07 and wise maple, nothing turned up. (in general the places I looked don't identify what version they are selling).
It depends what shorted: does it still turn on? Do the display and buttons work? If not there's not much you can do as the MCU is probably dead. If it works then you might have blown a FET and you need to remove it. I can't really help you in this situation.
The sole mod you would need is the current limiting resistor mod for diode safety. If you don't feel like modding the board just get a XT-90 "anti spark" connector and solder that to the power cables of the welder.
Hey Luca, How can I tell where this diode is on my board to modify the diode portion of the circuit. I would like to use this spot welder but I am not sure it has been revise as you show in your video. I don't want to blow the MOSFETs, I just purchased it
You can locate it by just looking and comparing the images shown in the video with your board - 99% you need to add the current limiting resistor as I haven't had any feedback on the matter. It's that black smd component near the positive terminal and capacitor as shown in the video with a stripe on one side. You can check my other latter videos for more info and circuit description.
As I said in my videos, I suggest AGM 12V 40Ah batteries (a car battery) for fire hazard reasons. However if you are in a protected environment you can use 3S LiPo packs with at least 50C discharge starting from 4000mAh (the more C the better). It will work even with a 2S pack - basically you are looking for the lowest internal resistance solution - it's the current that matters not the voltage in this application.
I have BL18-2k still new never used will add the resistor and check it thank u man I have a questing can i use the device wil DIY Li Ion 4S 15P Voltage (3.6 nominal) 14.4V Amp Hours 33.499 Ah Watt Hours 482 WWH
Hi ... I also need help ... I accidentally dropped the screwdriver in this transistor that says Y1 on it ... Can you tell me exactly what transistor it is to look for in an electronics store
Hi, it *should be* an SS8050 1.5A NPN transistor (you can never be 100% certain from these sources) as show here: lcsc.com/product-detail/Transistors-NPN-PNP_MMBT8050D-1-5A-Y1_C118742.html and here: www.alibaba.com/product-detail/Original-new-sot-23-Y1-smd_60364397308.html It is in the SOT-23 package (smd). It's PNP counterpart is the 8550 FYI. Be *sure* to replace it with the correct part as it is part of the gate push-pull circuit and an equivalent may not work properly.
Might I ask one more question can you explain to me a little bit about if I use a car battery/deep cycle instead of a three cell life of power this what do you mean by adding an additional resistor on the input like how many watt? you were saying something about a 50 ohm resistor there so I guess what specs what I need on that resistor and how exactly what I wire that to use a large 12 V deep cycle battery?Yes thank you so much for your time, sir I really have enjoyed watching your videos.
Dnes jsem opravil BK11-1K,je v pořádku. Neumím anglicky, text, dávám do překladače. Prosím uvolněte vše kolem zařízení, pomůžete všem, a číňan praskne vzteky, protože mu zbroušení na součástkách nepomohlo. Ba naopak ,se dozvěděl, že na druhé straně zeměkoule, jsou chytřejší lidí než v číňe. Jinak přeji mnoho úspěchů Z.
I must apologise in advance for my limited knowledge and experience of electronics although I do understand the principles slightly more than someone with no knowledge.After watching most of the videos on this particular product and the optimum levels for welding a 18650 I have to pose a question.with all the knowledge you guys have on this subject and this product,would it not be easier and cheaper designing a simple board that has a chip that is timed to 10 mil seconds with an on switch which we can add our own components to? By that I mean just the ICB and we buy and add everything to it including a time delay chip.Or instead of a chip a simple flip flop circuit timed at 10 mil secs?
The problem is that 10ms usually aren't enough to spot weld without a powerful battery plus consider that everyone has a different setup with a different battery condition so having a fixed delay is not versatile which is why this mini spot welder is handy (when all the qwirks are fixed). Cheap or similar solutions without an OLED screen simply have 3 fixed settings which you can manually set (low medium high or rather short average long) with a button and the state is indicated with a flashing LED. It's cheaper and also works (such as the BFRC) but is less fine tunable and you can't find that sweet spot or adjust the spot weld time a little while welding due to battery discharging and contacts heating up. The BFRC or similar without display are also fine if you do a few spot welds, it's really up to your needs.
@@txwingsrc7094 What do you mean? That's the whole display with control MCU and flat cable which connects to the connector on the board - what control board are you referring to?
Hey Luca! I finally built an 3s2p (6*18650) pack for my CA04-2K. Voltage is shown as 12.7v in the display. I have done all the mods besides the button (and checked them multiple times) on the welder before. But i doesn't work correctly: Everytime I try to weld, it just gives a little tick at the welding tips. The display turns off during the tick. Increasing the welding time with the buttons doesn't make any difference, it's always same. The MOSFETs are OK, there's no short. I don't have 12V lightbulb for doing the test right now :( Do you have an idea what this might be? Thank you! :)
If you experience a weak but present current peak you have to determine whether the FETs are getting the correct pulse and what current is being drawn. Are you certain your battery pack is able to handle 150+ Amps? 18650 cells are pretty weak in terms of peak current (rated 2C max usually) due to also their internal PTC. If you have a 2P you will max have a 5000mAh pack but pure Li-Ions are not rated for such high peak discharge currents, especially considering the small 2P configuration. I suggest you either get hold of a 3S 5000mA 50C LiPo pack or a regular 12V AGM 20Ah+ battery and try again starting from 5ms upwards.
@@Luca_Techy Hello! It's a bunch of unprotected CGR18650EA cells, that I salvaged from some old notebook battery packs. And probably you are right: They have just 2C continuous discharge current (at 2550mA capacity per cell), as I have seen now. When I was building the pack I had seen some datasheet claim these cells could do 10C peak current, but maybe this was overestimated. The reason I liked to use these cells is because I had them laying around and I only have an SkyRC-MC3000 charger. Getting a retail pack will require me to get another charger, too. Do you have a recommendation on an affordable 3S 5000mA 50C LiPo pack and an balanced charger? (An AGM ist way too bulky for my tiny workspace). And: The pack I built is not soldered, but actually consists of two x3 plugin adapters for 18650s. So, could I replace the cells by some of these?: Samsung INR18650-25R ) They are said to achieve 100A pulse.. Thank you so much :)
@@elmariachi5133 A good 3S 5000 50C LiPo pack is the one I linked in my previous video descriptions which I got from Banggood - payed around 30Euros if I remember correctly.
I watched your videos and will buy a BL18-2k or newer, unfortunately the seller is unable to tell me the PCB version. I have SS34 with I_FSM = 80A used by a different mini spot welder. Do you think substituting SS34 for M7 will work?
The type of diode and it's rating isn't really so important as long as it can handle over few amps or so of peak (not sustained) current - what's most important is to add a limiting inrush current resistor in series with the diode (before or after it), 10-20 Ohms or so.
The CA-04 revision has the same issue. 10 ohm / 12 v => peak power of 14W (even if briefly). Might better to use a higher value ? Addendum : I checked my first (blown) board, indeed the diode is shot. Nice catch ! I've fixed it slightly differently photos.app.goo.gl/i1Y2fuFDdrjYGQCbA you have to cut the track between the pad and V+ and move the diode to the right
The inrush current near instantly drops (in the millisecond range) to an acceptable current, 20 Ohms is pretty safe for a 12V source - the average power dissipated is very low - no worries. The 14Watts with a 10Ohm resistor would be with a continuous short, but in about 60ms it drops to 6V, you see what I mean. 20 Ohms is well on the safe side! I see you used an smd resistor so going up is safer for it. Yeah I didn't want to cut tracks so I went for a less intrusive mod for everyone using a non smd resistor, but whatever works and fixes it is fine! Cheers
No that is highly improbable (unless you overheated it when removing it which is also highly unlikely): are you sure your diode wasn't already shorted? It's highly probable that it was alsready shorted before!
@@hamidkeshvaripour2380 are you connecting the resistor in series with the diode? You have to remove the diode and add the 10Ohm resistor after it and connect the leg of the resistor to where one of the diode pads was soldered. So it's one contact -> diode -> resistor -> second contact. Hope you understand.
No, it looks maybe like that but I explained it is *in series* by desoldering the diode, turning it 180degrees to make space for the resistor and connect other side of the resistor to the pad where the diode was.
I don't believe he did - at least I have just the main PCB one. I made a KiCad one and the user meanX also made one posted on his blog here: goingbacktoelectronic.blogspot.com/2021/02/mini-spot-welder-better-schematic.html
@@Luca_Techy Ahhh, apologies Luca. Will you share your very nice KiCad schematic so that I may show it on the EEVBlog with full Credit to you of course :)
@@Luca_Techy Just read @Carlos Lopes comment.Why is it necessary to replace R4(=30 Ohm) with a 470 Ohm resistor? If the circuit diagram is correct then the much higher value of 470 Ohm would greatly(?) reduce the driving capability of Q2. Anyway:nice video....
@@toxytronic7364 R4 is 1K not 30 Ohms, you are mixing boards or labels - careful. R4 is on the MCU board and it is in series with pin 19 of the MCU before going down to the driver transistor on the main board. I show it in my previois videos several times
@@Luca_Techy I see....I was looking for R4 in the diagram in the video above.Thanks for clarifying - I haven't seen your other videos yet.Should you post another video maybe you could show a short summary of what you did so far and for each step you could then refer the appropriate video for further explaining.Just a suggestion as creating videos is already a lot of work.Thanks for giving such a speedy answer - appreciated !
That's my KiCad schematic - the STM was the closest (same outline). The MCU is a NUVOTON N76E003AT20 - a kind of STM8 series clone 8051 based but different IDE.
@@coolmonkey619 Well you could but keep in mind you shouldn't extend the welder power cables as they are "calibrated" for that energy. If you extend them using for ex. jumper cables you would have to use very good quality cables and even then you would have losses (they inherently have a small resistance no matter how good they are, plus the alligator clips have their losses). Also, if your car is a modern carn with Intelligent Battery System analyzer alwayshooked up, these large current pulses may trigger some red flags in your car's diagnostic as the voltage would drop below 12V. If your car has none of these devices then just take care not to make any shorts. Overall I would suggest getting a 3S 5000mAh 50C+ Lipo or using a seperate Lead Acid or AGM battery.
With everything disconnected using a multimeter in continuity (Ohms) test to see that there is no short between Drain an Source (negative of battery and negative contact terminal).
@@txwingsrc7094 All the schematics and parts of the various spot welders are described in this video and you can download them from the links in the description: ruclips.net/video/RSrlXqFxhp8/видео.html
U do a very good job luca, could you help me to fix mine, nothing happens after the 3 beeps, the mosfet are not driven. Maybe in messenger or whatsapp, is would be easier to share pictures or videos. Thanks for your work.
@@hamidkeshvaripour2380 I did it, and I removed the shorted one but now, I have the 3 beeps but no current in the mosfets. On the other one, no mosfet died, but I have the 3 beeps too and no current in the mosfets.
Power MOSFET's $1.75 each (US) from www.allelectronics.com/item/mtp75n03hdl/power-mosfet-mtp75n03hdl/1.html - 1n4007 diodes are 10 for $1 and 1000uF/16volt 40 cents each, 1/2 watt resistors are 10 for 80 cents. I known and dealt with this company for more than 40 years. They do mail order. I'm not getting anything from them for this. I just know of them and have bought stuff from them myself.
Thank you Luca for the additional advice to make this BK11 mini spot welder to work reliably. I had bought a BL01-2K mini spot welder and was worry about some of these design/manufacturing problems and not dare to use it until it is mature enough over time. Thank you for the in-depth explanation on this product. Brilliant, priceless and appreciated. Thank you Luca.
You're welcome!
I have a BL01-2K, just checked the diode and it was shorted, Thanks for all your work already did the 470 ohm mod. I am using a 6000mah 60c battery
Hi, Luca I just did mod. This time I was lucky so diode wasn't burned. Now with 3 FETs I am getting even stronger weld. Thanks a lot. Your work with this is great.
I Luca,
Thanks a lot for all these videos.
I began using this welder as a basic customer (plug it and play with). I did not ran into problems with this welder but I was worried by the spark seen when I connected it to the battery. I have to precise that I use a booster/starter portable battery that can deliver 1000A (peek 2000A). So I started to look into the box and was astonished by this huge capacitor: 10000 µF are quite unusual.
So I quickly find the diode (which was burned/shorted) and noticed the lack of drop resistance in serial between. Get rid of the SMD (dead) diode and put two 10 ohm in parallel followed by two 1N4xxx in parallel - not the best choice but I had them in stock). Bingo no more sparks and my diode are still alive.
Then I think to google on it and find your videos.
So I congratulate you for these analysis and for sharing it. The fact I used a powerful booster battery probably explain why I didn't ran into more trouble.
I'm myself an electronic engineer for more than 30 years and I agree with the poor manufacturing quality (I re-flux many soldering). But the product is cheap (less expensive than the MOS) so I am not surprised.
Again, very nice video, excellent analysis and congratulation.
Best regards. Michel
Hi Luca!!! BINGO!! You have found my first board BL01-2K failure!! The diode in the my board is short circuited!!! I have blown 3 power mosfet!! Now I am waiting the 10 x 4N04R8 I have purchased...
Luca, THANK YOU SO VERY MUCH for all of your videos! I am so happy I found them as the “capacitor” videos of others didn’t make sense. Your video for my CR04-2K was perfect and so very helpful!!! As an engineer, I really liked your freestyle analysis.
I want to say thank you. I received one of these and opened it up when I first got it and noticed a resister stuck (not soldered) to the controller board and noticed the missing resister. Well I put it back on thinking it was a defect from the factory. As we now know it is not. Well powered it up and tried to use it and it powered up seem to work fine sensed and acted like it was welding but nothing.
Well did the 470ohm controller mod and the 15ohm mod from the battery. Turned out the diode was bad.
Lucky for me I had a few parts and a soldering iron. It's not pretty as it was repaired with thru hole parts but for the first time it works.
Good job diagnosing that and coming up with a fix. My original welder never had any spark when connecting the battery and never had any output, even a low one, from the probes so I'm assuming the diode wasn't the problem. If I hadn't sent it back already I'd test it, but too late now. When the Wise Maple unit I ordered arrives I'll definitely be adding an inrush resistor, even if the smaller cap works around the problem there should be inrush protection. Thanks for the great work and the informative video!
I suspect your first one had a short between some Gate pin and the source or something similar - if you got no activity with a good battery there was surely no Gate pulse present. The Wise Maple will surely work.
Thank you for the info.....I've done the mods you have showed and my welder seems to be working well.
Hey Luca, Kai here from reddit. Nice to see my schematic in your video :)
Thank you for the investigation. Unbelivable - how many flaws can you design into such a simple circuit? I will check my board and add the resistor. I think I got lucky because I used a very old and weak battery, this might have saved the diode.
Hey Kai! Yeah that came in handy and saved me some time;) Yes I'm sure that with weaker batteries the diode may live a bit longer but it's prone to definitely fail (plus with a weaker battery u risk killing your FETs if it has failed;). Let's hope that this is the last flaw!.
thank you for your analysis of the circuit.
I love your "daily soap". Great stuff!
Glad you enjoy it!
I love this analysis.
These new welders have a few changes. I'm not tech enough to spot all of them, but they use alloy bus bars along the long solder traces. The diode that he put a resistor around is no longer there (or moved). I'd be curious how the units made today have improved over what is reviewed here.
I haven't had the chance to review any updated bk/bl versions - be sure to check out my other videos on the different versions in the playlist.
@@Luca_Techy I've been working my way through your videos. (I just bought a new welder last month and have been looking at the differences. Welded together a 14s5p pack off a 38 ah AGM with the welder stock out of the box. I had to use "45" setting (ms?) to get good welds (.006" nickel) but then again I lengthened the battery leads 18" with 8 ga. wire. I'm sure that doesn't help performance. Thanks!
Good that you noticed that flaw, you are more professional than the guys whose design this circuit.
_R-E-S-P-E-C-T_
You need to do this video in Chinese so the kids at the factory can make changes to the design.
I was hoping someone would actually watch them as I was contacted by a Chinese company to review products but when I asked for a mini spot welder they had I never heard back!
The inrush current can also destroy the 10,000uF capacitor, which might be spectacular.
Mine was killed on the first attempt unfortunately. I wonder if a mechanical relay would work better instead of the electronic solution with fets.
It can work and has been done but it's in *no way* precise (a relay can't be as fast and precise in the sub 20 ms range as electronically driven FETs). There are videos showing many using a timer driving a 100Amp power relay and it does work though the spots are an overkill - plus they all use a modified MOT with the secondary removed and wound with 2 turns of AWG6 or less (not realy portable). It's all really too overkill plus it can even trip your household circuit breaker.
if it the inrush current from connecting to the battery cant you use an xt90 anti spark connector?
the anti spark xt90 connector has a built in resistor to stop capacitors from causing sparks
Yes if you use the inrush current limiting XT connector (with green strip) you needn't apply that mod.
Can the boards be modified to a separate power supply on the control board thus eliminating the voltage drop.Has any one used headway cells to power the board.
It is certainly possible but not really convenient as with the decoupling cap and the inrush current limit resistor you don't need to seperate the power lines - it would defeat the portability of the device. Just be sure to apply the correct mods and it will work fine within it's operation limits.
Thanks for your great job
I hawe this second eddition of spot welder. With p7 diode and 4 resistors near. Connect this to 70Ah 12V car battery with good quality screw terminals. Try to make first weld with 20ms time. And one fet blew inmidiatly.
You need to apply 2 mods before using these welders safely - modify R4 with a 470 Ohm and add inrush current limiting resistor as explained in my videos.
@@Luca_Techy Thanx. And I can use it with 4 fets only after mod? Of course I will remove burned fet.
@@primoziskra6394 If you apply the mods (swap R4 resistor with 470 Omhs, check Cap diode if not shorted and add 20 Ohm resistor in series) and check all the solderings it will work fine - just start your weld tests from 5ms value upwards, don't jump to 20 directly without testing.
Thanks for this video Luca; excellent work. I reckon that resistor will sort out most failures but the 20uS turn on time is very long indeed IMHO. (It would be interesting to see (on your Tek) if those gates are actually ringing.) I would have expected to design for around 200 - 500nS max? - but that would mean major mods. I shall leave you to do the hard work and wait a few more days before trying out my Bk11-1k. Thanks again for your hard work.
I did some more analysis and will make another video exactly about this, a little more in depth on rise and fall time
Thank you for the useful information keep it up.
Very well explained, Thanks. Completely understand.
Great to hear!
So who is selling the BJ-07. All the ones I have seen are earlier versions. (the one I got in January from an Amazon seller is the style with the driving transistors on the CPU board.) Searched ebay, and aliexpress for bj-07 bj07 and wise maple, nothing turned up. (in general the places I looked don't identify what version they are selling).
I linked the aliexpress listing in my previois Yet Another Mini Spot welder video, it's in the description.
nice video but i still haven't seen a spark
i have another diode soldered Shockley diode or a P-n
i hope the right diode
I think I just blew up my welder when something fell inside it. It no longer works. How can I troubleshoot it?
It depends what shorted: does it still turn on? Do the display and buttons work? If not there's not much you can do as the MCU is probably dead. If it works then you might have blown a FET and you need to remove it. I can't really help you in this situation.
@@Luca_Techy It does not turn on.
Ok that was a lot. So your saying no upgrades needed for the W maple?
The sole mod you would need is the current limiting resistor mod for diode safety. If you don't feel like modding the board just get a XT-90 "anti spark" connector and solder that to the power cables of the welder.
Hey Luca, How can I tell where this diode is on my board to modify the diode portion of the circuit. I would like to use this spot welder but I am not sure it has been revise as you show in your video. I don't want to blow the MOSFETs, I just purchased it
You can locate it by just looking and comparing the images shown in the video with your board - 99% you need to add the current limiting resistor as I haven't had any feedback on the matter. It's that black smd component near the positive terminal and capacitor as shown in the video with a stripe on one side. You can check my other latter videos for more info and circuit description.
What's the part number for those MOSFETs?
4N04R8 - There's a link to all the major components in the descriptions of my videos
@@Luca_Techy Where is that?
Whats a about the bl15 2k model
Great stuff, thanks for sharing! 👍
thank you for your time great info. so i have a question this board claim you can use a lithium battery pack what do you think about it
As I said in my videos, I suggest AGM 12V 40Ah batteries (a car battery) for fire hazard reasons. However if you are in a protected environment you can use 3S LiPo packs with at least 50C discharge starting from 4000mAh (the more C the better). It will work even with a 2S pack - basically you are looking for the lowest internal resistance solution - it's the current that matters not the voltage in this application.
I have BL18-2k still new never used will add the resistor and check it thank u man
I have a questing can i use the device wil DIY Li Ion 4S 15P
Voltage (3.6 nominal) 14.4V Amp Hours 33.499 Ah Watt Hours 482 WWH
Hi ... I also need help ... I accidentally dropped the screwdriver in this transistor that says Y1 on it ... Can you tell me exactly what transistor it is to look for in an electronics store
Hi, it *should be* an SS8050 1.5A NPN transistor (you can never be 100% certain from these sources) as show here: lcsc.com/product-detail/Transistors-NPN-PNP_MMBT8050D-1-5A-Y1_C118742.html
and here:
www.alibaba.com/product-detail/Original-new-sot-23-Y1-smd_60364397308.html
It is in the SOT-23 package (smd). It's PNP counterpart is the 8550 FYI.
Be *sure* to replace it with the correct part as it is part of the gate push-pull circuit and an equivalent may not work properly.
@@Luca_Techy so do you think I should take SS8550 as y1?

No, you need the same type that failed which is an NPN 8050 type.
@@Luca_Techy RON 3.27 | 100PCS SS8050 SOT23 MMBT8050 SOT MMBT8050LT1G SMD Y1 SOT-23 new transistor
a.aliexpress.com/_m0TBSgN
if this order is okay?
@@Luca_Techy Hi, I'm bothering you ... I found it on a plate smd j3y .Will it work with this?
Now im lost if im going to modify bl01-2k when it arrives or order wm version right now
That's what I have and died before welding my first battery, do it before using this crap!
So what watt value for the 10 ohm resistor and what watt value for the 470 ohm resistor?Thanks
Any 1/4 Watt or even 1/8 Watt will do fine.
Thanks!
So a 1/8 watt on both the 20 ohm and the 470 ohm?
@@CustomBuiltDIY Yes that's fine.
Might I ask one more question can you explain to me a little bit about if I use a car battery/deep cycle instead of a three cell life of power this what do you mean by adding an additional resistor on the input like how many watt? you were saying something about a 50 ohm resistor there so I guess what specs what I need on that resistor and how exactly what I wire that to use a large 12 V deep cycle battery?Yes thank you so much for your time, sir I really have enjoyed watching your videos.
Thanks for the thorough rundown on these mini spot welders. Is there a listing for the "Wise Maple" mini spot welder, that do not require any mod?
Yes it's in my prior video here: ruclips.net/video/n2qybkfKlAU/видео.html
Ahh, shouldv checked. Many thanks ! 👍🏻
Dnes jsem opravil BK11-1K,je v pořádku. Neumím anglicky, text, dávám do překladače. Prosím uvolněte vše kolem zařízení, pomůžete všem, a číňan praskne vzteky, protože mu zbroušení na součástkách nepomohlo. Ba naopak ,se dozvěděl, že na druhé straně zeměkoule, jsou chytřejší lidí než v číňe. Jinak přeji mnoho úspěchů Z.
I must apologise in advance for my limited knowledge and experience of electronics although I do understand the principles slightly more than someone with no knowledge.After watching most of the videos on this particular product and the optimum levels for welding a 18650 I have to pose a question.with all the knowledge you guys have on this subject and this product,would it not be easier and cheaper designing a simple board that has a chip that is timed to 10 mil seconds with an on switch which we can add our own components to? By that I mean just the ICB and we buy and add everything to it including a time delay chip.Or instead of a chip a simple flip flop circuit timed at 10 mil secs?
The problem is that 10ms usually aren't enough to spot weld without a powerful battery plus consider that everyone has a different setup with a different battery condition so having a fixed delay is not versatile which is why this mini spot welder is handy (when all the qwirks are fixed). Cheap or similar solutions without an OLED screen simply have 3 fixed settings which you can manually set (low medium high or rather short average long) with a button and the state is indicated with a flashing LED. It's cheaper and also works (such as the BFRC) but is less fine tunable and you can't find that sweet spot or adjust the spot weld time a little while welding due to battery discharging and contacts heating up. The BFRC or similar without display are also fine if you do a few spot welds, it's really up to your needs.
Helpful, thank you
Is there anywhere I can buy just the display/control board? I have ruined some copper traces on mine in an attempt to replace the 3.3v regulator.
They sell the display on Aliexpress. All the links are in the descriptions in my other videos
@@Luca_Techy I can't find the display. Do you have a link?
@@txwingsrc7094 check the description of my video here: ruclips.net/video/VQR9cTcP5Bo/видео.html
@@Luca_Techy Still can't find a control board for it.
@@txwingsrc7094 What do you mean? That's the whole display with control MCU and flat cable which connects to the connector on the board - what control board are you referring to?
Hey Luca! I finally built an 3s2p (6*18650) pack for my CA04-2K. Voltage is shown as 12.7v in the display. I have done all the mods besides the button (and checked them multiple times) on the welder before. But i doesn't work correctly: Everytime I try to weld, it just gives a little tick at the welding tips. The display turns off during the tick. Increasing the welding time with the buttons doesn't make any difference, it's always same. The MOSFETs are OK, there's no short.
I don't have 12V lightbulb for doing the test right now :(
Do you have an idea what this might be?
Thank you! :)
If you experience a weak but present current peak you have to determine whether the FETs are getting the correct pulse and what current is being drawn. Are you certain your battery pack is able to handle 150+ Amps? 18650 cells are pretty weak in terms of peak current (rated 2C max usually) due to also their internal PTC. If you have a 2P you will max have a 5000mAh pack but pure Li-Ions are not rated for such high peak discharge currents, especially considering the small 2P configuration. I suggest you either get hold of a 3S 5000mA 50C LiPo pack or a regular 12V AGM 20Ah+ battery and try again starting from 5ms upwards.
@@Luca_Techy Hello! It's a bunch of unprotected CGR18650EA cells, that I salvaged from some old notebook battery packs. And probably you are right: They have just 2C continuous discharge current (at 2550mA capacity per cell), as I have seen now. When I was building the pack I had seen some datasheet claim these cells could do 10C peak current, but maybe this was overestimated. The reason I liked to use these cells is because I had them laying around and I only have an SkyRC-MC3000 charger. Getting a retail pack will require me to get another charger, too.
Do you have a recommendation on an affordable 3S 5000mA 50C LiPo pack and an balanced charger? (An AGM ist way too bulky for my tiny workspace).
And: The pack I built is not soldered, but actually consists of two x3 plugin adapters for 18650s. So, could I replace the cells by some of these?: Samsung INR18650-25R )
They are said to achieve 100A pulse..
Thank you so much :)
@@elmariachi5133 A good 3S 5000 50C LiPo pack is the one I linked in my previous video descriptions which I got from Banggood - payed around 30Euros if I remember correctly.
Awesome video. Great work.
how about replacing it with M1 diode?
I watched your videos and will buy a BL18-2k or newer, unfortunately the seller is unable to tell me the PCB version. I have SS34 with I_FSM = 80A used by a different mini spot welder. Do you think substituting SS34 for M7 will work?
The type of diode and it's rating isn't really so important as long as it can handle over few amps or so of peak (not sustained) current - what's most important is to add a limiting inrush current resistor in series with the diode (before or after it), 10-20 Ohms or so.
@@Luca_Techy Very true!
The CA-04 revision has the same issue. 10 ohm / 12 v => peak power of 14W (even if briefly). Might better to use a higher value ? Addendum : I checked my first (blown) board, indeed the diode is shot. Nice catch ! I've fixed it slightly differently photos.app.goo.gl/i1Y2fuFDdrjYGQCbA you have to cut the track between the pad and V+ and move the diode to the right
The inrush current near instantly drops (in the millisecond range) to an acceptable current, 20 Ohms is pretty safe for a 12V source - the average power dissipated is very low - no worries. The 14Watts with a 10Ohm resistor would be with a continuous short, but in about 60ms it drops to 6V, you see what I mean. 20 Ohms is well on the safe side! I see you used an smd resistor so going up is safer for it. Yeah I didn't want to cut tracks so I went for a less intrusive mod for everyone using a non smd resistor, but whatever works and fixes it is fine! Cheers
Hi The diode looks revised in the photo?
Yes it's an SS1 not an M7, doesn't really change anything, you still need an inrush current resistor.
@@Luca_Techy Thanks I will apply the mods, I have just received the welder today
after adding 10 ohm resister shorts the diode! is that normal?
No that is highly improbable (unless you overheated it when removing it which is also highly unlikely): are you sure your diode wasn't already shorted? It's highly probable that it was alsready shorted before!
@@Luca_Techy no when I remove it the short goes away!
@@hamidkeshvaripour2380 are you connecting the resistor in series with the diode? You have to remove the diode and add the 10Ohm resistor after it and connect the leg of the resistor to where one of the diode pads was soldered. So it's one contact -> diode -> resistor -> second contact. Hope you understand.
@@Luca_Techy what you did is parallel to diode one side of resister to pos and the other side to after diode.
No, it looks maybe like that but I explained it is *in series* by desoldering the diode, turning it 180degrees to make space for the resistor and connect other side of the resistor to the pad where the diode was.
Can you please provide a link to the MCU schematic that Hieroben_de produced. I found his MOSFET board schematic but not the MCU one. Thank You :)
I don't believe he did - at least I have just the main PCB one. I made a KiCad one and the user meanX also made one posted on his blog here:
goingbacktoelectronic.blogspot.com/2021/02/mini-spot-welder-better-schematic.html
@@Luca_Techy Ahhh, apologies Luca. Will you share your very nice KiCad schematic so that I may show it on the EEVBlog with full Credit to you of course :)
@@fraserc9768 here's the circuit: drive.google.com/file/d/1HF3QXNXZBXH32uNsXtW9mG0vrX7RZF2V/view?usp=sharing
@@Luca_Techy Thank you. I have requested access to the file on the Google Drive :)
@@fraserc9768 You should be able to now
Someone told me to change R4 to 470ohms.
Is it necessary?
It's highly suggested to keep those Gates happily driven! P.S. R4 is the 1K resistor *on the MCU board* for clarity, not on the main FET board.
@@Luca_Techy Just read @Carlos Lopes comment.Why is it necessary to replace R4(=30 Ohm) with a 470 Ohm resistor? If the circuit diagram is correct then the much higher value of 470 Ohm would greatly(?) reduce the driving capability of Q2.
Anyway:nice video....
@@toxytronic7364 R4 is 1K not 30 Ohms, you are mixing boards or labels - careful. R4 is on the MCU board and it is in series with pin 19 of the MCU before going down to the driver transistor on the main board. I show it in my previois videos several times
@@Luca_Techy I see....I was looking for R4 in the diagram in the video above.Thanks for clarifying - I haven't seen your other videos yet.Should you post another video maybe you could show a short summary of what you did so far and for each step you could then refer the appropriate video for further explaining.Just a suggestion as creating videos is already a lot of work.Thanks for giving such a speedy answer - appreciated !
STM85003F3P ?????????????????? + circuit diagram with board ???
That's my KiCad schematic - the STM was the closest (same outline). The MCU is a NUVOTON N76E003AT20 - a kind of STM8 series clone 8051 based but different IDE.
I can use a car battery right
Yes a 12V 45Ah AGM will do.
@@Luca_Techy what about lead acid?
@@coolmonkey619 that's fine too of course, it's equivalent in terms of discharge to an AGM.
@@Luca_Techy can I keep my car connected because its not easy to take the battery out
@@coolmonkey619 Well you could but keep in mind you shouldn't extend the welder power cables as they are "calibrated" for that energy. If you extend them using for ex. jumper cables you would have to use very good quality cables and even then you would have losses (they inherently have a small resistance no matter how good they are, plus the alligator clips have their losses). Also, if your car is a modern carn with Intelligent Battery System analyzer alwayshooked up, these large current pulses may trigger some red flags in your car's diagnostic as the voltage would drop below 12V. If your car has none of these devices then just take care not to make any shorts. Overall I would suggest getting a 3S 5000mAh 50C+ Lipo or using a seperate Lead Acid or AGM battery.
How can I test the MOSFETS?
With everything disconnected using a multimeter in continuity (Ohms) test to see that there is no short between Drain an Source (negative of battery and negative contact terminal).
@@Luca_Techy OK. It seems the 3.3 volt regulator is bad. What's the part number? Nothing written on it.
@@txwingsrc7094 All the schematics and parts of the various spot welders are described in this video and you can download them from the links in the description: ruclips.net/video/RSrlXqFxhp8/видео.html
U do a very good job luca, could you help me to fix mine, nothing happens after the 3 beeps, the mosfet are not driven. Maybe in messenger or whatsapp, is would be easier to share pictures or videos. Thanks for your work.
just check the single point or gate on your mosfet to the ground (Drain)and to the source of the mosfet for each five to see which one is shorted!
@@hamidkeshvaripour2380 I did it, and I removed the shorted one but now, I have the 3 beeps but no current in the mosfets. On the other one, no mosfet died, but I have the 3 beeps too and no current in the mosfets.
@@SebVsR make sure it’s not set to manual mode, if it is then it’s waiting for switch contact.
@@hamidkeshvaripour2380 if it was on manual mode, I shouldn't have the 3 beeps. It is in auto mode.
@@SebVsR sebast, send Luca the message he is the one who knows, I told you what I knew!
You are genius!!! 👌👌👍👍👍
Just trying to help out;) Cheers!
Power MOSFET's $1.75 each (US) from www.allelectronics.com/item/mtp75n03hdl/power-mosfet-mtp75n03hdl/1.html - 1n4007 diodes are 10 for $1 and 1000uF/16volt 40 cents each, 1/2 watt resistors are 10 for 80 cents. I known and dealt with this company for more than 40 years. They do mail order. I'm not getting anything from them for this. I just know of them and have bought stuff from them myself.
I had 2 of these spot welders,simply its piece of crap,no protection,mosfets blows up, or you get defective unit.
That's absolutely true and that's also why I decided to make these videos so you wouldn't just throw away your money and at least fix them!
You must be an electrical engineer? It it hard to solder these very tiny components?
If you've never soldered any component on any pcb before then it's a very hard first attempt - better ask for some help!
The man is mal hero
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