diyBMS - Soldering a Cell Module - 12v Solar Shed

[@TheAnqueetas]

Better than Season 8 of Game of Thrones! Can't wait for next episode.

[@AdamWelchUK]

High praise indeed (although I haven't seen it)!

[@TheAnqueetas]

It's due to premier in 2019! Too long. I'd like your input on another BMS that is in develeopment over here secondlifestorage.com/t-18650-equaliser. Brian Drury calls it an 18650 equaliser. It uses the power in floating cells to balance the main pack, which he calls the static cells. So no wasting energy to heat via a resister. Looks like a brilliant idea.

[@lonnie776]

Looking forward to the next video. I will probably have to build one of these in the future.

[@CrankyCoder]

I ordered my pcb yesterday for this! I got mine coming with the laser cut stencil too.

[@jaymiddleton772]

That's fantastic! I always thought SMD was really just out of reach for enthusiasts. I'm going to pick up a SMD station and have a go!

[@AdamWelchUK]

Cool. Good luck!

[@ernestmyers2805]

This video was very enjoyable. I can't wait to see your next video on this device.

[@CrankyCoder]

Adam this was such a fantastic find. I have been trying to figure out how to build something for my batteries too. This is now the second time you have been able to help me move forward. Last time on the pwm charge controller. Keep up the work man.

[@AdamWelchUK]

Good to hear - thanks.

[@ahaveland]

smds are a whole new world of fun.. tip, suggest keeping the blade at around 45° angle or higher. It's not quite like plastering a wall - if the wiper angle is too flat it could push the solder paste under the mask. Ideally one wipe should be enough to fill the voids.

[@AdamWelchUK]

Cheers Andy. I might find a more suitable spreader too!

[@hisanglinliew9937]

Looking forward to the next video By the way, can you do an update for the 555 Desulfator Kit you have build last year? I am planing to buy one. Thanks!

[@RWBHere]

It looks as though that resistor should be 470R, giving a current closer to 10mA. Thanks for the informative video, Adam.

[@vgamesx1]

10:48 That's some interesting reading material you've got there, gonna have to pick one of those up sometime.

[@AdamWelchUK]

Every night before bed I try to read at least one chapter. :-)

[@spikeydapikey1483]

Quick tip, use a loop of sticky tape to lift the solder stencil when finished applying the paste. HTH.

[@AdamWelchUK]

Good tip. Thanks.

[@Pops180]

When reflowing small SMD, use more heat and less air. It's a feel sort of thing. You'll get better with time.

[@WereCatf]

Whenever I do SMD-components, I always try to apply heat from straight up instead of from the side like you do, because it seems to me that the components don't fly around quite as easily then. Of course, adjusting the airflow down can also help.

[@AdamWelchUK]

Yes thank you. I'll definitely try that with the next six boards. It was tricky with the camera and the height I have to play with above the bench. Airflow was set pretty low, so the direction must be the issue.

[@WereCatf]

Adam Welch I do realize the issues with camera and I don't have any particularly good recommendations on that. Maybe look at the Reflowr, if you plan on doing more SMD in the future? I'm going to get one myself as soon as my budget allows.

[@lalortech5286]

Hi Adam, I built two of cell modules and two controllers, while I can get the controllers to work, they cannot detect any of the cell modules, I am guessing it is something to do with I2C, I checked all the voltages on both sides of the circuit all within spec of 3.3v, I don,t have a oscilloscope to check the I2C signal. If I send one of my cell modules to you, it could be a nice repair video for you, let me know if you are interested.

[@threeparots1]

Nicely done sir...very informative and interesting..

[@3D_Printing]

17:12 air blows it over: just read: I'm fairly sure it was due to the angle of the blown air - as a few people have pointed out straight down should work best. It was tricky though with the camera in the way. However there is also a chance that my solder was going off a little due to the extended time of filming also the ambient temperature in the shed was dropping. Take your pick! 1

[@MrBrymstond]

It all worked out fine.

[@electronic7979]

Excellent

[@shehryarshaheen7115]

Dear adam Absolutely love your videos.because You provide well organized step by step easy solutions for a complicated process. Please build Julian ilett's muppet 1. Or at least upload the code for muppet 1 on your website. Because muppet 2 will take a while.

[@AdamWelchUK]

Muppet is nothing to do with me but I have a feeling Julian did release the code somewhere? Anyway, thanks for the nice comments

[@oldtimeengineer26]

high Adam glad I was late ordering mine. Do you have a parts buying guide or list. I know I can do one from the schematic but figured I would ask first? Thanks for doing this I will start mine soon. One last question are all the resistor and caps 1206 smd?

[@rhyslbw]

At the bottom of the project's Readme: github.com/stuartpittaway/diyBMS/blob/master/README.md

[@AdamWelchUK]

Yes as mentioned Stuart lists the parts, but do double check against the schematic. All parts are 1206 - not too small thankfully. Cheers OTE

[@snipersquad100]

Hey Adam, What's the name of the cable connectors and the fuse, I can't seem to find them on github page. Thank You.

[@graemepinnock]

Hi Adam, another great video but I think your LED resistor calculation is not quite right. You need to subtract the forward voltage of the LED from the supply (battery) voltage to calculate the voltage across the resistor. The forward voltage of LED depends on the colour but the diode test setting on your meter (that you used to test polarity in the video) should tell you the forward voltage of your LED. It flashed up as about 1.7v I think. If that was the case then voltage drop across the resistor will be 4.2v - 1.7v = 2.5v. Assuming you want a maximum led current of say 20 mA then 2.5v divided by 0.02A = 125 ohms.

[@AdamWelchUK]

Thanks - yes I should have thought about that, I was working it out more like a resistor wasn't I? The led in question was red, so a low forward voltage. I'll see how bright it is once this is up and running adjust if I need to. Thanks again Graeme for the full explanation.

[@JulianIlett]

Hi Adam - do you think C2 rotated due to surface tension of the solder, or was it blown by air from the gun?

[@ANDYMCNET]

Your channels are currently synchronized with both your solder past dispensing ideas. =)

[@AdamWelchUK]

I'm fairly sure it was due to the angle of the blown air - as a few people have pointed out straight down should work best. It was tricky though with the camera in the way. However there is also a chance that my solder was going off a little due to the extended time of filming also the ambient temperature in the shed was dropping. Take your pick!

[@Magic-Smoke]

Nicely done Adam - which hot air gun are you using?

[@JakubChalupnik]

Famous last words: "For now, I'm just gonna remember it's the wrong way around."

[@AdamWelchUK]

A year on and I they’re all still working :-)

[@jamest.5001]

yes reverse pole protection is s must. I didn't know how dumb I can be. I have 3 tp4056 I fried.

[@GarmnCX]

if you remove the heatgun head it will give more spread with the same air flow and it will heat faster and get more area in less time

[@AdamWelchUK]

I'll give it a go - thanks.

[@oldtimeengineer26]

Adam what site do you buy the boards from it has been years since I had to order any Thanks

[@AdamWelchUK]

I used AllPCB.Com because I wanted them delivered fairly quickly so I could make the video. If you're happy to wait, JLCPCB is cheaper and still make excellent quality boards. Both are in China, but AllPCB got 24 boards to me (I ordered 20) in exactly a week for $21. Its the parts that took the time to arive from ebay/aliexpress. Just remember the code is still a work in progress, but I think the hardware is pretty much set.

[@mattivirta]

i have buy capasity controlelr same what you use ,many video, and i has 18650 battery holders 4 battery one holder and 7 holder, 4x7, what bms this need be ? how connect all wires schematic ? i need do 12V wall battery strore and charge this whit solar panel.were can orden 7S connector and wires need solden to battery can use capasity controller. i no has found anywere in thailand and aliexpress. need 12V power pack, 4S bms or 7S bms how connect all battery. ??????

[@lauwengyew8218]

Adam, can I use this board for a 4 x 6 cell pack by 7 of this pack to make up a 24v system

[@AdamWelchUK]

Yes this system will work with 2s-14s I believe. You can adjust the bypass load resistor to suit your pack size.

[@1over137]

Calm down a bit Adam, take your time and get some better/smaller SMD tweazers, you might as well be using pliers with those things!

[@AdamWelchUK]

New tweezers on order :-)

[@brandonwalker4805]

I cant seem to figure out how to order to the blank PCB from gitHub. Could someone lead me in the right direction. I have never used the site.

[@lalortech5286]

Go to github.com/stuartpittaway/diyBMS, click the green clone or download button, then download to zip. go to your download folder and extract the files. in the BMS-Cell-Module-Circuit folder, right click on Gerber folder and add to zip Note where its saved. Now go to JLCPCB.com, click buy now, and upload the gerber.zip file. Register and buy, to save on delivery cost select the register delivery.

[@MrBrymstond]

Use a 12v ~ 60 to 100 watt halogen lamp from a car, try and find one that has a reflector and use sun glasses. This will work and wont blow the components around.

[@error39]

kzbin.info/www/bejne/pWWYhZVpasmHidU

[@MrBrymstond]

error39+ yes and he did the whole procedure step by step perfectly and correct. Great example.

[@CuriousTimo]

Adam, There is a discussion going on about the value for R2: github.com/stuartpittaway/diyBMS/issues/6 Using.. www.digikey.co.uk/en/resources/conversion-calculators/conversion-calculator-led-series-resistor 4.2V supply, 3.3V forward voltage (blue LED) and 20mA current gives 45ohm resistor - so the 47 is a logical choice. Note that R2 also adds to the balance load on the cells in addition to the load resistor. What are your thoughts?

[@AdamWelchUK]

I did make a mistake here - I forgot to account for the voltage drop across the led as others have pointed out. So the calculation Stuart refers to in that post is accurate. So it boils down to how much current do you want to put through your resistor. You want it low enough so it doesn’t burn out. You want it bright enough so you can see it in your environment then you need to factor in that it is not constantly on, so a higher current will do less damage over a particular time span and that you need to factor in the current when calculating your r1 value. If you only want to discharge your pack at 200ma then a 20ma led draw is quite a large difference. 20ma when looking at 1-1.5amps is not a lot. I’ve also put a red LED here because that makes more sense to me when we are burning off power. They have a lower forward voltage than the blue led that Stuart proposed. There’s an argument to say anything between the 47-510 ohm region will be fine too! Sadly I can’t go back and re do that bit of the video to clarify, but I might discuss it in a future one.

[@dennisolsson3119]

Blue LED drops about 3 volts, so (4.2-3)/47=25 mA though... ;)

[@AdamWelchUK]

I stand corrected - good point. Still a bit much though, I'm sure Stuart just made a little error - 510 ohm much more suitable don't you think?

[@Alan2E0KVRKing]

Maybe it was a typo and should be 470?

[@maicod]

great idea that 1 mil syringe

[@AdamWelchUK]

Cheers Maico

[@mattroadfeldt9012]

Where can I order the circuit board from?

[@AdamWelchUK]

You need to download the gerber files from Stuart’s github and upload it to a manufacturing company. I use Chinese companies, either JLCPCB, PCBway or AllPCB.

[@cmj20002]

Turn the air speed down and solder one area at a time. Hold the hot air gun over the top not to the side and you will have better results.

[@randomsporadicprojects8941]

I've been following you and Colin making this BMS. I've been looking at a relay based solution (16 channel relay and rpi zero W) as I don't fancy all that SMD stuff, and have documented my efforts so far on randomsporadicprojects.blogspot.co.uk/2018/04/7s-lipo-balancing-with-relays.html it's now tested and seems to be working - but so far my bg-8s has been keeping my packs balanced OK so not had to deploy it yet.

[@notyoung]

Your camera appears to block good work. Using the hot air gun vertically isn't likely to blow components to one side. Perhaps a 90 degree tip to allow the body of the hot air gun to fit under the camera?

[@AdamWelchUK]

An angled tip is a good idea - I'll look into that thank you.

[@tomstdenis]

try blowing perpendicular to the board instead of from the side...

[@jmanbrosef689]

Nice

[@SidneyCritic]

He must of meant 470R not 47R. Shame you don't have an old toaster oven.

[@tengelgeer]

10:10 I agree 47R is wayyy to low but you math is flawed ;) Don't forget tot subtract Vf of the LED ;)

[@AdamWelchUK]

You’re right - and not he first person to point it out. I appreciate it anyway, thank you.

[@tengelgeer]

Adam Welch Thanks for the reply! Sorry to be late to the party! I scrolled through the top 20 replies or so and didn't notice anyone saying it. :/

[@bren106]

Oh dear! Julian, dramaless solder paste video.

[@hkobbermann]

Does anyone sell these pre fab?

[@demoncloud6147]

Are you some old Chinese pick and place machine from the 70's ?

[@AdamWelchUK]

I'm an English one from the eighties. :-)

[@lalortech5286]

Hi Adam, would you be able to print me a stencil for the diybms board. I will pay via PayPal.

[@MrBrymstond]

Try to sit the components in place not smearing them across the solder.

[@AdamWelchUK]

I was trying my best - but it's even harder with a camera in the way of the filming. I'll see if the boards I solder off camera work better - or if I do!

[@noleftturnunstoned]

Pink should be 20 gauge.

[@MrBrymstond]

Use a credit card or guitar pick

[@AdamWelchUK]

Not the decorators palette knife? :-)

[@maicod]

Adam Welch no he wants it back :D

[@daikiryoku]

Can you use an oven instead of a hot air gun? Or would it burn the fibreglass?

[@AdamWelchUK]

No it shouldn't damage the board - many people do use an oven, I just can't fit one in the shed!