Finally i could calibrate, but i don’t know why it didn’t work before. Curious… 
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Today testing difference of V4.21 to V4.40 module. Cool that we can mix it on the new controller, and getting an Info.
The main difference is the balancing power.
4.40 is starting with 1Amp balance power, when reaching max temperature goes to PWM mode and then jumps 200-900mA
4.21 is starting with 800mA, but holds this much longer (the large amount of resistors results in bigger surface too cool I think)
Then when reaching temperature it jumps between 300-600mA
I will do a long balance test later to look if old or new is the stronger one in long term.
4,40 took 8 minutes to balance a 300Ah Lifepo from 3,55 to 3,45
4,21 took 11 minutes.
Another difference is.
4.40 is hammering the voltage down to the set value (3,45V in my case), and it stands there fixed, maybe one or two times after-balance balancing.
4.21 is doing it also, but still needs “minimal” balance shots of a few seconds.
(after 40 minutes …) and still has 3,455 and not 3,450 constant.
The mysteries of life Karl … 
Hello, greetings from Sri Lanka. I built a esp32 controller board and some modules for my LiFePO4 batteries. I half built the controller module from JLC and ordered all the extended parts from LCSC and soldered them myself.
I am wondering if there is any way to send MQTT data to a cloud broker ( I am trying to use hivemq ) with a TLS/SSL certificate. Has any one done this before?
The thread below may help you:
Looking great.
ESP32 does support TLS, but it’s not written into the code. Can you raise a new issue on GitHub as a feature request and I’ll see what I can do.
Hi, this is not what I am looking for. Thanks anyways!
Already raised an issue on GitHub. If possible, please look in to it.
I think it is better to add a field where we can select a CAFILE and the code will be able to use the same for data transfer.
Thank you!
There’s no mention of MQTT in that particular thread. 
I now tried to build the CPL File on my own. The PCB File can’t be opnened on my Windows. Already updated to latest KICAD.
An Issue is opened.
Apparently I missed a version update of the controller
full pictures at : TJA1057GT/3J · Issue #83 · stuartpittaway/diyBMSv4 · GitHub
The new controller have push buttons now?
what do they do and can they be added to the old design?
(obvious not as nice looking, they make a contact between A and B, sometimes one can simply solder thin wires with a “lose” button, what will give the same result.)
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Its a minor update, and the buttons can be easily added to the original board - its main purpose is to wake up the controller screen if you have it in a case. At the moment only 1 of the buttons work - its connects to the J13 connector on the older board.
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Hi, interestingly my time out issue has chabged from module 43 to module 33.
It shows wrong voltage and cannot be calibrated…
Regards
Karl
I had some 4.4 modules which I was unable to calibrate - I had forgotten that JLCPCB couldn’t supply and fit D1 (1.25v voltage reference diode).
I kept increasing the calibrate value until it maxed out.
Adding the diodes (which I had in a separate shipment) from LCSC fixed the problem.
Maybe try a high precision multimeter between pin 13 and 14 of the ATTiny. Expect 1.25v.
Ok, I think this is likely a bug.
Can you open an issue on GitHub for this please?
has anyone in europe got a spare 4.2 controller board for sale pre populated with the smd stuff?
i managed to blow mine up very badly, please be careful when flashing the modules if using the leaf version, when you are using the battery to power the controller the isp is no longer isolated power source like when it was done via usb and powered from a laptop
i had it all up and running but wanted to update the module firmwares as soon as i plugged in the isp cable i got a huge bang and all went dead, took out c4 very bad but pcb is fine, just getting no more communication to the esp any more and it wiped out my lcd too 
an expesive mistake lol if it aint broke dont try fix it haha
i basially put 48v through it as the ground is common when running it off the battery itself
Hi all !
First of all thank you Stuart for awesome idea! I just order 10 controllers and 30 ‘satelites’ for my project. It ll be preasembled but JLCPCB doesnt have some components so i had to order from Ali. however… I cant find any “TJA1057GT/3” Mayby someone can help with ? Thanks!
PS Im newbie so sorry for stupid questions as what
Don’t worry about the TJA, looks like a global shortage. The board will work without it.
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Hi, thanks for response, so can I do not assemble it ?