DIYBMS v4

[stuart]

@Ross did you just lower the resistor values or did you change anything else?

What balance current are you now running with?

[Jon_Coop]

Where is a list of components that still need to purchased and installed after jlcpcb smt service?

[stuart]

Hi, I don’t think a list exists.

You will need cables and JST sockets/plugs and the ATTINY841 chips.

[brian_holden]

Stuart I’m looking to order from jlcpcb but they still have Q1 missing, but two other makes that you can choose
when comparing the data sheets they are slightly different
Do you know if I can choose one of the other makes

[Lex_Poel]

Hello all,

I’m currently building multiple 4S10P lithium battery’s with cells i recycle from my work. (Third almost done)
Is it possible someone could make a small diybms board compatible with 4 cells instead off 1?

Greetings,

Lex

[stuart]

@brian_holden

Do you know if I can choose one of the other makes

Hi Brian, I’ve not used the other devices so I can’t recommend either one I’m afraid. The OEM shop has stock of the boards available if you want a complete kit of parts.

[Lex_Poel]

@stuart I can donate a few esp32 devkit’s, for testing the esp32 controller code

[stuart]

@Lex_Poel

Is it possible someone could make a small diybms board compatible with 4 cells instead off 1?

This should already be possible, what size/type of battery are you trying to build?

[kemot96 (Tomasz Schmidt)]

Hi,
I’m having trouble programming the modules, I bought SMT assembled v4.21 modules from JLC PCB I just soldered the attiny841 to 10 modules and only 2 of the 10 boards did upload successfully. (I followed Start steps from YouTube)

avrdude: 7816 bytes of flash written
avrdude: verifying flash memory against .pio/build/attiny841_V421/firmware.hex:
avrdude: load data flash data from input file .pio/build/attiny841_V421/firmware.hex:
avrdude: input file .pio/build/attiny841_V421/firmware.hex contains 7816 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 4.49s

avrdude: verifying …
avrdude: verification error, first mismatch at byte 0x0010
0xff != 0x70
avrdude: verification error; content mismatch

avrdude: safemode: lfuse reads as E2
avrdude: safemode: hfuse reads as D6
avrdude: safemode: efuse reads as F4
avrdude: safemode: Fuses OK (E:F4, H:D6, L:E2)

avrdude done. Thank you.

*** [upload] Error 1
============================================== [FAILED] Took 11.23 seconds

On my MacBook the first mismatch is always at byte 0x0010 but I also tried programming the module from a windows computer and there the first mismatch is changing eg. 0x0200 or 0x0520…

I tried to reupload one of the modules that was programmed successfully and the same error occurred. I’m using a usbasp programer

Has anyone any suggestions what should I do to make it work?

[Sordo (S. O.)]

Is it possible to run diyBMS without Wi-Fi?

I’d like to add a small LCD for a mobile battery.

Are there any examples of anyone adding an LCD, code wise? If not, whereabouts in the code would it make sense to output important status values to the LCD? I have some limited experience with adding LCDs to arduino projects.

[stuart]

@Sordo

Is it possible to run diyBMS without Wi-Fi?

I’d like to add a small LCD for a mobile battery.

I created an issue just for this purpose [Controller to stay in access point mode for offline applications · Issue #6 · stuartpittaway/diyBMSv4Code · GitHub]

although at the moment, I’ve not worked on it. I’m also planning to add a small display (optional) for the next version of the controller.

[stuart]

@kemot96

I bought SMT assembled v4.21 modules from JLC PCB I just soldered the attiny841 to 10 modules and only 2 of the 10 boards did upload successfully.

Hello @kemot96, assuming that you didn’t change any of the parts when you ordered from JLCPCB, this will be a soldering issue, particularly as 2 of the boards work.

From the pictures, the soldering looks very neat, however, take a closer look…

I’m seeing small blobs of solder - it could just be the photo, but theres probably some “splatter” near the pins.

[Sordo (S. O.)]

Thanks! So does that mean without wifi, the bms won’t function? What if the local router dies?

[stuart]

If the router/internet goes down the BMS continues to function, but you can’t get to the web interface. It should be easy enough to leave the ESP8266 access point enabled rather than switching to the router wifi.

The two time based rules (for driving relays) won’t work without an internet NTP server to calibrate the current time.

[Sordo (S. O.)]

That makes sense. So once connected via soft access point, the web ui can be accessed? Is there a specific ip address/address to access the ui when connected like this?

[stuart]

@Sordo

Is there a specific ip address/address to access the ui when connected like this?

Its the default ESP one 192.168.4.1

[kemot96 (Tomasz Schmidt)]

Thank you @stuart, I ended up reflowing it with a heat gun and it work like a charm.
And thank you for the excellent work you did designing this BMS!