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DIYBMS v4

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Its not a part JLCPCB have as part of the automated assembly

I wish - PCBWAY seem to have this feature but not JLCPCB

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But where is the 4.1 BOM?

Hello, I’ve been testing DIYBMS v4.2 since yesterday, but the measurements of the voltage are very inaccurate and fluctuate a lot. Even after I entered the measured voltage the fluctuations did not stop. Is this normal or do the modules calibrate in the beginning?

The cells are charged to 4.15 - 4.18V. I set the maximum voltage to 4.19V in the BMS, but the BMS still discharges cells that are at 4.15V.

BTW: dark mode looks nice :wink:

Here it is… V4.21 Bill of material

4.1 was not published for very long. v4 or v4.21 are the current options depending on if you want to hand solder or machine assemble.

No thats not normal - the voltage readings should be very stable. What board do you have and who built it? Have you changed the design or code at all?

When programming the modules, don’t forget to program the fuses as well.

Hi Stuart, thanks for reply.

Oh, it seems I missed something :thinking: Can you tell me what I forgot to adjust?
I ordered the boards from JLCPCB in early January. Version 4.2.

It could be this commit

If you are programming using platformio (which I recommend) then press the “upload & burn fuses” option to program the ATTINY841.

no, I didn’t do that. I used PIO, but I only changed the COM port and uploaded the code. “upload & burn” is a function in vscode/pio or do i need the console (–target fuses)? Do I need to upload the code again?

I’ll test it this afternoon. many thanks in advance

I just use the option in VSCODE and it seems to work okay. This may not fix the problem you are seeing though - the voltage readings I have on my cells fluctuate a little but only +/- 0.002V this is to be expected as part of the way ADC sampling works.

hi,
I read one thousand of post´s and … i need read again :slight_smile:
I like to use this diybms im may 32 lifepo4 cells, two backs (16+16) is possible with one controller ?
another think, were I can buy this boards 4.3? assembled (35 boards) more the controller ?
great job !!

Yes 16+16 is possible on a single controller. You can’t get the 4.3 boards at the moment, I’m still testing these! Version 4.21 is the current pre-assembled boards via JLCPCB.

… but this version 4.21 don´t have some problem with the resistors ?
watts the big difference between the 4.21 and the 4.3 ?
how i can get this boards 4.21 from JLCPCB ?

4.21 fixes the resistor problem (R19)

I find it !! :slight_smile: it´s a shame, í only need 32 boards, but I need buy 50 !! :frowning:

there is someone in europe who has 32 boars to assembled, to sale ?

If you will ship them to the US I’ll take some. I only need 4 battery boards and 1 controller board but I can ask around and see who else might need some.

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I would prefer machine assembly. I only saw branches for master and 4.2, is there a separate branch for 4.21 or is it just corrections in the 4.2 branch?

Actually I was looking at the schematic last night and I see that there are some resistor voltage dividers used, which makes me wonder if it’s okay to use these resistor values with 3.2v 86Ah 90Ah LiFePO4 cells. My use is a 4P4S 360AH battery on my sailboat, where each cell voltage has a minimum voltage of 2.8V and a max of 3.65V.

Also I see for current sensing it uses a current sensor from DF Robot. I’m wondering if a standard current shunt could be used? I would think so since it uses an A/D for voltage sensing, although perhaps firmware changes would be needed.

Its the 4.2 branch