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BotoX / xiaomi-m365-compatible-bms

Xiaomi M365 compatible, open source firmware for ATMega328p+BQ769x0 BMS. Ninebot in proto_test branch
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Is it possible to do smart bms with more 30A ? For example 40 or 60A ? #41

Open g4seb opened 4 years ago

g4seb commented 4 years ago

Hi, i search a bms for my custom battery. But if i understand, yours is a 30A. Is it possible to do this mod with a more amper bms ? Last question, some people sell bms or not ? Regards

BotoX commented 4 years ago

The 30A version has 4 or 5 of these Mosfets in parallel: https://lcsc.com/product-detail/MOSFET_KIA-Semicon-Tech-KNB3308A_C176861.html I did measure them to have around 6-7 mOhm when driven at 12V by the BMS. So that's like 1.4 mOhm total. At 50A it'd be this much waste heat: P = R I^2 = 1.4m 5050 = 1.4m 2500 = 3500mW = 3.5W That's no problem for the BMS

g4seb commented 3 years ago

Sorry for delay. Hi, ok, so i try with this BMS with 60A : https://fr.aliexpress.com/item/32819508078.html?spm=a2g0s.9042311.0.0.79106c376b8ChE. I arrive to patch this, apparently, all is ok, i'm doing a cfw with 76800 bauds, but when i put it on my scooter, nothing append. It doesn't communicate with scooter (Error 21) . Do you have a idea to check that ?

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g4seb commented 3 years ago

Hi have this message on m365_downG. I try to change tx rx, same problem

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BotoX commented 3 years ago

If you've only flashed the bootloader then you also have to flash the actual BMS firmware. Either through ISP or over serial UART with platformio. Read the README.md

If you did try debug_print on your PC, swapping RX/Tx etc all in the readme

g4seb commented 3 years ago

Hi, i read the readme, and i flash the bootlaoder and after the optiboot...So i think it's good, not ??

I don't know where is my mistake....I checked box 76800 in the CFW, but same thing too...

https://drive.google.com/file/d/1rFxdwWE6nAyFzRGvGo5B5Av9bqFc7muJ/view?usp=drivesdk

I'm doing the change on plateformio and flash it on BMS

Is it good ??

Sorry for my stupid question, but i really want to understand.