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V0.2 in assembly.

A project log for 2nd Use BMS

A high energy capacity Battery Management System for re-purposing used cell modules from EVs and other sources

Nathaniel VerLeeNathaniel VerLee 11/28/2020 at 20:050 Comments

I managed to shrink the size of this PCB down a lot to 80x80mm at the expense of 2 of the 10 series cells possible with the BQ76930 IC. Eventually, I am hoping to make a few other variants that will open this project up to 12V and 48V applications, these versions will probably keep the 80mm length but grow up or down in width to accommodate differing numbers of cells. I have almost all of the parts ordered and on hand and once I get everything all assembled this week and I am looking forward to getting set back up to do more code development and testing with the new boards. My target for PCB V0.3 is to adjust a few minor things (V0.1 to V0.2 was a huge re-design by comparison) and finalize some of the more mechanical and thermal aspects of the design like how to mount heatsinks, what kinds of terminals to use, the enclosure, etc. and take care of that and any V0.2 mistakes on V0.3 late December. I will hopefully be doing thermal testing soon in order to understand more about how hard it is going to be to manage the heat from the MOSFETs and the sense resistor, which will be somewhere between 1-4W under full load depending on the configuration of the board. I will be posting some photos soon, stay tuned...

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