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Discussion Starter · #1 ·
I'm trying to understand how the Ryobi 40V mower battery works....
These batteries have a locking problem. https://www.diyelectriccar.com/foru...0v-bms-troubleshooting-and-repair-197409.html
The BMS locks while all cell are good.
I orderer an aliexpress compatible battery.
After discuss, the seller sent me photos of the BMS




The controller seem to be a PIC16F1933
I started to note the schematic.


I wonder how the PIC manage to measure the voltage cells ?
I didn't note any other wires.
I scared to see the voltage cells not measured, unless the cells own specific protections directly.
The schematic is just approximate, just looking wire and component.
The transistor could be an other model and pinout.
I'm waiting the parcel to explore the battery.
Else, did you have an idea ?
 

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Discussion Starter · #3 · (Edited)
Thank you very much Kenny,

With your analysis, i think i understood the PCB
The P mofset internal diodes allow to transmit the cell voltage to be mesured by the PIC.
R17+R27 and R7 make a voltage divider bridge. But the internal mosfet diode forward voltage must be compensated.
 
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