Slave BMS module to monitor 24s cells voltages and temperatures.
Latest first
- Filippo Volpe
- 24 cells series
- 32 temperature measurements
- LTC6811-1/-2 both are compatible
- isoSPI cost effective communication interface to the monitor IC directly
- cell balancing
- STM32L0 can be fitted to add logic to the board by itself
- IRda optional communication to the MCU
- compatible, for temperatures, with both NTC and shunt references
- direct SPI connection to the monitor ICs
- usable as two 12S monitor with breakaway slots
- cost reduction in the isolation components if used as 24S monitor
- small footprint, 65mmx115mm
For use with "-1" version the isoSPI link must be daisy chained, hence connecting the master of PORTB to the slave of PORTA of the next IC in the chain.
For use with the "-2" version only populate the slave PORTA of each section and connect them in parallel. Then set the address of each section using the solder jumpers.
Using LTC6811-1 version.
| Component reference | To fit | Comment |
|---|---|---|
| R11 | ✔️ | |
| R12 | ✔️ | |
| C18 | ✔️ | |
| U12 | ❌ | |
| R22 | ✔️ | |
| R23 | ✔️ | |
| C37 | ✔️ | |
| U13 | ❌ | |
| FL1 | ✔️ | |
| C1 | ✔️ | |
| C2 | ✔️ |
The board can be splitted along the cutouts to obtain 2 12S monitors of which one has the option to be used with the MCU but both still has full SPI and isoSPI functionality. In this case using LT6811 -1 or -2 version won't change any functionality.
For a more efficient PSU the voltage can be stepped down using a switching regulator.
| Component reference | To fit | Comment |
|---|---|---|
| Q1 | ❌ |
All other PSU components must be populated.
To power the stack monitor a low component count but less efficient psu can be populated using transistor Q1.
| Component reference | To fit | Comment |
|---|---|---|
| Q1 | ✔️ | |
| R14 | ✔️ | |
| C19 | ✔️ | |
| C21 | ✔️ | |
| C27 | ✔️ | |
| C29 | ✔️ |
All other PSU components can be left unpopulated.
To use the isoSPI connection, connect ISOMD to 1. To use the direct SPI connection, connect the ISOMD switch to 0 and the ICMP and BIAS resistor can be left unpopulated.