Hardware v0.3 Testing - Tracking Issue about bms-c1 HOT 7 CLOSED

Pre-discharge circuit is working with latest firmware (LibreSolar/bms-firmware@45df96b). Below tests were performed with a 24V LFP-Battery.

Yellow (CH1): PDSG (TP7), Blue (CH2): DSG (TP6)

1. BAT+ and BAT- terminals open.

2. BAT+ and BAT- terminals connected to 1200 uF electrolytic capacitor.

The PDSG MOSFET is enabled first (P-channel MOSFET, i.e. gate pulled low) and pulls up the bus voltage through the resistor. The DSG follows the bus voltage. 250 ms after the bus voltage reached the battery voltage, the DSG FETs are enabled (gates 12V above battery voltage)

For this test, the PDSG MOSFET had to be wired manually to fix #36.

from bms-c1.

The current and voltage measurement results from the bq76952 are less accurate than expected.

An example from testing:

• Pack current
  • BMS 3.76 A
  • Fluke multimeter: 3.95 A
• Pack voltage
  • BMS 26.98 V
  • Fluke multimeter: 27.20 V

The root cause has yet to be investigated. The bq76952 features different calibration features which can be leveraged to improve the accuracy.

from bms-c1.

I have a circuit problem and would like to ask, why not use the built-in LDO of BQ76952 to replace the external DCDC module?

from bms-c1.

Which circuit problem do you have?

The LDO cannot handle the current required for the ESP32-C3.

from bms-c1.

Which circuit problem do you have?

The LDO cannot handle the current required for the ESP32-C3.

If I use a general MCU, for example, the current is less than 45mA, could I not use the external DCDC circuit?

from bms-c1.

It really depends. Also a CAN transceiver can draw considerable amount of current. I didn't do the math, but dropping voltage from 60V to 3.3V will dissipate a lot of heat even for very small currents. For ESP32-C3 with WiFi it's not feasible for sure.

Let me know if you did some calculations and you think it may be doable with LDO only.

from bms-c1.

Final test report was added to the repo, closing this issue.

https://github.com/LibreSolar/bms-c1/blob/main/testing/v0.3/README.md

from bms-c1.