Prepared by @Joe Dai on August 14, 2023

Relevant Documentation

[1] Internal V & V documentation: V & V BMS

[2] BQ76952 datasheet: https://www.ti.com/lit/ds/symlink/bq76952.pdf

[3] BQ76952 technical reference manual: https://www.ti.com/lit/ug/sluuby2b/sluuby2b.pdf

[4] Yageo chip resistor datasheet: https://www.yageo.com/upload/media/product/productsearch/datasheet/rchip/PYu-RC_Group_51_RoHS_L_12.pdf

[5] Vishay chip resistor datasheet: https://www.vishay.com/docs/20043/crcwhpe3.pdf

Overview

To address issues found during verification of the “FINCH EPS Battery Board” rev. 1, multiple board reworks have been completed to allow for the proper operation of the board. Notes in the form of informal journal entries can be found in the bottom of [1].

Description of Work Done

BQ76952 (U1) Rework

The following procedure shall be conducted to fix the issue of unused pins being tied to GND, by tying them to the adjacent VC15 pin.

  1. Desolder BQ76952 IC (U1).
  2. Bend pins 2 (VC14) through 13 (VC3) on BQ76952 IC, such that they do not contact the pads on the board.
  3. Resolder BQ76952 IC (U1). Visually inspect under Mantis to ensure proper soldering.
  4. Bridge pins 2 (VC14) through 13 (VC3) on BQ76952 IC with thin wire, such that they electrically connect to each other.
  5. Bridge above construction to VC15 side of R34. It is indicated as pin 2 on the layout and is the right side of the resistor, viewed with silkscreen text upright.

R33 Rework

The following procedure shall be conducted to fix the issue of the 20 ohm resistor on the power path.

  1. Desolder R33.