About this replacement
PCE Instruments Colorimeter PCE-CSM 10 Series — 3.7V Li-Polymer Replacement Battery (BQ021 / PCE-CSM-BAT)
This 3.7V 3500mAh lithium-polymer pack replaces the original battery in the PCE Instruments PCE-CSM 10, PCE-CSM 3, PCE-CSM 6, and PCE-CSM 7 colorimeters. These portable color measurement instruments share a common battery bay and connector layout across the CSM series. Capacity is 3500mAh (12.95Wh), matching the original specification.
- PCE-CSM series compatibility: The CSM 3, 6, 7, and 10 run on the same 3.7V single-cell architecture with identical connector pinout and BMS handshake requirements. Swapping between models in this series does not require firmware changes or repairing — the instrument reads pack state over the same communication line.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on the PCE-CSM platform, monitoring BMS response during sensor initialisation. The protection circuit handled the current spike at probe power-up without triggering a false cutoff, and the pack held voltage through sustained spectral measurement logging.
- Post-install calibration requirement: After fitting this pack, run a full calibration cycle through the instrument menu before field deployment. The PCE-CSM maps battery state during calibration, and skipping this step causes the low-battery indicator to fire prematurely on the first measurement session — even when the pack is fully charged.
PCE-CSM shutting down mid-measurement with voltage still showing on screen
This happens when the sensor array initialises a new measurement cycle and pulls a short current spike the aged cell can no longer sustain. The BMS reads the resulting voltage sag as an undervoltage fault and cuts the output before the display can update. A new cell with lower internal resistance handles the same spike without the sag. If the instrument shuts down at the moment you press measure, the cell is the cause — not the sensor module.
Pack will not charge after the colorimeter sat unused for several months
Li-polymer cells that self-discharge below approximately 2.5V during storage will cause the BMS to enter a locked sleep state. Most chargers send a standard charge current on connection, see no response, and halt. To recover the pack, connect it to the instrument and apply the charger for at least 10–15 minutes at a low rate — some chargers include a trickle or recovery mode that slowly brings the cell back above the 2.8V threshold the BMS needs to re-initialise. If the cell has dropped below 2.0V and the instrument shows no response after 20 minutes on charge, the cell is not recoverable and replacement is the correct step.