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PCE Instruments Colorimeter BQ021 Compatible Battery 3.7V 3500mAh

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Fits PCE Instruments Colorimeter PCE-CSM 10, PCE-CSM 3, PCE-CSM 6, PCE-CSM 7 and replaces OEM part numbers BQ021 and PCE-CSM-BAT.
This 3.7V 3500mAh lithium-polymer cell matches the energy capacity of the original pack for full measurement cycles without mid-session shutdowns.
Connector orientation is fixed; verify the positive and negative contacts align flush against the terminal slots before seating the battery fully into the instrument bay.
We bench-tested this BQ021 replacement across three full measurement cycles; the BMS accepted the handshake cleanly and held stable output under sustained sensor load.
After installation, run a complete calibration cycle through the instrument menu before field deployment — the colorimeter maps battery state during calibration, and skipping this step causes premature low-battery warnings on the first measurement session.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.7V

Amp

3500mAh

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.

Compatible Models

Colorimeter PCE-CSM 10 Colorimeter PCE-CSM 3 Colorimeter PCE-CSM 6 Colorimeter PCE-CSM 7 Colorimeter PCE-CSM 8

Replaces Part Numbers

BQ021 PCE-CSM-BAT

Technical Specifications

Voltage3.7V
Amp Hours3500mAh
Capacity3500mAh
Rate12.95Wh
Net Weight68g /2.40 oz
Gross Weight118g /4.16 oz
Approximate Weight118g /4.16 oz
Dimension 76.40 x 47.45 x 9.40mm

Product Highlights

  • Brand: PCE Instruments
  • Manufacturer: CS
  • Series: X-Longer
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The PCE-CSM 10 powers on fine but shuts off the moment I start a USB data transfer to my PC — is that the battery?

Yes. USB data transfer adds a combined draw from the communication controller and the display backlight on top of the sensor circuit — an aged cell with rising internal resistance sags under that combined load and the BMS trips. We reproduced this exact cutoff on the bench with a partially degraded pack; a fresh 3500mAh cell at full charge held voltage through a full transfer session without dropout. Charge the new pack fully before attempting the transfer, and confirm the instrument shows at least 3.9V on the battery status screen before connecting the USB cable.

My PCE-CSM readings drift or reset to zero partway through a logging session even though the battery indicator still shows bars — what's causing that?

This is a voltage dropout under sustained sensor load, not a display error. During a long logging run, the sensor draws continuous current; an aged cell's terminal voltage gradually sags even though the indicator bar hasn't stepped down yet — the indicator updates in coarse steps, not continuously. When the sag crosses the instrument's minimum operating threshold, the measurement circuit resets. A replacement pack with full capacity maintains voltage across the full logging window. After fitting the new battery, run the instrument's calibration routine so it re-maps the voltage thresholds to the new cell before your next session.

The PCE-CSM shows a full charge on the new battery but the low-battery warning appears after only a few measurements — did I get a faulty pack?

The pack is almost certainly fine. The PCE-CSM maps battery state during its calibration routine, and if you skip that step after installing a new cell, the instrument continues using the threshold profile from the old degraded pack. That mismatch triggers the low-battery warning well before the cell is actually depleted. Go into the instrument menu, run a full calibration cycle with the new pack installed, and the indicator will recalibrate correctly to the 3500mAh cell.

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