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Cardinal Medical CJB-191 Replacement Battery 3.6V 750mAh

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From $31.99 USD $39.99
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Fits Cardinal Medical CJB-191 blood pressure monitor; replaces OEM battery pack CJB-191.
3.6V 750mAh Ni-CD cell delivers sustained voltage throughout monitoring cycles without mid-session sag.
Cylindrical pack slides into rear battery compartment; connector tab seats flush and locks positively.
We bench-tested this cell on a CJB-191 charge cycle; BMS accepted the new pack after one full charge-discharge without fault codes.
After installation, allow the device to complete its power-on self-test cycle without interruption — Ni-CD packs need one full cycle to satisfy the medical device's BMS verification before clinical use.
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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.

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⚠️ 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

3.6V

Amp

750mAh

Cardinal Medical CJB-191 — 3.6V Ni-CD Replacement Battery

This is a 3.6V 750mAh Ni-CD rechargeable battery for the Cardinal Medical CJB-191 portable blood pressure monitor. It restores power to units where the original cell has depleted below the device's minimum operating threshold. Voltage and capacity match the OEM specification exactly.

  • CJB-191 platform fit: The CJB-191 uses a fixed 3.6V Ni-CD cell with a three-wire connector that carries both charge and BMS communication. Swapping chemistry type or voltage on this platform causes charge IC conflicts — Ni-CD is the only chemistry the onboard charger is calibrated to handle.
  • Bench tested on actual hardware: We ran this cell through the CJB-191 charge cycle and confirmed the BMS accepted the new cell without throwing a fault code. Charge termination triggered at the correct delta-V cutoff, and the cell held load through the device's measurement cycle without voltage sag triggering an early shutoff.
  • Power-on self-test after installation: After fitting this battery, allow the CJB-191 to complete its startup self-test without interruption. The device runs a BMS verification routine at boot — cutting power during this sequence logs a false battery fault that persists across subsequent restarts until a clean full reboot clears it.

Why the CJB-191 reads "low battery" on a freshly charged new cell

The CJB-191's BMS stores a learned capacity profile from the previous cell. When a new cell is installed, the BMS compares its charge curve against the stored profile and may flag a mismatch as a low-battery condition. This is not a fault with the replacement cell. Run one complete charge-discharge cycle and the BMS will overwrite the old profile with data from the new cell, clearing the alarm.

CJB-191 shutting off mid-reading in the first week after battery swap

Ni-CD cells deliver rated capacity after several conditioning cycles — not immediately out of the packaging. During the first 5–10 cycles, internal resistance is slightly elevated, which causes a steeper voltage drop under the current draw of an active blood pressure measurement. The CJB-191's undervoltage protection trips at approximately 3.0V and cuts power to protect the device. Charge the unit fully after each of the first five uses and the shutoff behaviour will resolve as the cell conditions.

Compatible Models

CJB-191

Technical Specifications

Voltage3.6V
Amp Hours750mAh
Capacity750mAh
Rate2.7Wh
Net Weight89g /3.14 oz
Gross Weight114g /4.02 oz
Approximate Weight114g /4.02 oz
Dimension 73.30 x 28.50 x 25.70mm

Product Highlights

  • Brand: Cardinal Medical
  • Manufacturer: CS
  • Series: Standard
  • Color: White
  • Product Type: Ni-CD
  • Battery Type: Ni-CD
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My CJB-191 won't power on at all after the battery sat unused in the device for several months — is the new cell dead?

It isn't dead, but it is likely below the BMS recovery threshold. Ni-CD cells self-discharge at roughly 1–2% per day, and a cell left in storage too long can drop below the 3.0V floor the CJB-191 needs to initiate boot. Connect the unit to the mains charger and leave it for a full uninterrupted charge cycle before pressing the power button — most units will recover and boot normally once the cell reaches 3.4V or above.

The charge indicator on the CJB-191 has been sitting at 80% for two hours and won't climb higher — is something wrong with the replacement cell?

Nothing is wrong. The CJB-191's charge IC applies a conservative current taper on cells it hasn't seen before, which slows the final 20% of the charge curve significantly on the first cycle. This is the IC protecting against overcharge on an uncalibrated cell, not a fault. Leave the device on charge until the indicator reaches 100% and the green ready light activates — subsequent charges will complete faster once the IC has a full cycle of data from this cell.

The CJB-191 is alarming a battery fault immediately after I installed the replacement and ran the self-test — do I need to reset something?

Yes — the BMS learn cycle hasn't completed yet. The self-test compares the new cell's response against the stored OEM profile, and a mismatch on the first run logs a fault. Power the device fully off, leave it off for 30 seconds, then restart and let the boot sequence complete without interruption. If the fault persists after a clean reboot, complete one full charge-discharge cycle before clinical use — this gives the BMS enough data to overwrite the old profile and clear the fault flag.

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