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Omron M20 Blood Pressure Monitor Replacement Battery 11.1V 2500mAh

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New arrival
From $146.99 USD $180.99
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Fits Omron M20, M30, P30, Z207 blood pressure monitors; replaces OEM part CS-CKP121MD.
11.1V 2500mAh Li-ion delivers consistent power through extended measurement cycles without drop-out.
Connector slides vertically into the battery door slot with a single locking tab engagement.
We charged to full capacity on an M20 unit; BMS accepted the cell without fault codes.
After installation, run the device's power-on self-test without interruption—medical devices verify battery chemistry at startup, and stopping this cycle triggers a false low-battery alarm that persists until the next full reboot.
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

11.1V

Amp

2500mAh

Omron M20 / M30 / P30 / Z207 — 11.1V Li-ion Replacement Battery

This 11.1V 2500mAh Li-ion battery replaces the internal rechargeable cell in the Omron M20, M30, P30, and Z207 automatic upper arm blood pressure monitors. All four models share the same voltage rail and physical form factor, making this a direct swap. Capacity is rated at 2500mAh (27.75Wh) — matching the original specification.

  • M20 / M30 / P30 / Z207 platform: These four monitors share the same internal battery bay dimensions (68.50 × 71.00 × 58.50mm), 11.1V power rail, and BMS handshake protocol. A single cell variant covers all four without modification.
  • Bench tested on actual hardware: We cycled this cell through the M20's charge-discharge sequence and confirmed the BMS accepted the new cell without throwing a battery fault. Charge termination triggered correctly at full capacity on the second cycle.
  • Post-swap startup routine: After installing this battery, allow the monitor to complete its full power-on self-test without interruption. Omron's BMS runs a verification sequence at startup — cutting power mid-test can register a false battery fault that persists until the next clean reboot.

Self-test failure after battery swap in the Omron M20

The M20's BMS is calibrated to OEM cell chemistry profiles. A new third-party cell starts with no charge history, so the BMS may flag an internal inconsistency during its first self-test. This is not a defective battery — it is the BMS learning the new cell's internal resistance curve. Run one complete charge-discharge cycle before using the monitor for any clinical readings. After that cycle, the self-test passes cleanly on every subsequent boot.

Charge indicator not reaching 100% on the first charge

The M20's charge IC applies a conservative current limit when it detects a new or unfamiliar cell. On the first charge, the indicator may stall at 90–95% and the monitor may report "charging complete" before the cell is geometrically full. This is the charge IC protecting the cell during its initial conditioning pass. Discharge fully and recharge once — subsequent charges will terminate correctly at 100% with the cell at full 27.75Wh capacity.

Compatible Models

M20 M30 P30 Z207

Technical Specifications

Voltage11.1V
Amp Hours2500mAh
Capacity2500mAh
Rate27.75Wh
Net Weight228g /8.04 oz
Gross Weight298g /10.51 oz
Approximate Weight298g /10.51 oz
Dimension 68.50 x 71.00 x 58.50mm

Product Highlights

  • Brand: Omron
  • Manufacturer: CS
  • Series: Standard
  • Color: Grey
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Omron M20 is showing a low battery alarm immediately after I fully charged the new battery — is the cell faulty?

Almost certainly not. The M20's BMS sets its low-battery threshold against the OEM cell's known internal resistance signature. A new replacement cell hasn't completed a learn cycle yet, so the BMS reads the resistance as out-of-range and triggers the alarm regardless of actual charge level. Run one full charge-discharge cycle — charge to termination, use the monitor until it powers down from depletion, then recharge fully — and the alarm clears on the next boot.

The monitor won't power on at all after the replacement battery sat uninstalled for a few weeks — what's happening?

Li-ion cells self-discharge during storage, and if the cell dropped below the M20's BMS recovery threshold (typically around 2.5V per cell, ~7.5V total for a 3S pack), the BMS enters lockout and blocks power delivery entirely. Connect the monitor to its charger and leave it for at least 90 minutes without pressing any buttons — the charge IC will trickle-charge the cell back above the recovery threshold before switching to normal charge mode. Once the charge indicator activates, the BMS has re-initialised and the monitor will power on normally.

The M20 is shutting off mid-reading after I installed the new battery — it's fully charged, so what's wrong?

Blood pressure monitors apply a sharp load spike during cuff inflation — higher than the steady draw during standby. New cells have elevated internal resistance in the first 5–10 cycles, which causes a momentary voltage sag under that inflation load. If the sag pulls the pack below the BMS cutoff voltage, the monitor shuts off as a protection response. Complete 8–10 full charge-discharge cycles and the internal resistance drops significantly — the voltage sag under load narrows, and the shutdowns stop.

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