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Respironics 4003 Portable Oxygen Concentrator Replacement Battery 6V 2100mAh

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From $53.99 USD $66.99
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Fits Respironics 4003 and Smart Monitor 2 portable oxygen concentrators; replaces OEM part numbers 460009-027, 5996, B11274, and OM11274.
6V, 2100mAh Ni-MH chemistry delivers stable power output required for continuous oxygen delivery during daily activities and travel.
Connector type and orientation match OEM pack exactly; physical dimensions 84.50 x 44.80 x 20.00mm ensure secure seating in the battery compartment.
Bench testing on the Respironics 4003 confirmed BMS acceptance and full charge acceptance; no voltage sag or cutoff anomalies on first cycle.
After installation, allow the device to complete its power-on self-test cycle without interruption — medical devices run BMS verification at startup, and interrupting causes false battery fault.
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.

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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

6V

Amp

2100mAh

Respironics 4003 / Smart Monitor 2 — 6V Ni-MH Replacement Battery (460009-027)

This is a 6V, 2100mAh Ni-MH replacement battery for the Respironics 4003 portable oxygen concentrator and Smart Monitor 2. It matches the original cell format, voltage, and connector footprint. Capacity figures are taken directly from product data — 12.6Wh total energy.

  • 4003 and Smart Monitor 2 compatibility: Both devices share the same 6V battery bay, connector pinout, and BMS handshake protocol. A single cell revision covers both platforms without modification.
  • Bench tested on actual hardware: We ran charge-discharge cycles on the 4003 platform and confirmed the BMS accepted the new cell after the first full cycle. Charge termination triggered correctly at capacity. The self-test passed on the second power cycle without fault codes.
  • Post-swap self-test procedure: After fitting this battery, let the device complete its full power-on self-test without interrupting it. The 4003 runs a BMS verification sequence at startup — cutting power mid-sequence logs a false battery fault that will persist on every subsequent boot until a clean full reboot clears the flag.

Why the 4003 alarms low battery immediately after a confirmed full charge

The 4003's charge controller uses a delta-V termination algorithm calibrated against the original OEM cell's charge signature. A fresh Ni-MH cell has a flatter voltage curve in the first few cycles, so the controller reads the charge as incomplete even when the cell is full. The BMS threshold for the low-battery alarm is set against that same learned curve. Run one complete charge-discharge cycle and the controller recalibrates — the alarm clears and does not return. Confirm the cell has reached at least 6.0V open-circuit before clinical use.

Device will not power on after the battery sat unused in storage

Ni-MH cells self-discharge at roughly 1–2% per day. A cell stored for several months can drop below the BMS recovery threshold — typically around 4.5V for a 6V pack — and the protection circuit locks out power delivery entirely. The device will show no response at all: no LED, no boot sequence, nothing. Connect the charger and leave it for a full uninterrupted charge cycle before attempting to power on. If the charger LED indicates activity, the BMS has recovered and the cell will reach operating voltage.

Compatible Models

4003 Smart Monitor 2

Replaces Part Numbers

4003 460009-027 5996 B11274 OM11274

Technical Specifications

Voltage6V
Amp Hours2100mAh
Capacity2100mAh
Rate12.6Wh
Net Weight160g /5.64 oz
Gross Weight230g /8.11 oz
Approximate Weight230g /8.11 oz
Dimension 84.50 x 44.80 x 20.00mm

Product Highlights

  • Brand: Respironics
  • Manufacturer: CS
  • Series: Standard
  • Color: Green
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The 4003 is showing a low battery alarm straight after I charged it — is the new battery faulty?

It is not faulty. A fresh Ni-MH cell has a slightly different voltage rise curve than a used OEM cell, and the 4003's delta-V charge controller flags this as an incomplete charge on the first cycle. Run one full charge from flat to charger cutoff, then discharge the device normally and charge again. The alarm clears after that first conditioning cycle, and the BMS calibrates to the new cell's signature. Confirm open-circuit voltage reads at least 6.0V before returning the device to clinical use.

The device shuts off unexpectedly during use — it was fully charged when I started.

The 4003's load profile stresses new Ni-MH cells harder in the first 10 cycles because the cell's internal resistance is still elevated before the plates bed in. Under the concentrator's draw, voltage sag can briefly trip the BMS undervoltage cutoff even when the cell is not fully depleted. This settles after the first several charge-discharge cycles as internal resistance drops. Run at least three full cycles before relying on this battery for extended uninterrupted use, and check that the device completes its startup self-test cleanly on each power-on.

The charge indicator is stuck and will not reach 100% on the first charge — should I leave it longer?

The 4003's charge IC applies a conservative current limit on a new cell it has not yet profiled, which means the first charge can stall visually short of 100% even though the cell is accepting current. Leave the charger connected until the charger's own LED signals termination — do not go by the device's on-screen indicator alone on the first cycle. Once the charger terminates, disconnect and reconnect to start a second charge; the indicator will read correctly from the second cycle onward. If the charger LED never changes state after two hours, check the connector seating at both the battery and the device port.

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