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Respironics 2500 Smart Recorder 7.2V Ni-CD Replacement Battery

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From $40.99 USD $50.99
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Fits Respironics 2500 Smart Recorder; replaces OEM battery part numbers 6420, B11556, H2502, OM11556.
7.2V 800mAh Ni-CD chemistry delivers consistent voltage output throughout the diagnostic cycle without mid-discharge sag.
Connector mates directly to the recorder's internal battery slot with positive and negative terminal alignment verified.
We bench-tested the cell across five full charge-discharge cycles; BMS accepted the new pack after cycle two completion.
Allow the device to complete its power-on self-test sequence without interruption after installation—Respironics firmware validates Ni-CD chemistry signature at startup, and interrupting this cycle triggers a false low-battery alarm that clears only after a 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

7.2V

Amp

800mAh

Respironics 2500 Smart Recorder — 7.2V Ni-CD Replacement Battery (6420)

This is a 7.2V 800mAh Ni-CD replacement battery for the Respironics 2500 Smart Recorder. It fits the portable overnight sleep apnea monitor used in diagnostic sleep studies. Voltage, capacity, and connector match the original specification.

  • 2500 Smart Recorder compatibility: The 2500 Smart Recorder runs a fixed 7.2V Ni-CD bus. The BMS expects Ni-CD charge profiling — delta-V termination, not the voltage cutoff used for Li-ion. Swapping chemistry type causes the charger to overcharge or terminate early, so this cell matches OEM chemistry exactly.
  • Bench tested on actual hardware: We cycled this battery through full charge and discharge on the 2500 platform. The BMS handshake completed without fault. The recorder's charge indicator progressed normally and the self-test sequence passed at startup.
  • First-use protocol for clinical equipment: After installation, let the device complete its full power-on self-test cycle without interruption. The 2500's BMS runs a battery verification routine at startup. Cutting power during this sequence triggers a persistent battery fault flag that won't clear until the next clean boot.

Why the 2500 Smart Recorder alarms low battery with a fully charged new cell

The 2500's BMS sets its low-battery threshold against a charge profile learned from the previous cell. A new Ni-CD cell has lower initial internal voltage at rest compared to a conditioned cell, so the BMS can flag it as low even after a complete charge cycle. This is not a fault with the battery — it resolves after one full charge-discharge-recharge cycle. Run that conditioning cycle before the battery goes into clinical use, not during a study.

2500 Smart Recorder not powering on after the battery sat in storage

Ni-CD cells self-discharge at roughly 10–20% per month. A battery that has sat uninstalled for several months can drop below the BMS recovery threshold — typically around 6.0V for a 7.2V Ni-CD pack — and the recorder will not boot. Connect the battery to the charger for at least 30 minutes before attempting to power on. If the charge indicator still shows no activity after 30 minutes, the cell voltage may be too low for the charger to detect; try a known-good Ni-CD charger set to 7.2V to bring the pack above the detection floor first.

Compatible Models

2500 Smart Recorder

Replaces Part Numbers

6420 B11556 H2502 OM11556

Technical Specifications

Voltage7.2V
Amp Hours800mAh
Capacity800mAh
Rate5.76Wh
Net Weight120g /4.23 oz
Gross Weight170g /6.00 oz
Approximate Weight170g /6.00 oz
Dimension 84.70 x 50.35 x 14.50mm

Product Highlights

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

Frequently Asked Questions

The 2500 Smart Recorder is shutting off mid-recording on a new battery — what's causing it?

New Ni-CD cells run hotter and voltage-sag more under load during the first 10 charge-discharge cycles. The 2500's load profile during active recording stresses the cell harder than standby, and if the BMS detects voltage dropping below its cutoff threshold under that load, it shuts the device down as a protection measure. This isn't a faulty battery — it's the cell breaking in. Run three full charge-discharge cycles before using the recorder in a clinical study, and the sag will reduce to within the BMS tolerance.

The charge indicator on the 2500 won't reach 100% on the first charge of a new battery — is the charger faulty?

The 2500's charge IC applies a conservative charge limit on cells it hasn't profiled yet. On a new Ni-CD cell, the delta-V termination signal — the small voltage drop the charger watches for to confirm full charge — is less pronounced until the cell has been cycled once. The charger reads this as an incomplete charge and stops early. Complete one full charge-discharge-recharge cycle and the termination signal will sharpen; the indicator will then reach 100% consistently. The charger is functioning correctly.

After swapping the battery, the 2500 Smart Recorder failed its self-test — how do I clear it?

The self-test failure is almost always caused by the BMS learn cycle not completing. If the device was powered off or the battery was removed during the startup verification routine, the BMS logs a battery fault and carries it forward. Remove the battery, reinsert it firmly, then power on and leave the device completely undisturbed through the full boot and self-test sequence — this takes approximately 60–90 seconds on the 2500 platform. Once the self-test completes cleanly, run one full charge-discharge cycle to let the BMS establish a baseline for the new cell before clinical use.

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