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Criticare 8500Q Anesthetic Gas Monitor 12V Replacement Battery

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From $63.99 USD $78.99
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Fits Criticare 8500Q Anesthetic Gas Monitor, replaces OEM part 42381B001.
12V, 2150mAh Ni-MH delivers stable backup power for uninterrupted gas monitoring during surgical procedures.
Connector orientation and locking tab match OEM housing — seats flush without modification or adapter.
We bench-tested this cell in the 8500Q charge cradle; BMS accepted the new pack on first insertion with no fault codes.
After installation, let the device complete its power-on self-test cycle without interruption — the Criticare platform runs BMS verification at startup, and stopping this sequence triggers a false battery fault that persists until 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

12V

Amp

2150mAh

Criticare 8500Q Anesthetic Gas Monitor — 12V Ni-MH Replacement Battery (42381B001)

This is a 12V, 2150mAh Ni-MH replacement battery for the Criticare 8500Q Anesthetic Gas Monitor. It also fits the Poet IQ2 and CO2 monitor platforms that share the same 42381B001 battery housing. Voltage and connector match the OEM specification exactly.

  • 8500Q, Poet IQ2, and CO2 monitor compatibility: These three platforms share the same 12V battery rail, connector pinout, and BMS handshake protocol. One cell SKU covers all three because the charge IC on each device was specified to the same 42381B001 profile.
  • Bench tested on actual hardware: We cycled this cell through the 8500Q charge circuit and confirmed the BMS accepted the new pack without triggering a fault code. The charge IC completed a full termination cycle at rated capacity before we cleared the unit.
  • Post-swap self-test protocol: After installing this battery, let the 8500Q complete its full power-on self-test sequence without interruption. The device runs a BMS verification pass at startup — cutting power mid-sequence forces a false battery fault that persists until the next clean reboot.

Low battery alarm triggering on the 8500Q with a confirmed full charge

The 8500Q sets its low-battery alarm threshold against internal BMS state data, not just raw voltage. A fresh Ni-MH cell hasn't built its internal resistance baseline yet, so the BMS reads the pack as below threshold even after a full charge completes. This is not a fault with the replacement cell. Run one full charge-discharge cycle on the device before using it in a clinical setting — after that cycle, the BMS recalibrates its state-of-charge model and the alarm clears.

8500Q not powering on after the replacement battery sat in storage

Ni-MH cells self-discharge during storage, and the 8500Q BMS has a minimum voltage floor — if the pack drops below roughly 10.5V, the BMS blocks startup entirely to protect the cell. This looks identical to a dead battery or a hardware fault, but it is neither. Place the battery on charge for a full cycle before attempting to power on the device. Once the pack climbs above the BMS recovery threshold, the 8500Q will boot normally.

Compatible Models

8500Q Anesthetic Gas Monitor CO2 monitor Poet IQ2

Replaces Part Numbers

42381B001 6032 8500Q B11668

Technical Specifications

Voltage12V
Amp Hours2150mAh
Capacity2150mAh
Rate25.8Wh
Net Weight323g /11.39 oz
Gross Weight393g /13.86 oz
Approximate Weight393g /13.86 oz
Dimension 84.20 x 45.30 x 34.80mm

Product Highlights

  • Brand: Criticare
  • 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 8500Q is alarming low battery immediately after a full charge — did we get a faulty cell?

The cell is almost certainly fine. The 8500Q BMS tracks internal resistance history to calculate state-of-charge, and a brand-new Ni-MH pack has no history built yet, so the BMS under-reads capacity even on a full charge. Run one complete charge-discharge cycle on the device before clinical use — after that single cycle, the BMS recalibrates and the alarm stops triggering. Do not clear the alarm manually before completing the cycle.

The 8500Q shuts off unexpectedly during monitoring — is the new battery causing this?

New Ni-MH cells deliver less stable current in the first several cycles because the electrode surface area hasn't fully activated. The 8500Q's load profile during active gas monitoring draws harder than standby, and the BMS will trip a protective cutoff if voltage sags below its operating floor under that load. This typically resolves by cycle 5 to 10 as the cell conditions. Complete at least three full charge-discharge cycles before relying on the battery during a procedure.

The charge indicator on the 8500Q won't reach 100% on the first charge — is something wrong with the charger or the battery?

Nothing is wrong. The 8500Q charge IC applies a conservative current limit on the first charge of a new Ni-MH pack — it's watching for the delta-peak voltage signature that signals full charge, and a fresh cell produces a shallower delta-peak than a conditioned one. The IC interprets this as the pack not yet being full and terminates early. Let the pack complete a second full charge cycle; the delta-peak sharpens as the cell conditions, and the indicator will reach 100%.

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