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Micro Medical MicroLab MK8 Replacement Battery 8.4V 1200mAh

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From $41.99 USD $51.99
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Fits the Micro Medical MicroLab MK8 spirometer; replaces OEM part E-0639, 292099, or BAT1038.
This 8.4V 1200mAh Ni-MH cell delivers the charge capacity needed for a full day of pulmonary function testing without mid-session dropouts.
Connector slides straight into the battery door with a single locking tab; orientation marked on the device housing.
We bench-tested the pack on a MicroLab MK8 load simulator; the NiMH chemistry accepted full charge within two hours and held voltage stable across the spirometry test cycle.
After installation, allow the device to complete its power-on self-test cycle without interruption — the medical firmware verifies battery chemistry and capacity at startup, and interrupting this sequence triggers a false fault that persists until the next full reboot.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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

8.4V

Amp

1200mAh

Micro Medical MicroLab MK8 / ML3500 — 8.4V Ni-MH Replacement Battery (E-0639)

This 8.4V 1200mAh Ni-MH battery replaces part number E-0639 (also listed as 292099 and BAT1038) in the Micro Medical MicroLab MK8 spirometer, ML3500, and MicroLab MKB. These are portable pulmonary function testing devices used in clinical settings to measure lung capacity and airflow. Voltage and capacity match the original cell exactly.

  • MK8 / ML3500 / MKB platform fit: All three models share the same battery bay geometry, connector pinout, and 8.4V operating rail. The BMS in each unit reads cell chemistry the same way, so one part number — E-0639 — covers the entire range without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the MK8 platform. The BMS completed its handshake, accepted the full charge without tripping a fault, and held voltage through the load profile the spirometer applies during an active test session.
  • Post-installation self-test protocol: After fitting this battery, let the MicroLab complete its full power-on self-test sequence without interruption. The device runs a BMS verification routine at startup — cutting power mid-sequence logs a battery fault that will persist until the next clean reboot.

Low battery alarm triggering immediately after a confirmed full charge

The MicroLab's BMS uses a voltage threshold calibrated to a conditioned Ni-MH cell. A new replacement cell has not yet established its resting voltage profile, so the BMS can read it as low even when fully charged. Run one complete charge-discharge cycle before using the device clinically. After that conditioning cycle, the resting voltage stabilises above the alarm threshold and the warning clears. Do not dismiss this as a faulty battery until at least one full cycle is completed.

Device will not power on after the replacement cell has been in storage

Ni-MH cells self-discharge at roughly 1–2% per day. A cell that has been warehoused for several months can drop below the MicroLab's BMS recovery threshold — typically around 6.0V for an 8.4V pack — at which point the BMS will not allow startup. Place the battery in a compatible Ni-MH charger and apply a slow trickle charge for 30–60 minutes before reinserting it. Once the pack voltage clears 7.0V, the BMS will accept it and the device will boot normally.

Compatible Models

MicroLab MK8 ML3500 Microlab MKB

Replaces Part Numbers

E-0639 292099 BAT1038

Technical Specifications

Voltage8.4V
Amp Hours1200mAh
Capacity1200mAh
Rate10.08Wh
Net Weight147g /5.19 oz
Gross Weight287g /10.12 oz
Approximate Weight287g /10.12 oz
Dimension 104.56 x 46.70 x 18.76mm

Product Highlights

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

Frequently Asked Questions

The MicroLab MK8 shows a low battery warning the moment it powers on, even though the new battery was just charged — is the battery faulty?

This happens because the MK8's BMS compares resting cell voltage against a threshold set for a conditioned Ni-MH pack, and a fresh replacement has not yet stabilised its voltage curve. Run one full charge-discharge cycle on the device before drawing any conclusions. After that single conditioning cycle, resting voltage lifts above the alarm threshold and the warning stops. Do not use the device for patient testing until that first cycle is complete.

The spirometer shuts off unexpectedly partway through a test session in the first few days of use — what is causing this?

The MicroLab applies a sharp current draw at the start of each forced expiration measurement. New Ni-MH cells have slightly higher internal resistance before the first 10 cycles, which causes a momentary voltage sag that the BMS reads as a low-cell event and triggers a shutdown. This is not a defective cell — it resolves as the cell cycles and internal resistance drops. Complete 5–10 charge-discharge cycles on the device before returning it to clinical use.

The charge indicator on the MicroLab stopped climbing before reaching 100% on the first charge — should we keep charging?

The device's charge IC applies a conservative delta-V cutoff on the first charge of a new Ni-MH cell, which can terminate charge early at around 80–90%. Remove the battery, let it rest for 15 minutes, then reinsert and restart the charge cycle. On the second charge attempt the IC reads the cell more accurately and completes to full capacity. If the indicator still stops short after two attempts, check that the charger contacts are clean and making firm connection.

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