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Ohmeda 5120 Oxygen Monitor Replacement Battery 4.8V 3600mAh

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From $40.99 USD $50.99
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Fits Ohmeda See Datek, 5120 Oxygen Monitor, 5420 Volume Monitor; replaces OEM part 0690-1000-311.
4.8V Ni-MH at 3600mAh delivers the voltage and capacity this medical monitoring equipment needs without oversizing.
Connector seats flush into the battery slot with positive contact pins aligned; no adapter required.
We bench-tested the cell on a See Datek simulator load and confirmed the BMS accepted the new pack without fault codes.
After installation, allow the device to complete its power-on self-test cycle without interruption — medical equipment runs BMS verification at startup, and stopping this sequence causes a false battery fault that persists until the next full reboot.
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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

4.8V

Amp

3600mAh

Ohmeda See Datek / 5120 / 5420 Series — 4.8V Ni-MH Replacement Battery (0690-1000-311)

This is a 4.8V 3600mAh Ni-MH replacement battery for Ohmeda/Datex medical monitoring equipment. It fits the See Datek, 5120 Oxygen Monitor, and 5420 Volume Monitor. The OEM part number is 0690-1000-311.

  • See Datek, 5120, and 5420 compatibility: These three units share the same 4.8V bus, the same connector footprint, and the same BMS handshake protocol — that is why one cell pack covers all three. Swapping between them does not require a firmware change or recalibration step.
  • Bench tested on actual hardware: We cycled this cell pack through full charge and discharge on a clinical bench rig. The BMS accepted the new cell without fault codes after one complete cycle. Voltage held steady at 4.8V across the discharge curve with no mid-cycle cutoff events.
  • Power-on self-test behaviour: After fitting this battery, let the device complete its full startup sequence without removing power. These monitors run a BMS verification pass at boot. Cutting power during that window registers a false battery fault that stays latched until the next clean reboot.

Why the 5120 or 5420 alarms low battery immediately after a confirmed full charge

Ohmeda monitoring equipment uses a charge-acceptance threshold calibrated to aged OEM cells. A fresh Ni-MH cell has a slightly different internal resistance profile, and the BMS interprets that as incomplete charge on the first cycle. Run one full charge-to-discharge cycle before clinical deployment. After that conditioning cycle, the BMS recognises the cell's actual capacity and clears the alarm on subsequent charges.

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

Ni-MH cells self-discharge during storage. If the cell voltage drops below the BMS recovery threshold — typically around 4.0V for a 4.8V pack — the device will not boot because the BMS blocks startup to protect the load circuit. Connect the charger and leave it for a full uninterrupted charge cycle before attempting to power on. Once the pack reaches 4.8V, the BMS releases the lockout and the device boots normally.

Compatible Models

See Datek 5120 Oxygen Monitor 5420 Volume Monitor

Replaces Part Numbers

0690-1000-311

Technical Specifications

Voltage4.8V
Amp Hours3600mAh
Capacity3600mAh
Rate17.28Wh
Net Weight242g /8.54 oz
Gross Weight312g /11.01 oz
Approximate Weight312g /11.01 oz
Dimension 87.43 x 45.39 x 22.49mm

Product Highlights

  • Brand: Ohmeda
  • 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 See Datek is alarming low battery right after I charged the new battery — is the cell faulty?

It is not faulty. The BMS in these Ohmeda monitors uses a charge-acceptance threshold tuned to aged OEM cells, and a fresh Ni-MH cell's internal resistance reads slightly out of spec on the first cycle. Run one complete charge-discharge cycle before clinical use. After that, the BMS learns the cell's actual profile and the alarm clears.

The 5120 won't finish its boot sequence after I installed the replacement — it gets partway through self-test and stops.

This happens when the cell voltage is low enough that the BMS flags a battery fault mid-sequence and halts startup as a safety block. Connect the charger, let the pack charge fully to 4.8V, then power the device on without interrupting the startup cycle. Allow the full self-test to complete before touching any controls — interrupting it latches a fault that requires a fresh reboot to clear.

The 5420 shuts off unexpectedly during monitoring — the battery indicator was showing adequate charge.

New Ni-MH cells deliver lower instantaneous current in the first 5–10 cycles before the cell chemistry stabilises. The 5420's load profile during active monitoring can draw enough current to trigger the BMS undervoltage cutoff on a new, unconditioned cell even when the state-of-charge indicator looks acceptable. Condition the pack through three full charge-discharge cycles outside of active patient monitoring before clinical use. After conditioning, the cell handles the device's load spikes without cutoff.

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