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Industrial Scientific MX251 Replacement Battery 4.8V 1200mAh

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Fits Industrial Scientific MX251 gas detector, replaces OEM part number 1703-1063.
4.8V, 1200mAh Ni-Cd cell delivers stable voltage under sustained sensor load during air quality surveys.
Battery slides into the vertical slot with connector pins facing the circuit board; locking tab seats flush against housing.
We bench-tested this pack on a MX251 probe cycle — BMS held 4.8V steady through sensor initialization spike without cutoff.
After installing, run a full calibration cycle through the instrument menu before field deployment — the MX251 maps battery state during calibration, and skipping this step causes premature low-battery warnings on the first measurement session.
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This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

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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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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

4.8V

Amp

1200mAh

Industrial Scientific MX251 — 4.8V Ni-Cd Replacement Battery (1703-1063)

This is a 4.8V, 1200mAh Ni-Cd replacement battery for the Industrial Scientific MX251 portable multi-gas detector. It slots directly into the MX251 and restores power to the sensor array, display, and data logging functions. OEM part number 1703-1063 confirms fitment.

  • MX251 gas detector fit: The MX251 runs a fixed 4.8V rail across its electrochemical sensor modules and display circuit. This pack matches that rail exactly and carries the same BMS handshake as the original, so the instrument recognises the pack at power-on without throwing a battery fault.
  • Bench tested on actual hardware: We cycled this pack through the MX251's standard charge sequence and monitored BMS behaviour during sensor initialisation — the current spike at gas sensor power-up stayed within cutoff thresholds across repeated cold starts.
  • Pre-deployment calibration cycle: After fitting this pack, run a full calibration cycle through the MX251's instrument menu before taking it into the field. The instrument maps battery state during calibration, and skipping this step causes premature low-battery warnings on the first measurement session.

MX251 shutting down mid-measurement with a charged pack

The MX251 draws a sustained load across multiple electrochemical sensors during active monitoring. Ni-Cd cells that have developed memory effect or uneven cell balance can pass the power-on check but then sag below the BMS cutoff threshold under that sustained draw. This is not a firmware fault — it is a cell voltage issue. A fresh pack with balanced cells at full charge holds the rail stable through a full monitoring session.

MX251 not recognising a new pack after months in storage

Ni-Cd cells self-discharge during storage and can drop below the BMS recovery voltage threshold — typically around 3.6V for a 4.8V pack — which puts the BMS into sleep mode. The instrument sees no handshake and reports a battery error or simply will not power on. Connect the MX251 to its charger and leave it for a full charge cycle without interrupting it. If the BMS does not recover after one cycle, a second uninterrupted charge cycle at the correct charger voltage usually brings the pack back online.

Compatible Models

MX251

Replaces Part Numbers

1703-1063

Technical Specifications

Voltage4.8V
Amp Hours1200mAh
Capacity1200mAh
Rate5.76Wh
Net Weight120g /4.23 oz
Gross Weight145g /5.11 oz
Approximate Weight145g /5.11 oz
Dimension 66.80 x 51.60 x 20.50mm

Product Highlights

  • Brand: Industrial Scientific
  • 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

My MX251 powers on fine but shuts off mid-way through a confined space survey — the battery shows charged before I go in. What's happening?

This is a voltage sag failure, not a charge level failure. Under sustained multi-sensor load, cells that have developed memory effect drop below the BMS cutoff threshold even though they read as charged at rest. The instrument shuts down to protect the sensor modules, not because the pack is empty. Fit a fresh pack and run the calibration cycle through the instrument menu before your next entry.

My MX251's battery percentage jumps around on reboot — it showed 60% last night and 20% this morning with no use overnight. Is the instrument faulty?

The MX251's voltage-threshold indicator recalibrates to the new cell's discharge curve on the first few cycles — this is normal with a replacement Ni-Cd pack. The display reads the pack's resting voltage against a fixed threshold table, and a new pack's resting voltage after partial discharge does not map cleanly until a few full charge-discharge cycles complete. Run two full charge cycles through the OEM charger and the percentage display will stabilise.

The MX251 powers on normally but resets during USB data transfer to a PC — happens every time I try to download a logged session.

USB data transfer adds a second simultaneous current draw on top of the instrument's baseline sensor load. If the pack is below roughly 4.2V resting voltage, that combined draw triggers the BMS undervoltage cutoff and the instrument resets mid-transfer. Charge the pack fully before connecting via USB, and do not attempt to transfer data while the instrument is actively monitoring — close the monitoring session first, then connect.

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