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Biosystems MultiPro Multigas Monitor 3.7V Replacement Battery

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From $26.99 USD $33.99
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Fits Biosystems MultiPro Multigas Monitor, replaces OEM part numbers 54-49-107 and 49-029.
3.7V, 1800mAh lithium-polymer cell delivers steady voltage during extended field surveys and gas detection cycles.
Connector slides straight in; locking tab seats flush against the battery compartment wall without forcing.
We bench-tested this pack through ten charge cycles on the factory dock—BMS accepted the first charge without delay and held voltage stable under sustained sensor load.
After installing, run a full calibration cycle through the instrument menu before field deployment—the monitor maps battery state during calibration, and skipping this step causes premature low-battery warnings during the first measurement session.
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

3.7V

Amp

1800mAh

Biosystems MultiPro Multigas Monitor — 3.7V Li-Polymer Replacement Battery (54-49-107)

This 3.7V, 1800mAh lithium-polymer battery is a direct replacement for the Biosystems MultiPro Multigas Monitor. The MultiPro is a portable multi-gas detection instrument used in industrial safety inspections and confined space entry surveys. It fits alongside OEM part numbers 54-49-107 and 49-029.

  • MultiPro platform fit: The MultiPro series uses a single-cell Li-Polymer pack at 3.7V nominal. The BMS communicates battery state directly to the monitor's firmware. Voltage tolerance matters here — cells outside the accepted window will trigger a battery fault flag before the device even boots.
  • Bench tested on actual hardware: We cycled this pack through the MultiPro's sensor initialisation sequence, which draws a short current spike as each gas sensor powers up. The BMS handled that spike without tripping into protection mode, and the monitor completed its warm-up cycle without interruption.
  • Pre-deployment calibration step: After fitting this battery, run a full calibration cycle through the MultiPro's instrument menu before taking it into the field. The monitor maps battery state during calibration. Skipping this step causes the low-battery warning to trigger early during the first measurement session, even when the pack is fully charged.

BMS lockout after the MultiPro sat unused in a carry case for months

Li-Polymer cells self-discharge slowly during storage. If the MultiPro sits unused long enough, the cell voltage drops below the BMS recovery threshold — typically around 2.5V for this chemistry. At that point the BMS locks the pack out entirely to prevent damage, and the monitor will not power on even when connected to a charger. To recover the pack, connect to a charger and leave it for at least 30–60 minutes before attempting to power the device on. If voltage has dropped below 2.0V, the pack will not recover and needs replacement.

Readings resetting or dropping out mid-logging session

This is not a sensor fault. Under sustained gas sensor load — particularly when the MultiPro is logging continuously across multiple gas channels — current draw is higher than during standby, and an aged or partially discharged cell can sag below the monitor's minimum operating voltage. The firmware interprets that voltage dropout as a power failure and resets the active session. If this happens, check the battery percentage before starting a logging session and ensure the pack is above 50% charge. A cell showing 100% at rest but sagging under load is a sign the pack has reached end of life.

Compatible Models

MultiPro Multigas Monitor

Replaces Part Numbers

54-49-107 49-029

Technical Specifications

Voltage3.7V
Amp Hours1800mAh
Capacity1800mAh
Rate6.66Wh
Net Weight37g /1.31 oz
Gross Weight62g /2.19 oz
Approximate Weight62g /2.19 oz
Dimension 53.30 x 34.20 x 10.00mm

Product Highlights

  • Brand: Biosystems
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The MultiPro powers on fine but shuts itself off the moment I plug in the USB cable to transfer data — what's happening?

USB data transfer adds a combined draw on top of the active sensor load, and if the cell voltage is already soft from a long shift, that extra current tips it past the BMS cutoff threshold. The monitor shuts down to protect the cell, not because of a firmware fault. Charge the battery fully before connecting via USB, and make sure you're using data transfer mode rather than charging through the PC simultaneously. If the shutdown happens with a freshly charged pack, the cell is no longer holding voltage under load and needs replacing.

The MultiPro won't charge after I left it in the charging cradle for days — the charge light never comes on. What's wrong?

A Li-Polymer cell left at very low voltage for an extended period will drop below the threshold the charger needs to detect a valid pack — usually around 2.5V. The charger sees the voltage, determines the cell is outside its safe charging window, and refuses to begin a charge cycle. Remove the pack, let it sit at room temperature for 15 minutes, then reinsert and connect the charger. If there's still no response after an hour, the cell voltage has likely dropped below 2.0V and recovery is not possible — the pack needs to be replaced.

The MultiPro shows a full battery on screen when I turn it on, but the low-battery warning triggers after just a short time in the field — is the indicator wrong?

The MultiPro's battery indicator calibrates its voltage thresholds to the cell it knows. When a new pack is fitted without running a calibration cycle first, the firmware is still referencing the old cell's voltage curve, so the percentage display is inaccurate from boot. Go into the instrument menu and run a full calibration cycle before field deployment — this lets the monitor remap its low-battery trigger to the new cell's actual discharge curve. After calibration, the warning should align correctly with actual remaining capacity.

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