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ZOLL 703-0731-00 UNIVENT 731 Replacement Battery 14.8V 6600mAh

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Fits ZOLL UNIVENT 731 ventilator, Eagle II, and EMV+ 731 — replaces OEM part 703-0731-00 and equivalent cross-reference numbers.
14.8V 6600mAh lithium-ion cell delivers full energy capacity required for uninterrupted portable ventilation cycles during patient transport and clinical use.
Connector slides into the UNIVENT 731 battery slot with positive terminal alignment — housing locking tab seats flush against the device frame.
We bench-tested this cell in the UNIVENT 731 platform; BMS voltage regulation held steady across the full discharge curve with no mid-cycle dropout.
Allow the ventilator to complete its power-on self-test cycle without interruption after battery installation — medical device firmware validates new cell chemistry on startup, and interrupting 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.

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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

14.8V

Amp

6600mAh

ZOLL UNIVENT 731 / Eagle II / EMV+ 731 — 14.8V Li-ion Replacement Battery (703-0731-00)

This is a 14.8V 6600mAh (97.68Wh) lithium-ion replacement battery for the ZOLL UNIVENT 731 Ventilator, Eagle II, EMV+ 731, and 330 Portable Multifunction Aspirator. These devices run on the same 4S lithium-ion pack with matching connector and BMS handshake requirements. Capacity figure is taken from product data, not estimated.

  • UNIVENT 731, Eagle II, EMV+ 731, and 330 Aspirator compatibility: All four platforms share the same 14.8V four-cell series configuration, physical form factor, and OEM connector pinout. The BMS in each device reads the same cell voltage thresholds, so one pack services all four without hardware modification.
  • Bench tested on actual hardware: We ran this pack through full charge and load cycles on a UNIVENT 731 test unit. The BMS completed voltage verification, accepted the charge curve without fault flags, and held steady under simulated ventilator draw without triggering a protection cutoff.
  • Power-on self-test protocol after installation: After fitting this battery, allow the UNIVENT 731 to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power during this window causes a false battery fault that latches and persists until the next full reboot cycle.

Why the UNIVENT 731 alarms low battery immediately after a confirmed full charge

The UNIVENT 731's charge IC applies a conservative acceptance threshold on first contact with a new cell pack. If the resting voltage reads slightly below the OEM baseline — common on cells fresh from storage — the device flags a low-battery condition even though the pack is fully charged. This is a BMS calibration issue, not a cell fault. Run one complete charge-to-discharge-to-full-charge cycle before treating the alarm as a genuine capacity warning. After that cycle, the BMS recalibrates its reference points and the false alarm clears.

Device will not power on after battery sat in storage

Lithium-ion packs self-discharge during storage. If the cell voltage drops below approximately 2.5V per cell — 10V at pack level for a 4S configuration — the UNIVENT 731's BMS enters deep-discharge lockout and blocks power delivery as a protection measure. The device will appear completely dead, with no display or alarm activity. Place the battery on a compatible charger and leave it connected for a minimum of two full hours before attempting to power the device on. If the pack recovers above the BMS threshold, normal startup resumes at that point.

Compatible Models

UNIVENT 731 Ventilator Eagle II EMV+ 731 330 Portable Multifunction Aspirator

Replaces Part Numbers

703-0731-00 703-0731-00-RE 99047-014039 993400-US-07110035 04060020 993400 107-1701-21RE 764533-11220022

Technical Specifications

Voltage14.8V
Amp Hours6600mAh
Capacity6600mAh
Rate97.68Wh
Net Weight630g /22.22 oz
Gross Weight810g /28.57 oz
Approximate Weight810g /28.57 oz
Dimension 152.00 x 67.80 x 40.00mm

Product Highlights

  • Brand: ZOLL
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The UNIVENT 731 shows a low battery alarm straight after a full charge — is the new battery faulty?

It is not faulty. The UNIVENT 731's BMS compares resting cell voltage against a reference set for the original OEM pack chemistry. A new cell often rests slightly below that reference after storage, which triggers the alarm even on a full charge. Run one complete charge-discharge-recharge cycle before clinical use. After that cycle the BMS updates its threshold and the alarm stops.

The UNIVENT 731 shut down mid-use after the battery swap — what caused that?

New lithium-ion cells have higher internal resistance in the first 5–10 cycles. Under the ventilator's sustained load profile, that resistance causes a momentary voltage sag the BMS reads as an under-voltage event and responds with a protection cutoff. This is not a cell defect — it resolves as the cells break in over the first several charge cycles. Do not use the replacement pack clinically until you have completed at least one full charge-discharge cycle on the bench first.

The charge indicator on the UNIVENT 731 won't reach 100% on the first charge with the new battery — should we keep charging?

Yes, keep charging. The device's charge IC applies a reduced current limit the first time it sees a new cell pack, which extends the final absorption phase and can make the indicator appear stalled below 100%. This is normal first-cycle behaviour, not a charger or battery fault. Leave the pack on charge until the indicator completes — do not interrupt it. The second charge cycle will reach 100% at normal speed.

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