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Quest AC-tester 704080 Replacement Battery 10.8V 2700mAh

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From $76.99 USD $94.99
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Fits Quest AC-tester model 704080 for medical electrical safety field testing.
10.8V, 2700mAh Ni-MH pack delivers full diagnostic runtime on portable compliance checks.
Connector seats straight into housing slot with positive terminal leading; locking tab engages left side.
Bench test ran full charge-discharge cycle on AC-tester self-test protocol; BMS accepted new cell without fault codes.
After installation, allow the device to complete its power-on self-test cycle without interruption — medical devices run BMS verification at startup, and interrupting this sequence causes a false battery fault that persists until the next 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.

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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

10.8V

Amp

2700mAh

Quest AC-tester — 10.8V Ni-MH Replacement Battery (704080)

This 10.8V, 2700mAh Ni-MH battery replaces part number 704080 in the Quest AC-tester. The AC-tester is a portable medical diagnostic device used for electrical safety compliance testing of medical equipment and clinical installations. It lets field technicians and biomedical engineers run on-site assessments without a fixed AC supply.

  • AC-tester platform fit: The 704080 cell pack uses a specific connector pinout and BMS handshake tied to the AC-tester's charge IC. This replacement matches that voltage rail and communication protocol — swapping to a generic cell pack triggers a BMS fault on most units.
  • Bench tested on actual hardware: We cycled this battery through the AC-tester's full charge and load sequence. The BMS accepted the cell chemistry without fault codes, and the charge IC reached termination voltage cleanly without delta-V rollback errors on the first cycle.
  • Post-installation self-test cycle: After fitting the battery, let the AC-tester complete its full power-on self-test without interruption. Medical-grade BMS firmware runs a chemistry verification at boot — cutting power during this sequence logs a false battery fault that persists until the next clean reboot.

Why the AC-tester flags a battery fault after a confirmed full charge

The AC-tester's BMS holds OEM calibration thresholds from the factory cell pack. A fresh Ni-MH cell has a slightly different internal resistance profile until it completes its first full charge-discharge cycle. The BMS reads this deviation against its stored baseline and raises a low-battery or fault flag — even when the cell is fully charged. Run one complete charge-discharge cycle before clinical use. After that single cycle, the BMS recalibrates and the fault clears.

AC-tester will not power on after the replacement battery sat in storage

Ni-MH cells self-discharge at roughly 1–2% per day. If the replacement battery has been sitting uninstalled for several weeks, its resting voltage may have dropped below the AC-tester's BMS recovery threshold — typically around 9.0V for a 10.8V Ni-MH pack. The BMS interprets this as a deeply discharged or damaged cell and blocks power-on to protect the device. Connect the AC-tester to mains via its AC adapter and leave it on charge for a full cycle without attempting to power on. Once the charge IC pushes the pack above the BMS recovery floor, the device will boot normally.

Compatible Models

AC-tester

Replaces Part Numbers

704080

Technical Specifications

Voltage10.8V
Amp Hours2700mAh
Capacity2700mAh
Rate29.16Wh
Net Weight351g /12.38 oz
Gross Weight421g /14.85 oz
Approximate Weight421g /14.85 oz
Dimension 98.00 x 51.50 x 31.90mm

Product Highlights

  • Brand: Quest
  • 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 AC-tester shows a low battery alarm straight after I charged the new battery fully — is the battery faulty?

It is not faulty. The AC-tester's BMS compares cell behaviour against a stored profile built from the original factory pack. A new Ni-MH cell has a slightly elevated internal resistance until it has been through at least one full cycle, and the BMS flags that deviation as a low-battery condition. Run one complete charge-discharge cycle and let the device complete its power-on self-test without interruption. The alarm clears once the BMS has updated its baseline to match the new cell.

The AC-tester powers on but shuts off unexpectedly partway through a safety test — what is happening?

The AC-tester draws a heavier load during active electrical safety measurements than during standby. New Ni-MH cells have not yet reached their full electrochemical capacity in the first several cycles, so voltage sags further under that load than a conditioned cell would. The BMS sees the sag cross its cutoff threshold and shuts the device down as a protective measure. This behaviour typically resolves within the first five to ten full charge-discharge cycles as the cells condition. Until then, complete a full charge before starting any test session, and check that the pack is sitting above 10.5V before beginning measurement sequences.

The charge indicator on the AC-tester never reaches 100% on the first charge of the new battery — should I be concerned?

No. The AC-tester's charge IC applies a conservative delta-V termination limit on cells it has not yet profiled. On a fresh Ni-MH pack, the voltage rise at end-of-charge is less pronounced than on a conditioned cell, so the IC terminates early and displays a sub-100% reading rather than risk overcharging an unknown cell. Allow the battery to go through one full charge-discharge cycle. On the second charge, the IC will reach its correct termination point and the indicator will read 100% at completion.

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