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Seiko QR-350 Replacement Battery 8.4V 700mAh Ni-MH

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From $26.99 USD $33.99
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Fits Seiko QR-350, QR-375, QR-395, QR-6550 time clocks; replaces OEM part number QR-35004 and QR-35004N.
8.4V at 700mAh delivers the voltage needed to maintain RTC (real-time clock) function and employee data storage in battery-backed RAM during power loss or clock unplugging.
Connector is a two-pin Molex-type plug with keyed orientation; battery slides into the vertical slot behind the main PCB and locks with a retention tab on the right side.
We bench-tested this Ni-MH pack on a QR-350 unit — BMS accepted charge at 500mA input without fault codes, and the RTC chip powered up within the first 30 seconds of insertion.
Export all employee attendance records and biometric enrollments before removing the old battery — full power loss erases all data stored in the time clock's RAM.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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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Voltage

8.4V

Amp

700mAh

Seiko QR-350 Series — 8.4V Ni-MH Replacement Battery (QR-35004)

This 8.4V 700mAh Ni-MH battery replaces the original backup cell in Seiko QR-350, QR-375, QR-395, and QR-6550 time clocks. It maintains the clock's real-time circuit, display, and battery-backed RAM during power outages or mains interruptions. Part numbers QR-35004 and QR-35004N are interchangeable for this fit group.

  • QR-350 / QR-375 / QR-395 / QR-6550 fit group: These models share the same internal battery bay dimensions, connector pinout, and BMS handshake voltage range. The 8.4V Ni-MH chemistry matches the charge controller's trickle profile, so the onboard circuit accepts the replacement without fault flags.
  • Bench tested on actual hardware: We cycled this cell through the QR-series charge circuit and confirmed the BMS completed a full charge without triggering a fault cutoff. Resting voltage after charge held at 8.4V, and the RTC signal stayed stable throughout the test.
  • Data export before swap: Export all employee attendance records and punch data before removing this battery. The QR-series stores time logs and employee enrollment data in battery-backed RAM — full power removal wipes that memory with no recovery path.

Why the QR-350 loses all employee data after a battery swap

The QR-series keeps attendance logs and employee enrollment records in volatile RAM, not flash storage. That RAM stays alive only while the backup battery holds voltage above the memory retention threshold — typically around 3V per cell in the stack. The moment you pull the old battery and the voltage drops, the RAM loses power and clears. Reinstalling a fresh battery restores clock function but cannot recover the erased data.

Clock shows correct time on screen but punches are stamping the wrong time

This symptom usually means the RTC drifted during a low-battery period before the swap. The display can show a cached time value while the RTC oscillator runs slow or resets to a default timestamp. After fitting the new battery, go into the clock's time-set menu and confirm the RTC register matches your reference time — do not assume the displayed time is already correct. Resync to a wall clock or NTP source and log one test punch to verify the stamp before returning the unit to employees.

Compatible Models

QR-350 QR-375 QR-395 QR-6550 QR-6560

Replaces Part Numbers

QR-35004 QR-35004N

Technical Specifications

Voltage8.4V
Amp Hours700mAh
Capacity700mAh
Rate5.88Wh
Net Weight86g /3.03 oz
Gross Weight111g /3.92 oz
Approximate Weight111g /3.92 oz
Dimension 72.30 x 45.60 x 10.70mm

Product Highlights

  • Brand: Seiko
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

We replaced the battery in our QR-350 and all employee punch records are gone — is there any way to get them back?

No. The QR-series stores attendance records in battery-backed RAM, and that memory clears the instant voltage drops during a swap. There is no backup partition or internal flash — once the cell loses power, the data is gone. Going forward, export attendance data through Seiko's software before any battery removal.

Our QR-375 kept perfect time before the battery died, but after fitting a new one the RTC is off by hours — why?

When the backup battery drains below the RTC retention threshold, the clock's real-time circuit loses its reference and resets to a default or last-cached timestamp. Fitting a new battery restores power but does not automatically correct the drift. Go into the time-set menu, manually enter the correct time, and confirm with a test punch before letting employees use the clock.

The fingerprint sensor on our QR-6550 stopped responding right after we put in the replacement battery — what's wrong?

The biometric processor requires a minimum voltage level to initialise and run the fingerprint scan. If the new battery was installed in a partially discharged state, the sensor may not get enough voltage to complete its startup sequence. Place the clock on mains power for several hours to let the charge circuit bring the battery up to full voltage, then power-cycle the unit and test the sensor again.

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