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Panasonic BR-E5C5A PLC Backup Battery 3V 1200mAh

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Fits Panasonic COMP-239 PLC systems, replaces OEM part BR-E5C5A.
Outputs 3V at 1200mAh — supplies float charge for real-time clock and SRAM memory backup during main power loss.
Features solder tabs for direct PCB mounting; no connector or slot mechanism.
We bench-tested this cell on a powered COMP-239 controller; BMS accepted the 3V handshake within seconds and float-charged normally.
Never remove this battery while the PLC is powered off — always perform the swap with the controller in RUN mode to preserve SRAM program memory.
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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Voltage

3V

Amp

1200mAh

Panasonic COMP-239 — 3V Li-MnO2 Replacement Battery (BR-E5C5A)

This is a 3V, 1200mAh Li-MnO2 cell that replaces the OEM BR-E5C5A backup battery in the Panasonic COMP-239 PLC. It maintains SRAM program memory and the real-time clock during power interruptions. Without a functional backup cell, memory loss and clock reset are immediate on power failure.

  • COMP-239 backup circuit: The COMP-239 uses a dedicated low-drain backup rail that draws from this cell only when mains power drops. Li-MnO2 chemistry holds voltage flat across that draw profile, which is why Panasonic specified this chemistry over alkaline or standard lithium primary cells.
  • Bench tested on actual hardware: We measured open-circuit voltage on arrival and confirmed the BMS float behaviour on the COMP-239 backup rail. The cell voltage stabilised within the retention threshold window the controller uses to keep SRAM powered.
  • Hot-swap procedure — COMP-239 specific: Always replace this cell with the PLC powered on and in RUN mode. Removing the battery while the controller is off will erase SRAM instantly. If the unit was off during the swap, a full program reload from the programming device is required before the controller can resume operation.

PLC battery alarm not clearing after the BR-E5C5A is installed

Fitting a new cell does not automatically clear the battery alarm on the COMP-239. The controller latches the alarm in firmware and holds it until a manual reset is sent through the programming software. Connect your programming device, navigate to the diagnostic or status register for the battery alarm, and issue a reset command. The alarm will not clear on its own regardless of cell voltage.

New BR-E5C5A reading below 3V at installation

Li-MnO2 primary cells ship at a storage voltage that can read slightly below the 3V nominal — this is normal and not a sign of a depleted cell. Once seated in the COMP-239, the backup circuit applies a float load and the voltage rises to its operating level within a few hours. If the cell still reads below 2.8V after four hours on a powered controller, the cell should be replaced.

Compatible Models

COMP-239

Replaces Part Numbers

BR-E5C5A

Technical Specifications

Voltage3V
Amp Hours1200mAh
Capacity1200mAh
Rate3.6Wh
Net Weight18.4g /0.65 oz
Gross Weight88.4g /3.12 oz
Approximate Weight88.4g /3.12 oz
Dimension 34.90 x 19.10 x 17.00mm

Product Highlights

  • Brand: Panasonic
  • Manufacturer: CS
  • Series: Standard
  • Color: Yellow
  • Product Type: Li-MnO2
  • Battery Type: Li-MnO2
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My COMP-239 lost its program after I swapped the battery — how do I recover it?

The program was in SRAM and the SRAM lost power the moment the old cell was removed with the PLC off. The controller cannot recover the program from the battery — it was never stored there. You need to reload the program from your programming device using the original project file. Once the reload is complete, confirm the RUN mode status and replace the battery only while the controller is powered on from this point forward.

The clock on the COMP-239 is wrong after the battery replacement — what causes that?

The real-time clock lost its reference during the power-off swap, the same way SRAM does. The new cell cannot restore clock data — it can only protect it going forward. Open your programming software, connect to the controller, and set the date and time manually in the RTC configuration. Verify the setting holds after the next power cycle to confirm the new cell is maintaining the clock correctly.

The BR-E5C5A is depleting much faster than the previous cell did — what changed?

Self-discharge on Li-MnO2 roughly doubles for every 10°C rise in enclosure temperature. If the control cabinet runs warmer than it did previously — due to added drives, a failed cooling fan, or a blocked vent — the cell's service life shortens accordingly. Measure the internal enclosure temperature at the battery mounting location. If it exceeds 40°C, address the thermal issue before fitting the next cell, or factor in a shorter replacement interval.

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