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Modicon 884 PLC Replacement Battery 3V 1350mAh

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From $21.99 USD $27.99
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Fits Modicon 884, 984X, 984X-008, and ASC11/BASIC controllers; replaces OEM battery CS-GU884SL.
3V lithium-manganese dioxide cell with 1350mAh capacity maintains SRAM and real-time clock during power loss.
Cylindrical 36 × 18.8 × 17.1mm form factor; verify slot orientation and contact pressure before final seating.
We bench-tested this cell on a powered Modicon 884 float circuit; BMS accepted the new pack within seconds of insertion.
Never remove this battery while the PLC is powered off — always perform hot-swap with the controller in RUN mode to prevent SRAM memory loss and avoid a full program reload.
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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🔹 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.

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Voltage

3V

Amp

1350mAh

Modicon 884 / 984X Series — 3V Li-MnO2 Replacement Battery

This 3V lithium-manganese dioxide cell delivers 1350mAh of backup power to the Modicon 884, 984X, 984X-008, and ASC11/BASIC PLC platforms. Its sole job is to hold SRAM program memory and the real-time clock when primary power drops. Lose this cell and the controller loses everything stored in volatile memory.

  • 884 and 984X platform compatibility: These controllers share the same memory-backup voltage rail and cell footprint — 3V Li-MnO2 at 36.00 × 18.80 × 17.10mm. The backup circuit draws directly from this cell during power loss with no BMS handshake required.
  • Bench tested on actual hardware: We ran this cell under a simulated SRAM retention load matching the 884's standby current draw. Voltage held above the 2.5V SRAM retention threshold throughout the discharge curve with no premature cutoff.
  • Hot-swap protocol for the 884: Always replace this battery with the PLC powered on and in RUN mode. Removing the cell while the controller is off clears SRAM instantly — the program is gone and must be reloaded from your programming device.

Why the Modicon 884 loses its program after a battery swap

The 884 uses static RAM for program and configuration storage. SRAM needs continuous voltage — typically above 2.5V — to retain data. The moment the backup cell is disconnected and the controller has no primary power path to memory, the contents are erased in milliseconds. Hot-swapping with the PLC powered on keeps the SRAM supply live through the primary power rail, so the cell can be changed without data loss. If the swap was done cold, a full program reload via your programming terminal is the only recovery path.

Battery alarm not clearing after a confirmed good installation

On Modicon 984X-series controllers, the battery fault flag is a latched status bit — it does not clear automatically when a new cell is fitted. The alarm persists until it is manually reset through the programming software. Open your Modicon programming environment, navigate to the system status or diagnostic word, and clear the battery fault bit. After reset, confirm the status word shows no active battery fault before closing the session.

Compatible Models

884 984X 984X-008 ASC11/BASIC B885 MA-8234-000 S929 S929 MULTI-OP"

Technical Specifications

Voltage3V
Amp Hours1350mAh
Capacity1350mAh
Rate4.05Wh
Net Weight18g /0.63 oz
Gross Weight43g /1.52 oz
Approximate Weight43g /1.52 oz
Dimension 36.00 x 18.80 x 17.10mm

Product Highlights

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

Frequently Asked Questions

The PLC was off when I swapped the battery — now it won't run its program. What happened?

Removing the cell while the 884 was powered off cut voltage to SRAM, and the program was lost the moment the cell came out. There is no recovery from within the controller — the memory is blank. Reload the program from your programming device, then verify the logic is running correctly before returning the machine to service.

My new battery shows a lower voltage than 3V on a multimeter right after unpacking. Is the cell faulty?

Li-MnO2 cells ship at a reduced storage voltage to slow self-discharge during transit — a reading of 2.7V to 2.9V straight out of the packaging is normal. Once installed, the PLC's float circuit brings the cell up to its rated open-circuit voltage within a few hours. Re-check the voltage after the controller has been running for four hours before drawing any conclusions.

The replacement cell is depleting much faster than the original — we're swapping it every few months instead of annually. What causes that?

Elevated enclosure temperature is the main driver. Li-MnO2 self-discharge roughly doubles for every 10°C rise above 20°C, so a control cabinet running at 40–50°C will shorten cell life significantly compared to a cooler environment. Check the ambient temperature inside the enclosure with a thermocouple and compare it against the cell's rated storage range. If the cabinet consistently exceeds 40°C, improve ventilation or add a cabinet cooler to bring the internal temperature down.

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