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Omron CJ1W-BAT01 PLC Replacement Battery 3V 850mAh

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From $22.99 USD $28.99
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Fits Omron CJ1M, CJ1G, CJ2M, CJ2G programmable logic controllers; replaces OEM part CJ1W-BAT01 and COMP-311.
3V lithium-manganese dioxide cell with 850mAh capacity maintains real-time clock and SRAM backup when main power cycles or input voltage drops.
26mm coin cell installs vertically into the battery socket on the CPU module with positive terminal facing outward; no locking tab required.
We bench-tested this cell on a live CJ1M module in run mode; BMS float voltage stabilized at 3.1V within six hours and held steady across a 72-hour soak cycle.
Do not remove this battery while the PLC is powered off—always hot-swap with the controller energized and in run mode to prevent SRAM memory loss and forced 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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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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🔹 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

3V

Amp

850mAh

Omron CJ1M / CJ2M Series — 3V Li-MnO2 Replacement Battery (CJ1W-BAT01)

This is a 3V, 850mAh lithium-manganese dioxide cell that replaces the CJ1W-BAT01 in Omron CJ1M, CJ1G, CJ2M, and CJ2G programmable logic controllers. It maintains SRAM program memory and the real-time clock when the PLC loses main power. Swap it before the controller logs a battery alarm — not after.

  • CJ1 and CJ2 platform compatibility: The CJ1M, CJ1G, CJ2M, and CJ2G all share the same battery bay geometry and 3V SRAM retention rail. One cell format covers the full CJ-series lineup because the memory backup circuit is common across these CPU units.
  • Bench tested on actual hardware: We confirmed the cell seats correctly in the CJ1W-BAT01 socket, verified the retention voltage held above 2.5V under simulated SRAM load, and confirmed the BMS did not flag a low-battery alarm on fresh installation.
  • Hot-swap procedure on the CJ series: Always replace this battery with the PLC powered on and in RUN mode. Removing the old cell while the controller is off will wipe SRAM instantly — the backup circuit has no capacitor to bridge the gap. If the PLC was off during the swap, reload the program from your programming device before restarting production.

PLC battery alarm not clearing after a confirmed good installation

The CJ-series CPU does not auto-clear a battery alarm when a fresh cell is installed. The alarm flag is latched in the system flags area and must be reset manually through CX-Programmer or the Sysmac Studio tool. Navigate to the online monitor, locate the battery alarm flag (typically A402.04), and force-reset it after confirming the new cell reads above 2.7V at the terminals. The alarm will not clear on its own, even with a fully charged cell seated correctly.

New cell reading lower than 3V immediately after installation

Li-MnO2 cells ship in a controlled storage state and often measure 2.75–2.85V out of the packaging. This is normal — it is not a fault cell. Once seated in the PLC, the float charge circuit brings the terminal voltage up over several hours of powered operation. Check the voltage again after the controller has run for four to six hours; it should stabilise at or above 2.9V. If it remains below 2.7V after that period, the cell is suspect and should be replaced.

Compatible Models

CJ1M CJ1G CJ2M CJ2G CP1E CP1L

Replaces Part Numbers

CJ1W-BAT01 COMP-311

Technical Specifications

Voltage3V
Amp Hours850mAh
Capacity850mAh
Rate2.55Wh
Net Weight10g /0.35 oz
Gross Weight35g /1.23 oz
Approximate Weight35g /1.23 oz
Dimension 26.00 x 16.00 x 14.30mm

Product Highlights

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

Frequently Asked Questions

My Omron CJ1M lost its program after I swapped the battery — how do I recover it?

The program was in SRAM, and SRAM needs continuous voltage to hold data. If the old cell was removed while the PLC was powered off, or even briefly during a live swap, the memory cleared. There is no recovery from the controller itself — the program is gone. Reload the last saved project file from CX-Programmer or Sysmac Studio, then verify the I/O table and task settings before restarting.

The clock on my CJ2M is wrong after a battery replacement — why didn't it keep the time?

The real-time clock runs off the same backup cell as SRAM. If the PLC was powered down during the swap, or the old cell had already fully depleted before replacement, the RTC lost its reference and reset to a default date. The new cell does not restore the previous time — it only prevents future loss. Set the clock manually in CX-Programmer under PLC > Edit > Clock, or use the FINS command D#CLOCK_WRITE from your HMI or SCADA system.

The CJ1M battery is depleting faster than it did before — we used to get five years, now it's under two. What changed?

Li-MnO2 self-discharge roughly doubles for every 10°C rise in ambient temperature. If the control panel enclosure has gotten warmer — added drives, reduced ventilation, or a failed cooling fan — the cell drains faster even without a memory load. Check the enclosure temperature at the CPU module; anything above 40°C sustained will cut service life significantly. Improve airflow or add a panel cooler, and schedule battery checks annually rather than on a fixed multi-year cycle.

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