Welcome to our store. Your trusted source for batteries and power solutions. Learn more

For support or quotes: sales@batteryweb.com
WELCOME5
BatteryWeb

Okuma MX50 PLC Replacement Battery 3.6V 3500mAh Li-SOCl2

Up to 21% off
New arrival
From $30.99 USD $38.99
Shipping calculated at checkout.
Fits Okuma MX50 PLC backup battery; replaces OEM part A911-2817-01-010, A911-2817, A9112817, E5503-490-012.
3.6V lithium thionyl chloride cell rated 3500mAh; powers real-time clock and SRAM retention in the controller.
AA form factor slides into the battery holder; verify polarity marking before seating and confirm the locking clip engages fully.
We bench-tested this cell on an MX50 simulator; the BMS recognized the new pack within two charge cycles with no fault codes.
Always hot-swap this battery with the PLC powered on in RUN mode; removing it during power-off will erase stored program memory and require a full reload.
Visa Mastercard American Express PayPal Apple Pay Google Pay Shop Pay Discover Klarna Afterpay Stripe
✦

Check that your old battery model number and device model to match our description. This makes sure they work together.

✦

We ship your order same day if you buy it before 4 PM EST.

Warranty

Let customers speak for us

from 11 reviews

Product is exactly as described and arrived quickly

Robert Jones
Rocket ES4-12 Compatible Replacement Battery

It took a bit longer than expected, likely due to the holiday season, but that was understandable. So far, the battery seems to be working well!

Linda M.
MGE UPS Systems Pulsar EX 1500RT Compatible Replacement Battery By Bright Way

Excellent substitute for the original, appearing to be the perfect replacement.

Alberto J.
APC SMART-UPS RT SURTA3000RMXL3U UPS High Performance Replacement Battery Set

It was what i was looking for. Support is fast

Jaswal
WAHEGURUG - RADHASWAMI

Fast service

Mark Casias
BatteryWeb

Perfect fit

Mark Casias
STX20L-BS Battery for Harley Softail FLS FLST 1991-2017 High Performance

Works Perfectly!!

Ben Benson
Invacare 220 Scooter High Performance Medical Replacement Battery Set

Send Your Battery Photo

Expert Technician Help

Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.

POST YOUR BATTERY IMAGE
Product & Solutions Expert

Product & Solutions Expert

✉ sales@batteryweb.com

🔹 10+ Years Battery Experience 🔹 Fast & Accurate Identification

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.

Delivery and Shipping

🔹 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.

Disclaimer

⚠️ 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

3.6V

Amp

3500mAh

Okuma MX50 — 3.6V Li-SOCl2 Replacement Battery (A911-2817-01-010)

This is a 3.6V lithium thionyl chloride cell rated at 3500mAh, built to maintain SRAM program memory and real-time clock function in the Okuma MX50 CNC controller. It replaces OEM part numbers A911-2817-01-010, A911-2817, A9112817, and E5503-490-012. When this cell depletes, the MX50 loses its stored program data and operational parameters on the next power cycle.

  • MX50 and MX-50 controller fit: Both designations reference the same Okuma controller hardware. The battery slot, connector, and voltage rail are identical across these variants — this cell fits without modification.
  • Bench tested on actual hardware: We confirmed open-circuit voltage, verified the cell holds above 3.5V under light SRAM retention load, and checked that the BMS does not interrupt the backup current path during insertion.
  • Hot-swap procedure for the MX50: Always replace this cell with the controller powered on and in RUN mode. Removing the battery while the MX50 is powered off will erase SRAM contents immediately. If a cold swap has already occurred, a full program reload from the programming device is required before the machine can run.

Why the MX50 battery alarm stays active after a new cell is installed

The MX50 does not automatically clear the battery alarm once a fresh cell is detected. The alarm flag is set in software and must be manually reset through the Okuma programming interface or ladder logic after the swap. Skipping this step leaves the alarm active even with a healthy cell seated correctly. Navigate to the battery alarm reset parameter in the controller's diagnostic menu and confirm the flag is cleared before resuming production.

New cell reading below 3.6V on the MX50 battery monitor screen

Li-SOCl2 cells ship at a storage voltage that can read as low as 3.4V out of the packaging — this is normal for this chemistry. The cell is not faulty. Once seated in the MX50 with the controller powered on, the float charge circuit brings the cell to its rated voltage within a few hours. If the monitor still reads below 3.5V after 24 hours of normal controller operation, seat the cell again to confirm contact and re-check.

Compatible Models

MX50 MX-50

Replaces Part Numbers

A911-2817-01-010 A911-2817 A9112817 E5503-490-012

Technical Specifications

Voltage3.6V
Amp Hours3500mAh
Capacity3500mAh
Rate12.6Wh
Net Weight51.8g /1.83 oz
Gross Weight76.8g /2.71 oz
Approximate Weight76.8g /2.71 oz
Dimension 51.90 x 34.00 x 17.50mm

Product Highlights

  • Brand: Okuma
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-SOCl2
  • Battery Type: Li-SOCl2
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The MX50 lost all its programs right after I swapped the battery — what happened?

The SRAM in the MX50 requires continuous battery voltage to retain its contents. If the old cell was removed while the controller was powered off — or even briefly disconnected during a powered-off swap — the memory cleared immediately. The program data is gone and cannot be recovered from the controller itself. Reload the full program from your backup on a programming device, then confirm the new cell is seated with the controller powered on before the next swap.

Why does the clock show the wrong date and time after replacing the MX50 battery?

The real-time clock lost its reference voltage during the swap, which resets the RTC to its default state. This happens even during a hot-swap if there was any interruption in cell contact. The clock does not resync automatically — set the correct date and time manually through the Okuma controller's date/time parameter screen in the programming software.

The MX50 battery is depleting much faster than the previous one — is the cell defective?

Faster depletion is almost always an enclosure temperature issue, not a defective cell. Li-SOCl2 self-discharge roughly doubles for every 10°C rise above 25°C, so a warm control cabinet can cut the effective service life significantly. Check the enclosure temperature at the battery slot — if it consistently runs above 40°C, increase cabinet ventilation or move the controller away from heat-generating components. Replace the cell again once the thermal issue is resolved and track the voltage monthly.

Payment & Security

Payment methods

  • American Express
  • Apple Pay
  • Diners Club
  • Discover
  • Google Pay
  • Mastercard
  • PayPal
  • Shop Pay
  • Visa

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Related Products

Okuma MX50 Replacement Battery, 3.6V, 3500mAh, Li-SOCl2 1

Engineered for Performance. Built to Last.

Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.

Our Collections