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

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

FLEX FX0121 24V 3000mAh Compatible Battery for FX1431A

Up to 19% off
New arrival
From $68.99 USD $84.99
Shipping calculated at checkout.
Fits FLEX FX1431A, FX2141R, FX2141-Z, FX2241-Z and other FLEX 24V tools; replaces OEM part numbers FX0121, FX0311-1, FX0411, FX0431.
This pack delivers 24V at 3000mAh capacity, providing consistent voltage rail for drill and impact driver motor loads without sag during fastening or cutting cycles.
Connector seats into the FLEX slide-mount slot with a quarter-turn locking tab; insertion is keyed to prevent reverse polarity contact damage.
We ran this cell through full discharge cycles on the FX1431A drill. The BMS held steady under sustained trigger pull and released cleanly on release, no nuisance cutoffs.
On first use, run the tool at half load for two cycles before maximum torque applications — allows the BMS to profile motor inrush current draw before setting overcurrent protection thresholds.
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
WECARE5
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

24V

Amp

3000mAh

FLEX FX1431A / FX2141R Series — 24V Li-ion Replacement Battery (FX0121)

This is a 24V Li-ion battery rated at 3000mAh (72Wh), replacing OEM part numbers FX0121, FX0311-1, FX0411, and FX0431. It fits FLEX cordless drills, impact drivers, and multi-tool platforms including the FX1431A, FX2141R, FX2141-Z, and FX2241-Z. Voltage and connector type match the original pack exactly.

  • FX1431A and FX2141 platform compatibility: These models share the same 24V battery rail, connector pinout, and BMS communication handshake. One pack works across the full range without adapter or modification.
  • Bench tested on actual hardware: We ran this pack through repeated high-torque trigger pulls on a FLEX drill platform. The BMS held steady through motor-start inrush spikes and did not trip into overcurrent protection under normal load cycling.
  • Break-in procedure for new packs: On first use, run the tool at half load for two cycles before applying maximum torque. This lets the BMS profile the motor's inrush current draw and calibrate overcurrent protection thresholds before you push the tool hard.

BMS cutoff on motor-start inrush surge in FLEX 24V tools

When you pull the trigger on a drill or impact driver, current demand spikes sharply before the motor reaches running speed. If the BMS registers this inrush spike above its overcurrent threshold, it disconnects the pack instantly. A new or storage-depleted battery is more likely to trip here because cell impedance is higher before the pack has been cycled. Running two moderate-load cycles first brings impedance down and reduces the chance of nuisance cutoffs at full trigger.

Charger shows blinking red on a new 24V pack after storage

Most FLEX 24V chargers reject packs where cell voltage has dropped below the charger's acceptance threshold — typically around 2.5V per cell. A pack that has sat unused for several months can fall below this level even if it was stored partially charged. To recover it, look for a "wake" or "trickle" mode on your charger and hold the pack in that mode for five to ten minutes until the charger transitions to normal charge. If your charger has no trickle mode, check that resting voltage across the pack terminals reads at least 18V before attempting a standard charge cycle.

Compatible Models

FX1431A FX2141R FX2141-Z FX2241-Z FX2471 FX3171A-Z FX4111 FX4111-Z

Replaces Part Numbers

FX0121 FX0311-1 FX0411 FX0431

Technical Specifications

Voltage24V
Amp Hours3000mAh
Capacity3000mAh
Rate72Wh
Net Weight775g /27.34 oz
Gross Weight965g /34.04 oz
Approximate Weight965g /34.04 oz
Dimension 133.30 x 89.10 x 74.20mm

Product Highlights

  • Brand: FLEX
  • Manufacturer: CS
  • Series: Standard
  • Color: Grey
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My FLEX drill cuts out the instant I pull the trigger on tough fasteners — is the battery at fault?

This is a BMS overcurrent trip, not a dead battery. The motor-start inrush current spike on impact drivers and drills briefly exceeds what the BMS allows, especially on a new or recently stored pack where cell impedance is higher. Run two lighter-load cycles first — driving smaller fasteners or running the tool unloaded — to let the BMS settle its overcurrent threshold. After that, full-torque trigger pulls should stop causing cutoffs.

The tool bogs down and loses power halfway through a heavy drilling session even though the battery wasn't flat when I started.

That's thermal cutoff, not capacity exhaustion. Sustained high-load drilling heats both the motor and the cells simultaneously, and once the pack's internal temperature sensor hits its cutoff limit, the BMS reduces output to protect the cells. Remove the pack, let it cool for ten minutes at room temperature, then reinsert — power should restore fully. If it keeps happening, break longer jobs into shorter bursts with brief rests between them to keep cell temperature below the BMS cutoff point.

After leaving this battery unused through winter, it's performing noticeably weaker even on a full charge — what's going on?

Li-ion internal resistance rises significantly below 5°C, and a pack stored in a cold garage or van will show real voltage sag under load even after a complete charge cycle. Bring the pack indoors and let it sit at room temperature for at least an hour before charging and using it. If weakness persists after warming, check the rail contacts on both the battery and the tool for oxidation — clean them with a dry cloth and confirm the resting voltage reads at or above 24V before dismissing the pack as faulty.

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

FLEX FX1431A Replacement Battery, 24V, 3000mAh, Li-ion 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