Worx WA3520 20V Replacement Battery 4000mAh Li-ion
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Worx WA3520 20V Replacement Battery 4000mAh Li-ion - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
⚠️ 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.
Worx WA3520 20V Replacement Battery 4000mAh Li-ion - is backordered and will ship as soon as it is back in stock.
Voltage
20V
Amp
4000mAh
Worx 20V PowerShare — 20V Li-ion 4000mAh Replacement Battery (WA3520)
This is a 20V Li-ion replacement battery rated at 4000mAh (80Wh) for the Worx PowerShare platform. It covers the WG545, WG151, WG151.5, and over 128 additional 20V PowerShare tools. OEM part numbers include WA3520, WA3525, WA3575, WA3578, WA3678, WA3671, WA3575.2, WA3012, and WA3571.
- PowerShare platform fit: Every 20V PowerShare tool shares the same battery rail voltage, connector pinout, and BMS communication protocol. That shared architecture is why one pack runs drills, circular saws, string trimmers, and blowers without modification.
- Bench tested on actual hardware: We ran this pack on a WG545 and a WG151 drill under repeated motor-start cycles. The BMS handled inrush current without nuisance tripping and held rail voltage stable across load transitions.
- Motor inrush conditioning on first use: On the first two charge cycles, run the tool at half load — medium speed or partial trigger — before full-torque applications. This lets the BMS log the motor's inrush current signature and set overcurrent thresholds accurately before you hit maximum draw.
BMS cutoff on motor-start inrush surge across PowerShare tools
When you pull the trigger on a saw or drill, the motor draws a spike of current that can be three to five times the running load. A BMS that hasn't profiled the motor yet may read that spike as a fault and cut the pack off before the motor even spins up. This is more common on high-torque tools like circular saws and jigsaws where the start surge is steepest. Resetting the pack by removing it, waiting ten seconds, and reinserting it clears the latch — then condition as noted above before going to full load.
Charger shows blinking red on a new or stored 20V pack
Li-ion chargers have a minimum acceptance voltage — typically around 12–13V for a 20V pack. If a battery has sat unused for several months, self-discharge can pull individual cells below that floor, and the charger refuses to begin a full charge cycle. Most Worx chargers will show a blinking red or amber light in this state. Leave the pack on the charger for 15–30 minutes anyway — many chargers include a low-current recovery mode that trickle-charges cells back above the acceptance threshold before switching to normal charge.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Worx
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
My Worx circular saw cuts out the instant I pull the trigger hard — is the battery dead or is something else happening?
That's a BMS overcurrent trip, not a dead pack. The motor-start inrush on a circular saw can spike to three or four times the running current, and a BMS that hasn't seen that motor before may latch off before the blade gets up to speed. Remove the battery, wait ten seconds, reinsert it, and try starting the saw at half trigger first. After two or three partial-load starts, the BMS profiles the inrush signature and stops tripping on full trigger pull.
The battery feels warm and the tool suddenly loses power mid-cut through hardwood — what's causing that?
Sustained high-load cutting generates heat in both the motor windings and the battery cells. When cell temperature crosses the BMS thermal cutoff threshold — usually around 60–70°C — the pack shuts down to protect the cells. The tool will feel underpowered or stop entirely before a full cutoff. Let the pack rest off the tool for ten minutes to allow thermal dissipation, then resume; if it trips repeatedly on the same job, switch to a second pack and let the first cool between uses.
After sitting in the shed all winter, the battery charges fine but the drill bogs badly under load — is the capacity gone?
Prolonged cold storage raises Li-ion internal resistance, and high internal resistance causes voltage sag under load — the rail voltage drops when the motor pulls current, and the tool reads it as low charge and backs off power. Run two full charge-discharge cycles at moderate load to reconditioning the cells. Check the rail contacts on both the battery and the tool for oxidation while you're at it — clean them with a dry cloth and confirm contact resistance is near zero before writing off the capacity.
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