About this replacement
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.