About this replacement
Worx WX166 Series — 20V Li-ion Replacement Battery (WX152)
This 20V 2000mAh Li-ion battery replaces the Worx WX152 pack used across the WX166, WA3528, WA3551.1, WG151.5, and compatible 20V platform tools. It runs the same voltage rail and connector as the original, so it seats into existing Worx 20V chargers and tools without modification. Capacity is 2000mAh (40Wh), matching the standard factory spec.
- 20V platform fit: The WX166, WA3528, WA3551.1, and WG151.5 all share the same 20V slide-rail connector and BMS handshake protocol. One battery services the full tool lineup without adapter plates or firmware changes.
- Bench tested on actual hardware: We cycled this pack through repeated trigger-pull events on a WX166 drill. The BMS held stable through motor-start inrush and did not trip into overcurrent lockout under standard torque settings.
- Motor inrush break-in: On first use, run the tool at half load for two cycles before applying maximum torque. This allows the BMS to record the motor's inrush current signature and set accurate overcurrent thresholds before heavy drilling starts.
BMS cutoff on motor-start inrush with the WX166 drill
When you pull the trigger hard on a cold pack, the motor draws a short current spike two to four times higher than its running load. A new BMS with no usage history treats that spike as a fault and cuts power before the motor reaches speed. The WX152's BMS uses a learned threshold — it calibrates after the first few cycles. Running two low-load cycles first trains the BMS to distinguish a normal inrush from a genuine short-circuit event.
Charger blinking red on a new 20V pack that's been in storage
Worx 20V chargers reject packs that sit below roughly 12V — the charger sees the low cell voltage as a damaged or over-discharged battery and refuses to begin a charge cycle. A pack that shipped or sat unused for several months can drop below that threshold through natural self-discharge. To recover it, check the pack terminal voltage with a multimeter first. If it reads between 10V and 12V, most Worx chargers will accept a manual wake — hold the pack in the charger for 30 seconds, remove it, reinsert firmly, and the charger should shift from blinking red to solid red charge mode.