2Pack Compatible with Worx Battery 20V 4.0Ah WA3525 WA3520 WA3575 WG151s WG155s WG251s WG255s WG540s WG545s WG891 20V Cordless Power Tools Battery Pack

What It Is

This is a 2-pack of aftermarket 20V 4.0Ah lithium-ion batteries designed to replace Worx’s WA3525, WA3520, and WA3575 OEM packs. They power any Worx 20V cordless tool or mower that uses the standard slide-on battery platform, including the WG151s, WG155s, WG251s, WG255s, WG540s, WG545s, and WG891 models.

Fitment & Compatibility

Before buying, verify your mower or tool uses Worx’s 20V slide-on battery interface (not the older 18V or the newer 40V/60V platforms). Check the original battery part number—this pack matches WA3525, WA3520, WA3575, and WA3580. It will NOT fit Worx 40V or 60V tools, or any non-Worx brands. Measure the battery compartment: these are physically identical to OEM 4.0Ah packs, so if your original fits, these will too. No deck size or blade compatibility issues—this is purely a power source.

Key Things to Know

• Quality vs OEM: Aftermarket cells typically have lower cycle life than Worx’s own packs. Expect 300-500 charge cycles vs 500-800 for OEM. Capacity is usually accurate but may degrade faster under heavy loads (e.g., thick grass on a mower).
• Installation: Zero difficulty—slide on until it clicks, press the release button to remove. No tools or wiring required.
• Common Gotcha: The built-in LED charge indicator may be less accurate than OEM. Fully charge before first use, and don’t rely on the indicator for precise remaining runtime.
• Charging: Use only Worx’s 20V charger (e.g., WA3820 or WA3830). Third-party chargers can damage the battery or cause fire risk.

Should You Buy It

Buy this if you have multiple Worx 20V tools and need spare batteries for light-to-medium use (e.g., trimming, edging, or occasional mowing). It’s a budget-friendly way to extend runtime without paying OEM prices. Skip it if you mow large lawns weekly or need maximum durability—the OEM pack will last longer under heavy loads.