2Packs 4.0Ah WA3520 Li-ion Replacement for Worx Battery 20V Max Lithium Battery Compatible with Worx 20V Battery WA3578 WA3575 WA3525 WG151s WG155s WG251s WG255s WG540s WG545s

What It Is

This is a 2-pack of 4.0Ah 20V Max lithium-ion replacement batteries for Worx cordless lawn mowers, string trimmers, blowers, and other 20V tools. They are designed to replace Worx OEM batteries like the WA3520, WA3578, WA3575, and WA3525.

Fitment & Compatibility

Check your tool’s voltage and platform. These are 20V Max batteries for Worx’s 20V line only—not for 40V or 56V tools. Confirm your Worx tool or charger is marked “20V” and uses the same slide-on port as OEM batteries. Compatible with models: WA3578, WA3575, WA3525, WA3520, WA3555, WA3550, WA3570, WA3572, and tools like WG151s, WG155s, WG251s, WG255s, WG540s, WG545s, WG901, WG902, WG905, WG909, WG929.1, WG929.8.

Physical fit. These are aftermarket batteries—they match OEM dimensions and slide mechanism but may have slightly looser or tighter fit on some tools. Measure your OEM battery compartment if you have an older Worx model; some early 20V tools had slightly different guides.

Charger compatibility. Works with Worx 20V chargers (e.g., WA3740, WA3760, WA3880). Do not use with 40V or 56V chargers.

Key Things to Know

• Performance vs. OEM. 4.0Ah capacity is higher than the standard 2.0Ah WA3520—longer run time per charge. But aftermarket cells may degrade faster than Worx OEM batteries under heavy use.
• No fuel gauge. These do not have the LED charge indicator found on some Worx OEM batteries. You won’t know exact remaining charge until the tool slows.
• Installation is plug-and-play. No tools needed. Slide on until it clicks, then press release tab to remove. If it feels tight, check for debris in the slot—do not force.
• Storage note. Store at 40–80% charge in a cool, dry place. Leaving them fully drained or fully charged for months will shorten lifespan.

Should You Buy It

Buy this if you have multiple 20V Worx tools and need extra runtime without paying OEM prices. It’s a solid value for light-to-moderate use (small lawns, occasional trimming). Skip it if you rely on your mower for large yards daily—OEM batteries offer more consistent performance and a better warranty.