Replacement Battery for Ryobi 40v Battery OP4015 OP4050A OP4040 OP4050 Compatible with Ryobi 40V Cordless Power Tools, Capacity 4.0Ah

What It Is

This is a 40-volt, 4.0Ah lithium-ion replacement battery for Ryobi’s 40V cordless lineup. It powers push mowers, trimmers, blowers, and other outdoor tools that accept Ryobi’s 40V slide-on battery platform.

Fitment & Compatibility

• Compatible models: OP4015, OP4050A, OP4040, OP4050 (and most Ryobi 40V tools using the standard slide-in interface).
• Check your tool’s voltage: Only for Ryobi 40V systems—not for 18V or 36V tools.
• Physical fit: The battery uses the standard Ryobi 40V rail; it fits all Ryobi 40V mowers and handheld tools, but verify the battery bay isn’t obstructed by a different shape (rare, but check your manual).
• OEM vs aftermarket: This is a Ryobi-branded battery, so it’s a direct OEM replacement—no adapter needed.
• Measurement: Approx. 5.5” x 3.5” x 4.0”; weight ~2.2 lbs. Ensure your tool’s battery compartment accommodates these dimensions.

Key Things to Know

• Capacity: 4.0Ah gives moderate runtime—enough for a small to mid-size lawn (1/4 acre or less) on a single charge with a 40V mower.
• Installation: Slide onto the tool until it clicks; no tools required. Removal uses the standard release button.
• Charging: Works with any Ryobi 40V charger (sold separately). Charge time is about 2–3 hours from empty.
• Gotcha: This battery may not fit older Ryobi 40V tools with a different latch design (pre-2015 models). Check the battery rail shape before buying.

Should You Buy It

If you already own a Ryobi 40V tool and need a reliable, affordable spare or replacement for light-to-moderate lawn work, this is a solid pick. It’s a genuine Ryobi unit, so no compatibility worries, but for larger yards or heavy use, consider a 5.0Ah or 6.0Ah battery for longer runtime.