Ryobi OP40404 40V Battery 4.0 Ah Lithium-Ion Battery OEM (2021 Redesign with Easy Eject Latch)

What It Is

The Ryobi OP40404 is a 40V, 4.0 Ah lithium-ion battery, part of Ryobi’s 2021 redesign featuring an “Easy Eject Latch” for simpler removal. It’s designed for Ryobi 40V cordless lawn mowers, trimmers, blowers, and other outdoor OPE tools that require a high-capacity battery for longer run times.

Fitment & Compatibility

Before buying, check these three things:

• Tool voltage: Only fits Ryobi 40V tools. Not compatible with 18V One+ or 36V systems.
• Physical fit: The 2021 redesign has a slightly different latch shape and top handle. It will fit all Ryobi 40V tools with the standard slide-in battery port, but older mowers (pre-2018) may have a tighter insertion due to the new latch protrusion. Test fit if possible.
• Charger compatibility: Works with all Ryobi 40V chargers (standard and rapid). Does not include a charger.
• OEM vs. aftermarket: This is OEM Ryobi. Aftermarket 40V batteries often lack the Easy Eject Latch and may have lower capacity or shorter lifespan.

Key Things to Know

• Installation difficulty: Trivial. Slide battery into tool until it clicks. Press the Easy Eject Latch to remove—no more prying with a screwdriver.
• Run time: A 4.0 Ah battery typically runs a 20-inch mower for 30–40 minutes on a single charge, or a trimmer for about an hour. Real-world time varies with grass thickness and speed.
• Common gotcha: The Easy Eject Latch is plastic and can break if you force the battery into a tool that doesn’t align. Always align the battery rails before pushing.
• Storage note: Store at room temperature (50–80°F) to avoid reduced capacity or damage. Cold storage will temporarily lower performance.

Should You Buy It

Buy this if you already own a Ryobi 40V tool and need a reliable, higher-capacity spare battery with the improved latch design. It’s a solid upgrade over the older 4.0 Ah model and worth the price for the convenience of easy removal. Skip it if you’re on a tight budget—aftermarket options exist for less, but expect shorter life and no warranty support.