Ryobi 40V Battery and Charger Kit 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A

What It Is

This is a genuine Ryobi OP4040 4.0 Ah lithium-ion battery and OP403A charger kit, designed to power any Ryobi 40V cordless lawn mower, trimmer, blower, or other 40V outdoor tool. It’s a drop-in replacement or spare for existing Ryobi 40V systems.

Fitment & Compatibility

• Brand lock: Works only with Ryobi 40V tools – not compatible with Ryobi 18V or 36V/80V/other brands.
• Battery model: OP4040 (4.0 Ah) – physically identical to OP4026, OP4030, OP4040A, OP4050 (higher Ah have same footprint). Fits all Ryobi 40V mowers, string trimmers, blowers, chainsaws, hedge trimmers, and power heads.
• Charger model: OP403A – charges all Ryobi 40V batteries (2.0–6.0 Ah). Works with 110–120V AC outlets only.
• Measurements: Battery is ~5.5” x 3.5” x 4.5” – fits all standard 40V battery ports. No deck size or mower-specific restrictions beyond the 40V platform.
• OEM vs aftermarket: This is genuine Ryobi – guaranteed fit and performance. Aftermarket batteries may lack thermal protection or have slightly different dimensions.

Key Things to Know

• Installation: Zero difficulty – slide battery into tool until it clicks. Charger has LED indicator (red = charging, green = full). No tools or wiring needed.
• Run time (typical): ~40–50 minutes on a 40V mower (medium grass) or ~60–90 minutes on a trimmer/blower. Actual time varies by load and tool.
• Gotcha: Battery must be stored above 32°F for charging – cold weather will prevent charging until warmed up. Charger fan is normal during use.
• Quality note: Ryobi OEM batteries have a built-in BMS (battery management system) that prevents overcharge/overheat. Aftermarket batteries often lack this and can fail faster or damage tools.

Should You Buy It

Yes, if you already own Ryobi 40V tools and need a spare battery or a charger replacement. At $112 for a genuine 4.0 Ah kit, it’s a fair price for reliable OEM performance and compatibility. Skip it if you need more run time (go with OP4050 5.0 Ah or OP4060 6.0 Ah) or if you don’t own any Ryobi 40V gear – there’s no cross-brand use.