40V Lithium-ION 4.0 AH Battery and Fast Charger KIT

What It Is

This is a 40V lithium-ion 4.0 Ah battery and rapid charger kit designed to power cordless electric lawn mowers, string trimmers, blowers, and other 40V outdoor power equipment. It provides up to 45 minutes of runtime on a mid-sized mower and fully recharges in about 60 minutes.

Fitment & Compatibility

Before buying, verify these three things:

• Voltage match: Only works with tools requiring 40V nominal (not 36V or 80V systems).
• Brand-specific slide-in design: This is a generic replacement—not OEM for Greenworks, Kobalt, or Ryobi. Measure the battery terminal slot on your mower (typically 4.5" x 2.5") and compare to the battery’s base dimensions (listed as 5.1" x 3.0" x 4.2"). If your tool uses a proprietary locking tab, it likely won’t fit.
• Charger plug type: The charger uses a standard barrel connector (2.1mm inner pin). If your mower has a different charging port or uses a dock, this kit won’t work.

Key Things to Know

• Runtime vs. capacity: 4.0 Ah is a mid-range option—good for 1/4 acre lawns on a 40V mower. For larger yards, consider a 5.0 Ah or higher.
• Installation difficulty: None—slide battery into tool until it clicks. No wiring or tools needed.
• Common gotcha: The charger LED may stay red if the battery is deeply discharged. Leave it plugged for up to 2 hours; if still red, the battery’s internal BMS may be locked—try a manual reset (press the battery’s power button for 10 seconds).
• Quality note: Generic lithium cells may deliver slightly less peak power than name-brand equivalents under heavy load (e.g., thick grass). Expect 80-90% of OEM runtime after 100 cycles.

Should You Buy It

If you already own a 40V tool with a compatible slide-in slot and need a spare battery with a fast charger, this kit is a budget-friendly option. Skip it if your mower uses a proprietary battery system (e.g., EGO, Toro) or if you require guaranteed OEM reliability for daily commercial use.