Replacement for Kobalt 40V Battery 6.0Ah, Compatible with All Kobalt 40 Volt Lithium-lon Battery Power Tools, Replace for 40V Max Battery KB440-03 KB2540C-06 KB640-03 KB240-06

What It Is

This is a 6.0Ah lithium-ion battery replacement for Kobalt 40V cordless lawn mowers, trimmers, blowers, and other tools in the Kobalt 40V Max platform. It powers compatible equipment without needing a separate charger.

Fitment & Compatibility

• Exact models: Replaces KB440-03, KB2540C-06, KB640-03, KB240-06, and all Kobalt 40V Max tools using the same slide-on battery interface.
• Check your tool: Look for the “40V Max” logo on your mower or tool. This battery does not fit 80V or 24V Kobalt systems.
• Physical dimensions: 5.5 x 3.5 x 3 inches; same footprint as OEM 4.0Ah and 5.0Ah packs. Verify your battery compartment depth—some older mowers have tight clearance.
• Charger compatibility: Works with any Kobalt 40V charger (model numbers starting with KRC or KLC). Do not use with third-party chargers unless explicitly rated for 40V Li-ion.

Key Things to Know

• Aftermarket vs. OEM: This is a third-party replacement, not made by Kobalt. It may have slightly lower cycle life than genuine Kobalt batteries.
• Capacity: 6.0Ah provides roughly 50% more runtime than the standard 4.0Ah pack—good for larger lawns (up to 0.5 acre on a single charge in a 20-inch mower).
• Installation: Slide onto tool until it clicks; no tools required. If it doesn’t click, check for debris in the rails.
• Common gotcha: Some users report the battery indicator lights may not match OEM behavior—don’t rely solely on the gauge for precise remaining charge.

Should You Buy It

Buy this if you have a Kobalt 40V mower or tool and need a high-capacity backup or replacement at a lower price than OEM, and you’re comfortable with aftermarket performance. Skip it if you want guaranteed OEM reliability or need the longest possible lifespan—spend more for a genuine Kobalt battery.