Replacement for Kobalt 40V Battery: 6.0Ah Lithium ion Replace for 40 Volt Max Batteries KB-540-06 KB440-06‎ KB240-06 KB2540C-06 KB640-03 Cordless Power Tool Battery (Blue)

What It Is

This is a 40-volt, 6.0Ah lithium-ion replacement battery designed for Kobalt 40V Max cordless lawn mowers, trimmers, blowers, and other outdoor power tools. It offers higher runtime than the standard 2.0Ah or 4.0Ah packs.

Fitment & Compatibility

Before buying, confirm your tool uses the Kobalt 40V Max platform (not 24V or 80V). This battery is compatible with these Kobalt model numbers: KB-540-06, KB440-06, KB240-06, KB2540C-06, KB640-03. It fits all Kobalt 40V mowers (e.g., 80V mowers are different), string trimmers, blowers, and hedge trimmers that accept the standard slide-on 40V pack. Not compatible with older Kobalt 18V or 24V tools. Measure your existing battery slot: this pack is approximately 5.5" tall x 3.5" wide x 2.5" deep (the standard 40V size). If your tool uses a different connector shape (e.g., some early Kobalt 40V blowers), it won’t fit.

Key Things to Know

• Aftermarket, not OEM: This is a third-party replacement, not made by Kobalt. Quality varies—check recent reviews for swelling or premature failure.
• No installation needed: Slides directly onto the tool’s battery mount. No tools or wiring required.
• Runtime vs. weight: 6.0Ah provides ~50% more run time than a 4.0Ah pack, but adds ~0.5 lb. Expect ~45-60 minutes of mowing on a standard 20" deck.
• Charger compatibility: Works with any Kobalt 40V charger (model KC-540-06, etc.). Do not use with a 24V or 80V charger.
• Battery gauge: Most packs have a push-button LED indicator to check charge level.

Should You Buy It

If you have multiple Kobalt 40V tools and need longer runtime for larger yards (1/4 acre or more), this is a solid budget-friendly upgrade over the stock 2.0Ah or 4.0Ah packs. However, for occasional light use or if you want guaranteed OEM reliability, stick with Kobalt’s own 40V 6.0Ah battery (usually $20–$30 more).