https://www.lowes.com/pd/CRAFTSMAN-V20-20-Volt-Max-4-Amp-Hour-Lithium-Power-Tool-Battery/1000595609 Craftsman V20 20V 4.0-Ah Lithium-Ion Battery (CMCB204) for $39. Shipping is free for My Lowe's Rewards Members , otherwise choose store pickup where stock permits.