Lowes offers CRAFTSMAN V20 20 -Volt 1 -Pack Lithium-ion ( 4.0 Ah Battery ) for $39 (reg. $129) with free shipping. 

Product Description:
This V20* 4.0Ah Lithium Ion Battery pack provides up to 3x the capacity versus the standard of a standard 20V MAX* lithium battery. It is compatible with the CRAFTSMAN® V20* cordless power tool and outdoor tool lineup. The professional grade high performance cells provide improved power and a longer cycle life. Each pack is equipped with a 3-LED state of charge for immediate battery charge feedback. No memory and virtually no self-discharge means this CRAFTSMAN® 20V MAX* battery is ready when you are.

• Improved power: Premium grade high performance cells
• Longer cycle resulting in an extended battery life
• Battery charge feedback: 3-LED state of charge indicator
• Maximum productivity: No memory and virtually no self-discharge
• Common applications include powering V20 cordless tools, powering V20 cordless outdoor tools
• Includes: (1) CMCB204 V20* 4.0Ah Lithium Ion Battery
• Versus 20V MAX* CMCB201 (1.3Ah) Lithium Ion Battery