Woot offers DEWALT DCBP034 20V MAX Powerstack Compact Battery for $45.99 (orig. $129). Free shipping for Prime Members.

Product Description:
Introducing THE NEXT DIMENSION IN POWER™ with the 20V MAX* DEWALT® POWERSTACK™ Compact Battery. Get 50% more power** with a 25% smaller footprint using this battery that works with the 20V MAX* tools you already have.
This battery provides twice the lifetime** of standard cylindrical battery cells and features an impact-resistant, overmolded base with non-marring material. Take advantage of our lightest and most powerful battery** as the rubber overmold base and twice the lifetime** combine to form a dependable lithium-ion solution.

• 50% MORE POWER in a 25% more compact battery**
• DESIGNED TO RESIST WEAR-AND-TEAR: Durable, overmolded base provides impact resistance
• LONG-LASTING: Battery provides 2X Lifetime**
• AVOID UNPLANNED WORK STOPPAGES: LED fuel gauge displays state-of-charge
• 20V MAX* SYSTEM COMPATIBILITY: Battery works with all DEWALT 20V MAX* tools and chargers
• 1.7Ah battery