The Belkin BoostCharge Pro Fast Wireless Charger for Apple Watch + Power Bank 10K is a capable battery pack, but it's not cheap.
Belkin BoostCharge Pro wireless charging stand - with MagSafe - +
Belkin BOOST↑CHARGE™ PRO Portable Fast Charger for Apple Watch
Fast Wireless Charger for Apple Watch + Power Bank 10K
Belkin's new power bank is a godsend for Apple Watch users going
Belkin BoostCharge Pro MagSafe 3-in-1 Wireless Charger for iPhone
Buy the Belkin BoostCharge Fast Wireless Charger for Apple Watch +
Belkin MagSafe 3-in-1 Wireless Charging Pad Fast Wireless Charging
Belkin Boost Charge Pro 3-in-1 MagSafe Wireless Charging Pad Black
Belkin BoostCharge Pro Fast Wireless Charger for Apple Watch +
Belkin BoostCharge Pro 3 in 1 Wireless Charger with MagSafe
Belkin BOOST↑CHARGE™ PRO Portable Fast Charger for Apple Watch