No matter if you're going camping, or just want a powerful battery backup in the event of power outages, Anker's PowerHouse power stations are popular options. Right now, you can get the PowerHouse II 388Wh battery for $299.99 on Amazon, a $100 savings from the usual price.
The PowerHouse II is a 388.88Wh battery with a 300W AC outlet, a 60W USB Type-C port, three USB Type-A connectors, and a car power socket. The current charge status is displayed on the built-in LED screen, and when it comes time to top up the battery itself, you can use the included DC power plug or Anker's (sold separately) solar panels.
The battery normally retails for $399.99, but you can use coupon code ANKR1730111 at checkout to take $100 off. The PowerHouse is available from Amazon at the link below.