Rent a power station when you are in the field and need a battery bank to keep your lights or camera running all day or all night. This unit has a capacity of 512 watt hours, so in theory, will run a 512 watt device for 1 hour, a 256 watt device for 2 hours, and so on. These are the manufacturer’s specs under perfect conditions, so assume it will be 80% of that and you’ll be happy.