Power banks are only good as long as they’re already charged, but this one charges itself! A huge 4,000mAh internal battery bank provides you with loads of power for device recharging via the USB charging outlet, up to 2A. The unit can be recharged using the MicroUSB cable provided, or self-charge with its integrated solar panel. Solar charging is probably more considered the backup or emergency plan though, as it can take a few days (about 31 hours) to fully charge. However if you’re leaving the unit on a dashboard or in a sunny window when not in use, it’ll keep itself topped up and ready to go any time!