I don't know how long it will last before losing its charge. But I'm going to charge it fully (it's still showing full but you know what i mean...top it off I guess) before I go on vacation. I have to leave my car in a lot for a week and want to make sure I have it in case I need it.

My experience with other battery packs is that they hold a charge for a several weeks before showing noticeable loss. I'll start the timer before I leave and see when it ticks off that 50% bar. They say not to jump unless it's at least 50% so I'm figuring 2-3 months?