In addition to using it on trips, you can also use it to quickly charge your battery on any occasion you need it. For example, in extreme weather (hurricane/blizzard) we may face a 2-3 day power outage and we need to fully charge the battery in advance for emergencies. And at that time, your solar system may not be able to provide enough power anymore. That’s when this Renogy 40 Amp charge comes in handy.