I have a 20,000mah portable charger. I'll fully charge it then play zelda and when it gets low, hook it up, continue playing and see how long it lasts. Lets see... Switch battery is 4310mah so that gives me about 4 and half full charges. It's supposed to last 3 hours with Zelda. So 3 + (3 x 4) + .5 = 15.5 hrs. Damn even that's not enough for a camping trip, I'm gonna have to buy another portable charger cause I'll wanna charge my iPhone 7 Plus too.