Since a 5V/1A charger charges at a maximum of 5 watts, if you were playing a graphically-intensive game, your Switch would use more power than your charger could give it. It would last longer than 3 hours, sure, but your battery percentage would drop slowly as you play.

So a usb-c output on the adapter means the best case scenario. If the charger you use has usb-a (the classic one) out, you'll end up with a max voltage of 5, usually, which is prone to drop over length.As for portable batteries, there are many, and 5V is the best we're gonna get for Switch I think (could be wrong, please chime in if there's 15V!). But again, to get the fastest charge speeds we need a 3A current, which means we need USB-C. So far I'm eying the RavPower 20,100mAh (mAh = milliAmp hours) and the Anker 20,100 So higher amps don't matter. Too high a voltage means damage. More amps means more to draw in a shorter amount of time: higher throughput. One thing to watch for when purchasing a third-party AC adapter for the Switch Lite is that it outputs at 15V/2.6A. A product that outputs 5V/1.5A will charge the battery, but doesn’t provide enough power to allow users to play games simultaneously. Using a weaker charger will cause the battery to continue draining, albeit at a slower pace, while using the console. The dilemma comes from charging speed. If the amperage is low, the speed goes down. If you are able to draw 2 amps, a rough calculation is switch battery capacity / amp feed. Chargers often don't charge devices with as many watts as advertised. For example, in the Huawei Ascend Mate 7 review I linked above, even though the charger was rated as a 10 watt charger, for most of the charge the charger only gave the battery 7-8 watts. Because of this you'll want the charger you buy to be rated a decent amount higher than the Switch's (theoretical) maximum energy usage of 6.38 watts. Also, the higher the rating, the faster your Switch will charge, up to the Switch's maximum accepted amps (which, like I said above, is probably somewhere between 2 amps and 2.4 amps, or 10 watts and 12 watts).

In short: the output being 5 volt, you will never blow up anything. I don't know what the switch max voltage is (if the charger can seed 15 volts, let's assume that) and then finding a powerbank that outputs that kind of charge takes away the portability lol. Switch uses USB-C to charge. The standard AC Adapter that comes in the box is a 5V-15V 2.6A charger (max 39 watts, because Watts = Voltage X Amps). And although we don't know exactly how much, Nintendo did state Switch could charge faster via USB-C, which most chalked up to the fact direct USB-C can provide 3A over the 2.6 of the official charger. Standard USB cables can only provide 2.4A, and the standard voltage is 5V. So if you buy a USB wall charger or adapter, it's likely 5V with 2.4A for a total of 12W. But of course, USB-C can actually do up to 3A. I say CAN because all cables are different, and although all will advertise 3A, very few actually attain it.Been planning to make this thread for a while, but until now all anyone could do was speculate. With the system now being reviewed and ready to launch, it's time to start thinking about which cables to use. And it's a lot more complicated than some people think. I'll try to break it down the best I can.