Battery life so far conforms to Nintendo's stated specsI can get about three hours of portable Zelda play on a full battery charge, depending on the screen brightness. The included AC adapter seems to fill about 1 percent of the battery per minute (give or take) when the system is in sleep mode (that mode is very power conscious, incidentallyafter eight hours in "sleep," a fully charged battery had only drained to 98 percent).
I thought the Switch's USB-C charging port would mean I could use any standard external battery pack to charge the system away from an outlet on long trips. Testing with the Jackery Titan S, though, I was only able to get a trickle charge of about 1 percent every six minutes. That charge was so weak that, during normal gameplay, the Switch actually died on me while it was still plugged in to the external battery pack.
This could just be an issue of voltagethe packaged wall outlet is rated for 15V/2.6A, while the battery pack is only rated at 5V/3Aor it might be an issue with confusing USB-C charging standards. In any case, don't expect perfect compatibility with third-party chargers.