One thing that Nikon has introduced with their mirrorless cameras is external USB-C charging. The Z6II and Z7II, using EN-EL15c batteries, can be charged by simply plugging the camera into an outlet using the external EH-7P cord, or using a battery with suitable charger. If I am charging using an AC outlet, I will just take my battery out and charge it using the battery charger. But if I am on the road driving to another location, having an external battery that can charge the batteries is handy.
I purchased the Anker PowerCore 20000 portable charger to try out charging my EN-EL15c in-camera. Short answer…it works great. Anker has been making batteries for a long time, and this battery works well. Just plug the USB-C cord into your camera port from the USB-C port on the battery, and charging begins (turn off your camera). The battery doesn’t come with much instructions. Basically you see small blue LED lights letting you know the battery is on, and how much power you have left. Push the button until you see the blue lights. I bought a 20W Belkin wall charger. (PD Fast Charging USB-C adapter) that plugs into the battery to charge it using AC power. It would be nice if they had more info on the battery, but using the adapter with the Anker battery works fine.
Another nice thing about this external battery is you can actually use it to power up your camera while shooting. Imagine long time lapse exposures, or shooting northern lights in very cold conditions. You could easily just plug this battery into your camera and keep shooting. Also, you can charge batteries via the MB-N11 vertical grip (connection port on the side). Just remember USB-C charging only works with EN-EL15c batteries. I like carrying this external battery around on shoots…I can always plug my cameras in for a quick charge in-between photo sessions.