Batteries actually vary in voltage quite a bit as they discharge, and what is printed on the battery is the nominal voltage, roughly what you see on a battery at 50% capacity. For example, a 12V car battery is typically charged to 13.8V, and in order to recharge it quickly after you start the car your alternator is likely pushing something in the 14-to-16 volt range. Similarly, a 14.8V DTAP comes from 4 x 3.7V lithium cells. The fully charged voltage is really around 4.2V, yielding the 16.8V you'll measure if your DTAP is plugged into a fully charged battery. I don't know offhand what specific battery chemistry Nikon is using to yield 7.0V nominal to calculate the fully charged voltage, but the back of my MH-25a charger tells me that its output is 8.4V and I have no cause to doubt that. To power my Z 6II from USB requires USB-C power delivery. That it cannot function on standard 5V USB tells me that it's inputting at least 9V, as that is the next voltage available (prior to the brand new and nearly nonexistent in the wild USB-C programmable power supply spec). To make a long story short, the battery isn't connected directly to the main board of your camera. It's connected to a bunch of circuitry that takes the highly variable voltages ranging from the completely discharged battery voltage up to the 9V or more that is needed when simultaneously operating the camera and charging a battery from external power. You can be confident that 9.2V is within the acceptable input range for your camera's internal voltage regulators and is equivalent to powering your camera from the USB-C connector.

Yes, we do offer a variety of power supplies that would work with this cable. Any 12v power supply of ours will be compatible with this cable. Here are 2 different options that would work:1) <a href= https://www.bhphotovideo.com/c/product/1109311-REG/indipro_tools_pod144_power_pod_dual_lp_e6.html target= _blank >https://www.bhphotovideo.com/c/product/1109311-REG/indipro_tools_pod144_power_pod_dual_lp_e6.html</a>2)<a href= https://www.bhphotovideo.com/c/product/1303049-REG/indipro_tools_dslpxlr_dual_sony_l_series_power.html target= _blank >https://www.bhphotovideo.com/c/product/1303049-REG/indipro_tools_dslpxlr_dual_sony_l_series_power.html</a>