I was mistaken... the D500 ships with an EL-15b, not EL-15c. I did check the two third-party EL-15 type batteries that I use with my D750 and it has no trouble with them.
Now, I just need some time to play with the new camera!
Just make sure that your third party batteries have at least the same rating as the original 'b' battery of 1900 mAh / 14 Wh. You can always go with a battery that has higher specs, but it is never recommended to go with one that has less. If you are using the touch screen and/or not in airplane mode, the battery will drain much faster.
That second 'c' battery I purchased is what I've been using in my D750.
Have fun with your D500. It's an amazing camera! :encouragement: