Just kidding.
I'm up to nine batteries thanks to super good deals in the past. Not so much today.
I purchased this Ravpower pack when I only had a few batteries and was able to keep the Spark flying during the day by charging the remote, device, and batteries with the stock battery hub between flights.
I would fly at one location. Load the stuff in the car and charge while driving to the next spot.
I went with the Smatree. It charges 3 batteries simultaneously in under an hour. With 4 batteries I can continuously fly in cooler weather, but need to let them cool down when it's hot out. Might put a 5th battery in the rotation when it warms up. Wanted to stay with the DJI, but takes 2 hours to give a full charge.