Suggestions for battery powered 8x8x3 neopixel matrix

My project consists of 3 8x8 neopixel matrix panels. I need a way to power it by battery including the arduio itself. I would like to be able to charge it with a connection to a car battery. I would like to keep it as compact as I reasonably can. I would like to be able to leave the battery in during charging. Any suggestions for what I should be looking for? Thanks in advance.

Neopixels and Arduino all run from 5V. Get a 12V to 5V switching regulator for power. www.pololu.com look at the regulators. 3x8x8 = 192 RGB LEDs, which full on draw 60mA, so you may need a couple regulators to come up with 11.52A, perhaps per panel with some negligible amount of current for the Arduino, perhaps just a Promini.