Says working voltage is 10 to 30. Well..... any voltage less than 13.8V DC will make rows of LEDs go out. Running off a 12V car battery requires it to be under charging conditions for all the lights in the 4x4 array to come on - remove the charging supply of 13.8 volts and, within a short, variable while (less then an hour or two) and the LEDs will start going out. Great on a car - useless for my purposes as static display lamps. Hey ho... you live, you learn.
Refreshing to find a book which educates AND entertains at the same time. Kids loved it, and I enjoyed it immensely too ! Looking foward to the next in the series (well, it DOES say Book One.....). Celts V Romans Book One: Diarmid's First Battle