Ok, well my bag of balls turned up yesterday - those illuminated ones I mean. I was quite surprised at just how small they are, they can be no bigger than half inch across (thats about 1.2cm for you youngsters out there).
They are also lovely and bright as well, much more than I thought they might be to be honest.
Anyway I've been carrying out an experiment today to see just how long the run on the batteries they come with. So at 8.30am this morning I started one white and one multicolured ball to see. As of now they are both still alight, the white one just as bright as when I started it, the multicoloured one though is on its last legs. About 10 hours in it started to slow down cycling through the colours and then about an hour later the blue colour stopped, now it is finally down to just the red LED working (they usually need less current than the other colours). However this is now nearly 14.5 hours into my test.
This is quite impressive to my mind and even when the batteries are exhausted it will not necessarily be the end of the experiment as I intend to crack them open (if they don't just pop apart) and see what the innards are like. My thoughts are to attach wires to the battery terminals and then potentially I have a standalone lighting unit that could be fitted anywhere - in a lego brick, in a building, a train coach or whatever and powered from a switch/battery
If its possible to extract the mechanism from the ball they could prove an even more economic tool for lighting models