Coin Batteries and Project Boards

Does anyone have any real-world experience using Foxonix Project Boards with coin cells instead of AAs? It would be nice to be able to shrink my projects in physical size if coin cells can do the job. Would the downside to coin cells be that they don't last as long as AAs?

Just out of curiosity, if I power a Project Board at 6V (with two 3V coin cells, for example), would that extra .5V fry the board? What would happen?

Thanks!

-eric

Hi Eric:

Using coin cell batteries is a totally acceptable way to power a Project Board, but you are correct - the downside is that the capacity of a coin cell is much less than that of a AA or AAA cell. If your project is mainly speech and audio then coin cells will last quite a long time. You can even power LEDs pretty effectively and still get good life out of them. But if you're powering lots of LEDs, or leaving the LEDs on a lot, or if your project involves a motor (or some other high current draw device), then coin cells are not the best bet. But for speech projects or for projects that also have an LED or two, then they're a great way to save space.

We don't recommend powering a Project Board with 6V. If you're using coin cells then you can use two or three 1.5V cells, or one 3V cell. If you must use two 3V cells, then you can put a regular silicon diode (like 1N914 or 1N4148) in line with the output from the battery pack. This will drop the voltage by 0.6V or so to bring it down under 5.5V. The best configuration is probably to use three 1.5V cells. We use LR44 cells (also called A76) quite a lot, which is pretty standard in toys.