The 9V idea won't work. The key issue is that your circuit uses a certain amount of power, i.e. energy per time. A particular type of battery has some energy density per unit volume. It can vary a bit depending on the efficiency of the construction, but will be roughly the same for any standard alkaline cell. The 9V batteries have more units in series, delivering higher voltage, but that doesn't raise their energy density. In fact, the extra construction probably lowers it. Hooking them to inverters and transformers to step that voltage down would just be awkward and waste some more power.
So what you need to do is either switch to some more expensive AA
batteries with a higher energy density or simply switch to bigger
batteries, such as C's.
Another possibility would be to replace the (incandecent?) bulbs with LED bulbs, which use much less power for a given light output.
Mike W.
(published on 02/26/2012)
