Richard C asked:
I was wondering how many batteries, for example AA, you can place in series to increase the voltage? What are the limits? Will the current destroy the batteries?
Dave - A battery basically has a little chemical reaction inside which, in conventional ones, causes the voltage of one end of the battery to be one and half volts higher than the other end. You can join batteries together and voltage will get higher. I can’t see any intrinsic limit to how many times you can do that unless you get to a point where the voltage is so huge that you’ll cause sparks from one end of the battery to earth. It depends how good your insulation is - through air you cause a spark at about a thousand volts per millimetre. So if you’re getting into tens of thousands, or millions of volts, then you could create sparks. I think the bigger limit is how much money you have to buy the batteries and how much time you have to join them all together.
Chris - There was a place in Alaska, about five years ago, where they were having so many frequent power cuts that they decided that they will build a massive great Nickel Cadmium battery to prop up the town every time there was a power cut. It was something ridiculous like 13,000 NiCad batteries all linked up to produce mains voltage for a short while to sustain the town and overcome the power deficit problems.
Dave - In the past there have been research batteries at thousands and thousands of volts because it was the only way you can make these high voltages. Now we have easier ways using electronics.