Batteries Excerpted from Real Goods Solar Living Source Book, edited by Doug Pratt and executive editor John Schaeffer. If we look at the choices we have for AA, C, and D cell batteries, and compare their cost, we should look at cost per kilowatt-hour.
Disposable batteries are by far the most expensive way to use energy.
The full name of this cell type is nickel-cadmium. Nicads are made of nickel, cadmium, and potassium hydroxide in a water solution. Cadmium is a toxic material and should be recycled as such. All nicads, regardless of construction or size, produce about 1.25 volts per cell. Voltage is stable during charging and discharging, but this stability can present problems when you want to know how much energy is left in the battery.