Wow, a Water Powered Calculator (http://www.gadgets.dk/product_info.php?products_id=668&language=en) which actually doesn’t look Fisher Price. Amazing. One fill up lasts around 2 weeks. Not recommended for use in desert area accountancy. Around $70.00.Each water electric power capsule consists of two electrodes, copper (Cu) and zinc (Zn). When these two metals are immerced into an electrolyte (like water), the chemical reaction can be converted into electric energy. Copper (Cu+) ions and Zinc (Zn+) ions will be released simultaniously into the water causing the two metals negativly charged; however, the amount of zinc ions released is much larger than that of the copper ions. This results in an electro-potential difference between the copper and zinc electrodes which can then function as an energy source generating electric current.