Batteries back then used to be based upon lead-acid - these were very heavy and not nearly as efficient as today's technology, which is usually based upon lithium-ion tech. However, the old style of battery did have one advantage - their weight and bulk made them more resistant to debilitating weather and temperatures.
Around the year 1898, one of the first rear wheel electric bikes was invented - a belt was ran along the outside of the bike.
Electric Bikes didn't gain too much popularity for most of the 20th century, as motorcycles were seen as cheaper and more effective ways of getting around.
However, in the 1990's, several key technological developments ushered in a new era for the electric bike. In Japan, torque sensors and power controls were invented. A bike called "The Zike" was produced - this bike made use of Nickel-Cadmium batteries in addition to a permanent magnet motor (both of which were fixed to the bike).
During 1995, over 106 million electric bikes were sold. By the start of the 2000's, companies like Panasonic and Yamaha were producing 'sealed drive units' (where all the motor components were neatly packaged up into a single unit - this protected them from water and dirt).
Between 2000 and 2004, production of electric bicycles grew by over 40%.
The electric bike market is growing rapidly as each year goes by - growing concern about the cost and sustainability of fossil fuels is causing people to seriously consider an electric bike as their main mode of transport. Indeed in Asia, electric bikes are more prominent than cars due to the need for cheaper transportation.
Nowadays, you can find electric bikes in all sorts of different styles and shapes, so whether you're a road racer or a mountain rider, you'll always be able to go electric when you buy a new bike.