Monday, July 13, 2009

Thoughts on Flywheels

Back in the 70's we had a subscription to Popular Science magazine and there was a lot of interest in alternative energy. I remember reading articles on cars powered by flywheels - you'd plug them in or use a gas motor to spin it up to some outrageous RPM and then drive around until the flywheel stopped spinning. I guess the idea was you'd go to a service station when your tach showed low RPM for a quick respin and then you'd be on your way again...

So what does this have to do with my car? Well, there are two camps on flywheels on electric cars - one camp says they are good and another says they are additional unnecessary weight. I belonged to the second camp but wanted a clutch so was stuck with the flywheel. You might have read some of the early posts where I tried (in vain) to get my flywheel lightened.

Since I've been driving the car regularly, I've changed my mind. In my experience, the flywheel stores your kinetic energy (just as Popular Science described) and helps keep the car stay in motion - reducing the amps needed to maintain a given speed.

The downside is that the flywheel slows your acceleration from a standing start (since it takes a lot of energy to spin up that big heavy disk) and it slows your braking (when in gear, your brakes are not only slowing down the car but the flywheel too).

The plus side is you get to retain your clutch which makes shifting gears easier and you can always use the clutch (or neutral) when braking hard.

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