How to get more than 100 MPG from a Toyota Prius

The Toyota Prius has been the most successful and popular hybrid car produced so far but it has one weakness - it cannot go very far on battery power alone. This article tells how a large Lithium-ion battery was added to a Prius, giving it the ability to drive much further on battery power, thereby greatly increasing fuel economy.

By Jim Fell

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I first converted a car to purely electric operation in 1999 and after several improvements, particularly to the battery pack, the car was moderately successful.

I was generally able to travel about 80km on a charge and considerably more if care was taken. The car completed the London to Brighton Electric Vehicle (EV) Run in 2005 and 2006.

Unfortunately the Achilles heel of any EV is still the battery pack. With low-cost lead-acid batteries the range is severely limited and a long cross-country run must be planned like a military campaign.

There must be charging points every 80km or so and you need to stop for a couple of hours at each to restore some charge.

In 2005 I started looking at the hybrid cars that were available and the Toyota Prius in particular. The interesting thing about the Prius was that it could run for a limited period as an EV, however with the NiMh battery pack the electric motor can take the car only about 1.6km at less than 50km.

I wanted to reduce the fuel consumption of the Prius from 60 to 100 MPG, a massive cost saving, by the addition of a large Li-ion batterypack. This article describes how I achieved this using E-blocks and Flowcode as a control system.

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