Friday, August 21, 2009

The feasibility of rapidly charging EV's

Below is a poster I put together describing the feasibility of rapidly charging EVs.

There are three main things to consider: (1) Cell chemistry (2) Power source (3) Chargers and (4) Battery pack design.

The good news is that it's all totally feasible - though research & development is obviously required! A123 has already developed the cells necessary.

Remember that drivers would not rapid recharge all of the time. Most of the time they would charge EVs for the lowest cost - slowly - over night in their garage. But in the event they need the extra range, rapid charging should be an option.

Included is a chart Shane and I (with help from professional electrical engineer Dave Rodgers) put together. It shows how you could rapid recharge a motorcycle at home, while a sedan would require higher power - which is already available in most industrial buildings (think Home Depot, Best Buy, etc.).

Thus our vision is that the rapid recharge stations would not be at home - but rather at fueling stations like Hope Depot, Shell Gas Stations, etc. This is totally feasible - and the power already exists in many of these buildings.

(click to enlarge)


  1. So I did the math for the 200 mile range sedan.

    We pay about 15 cents a kWh once you add in the distribution fees, etc.

    If you were to charge in 15 minutes at 480V/600A it would cost a bit over $10. If you chose the 220V/70A it's a little over $2.

  2. 15.4kW * 4h ~= 288kW * 0.25h

    so the cost is the same!
    the only difference is Time only

  3. Radioman is on the money here, you pay for energy (kWh), and the amount of energy to fill up the battery is the same regardless how long it takes you.

    There is a difference in so called "demand charges": fast charging results in much higher demand charges for commercial and industrial customers. For now, residential customers do not pay demand charges.

  4. Why not make batteries easy remove and install on a sliding track so you simply pull into a station and they replace the battery with a fully charged one? eliminates the whole issue of having a dead battery in a few years.