Comments on: VC dollars now chasing fast battery charging

By: Anonymous

Anonymous — Tue, 08 Jul 2008 10:30:00 +0000

Charging , say, 18 kWh in ten minutes means a draw of more than 100 kW. In five minutes it’s more than 200 kW. In one minute it’s more than a MegaWatt. One minute or maybe two is about what’s needed for a busy ‘gas’ station near highways etc, otherwise the queue will be too long. Compared to what I draw from my home, it’s at least one and probably two orders of magnitude more. Remember, there are hundreds of millions of cars that have to be served. They won’t be served at the same time of course, but there will be peaks, e.g. during rush hour, and when I do go, I use vastly more power than in my home.

I think this is doable. But the amounts of power per person are huge, it will definately require grid managment. A smart grid would help a lot, with latent heat/cold storage in buildings and parked electric vehicles (V2G) responding to the load. But it’s still a nontrivial issue.

Serial plugin-hybrids are still the best proposal overall IMHO. Most cars are parked 90+ percent of the time, so it’s not like they have to charge quickly. Exceptions would be taxi’s and trucks etc. so eventually we’ll need a charging infrastructure for that (or an insanely good high energy density battery, which may very well happen in the long run). I’ve read some reports that say about 80 percent of car travel can be charged overnight without significant grid upgrades. What would the grid upgrades for 5 minute fast charging cost?

I think the best thing is slow charging wherever possible, and fast charging if necessary. But I would like to see some figures about the costs and issues of grid upgrades for large scale fast charging.

By: Anonymous

Anonymous — Sat, 21 Jun 2008 23:08:00 +0000

For overnight charging it’s fairly easy. If owners of plug-in hybrids or all-electrics are required to acknowledge this when they register their vehicle, then it’s easy for the power system operator to predict overnight charging.

Now, for fast charging, I agree — there’s always plenty of experience with the off-on nature of power-hungry industrial equipment. I think it might be a little rough at first, but once a trend line is established then really you just end up with software making the predictions of system load/demand. That said, it won’t be without some difficulties, but I don’t think there’s any showstoppers here. At worst, charging stations will have to meet certain standards and be licenses to provide quick-charge services.

By: Anonymous

Anonymous — Sat, 21 Jun 2008 15:48:00 +0000

The grid handles large loads now. Think about massive commercial air conditioners or large industrial motors.

It’s not as if every charging station will start at the same moment. The starts/stops will be staggered.

By: Anonymous

Anonymous — Fri, 20 Jun 2008 17:54:00 +0000

Did they think about the costs and engineering issues associated with the grid load of fast charging batteries? One would imagine the grid would have to be enhanced with large amounts of capacitors etc to level the spikes and peaks created by fast charging loads.