Lithium batteries charge ahead - Researchers demonstrate cells that can power up in seconds.

Nature News ^ | 11 March 2009 | Geoff Brumfiel

[GOPJ]

Thanks for the ping.

[SuziQ]

I’ve heard that the lithium batteries of the coming $40K Chevy Volt have to be replaces at 100,000 miles at the cost of $10K. Credibility?

Considering the amount of research being done, I doubt in 10 years the price would be that much. That info is usually tossed around by folks who don't like the idea of electric cars.

I'd love to have an electric car to do errands around town.

[RightOnTheLeftCoast]

The Prius’ traction battery is warranted for 150k miles in California as part of the emissions-related equipment. I’d imagine the same would be true of the Volt.

The same “$10,000” canard floated around about the Prius, and might even have been true back when it was brand new (and covered by warranty). In taxi service the batteries have routinely gone past 350k miles, and replacements nowadays run about $1500, or less than the cost of a transmission in a similarly well-used car. The batteries require no maintenance.

This type of battery, properly manufactured and used, is very reliable. There are some tricks to achieving close to unlimited life; for example the Prius’ computerized controls maintain charge between 40% and 80% of full. When run in that range, they go practically forever.

[RightOnTheLeftCoast]

"Her car does get an honest 45 MPG which I attribute to two factors: The engine runs at a constant speed to charge the battery pack (at optimum efficiency) and the Prius wheel motors turn into generators when you slow down, using the car momentum to recharge the battery pack."

Close. It uses an Atkinson cycle variant of the common Otto-cycle internal combustion engine. That yields about a 15% efficiency gain right there. The peaky personality of these engines would render them undrivable if it weren't for the clever differential-like electronically continuously variable planetary gearset, which as you say maintains the engine in a narrow speed band for maximum efficiency. Regeneration is another advantage, as you also point out. But then there's another thing: the gas engine need only be sized for pulling the car at-speed. For burst-power needs, the electric motor contributes. So the gas engine doesn't need to be oversized in order to accommodate acceleration, passing and hill-climbs. As a consequence, the Prius is quite a drivable vehicle. It is also very roomy, seating four adults quite comfortably and five when needed, with a cavernous cargo area. And one last thing: the a/c is electric, so the engine doesn't have to run at idle at stops in order to keep the cabin livable. (Flip side: since the engine's coolant provides heat to the heater as with all other cars, turning the heater setting up can make the engine start to run!)

Lots of Freepers get all gruff and dismissive about the Prius because it's, well, kind of the ultimate Al Gore-mobile. But it's a nifty car, very easy to live with, and competitively priced compared to others with equally capacious cabins.

[Secret Agent Man]

“Does it heat up and explode into flames?”

Yes, faster than you can read the first two sentences. /sarc

[normanpubbie]

ROTLC,

Thanks for the additional info on the Prius!

[justlurking]

I drove a Honda Civic Hybrid for an afternoon, in both stop-and-go traffic and on the (urban) freeway. It was a little unnerving at first when the engine shut down at intersections. I got used to it.

It had a "capacity" charge meter, plus an "instant" meter that showed whether it was charging or discharging the battery. So, I could see how it was reacting.

It was on the freeway that I could see the real advantage: when I lifted my foot off the accelerator, the "engine braking" that we all expect was used to charge the battery. When I stepped on the accelerator to speed up slightly, the electric "assist" kicked in, then settled back to normal when I was cruising at the new speed.

There was no need to jam more gas into the engine to make minor speed upward speed adjustments. It was like running on cruise control on a flat, open road all the time, when I get my best mileage in a regular car.

I reset the "average gas mileage" meter when I got into the car. Over my entire trip, I exceeded 50 miles/gallon.

I don't know if the additional cost and complexity is worth it at current gas prices. But, as the technology becomes more common (and cost goes down), and the price of gas inevitably goes back up, it will probably be standard on almost every car -- just like automatic transmissions.