jb_hybrid_ford wrote:

> OK, so NiMHs are not the best choice. <snip>

The NiMH chemistry has lower specific energy than li-ion, but auto
manufacturers are already using them in mass-produced vehicles. With
the Electro Energy batteries, we will be showing that NiMH batteries can
successfully power a PHEV. Some, if not all, mass-produced PHEVs may
well use NiMH batteries for the first few years until li-ion (or yet
another chemistry) takes over.

>
>
> As I recall Lithium Polymers had some good characterics (including
> weight) but had problems with adequate power. I haven't heard much
> talke about them.

I have been considering lithium polymer cells to be a type of li-ion.
In general, they have excellent high power handling capabilities but
equally high prices. They may or may not have safety advantages; each
product needs to be tested and evaluated separately. For example, 18650
cells can have built-in pressure cutout as well as temperature cutout
switches built in to help avoid fires, but the packaging of lithium
polymer cells may just bulge instead of activating such a built-in switch.

>
> Ron said: "-- and that still wouldn't affect similar peak hill-
> climbing and descent currents, which can last for minutes."

This remark applied to the use of supercapacitor banks to handle peak
currents. The point was that there can be real value to be gained by
having the battery pack able to handle full regenerative braking, if not
acceleration, currents, rather than depending on supercaps to do so.

>
> I think that the most economical PHEV would simply lose some charge
> from an extreme downhill and require some I.C. motorized assist on
> an extreme uphill. I don't know exactly what the extremes would be,
> but I could see that at some point, the cost for a given performance
> would rise dramatically. Sometimes I think there is a desire to
> have full E.V. behavior for the first 20 miles or so, but clearly
> that's probably not the least-cost option, especially under these
> extreme conditions. <snip>

I have previously talked about there being a range of EV vs. ICE
capabilities possible for PHEVs (just as for HEVs). Near one end is the
PRIUS+, which is capable of only limited EV operation in terms of both
speed and acceleration; and is capable of no more than doubling gasoline
mileage until the battery is depleted. At the other end is a serial
hybrid with a small ICE disconnected from the drivetrain and running a
generator as necessary to maintain the battery's state of charge above a
minimum. Lots of things between these extremes are possible AND WILL BE
TRIED, because no one yet knows what is optimum in the real world, and,
in fact, the optimum may vary for different costumers' driving regimes
-- just as the mildly hybridized Insight gets better highway mileage
than a Prius, but the Prius does its best in city driving.

For now, CalCars is focussing on what can be done with merely electrical
modifications to existing full hybrid vehicles, because this is where
the short-term leverage exists for quickly getting mass-produced PHEVs
into the marketplace. And even such vehicles, not originally optimized
as PHEVs, can be remarkably good! Later there will be plenty of time to
debate the fine points of PHEV optimization.

> "We model our effort on "Open Source" software development projects:
> We draw on the expertise and solutions of a broad group of experts
> and no individual owns any resulting intellectual property."
>
> "Since we don't keep our discussions secret, our MESSAGE ARCHIVES
> ARE OPEN to the public. We remain highly focused, relatively low-
> traffic and spam-free. In this working group, members post messages
> based on their specialties."
>
> And from the last post:
> > CalCars is pursuing Li-ion options that we can't yet talk about
> > publicly.

Well, we are trying to balance on a razor edge here. To pursue specific
batteries, Felix and I (CalCars' two full-time volunteers) have found
that we must respect various manufacturers' needs for confidentiality.
This means that there are certain specifics and deals that we cannot
discuss in our public forum until they have reached a point where we are
able to make a public announcement, as has now occurred with Electro
Energy Inc. This is one of the limits we have found to how thoroughly a
project can be run as a public forum.

>
> I apologize for posting items off-topic. Apparently, batteries for
> others to use fall in that category as well.

On-topic for this list are discussions of things directly related to
CalCars' current conversion projects, the PRIUS+ and the ESCAPE+. I
apologize that though I try to avoid it, I, too, sometimes allow myself
to be led off into more general PHEV discussions.

> <snip>
>
> -Jim

--
+++++++++++++++++++++++++++++++++++++++++
Ron Gremban, rgremban@...
California Cars Initiative, a nonprofit organization:
http://www.CalCars.org
Moderator & Technical Lead
http://www.priusplus.org
PRIUS+ PHEV Conversion Group: http://groups.yahoo.com/group/priusplus
Newsletter: http://groups.yahoo.com/group/calcars-news
+++++++++++++++++++++++++++++++++++++++++