Electro Energy <http://www.electroenergyinc.com> (Nasdaq: EEEI), a
company with an upcoming line of very innovative "bi-polar" nickel-
metal hydride batteries, is currently completing custom design of a
prototype battery pack for CalCars' PRIUS+. CalCars hopes to use
these batteries to demonstrate that NiMH, already in use in hundreds
of thousands of hybrid cars, are capable of powering effective
production-vehicle-based PHEVs. And in the future, we hope to
demonstrate EEEI's batteries on other vehicle platforms.

I am now at Electro Energy's facilities in Danbury, CT to complete
and verify operation in their Prius, after which the pack will be
shipped to CalCars. Though engineering has been in progress for
some time, I had not yet reported it here because we were still in
negotiations.

Electro Energy's bipolar design based on flat wafer NiMH cells, in a
sealed package, are stacked together under pressure in sealed
modules. This patented technique has resulted in higher power and
energy densities for the nickel-metal hydride chemistry, and results
in reduced weight, volume and costs, with increased performance.
Also, overcharging and overdischarging of any cell pack can be
detected non-electrically, eliminating the need to monitor tapped
voltages. Since we will be using two parallel strings of modules,
it is also worth noting that this system also provides a way to
disconnect the first-fully-charged of two parallel strings of
modules during charging, to ensure that both strings get fully
charged.

Our first prototype battery will be heavier than those that Electro
Energy is gearing up to produce in a few months. Here are the
specs, which I will soon put into my battery spreadsheet:

Prototype:
60 cells/module, 72V nominal, 17 Ah, 70 lb, approx. 0.2 ohm internal
resistance
6 modules => two strings of 180 cells in parallel, 216V
nominal, 34 Ah, 420 lb, approx. 0.3 ohm internal resistance (vs.
0.35 for the OEM pack)

Eventual: 90 cells/module, 108V nominal, 17 Ah, 73 lb, approx. 0.2
ohm internal resistance
4 modules => two strings of 180 cells in parallel, 216V
nominal, 34 Ah, 292 lb approx. 0.2 ohm internal resistance (vs. 0.35
for the OEM pack)

The eventual weight is similar to that of our current PbA battery
pack. Once we remove the OEM battery, added weight is expected to
be around 200 lb. However, with the prototype pack, unless we
immediately remove the OEM batteries, added weight will be over 400
lb! We are therefore looking for air shocks or other effective,
reversible means of raising the rear Prius suspension while it is
carrying double the eventual extra weight. I will post a request
for a solution, but if you are reading this and have one, please
chime in.

The expected PRIUS+ performance with the Electro Energy pack is as
follows:
EV-only range: 20-25 miles
Average mixed-driving mpg and range: 90 mpg for 40-50 miles
Charge time (Brusa charger, 120V, 15A outlet): 6 hours

Note also that the prototype pack should have lower internal
resistance than the OEM hybrid battery, and the eventual pack
should have much lower internal resistance. Though I haven't made
the internal resistance measurements myself, these are not, as with
the "D" cells I tested, gleaned from ideal 'typical' curves, but
specific measurements made by engineers with whom I have been
working closely. Given what we have learned from others that have
decreased a Prius battery's internal resistance, the eventual pack
should increase the hybrid system's efficiency enough to more than
make up for any mileage losses due to its additional 200 lb --
meaning that even non-plug-in city mileage should be increased at
least slightly (and non-plug-in highway mileage should continue to
be unaffected).

Since Toyota's existing fleet of RAV4EVs has already proven
that deep-cycled NiMH battery packs can have long lifetimes in
electric vehicles, Electro Energy and CalCars will thereby prove
that NiMH batteries are capable of powering effective production-
vehicle-based PHEVs.

At that point, having used our Prius conversion as a test-bed, we
hope to put EEI's batteries to use on other vehicle platforms.

+++++++++++++++++++++++++++++++++++++++++
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