FW from my mail...ment for the group

forwarded after discussion with Wayne:


-------- Original Message --------



Hi Group:


As I was leaving DFW (Dallas Fort Worth Airport) a couple of days ago
I chanced upon a Prius with a special decor and words stating "DFW
Guest Assistance". I walked over to the lady that was driving the
Prius and asked her if I could get a couple of shots of the car. She
said; "of course." All I had with me was my Clio Palm so the quality
of the photos I snapped are a bit low but the three pictures of it
are posted in our Photos section here. They are titled "DFW Guest
Assistance..."


I don't post very often these days, so I will do a quick update while
I am here. As many of you know that I added another 7.2 Ah of
lead-acid battery array to the NiMH array that our Prius come with
from the factory. It has been in the car for the last 20,000 miles
or so and I have had zero problems. I now have 28,500 miles on my 02
and everything checks out very nicely with the original NiMH system.


It appears that I am working the NiMH quite a bit less than normal
duty and the Lead/Acid array seems to be holding up very nicely to
the pseudo-charge cycle that naturally occurs between the actual
Prius THD, NiMH charge system and the slower leak-over from the NiMH
while in communion. The Lead/Acid takes charging on more slowly than
the NiMH and so it sips softly off the NiMH after the NiMH gets its
full charge. If the NiMH goes low enough the THD recharges the NiMH
and the sipping begins anew until the Lead/Acid array reaches around
300 volts also. The Lead/Acid array knows how to deliver juice much
more quickly than it knows how to take it back on so it actually
helps the acceleration loads that NiMH would normally bear alone.


My mileage seems to be significantly higher in the city with the
Lead/Acid in communion with the NiMH than when operating on NiMH
only. The highway mileage increase is only nominal. I don't think
I will be able to take advantaged of the increase in battery array Ah
on the highway until I can get access to the code in the THD system.
What are the chances of that? My guess is that I will have to go to
work for Toyota first. If this gets interesting enough, maybe I can
design my own THD controller to work with this marvelous system.


I am working on a super-cap system to help me capture more of the
brake regen and "leak" it slightly more slowly into the 13+Ah hybrid
Lead/Acid - NiMH system overall. I believe that both battery arrays
will respond more efficiently (take more of the available amps on)
that brake regen offers if I capture the large surges in a super-cap
buffer and "leak" them more slowly into the battery array. Leak more
slowly is relative here. The battery array charge efficiency seems
to favor 21 to 30 amps so I hope to finish a circuit that captures
amperages above 30 amps into a super-cap array that buffers and
continues to deliver a maximum of 30 amps into the battery array
until the voltages twixt the two balance.


The super-cap will also serve to buffer the punch off the line surges
that the THD calls for from the NiMH when performing quick and hard
acceleration changes.


Hopefully I can report again in another 6 months on a successful
trial of the super-cap system.


I should have probably posted this in the Technical group but the
above referenced photos belong here and I tend to ramble on if I ever
get started.


Wayne