[ausev] Series hybrids

[Christopher Robison]

On Mon, 2007-12-03 at 15:31 -0600, Roy Holder wrote:
> To keep the emissions low I was looking at DC marine diesel generators.
> They typically have a longer run life and reliability, and in the case of
> the Ossa, are lighter. 
> The Ossa have capacities of 6, 13.5, 25, 50, 100, 150 and 200kW.
> 13.5 and 25kw  were the 2 sizes I was interested in.
> I called and talked to an engineer and talked about the 25kw system.  It's
> less than 600 lbs and it consumed 1.3 gallons per hour at full load.  They
> could tweak the output voltage to match need with very little loss of
> efficiency.  It would run well on biodiesel and they had supposedly tested
> with biodiesel a lot, and is was VERY low emissions.
> The down side is they cost more. I think they said a generator was about
> $10,000
> 
> http://www.ossapowerlite.com/index.htm
> http://polarpowerinc.com/products/generators/index.htm

It's been a long time since I'd looked at the Ossa stuff. I'd forgotten
about them.

Actually, from a certain perspective, this isn't so bad. Compared with
the cost of another car for doing long distance trips, $10k and change
for one of these on a trailer seems reasonable.  It's still probably a
lot more accessible for most folks to rent a car for longer trips, but
if you have a reason to need to drive a specific EV (such as bringing a
certain eventually-to-be-completed race truck to the NEDRA Nationals in
Portland...) this would be a lot nicer than a trailer and tow vehicle,
as long as they've done their homework on emissions. The biodiesel or
SVO/WVO capability of diesel engines definitely sweetens the deal.

There is still a catch to the genset-on-a-trailer idea. Namely the motor
size and duty rating problem, mentioned in a previous post.

Another potential catch to think about is how to get the power to the
car without damaging the batteries, which doesn't seem to be a problem
with the Ossa products but is still worth knowing about for those who
might consider this with different products. It's important to limit
voltage to prevent damaging your batteries (which still need to be
in-circuit for acceleration) during periods of net recharge such as
going down long hills or driving more slowly. 

One way is to use a battery charger between an AC generator and the car,
plugging the car into the generator instead of the wall. The highest
rated battery charger currently available off the shelf (to my
knowledge) is the Manzanita PFC-50, which has a feature to allow it to
support this purpose but only delivers 12kW. You couldn't use 2 in
parallel to get more power, since they do not have isolated outputs (I
think they've played with that idea in the past). For more than 12kW
you'd need DC from the generator, and some way to voltage-limit the
output the way a charger would. 

Both of these vendors' products do generate DC (Polar's don't appear to
generate enough), but they don't seem to mention details about voltage
regulation unless I've missed it. I'm sure Ossa's support it though
since they mention hybrid configurations, but I wonder if it's set at a
particular voltage, or if it's user selectable to allow flexibility in
future pack voltage decisions.


-- 
Christopher Robison
chris at ohmbre.org
http://ohmbre.org          <-- 1999 Isuzu Hombre + Z2K + Warp13!