Date:         Mon, 28 Apr 2003 22:06:03 -0400
Reply-To:     David Brodbeck <gull@GULL.US>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Brodbeck <gull@GULL.US>
Subject:      Re: [vanagon] Re: electric or hybrid conversion?
Comments: To: Joel Walker <jwalker17@EARTHLINK.NET>
In-Reply-To:  <007701c30dec$ffd64020$0892aec7@D1DY3621>
Content-Type: text/plain; charset=us-ascii; format=flowed

Joel Walker wrote:
> see, to me, the better choice would be a hybrid .... but not the
> way they are doing it. back to the original porsche car ... first
> car he ever designed:  gasoline (or diesel) generator to power
> four electric motors, one at each wheel. all-time 4wd.

This is called a "series hybrid".  The hybrid cars currently on the
market are "parallel hybrids".

> only problem i can see is the transmission. how to have one. or
> do you need one?

It depends on the electric motor(s) you use.  If you do need a
transmission, it'll be a very simple one.  Most electric cars that have
been produced have used a simple fixed reduction drive.  Electric motors
start producing torque at 0 rpm, and have very flat torque curves, so
there's no need for multiple ratios.  The experimental series hybrid I
saw at my college used an 8:1 reduction drive.  This was good from 0 mph
all the way up to 80 mph (which corresponded to the motor's maximum RPM.)

> that seems to me to be a better idea than this toyota prius and
> honda insight hybrid stuff. those designs, to me, seem way too
> complicated ... i mean, you've taken the already complicate
> internal combustion engine and its emission problems and made it
> worse (by adding the electric side of things).

Well, a series hybrid doesn't get away from that.  You still have an IC
engine.  I think there are two reasons we've mostly seen parallel
hybrids so far:

- Expense.  You need a much bigger motor for a series hybrid.  Likewise,
the power electronics need to handle more current.  This all adds up to
a more expensive vehicle.

- Trust.  People don't really trust the electrical stuff in hybrids yet.
  A parallel hybrid has a built in limp-home mode, since it can move on
engine power alone.


--

David Brodbeck, N8SRE
'82 Diesel Westfalia
'94 Honda Civic Si