Re: 5000 pound EV???

[John Wayland <dat1200@europa.com>]

Hello to All,

Originally, this from Fitzgearld, Fredric:

>I expect that this truck will be just a bit over 5000 pounds when I'm done.
>That's even with the lighter front end and the weight reduction program.

    What percent of 'battery to vehicle weight ratio' (BVWR) are you planning
to have at that final 5000 lb. weight? 25%? 30%? 40%? 50%? I'm just curious
what your performance/range expectations are. If you go with the lower figures,
then your truck must be pretty heavy to start with....if you go with the higher
figures, then the truck must be fairly light to start with.
     Red Beastie weighs 5260 lbs......generally rounded off to 5300 lbs. for
the sake of general discussion....it has a healthy 47% BVWR to help it achieve
l-o-n-g range. If you subtract its 2500 lb. battery pack (2440 lbs. of lead +
60 lbs. in brackets to contain them), you can see that the converted truck
weighs in at 2800 lbs.

>I look at Red Beastie (and others) and I think that it should be easy to just
get
>those components because it's proven to work.

      Yes, it's really pretty simple to duplicate....an average power,
lower-than-156v  motor controller (affordable), a run of the mill 9 inch motor
(affordable and strong), the stock 5 speed manual tranny (helps the 9 inch
motor cope with all the weight at low speeds and offers reduced rpms for
freeway cruising for terrific freeway range), a set of 40 Trojan T-105s
(affordable), and a basic charger (the wet cells aren't that picky).

>What I don't know is how much gear reduction trucks like Red Beastie are
using.  Does a >vehicle that size use all the gears in a manual tranny?  I'm
assuming that it has a 5-sp (with
>over-drive) tranny.  If that monster starts off in 3rd, I have a very real
>chance of making it happen.

Response from Ron Schroeder:

>In the real world, you will use only 2 or 3 gears of the 5 speed, e.g. 2nd
>and 4th but you will want more than one speed.

      Ron must be referring to more average EVs, certainly not one that is a
hefty 5000 lbs.! Yes, with light EVs, one or two gears is just fine, but with a
super heavy EV, you'll need all the gears available.....I'll explain.
     My 2340 lb. 'Blue Meanie' , a converted '72 Datsun 1200 economy sedan, has
a 1200 amp controller and  a set of current-loving Optimas, and it is powered
by a 9 inch ADC motor through the factory 4 speed tranny. When the clutch was
healthy (it is scheduled for a competition clutch installation very soon) this
car could smoke the tires in the first three gears....it could smoke 'em from a
dead start in 3rd, too! I used to take off in 4th gear, and the acceleration
was very acceptable, though this was harder on the motor , the controller's
caps, and the clutch (that poor clutch). Because of the car's light weight, the
best formula is to use 2nd for take-off, shifting up to 4th once up to speed.
1st gear is too low for any reasonable acceleration because the motor quickly
revs past its flat torque area. Using 2nd gear, the car accelerates even better
from rest while it allows the controller to stay in current limit longer,
providing a constant, smooth delivery of torque.
      Red Beastie is a whole 'nother animal.

(1)  Instead of feisty Optimas that think nothing of 800 amp current draws, its
pack of wet cell Trojans, even when buddy paired up, don't want to see this
level of current, and in my opinion, anything over 300 amps per battery on a
regular basis, is asking for an early demise in their heady 650 cycle life
rating.

(2) The truck for most of it's life, has had a 400-500 amp controller in
interest of keeping the wet cell batteries alive for as long as possible....a
far cry from the 1200 amps of Blue Meanie's Rapter 1200 controller.

(3)  The truck weighs more than twice as much!

       Back to Fitzgearld, Fredric's hope that the Beastie could take off in
3rd gear.....not in your life! Moving so much weight from rest is a tough task,
even for a high torque 9 inch series wound motor. To add to the problem....the
'95 model year Toyota pickup that Red Beastie is based on, has a 3:58 rear gear
ratio, and this is a pretty 'tall' ratio. The older import trucks of the 70's
and 80's had smaller displacement 1600-1800cc 4 cylinder engines that struggled
to get to the 100 hp mark, so rear end ratios of 4:38 were the norm. One of
these older trucks as a converted EV can use 2nd and even 3rd gear for
take-offs, even when weighing in at 3500-4000 lbs. or so. Stuff one of these
early tough little trucks full with 40 of those 61 lb. batteries, and they'll
weigh in at 4500 lbs. or so...with this type of weight, using 3rd gear from
rest might be a stretch. As the newer trucks evolved, so did engine technology,
and today we have 2.2-2.6 liter four bangers that crank out 130-155 hp! These
larger engines also have substantially more torque than their smaller
predecessors did, and in the interest of lower engine noise at cruise speeds,
less engine wear, and higher mpg, rear end ratios have steadily become
'taller'. Back to Red Beastie...not only does this truck have that 3:58 rear
gear set, its factory 5 speed has a very 'tall' 1st gear, and it feels like the
2nd gear of yesteryear's trucks. Red Beastie can easily do 35 mph in 1st gear!
2nd gear is good for 60+ mph, and the truck can cruise at 55 mph while still in
2nd gear.
     Out of interest, in my many long range trips I took in this truck, I
learned that even with such 'tall' gearing, the transmission's full 5 gears
were very useful. For the best range per charge while taking 400+ mile freeway
trips, on flat and level ground, shifting up into 5th gear and letting the 9
inch loaf along, gave the highest range per charge. However, any slight incline
made it prudent to shift back to 3rd gear., where the motor could spin up and
have its internal fan keep things cool.
      I tried using 2nd gear a couple of times from rest, but the motor labored
while sucking big amps....3rd gear was out of the question. Yes, with a 1000+
amp controller and a big 'ol Kostov, a 2nd gear take-off would have been
easier, but what's the point when you have that nifty transmission at your
disposal?
     Continuing this discussion....I can also offer my thoughts on a direct
drive system, especially one that employs an 11 inch  Kostov, because I have
done this. With race oriented modifications, this large motor easily moved my
very light race car (1995 lbs.). In fact, merely moving it is an
understatement! However, to get the job done, required the following:

(1) The vehicle HAD to be light.

(2) A very high end, but oh-so-awesome 'Zilla motor controller was required.

(3) A high voltage battery pack (336v) was needed to keep the controller in
current limit for most of the duration of the 1/4 mile run.

(4) An expensive pack of AGM style batteries were needed to provide high
current.

   In summary, I like direct drive for racing and for use in light weight EVs,
but I recommend using a manual transmission for affordable street EV projects,
in that the transmission will allow the motor to be smaller, the controller to
be less powerful and more affordable, and the battery pack to be treated more
gently. In a hefty conversion that weighs around 5000 lbs., the advantages of
the transmission become even more apparent.

See Ya........John Wayland