New Member Introduction - Planning a 914 AC conversion
Tangerine Racing
I have been involved with 914s since 1984 when I bought my first one,
a 1970 tangerine 1.7L. In 1995 I started racing that car in SCCA. You
can see quite a few in-car videos at my Youtube account "Tangerine
Racing".
I also have a fair weather daily driver ('72 - currently 1.9L) that
also serves as a test-bed for some of the products I develop at my
business - Tangerine Racing Products.
My wife has been bugging me for quite a while now to build her a 914
for the steet that looks like my race car.
I have decided to make it electric instead of dumping a lot of money
into a high end Type 4 engine. She really likes the idea since she
already has a 2005 Prius daily driver.
I've done a little research online and I'm currently reading through
the 2nd edition of Build Your Own Electic Vehicle.
As hard as it will be to come up with the funds I really think it is
best to go for an AC conversion with Lithium Ion batteries right off
the bat.
We aren't looking for high performance for now but I want to build in
flexibility for upgrades as much as possible, without having to
replace too many components down the road. So modest speed/
acceleration and a range of 45 miles or so is fine for now. To me,
that means the motor and controller have to be sized for any future
upgrades.
Keeping the stock transmission but going clutchless looks like a good
choice.
Any suggestions would be greatly appreciated. Thanks.
Chris
David Dymaxion
Two thumbs up on your wife wanting a 914 and an electric!
From: Tangerine Racing <racer...@sbcglobal.net>
To: 914ev <91...@googlegroups.com>
Sent: Wed, December 30, 2009 11:16:41 AM
Subject: [914ev] New Member Introduction - Planning a 914 AC conversion
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eyec...@aol.com
I have used some of your products and I thank you for the quality.
I haven't seen much action on this site in a while but perhaps some of the more accomplished will come to your aid.
As for myself, I am in the middle of a DC conversion with lead batteries. What we do have in common is that I also am going clutchless which seems to be different than most of those who have posted in the past. At this point , I have mounted the trans and motor together with the adapter and installed temporarily in place. I had a chance to drive a clutchless conversion last year and it seemed to pose no issues.
Most of the last year has been spent simply making the car road worthy, and with the temperature at 25 degrees in my unheated garage, not a lot is happening at the moment.
I wish you all the best and hope others can help guide you. Certainly the websites of those before us will be of tremendous value.
Best Wishes
George O.
Wilmington,DE
From: Tangerine Racing <racer...@sbcglobal.net>
To: 914ev <91...@googlegroups.com>
Sent: Wed, Dec 30, 2009 1:16 pm
Subject: [914ev] New Member Introduction - Planning a 914 AC conversion
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Tangerine Racing
I've seen two motor/trans. adapters good for Porsches available on the
market. One sold with a hub for the flywheel to use a clutch and one
offered with a modified clutch disc that connects to the motor shaft.
Did you buy the one from Wilderness EV with the modified clutch hub?
Did you like the quality of the parts?
On Dec 30, 8:36 pm, eyeco...@aol.com wrote:
... At this point , I have mounted the trans and motor together with
the adapter and installed temporarily in place. I had a chance to
drive a clutchless conversion last year and it seemed to pose no
issues.
> George O.
I would think that being in the "right" gear is less important in an
EV since available torque is less rpm dependant. Therefore one would
shift less often in an EV, yes?
David,
Did what year is your 911? Has the trans been rebuilt, with new
synchros?
How much does your car weigh (est.)? What size motor/voltage did you
go with?
I was wondering if a lightened flywheel/PP would be a good choice
since the motor shaft has almost no rotating mass.
In a gas vehicle, clutchless shifting can be done with careful rev
matching, and in a race car this is vastly improved with a lightened
flywheel to speed the rpm loss of the engine.
Charles Turner
Mike S
Welcome!
The Azure Dynamics AC24 motor and DMOC445 controller are well worth
your consideration. Used them in my '73 together with a 168-volt PbA
pack and the results are good. Acceleration is adequate -- no Tesla
but seems spritely enough. With the regenerative braking, even the
standard 914 brakes are good enough. Keep the clutch. More details:
There are enough things to discuss we should probably use the phone.
Feel free to call 650 948 3670.
Mike
On Dec 30, 10:16 am, Tangerine Racing <racerch...@sbcglobal.net>
wrote:
David Dymaxion
I have a 1977 911. As far as I know the tranny is original and has 150,000 miles (240,000 km). It shifts so smoothly, has no side-to-side play in the shift shaft, axles and input shaft are tight, turns easily and quietly by hand, etc, that I don't think the clutchless hard shifting is due to wear. Steve Clunn http://www.GrassRootsEV.com says 911s are the worst of all the cars he has converted for clutchless shifting. You can see a fun little video of a 1-2 shift here: http://www.explodingdinosaurs.com/9electric/2009saltflats/MVI_0308burningsalt.MOV
It has a Fidanza flywheel, and a Kennedy Engineering Products pressure plate that collectively lightened the rotating mass by 10 lbs (5 kg). If you go clutchless I estimate you'd lose about that much again rotating mass, but your synchros still have to accelerate or deaccelerate the whole mass of the armature. Rotate your electric motor back and forth by hand, you'll see the armature has quite a bit of intertia.
I estimate the car weighs about 2300 lbs now with 8 Optima batteries, but that'll go to about 3000 lbs once I get the rest of the batteries in (aiming for 16 to 24 batteries, still working out the total number).
I have driven an ICE 65 Mustang without the clutch, and it shifted as easily as with the clutch, so I think the ease of shifting can vary greatly between brands of cars.
I don't want to sound all negative -- there are folks that shift clutchlessly just fine, too. You don't shift as often in an EV. I had some reasons that basically forced me to use a clutch:
- My WWIELOT controller (WWI Era Level of Technology) idles the motor, so I need the clutch to start smoothly
- I want to autocross my car, so quick shifts will help
- I live in a hilly area (home of the 2002 Winter Olympics), so I might need to shift quickly on a hill
- I want to run on the Salt Flats, it would be hard to get good acceleration and good top speed with just 1 gear
- My car does regen, and downshifting can give more regen
- Less rotating mass -- a pound off the flywheel is like 3 pounds off the car for acceleration
- Simpler build -- many clutch installs vibrate, there is less mass to vibrate with clutchless, and more tolerance for misalignment
- Cheaper
- Adapter depth less critical
Subject: [914ev] Re: New Member Introduction - Planning a 914 AC conversion
...
DanP914
Happy New Year. Am interested in what you've done with the AC24/
DMOC445 and 168Volt pack.
1. Have you had any issues with the Zivan NG3 charger and
overcharging? Their setup for FLA batteries seems to call for an
equalization or at least a fair amount of boiling each full charging
session.
2. Re: DC-DC converter...were there any options other than building
your own to handle the higher voltages of your pack
Thanks,
Dan
Tangerine Racing
Thanks for the info. I hadn't seen the EV Parts adapter the first time
I looked through their site. It looks like a good lightweight piece,
but a little more $$ due to the billet design.
I guess I should join the local EAA chapter and see if I can get a
ride in some cars to help decide on the clutch issue. Wrong time of
year for that in CT though.
Mike,
I am definitely looking at the AC24/DMOC445. It seems to provide a
good balance of light weight, moderate performance and reasonable
cost.
Seeing how you mounted the potbox opened my eyes. I was trying to
imagine how I would connect one directly to the "gas" pedal.
David,
Thanks for the additional info about your car. Cool that you've
already taken the car to the salt flats.
Mike S
Chris,
Am planning to re-do the potbox location. Even with a beefed up return
spring there is a little too much friction in that long throttle
cable, especially in cooler weather.
It seems sensible to have a short mechanical link from the pedal to
the 5 k-Ohm pot and let the electrical wires make the run to the
controller. The past need to move a carburetor butterfly valve way
back there should not dictate how electrical power is now
controlled...
Mike
Mike S
Hi Dan,
Am using PbA gel batteries and Zivan charger seems to be working fine
although it could be making gas bubbles (and probably is in some of
the monoblocks). It's hard to tell. I suspect it is not necessary to
equalize cells every time the pack is charged. When this pack needs to
be replaced and if I replace it with gel PbA, I intend to discuss with
Zivan the possibility of modifying this NG3 so it only subjects the
pack to equalization every N-th cycle where N is probably in the range
from 4 to 10 somewhere.
DC-DC converter: I did a little research on what was available and
then decided to make my own. The EE in me got fascinated with the
project. Besides, it was something to do while waiting forever for
enough parts to show up to start work on the car. If you are
interested, I can pull together the drawings, schematics etc. to get
you started.
Call or send an email and I will send you the spec. sheet. (Not sure
how to send attachments with these msgs.)
Mike
650 948 3670
Tangerine Racing
choice for my project.
The only thing that compares closely is the HPGC AC31 or AC50 with
Curtis controller. Their downside seems to be limited voltage and rpm
capabilities.
Azure Dynamics' factory isn't far from me so I'm wondering if I can
buy direct from them, or at least pick up there instead of having to
receive a shipment from Electro Automotive in California.
One thing I'm trying to determine about the AC24 package is how much
flexibility there really is as far as supply voltage. The Electro
Automotive kit specifies 144V and their motor spec page suggests a
range of 144-156V, with anything outside that adversely affecting
efficiency. The Azure Dynamics PDF data sheet suggests a usable range
of 100-240V in delta configuration. My original plan was for a 200V,
100AH LiFePo4 battery pack, but to save money and get the project
running more quickly I am considering a 120V AGM battery setup at
first. Another thought for the future is to install a hydrogen fuel
cell for greater range and ability to refill quickly, using
commercially available sources or a home H2 generator.
I joined the EAA during the holidays and just received notification of
the January e-newsletter on Saturday. After perusing that I followed a
link to my local chapter's website last night. Their monthly meetings
are the second Saturday of every month and less than an hour from my
home. Wouldn't you know it, I missed the meeting by only a few hours,
lol. Its not the best weather right now for a test drive anyway, which
is one of my primary reasons for meeting up with the local EV
community.
Chris
sk...@pobox.com
Chris> The Electro Automotive kit specifies 144V and their motor spec
Chris> page suggests a range of 144-156V, with anything outside that
Chris> adversely affecting efficiency. The Azure Dynamics PDF data sheet
Chris> suggests a usable range of 100-240V in delta configuration. My
Chris> original plan was for a 200V, 100AH LiFePo4 battery pack, but to
Chris> save money and get the project running more quickly I am
Chris> considering a 120V AGM battery setup at first. Another thought
Chris> for the future is to install a hydrogen fuel cell for greater
Chris> range and ability to refill quickly, using commercially available
Chris> sources or a home H2 generator.
No doubt you've read through the archives of this list. This thread seems
especially germane:
I don't know that David Hale ever got his performance problems completely
sorted out.
--
Skip Montanaro - sk...@pobox.com - http://www.smontanaro.net/
Hemant Bheda
Randy Pollock
Do not try to run the AC24 at 120V. Azure now lists a minimum voltage of 156V. ElectroAuto designed their kit when the minimum listed voltage was 144V. When I rebuild my car, I am going to set the voltage to be well above the 156V minimum when the batteries are low. My 144V kit was marginal on hills when the batteries were 50% full and since I live on the top of an extremely steep hill, that cut my effective range in half.
Good luck,
- Randy
Hemant Bheda
Tangerine Racing
Thanks guys!
I guess I'll stick with the lithium ion battery plan. For now I'll
just focus on prepping the chassis and saving for the motor/controls.
Skip, Thanks for the link.
I hadn't searched that far back yet. Did David Hale ever get a control
solution from Azure/Electro that corrected the poor performance?
That discussion tells me my original plan is right on in terms of
estimated power output/performance in a 914, rather than simply
swallowing the expected output stated by the mfr/retailer..
Can anyone give me an idea of reaalistic range with 200V, 100AH, LFP?
Most travel will be on hilly country roads, very little freeway and no
major elevation changes.
My conservative estimate says 45 mi, compared to 75+ in the sales
literature.
Tangerine Racing
LiFePO4 battery prices.
Looking at the price for 60Ah units of $87 ea/shipped, I was thinking
it might be wise to go straight for the high voltage wye configuration
with an AC24LS motor.
For $8700 I could have 320V power at 550 lb weight. That helps keep
the amps and therefore wire AWG size down.
So what kind of range would that allow?
I've gotten used to driving Raby MassIVe Type IV powered 914s with 200
LbFt torque and my sub 1800 lb FProd car with up to 140 LbFt torque.
This is going to be a different experience.