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  #11  
Old 04-28-2012, 04:56 PM
somanywelps somanywelps is offline
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Default Re: Update on my EV Porsche fiasco.

Quote:
Originally Posted by daniel1948 View Post
Thanks for all the ideas. I'll run them by Gordy and Tim when I next talk to them.


Too high, or too low???

(The fellow at NetGain said the voltage is ideal for the motor.)

The controller is from EV Source, designed in cooperation with and endorsed by NetGain. Since the Porsche is not at my home now, I cannot tell you the model name, but it's something like the third iteration of the controller. I was originally going to get one of the very first of these controllers, but because of delays in the project due to all the additional things that turned up wrong with the car, I ended up with a much-improved version of the controller.
Too low. The voltage is ideal for the motor, but not for the vehicle. If you want to go netgain, Warp 11HV + Soliton 1 (or maybe a netgain 1400A controller, does anyone have feedback on those?)

288V*1000A=288kw == 386 HP *.87 eff == 335 HP at the output shaft.
288V*1400A=403kw == 540 HP *.87 eff == 470 HP at the output shaft
(Caution, this is a lot of strain on the motor)

Other options are the Kostov 11" 250V or the Kostov 11 Alpha (Electric Forced Cooling).
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  #12  
Old 04-28-2012, 07:51 PM
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EVfun EVfun is offline
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Default Re: Update on my EV Porsche fiasco.

Perhaps take stock of the parts in the conversion as see what the upper voltage limit is. From there build a pack of Headway P or HP 8 amp hour cells in a series/parallel arrangement until it should meet the power needs. Based on some testing by Manzanita Micro the 8 amp hour P cells should be good for 200 amps each. If you can handle a 48 cell in series pack and you want 1000 amps for the ground then a 5p48s pack would work for a list price of about $4500. I bet when someone asks for 250 cells (a few spares) they will get a price break.
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  #13  
Old 05-01-2012, 09:43 AM
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daniel1948 daniel1948 is offline
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Default Re: Update on my EV Porsche fiasco.

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Originally Posted by DavidDymaxion View Post
Would you be doing the 144V Warp or the Warp 11HV (something like 220V?)? The numbers below assume you have a higher voltage pack, so when it sags the controller can still deliver the max voltage the motor can take.

1400 A * 144 V ~= 200 rwhp
1400 A * 220 V ~= 300 rwhp

300 hp is not enough in a car that heavy to do a 3.5 s 0 to 60.
I don't know the difference between those motors. All I know is that mine is an 11-inch Warp motor, and the fellow at Netgain said 144 v. was ideal for it. I don't want to do anything that might harm the motor. I want good, respectable performance, but this will not be a racing car. It will be a show-off car.

Quote:
Originally Posted by DavidDymaxion View Post
As a counterpoint, the Tesla does 0 to 60 in under 4 seconds, with about 300 hp -- but there are some caveats. Its AC motor has a broad torque curve, and it has awesome traction control. This would be tough to duplicate with a series DC motor. The Tesla is also likely lighter than your Porsche would be.
The Tesla is definitely lighter. These are precisely the points I made in talking with Tim. Especially the torque curve and no shifting of the Tesla. Tim and I are not exactly on the same page. We can still work together, but he would like to build a Tesla-killer to show off what he can do. I just want to be able to drive this beautiful car without people asking why it's slower than a Honda Civic.

Quote:
Originally Posted by somanywelps View Post
Too low. The voltage is ideal for the motor, but not for the vehicle.
Okay. But as I said above, this is not a race car for me. It would be an around-town show-off car. I want respectable performance from it (I was originally promised 6 to 8 seconds to sixty) and I don't want it to be capable of so much power that it damages itself. I gather that racing cars often need extensive work between races. I don't want something I have to keep repairing. I can floor the pedal in the Tesla without worrying that I'll break something.

Tim is finishing up some other projects, and soon he'll start again on the Porsche, by having the motor balanced and then taking out the bad battery cells and reorganizing the remaining ones. I don't have a time line, but it would surprise me if it's ready before fall. Actually, after 4 years it will surprise me if this car is ever in good driving condition.
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Old 05-01-2012, 09:20 PM
drgrieve drgrieve is offline
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Default Re: Update on my EV Porsche fiasco.

Quote:
Originally Posted by daniel1948 View Post
I don't know the difference between those motors. All I know is that mine is an 11-inch Warp motor, and the fellow at Netgain said 144 v. was ideal for it. I don't want to do anything that might harm the motor. I want good, respectable performance, but this will not be a racing car. It will be a show-off car.
You might have an old version of the motor. You could contact Netgain again and ask what voltage you can run your particular motor at - and what it would cost to be able to run at 170-192 volts like the current models. This is basically upgrading the brushes - I think this is around $200.

It would help if we knew what type of controller you are using. Knowing that we can make recommendations on the battery pack.

Also if you can tell us the what batteries are being used (manufacturer, ah rating, quantity, series / parallel configuration) then there are several options we could also recommend.
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