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Toyota Corolla Conversion

Posted: Mon, 01 Jun 2009, 04:59
by Squiggles
For what it is worth (very little really as my background is electrical trades / electronics engineering not mechanical) I believe that if your shaft adapter is within 5 thou and is balanced and your engine to transmission adapter plate is accurately manufactured there should be no need for a flexible coupling.


Toyota Corolla Conversion

Posted: Tue, 16 Jun 2009, 04:09
by lachlanmac
Still smiling and the car is driving again. I have wired up the motors 120 C normally open temperature sensor switch to the original oil warning light. I have been for a few drives around the block - which is up and down up here in the Dandenongs and tomorrow I drive to school again. It is now very quiet, just the Curtiss squeal and tyre noises - and my heart thumping. One point which may have affected the original overheating, I have been running in neutral down any hills (we have lots of them) and I realized that then the motor would not be spinning its fan blades so it would not cool down as much. I dont know if I should have installed another flexible coupling. The current coupling works and slid onto the transmission shaft easily. If it all falls apart again, I will fix it with a new model, hope I get a few K first. Now I can start doing all the other jobs, wiring protection, site the charger, put better springs in the rear etc. etc.

Cheers

lachlan

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 05:21
by lachlanmac
Well I drove to and from school today. It went very silently. We live in the hills and the drive to school is a lot of downhill. The drive back is the opposite. I think I may have only done about 6km per kWHr as measured by my charging. A bit disappointing but I think there is room for improvement. If anyone has suggestions for increasing that 6 to 7 or 8, please start sending. I will be checking the tyre inflation. I found that when driving up a long hill i was difficult to keep the amps down. It was easy to jump from 80 amps up to 140 amps in gear 4. Im only using gear 3 and 4 and I change at about 50 km/hr. At the end of the long hill, I stopped to check the engine temp etc. everthing OK but very warm, touchable but not holdable. I then had to drive up another about 5km of hill. Somewhere near the end, the drive missed a beat. Im thinking it was the controller as the squeal changed. Does anybody know if the controller cuts out if it overheats? Has anybody heard of a Curtiss missing a beat before?? The batteries still had life in them as I put back about 9kWHrs.

Cheers

Lachlan

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 05:27
by HeadsUp
do you have flat ground to check rolling resistance ?

jack up the wheels and check if the brakes are binding ( overadjusted in the case of drum brakes or sticking pistons in disc brake )

front wheel alignment might be something to check

you did tyre pressures already.......

and of course the gearbox has oil in it.

just looking for sources of friction.

.

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 05:28
by a4x4kiwi
Hi, If you can use a lower gear (just like an ICE) , your motor should not heat up so much as it will be under less load. The current will also decrease. I would think that 166Wh/km is quite good, especially with your uphill journey.

IMMV. I haven't driven DC before but compared to my utes 240Wh/km you are doing well.

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 10:21
by KDRYAN
Hi Lachlan

I am not sure what type Curtis controller you are using, I have a Curtis 1221C (120vdc @ 400amp) I had a suitation where I had too higher gearing due to direct drive setup causing the controller to overheat. Yes, you get a audible warning when it starts to overheat and a noticable and sudden power cutback if you persist driving as you were when the audible warning started. I cured my overheating controller with a water cooled heatsink under the controller. Water cooled heatsink can be viewed on thread (KDRYAN Proton Satria)

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 14:14
by Squiggles
HeadsUp wrote:

and of course the gearbox has oil in it.

just looking for sources of friction.

.


Put auto transmission fluid in the gearbox instead of it's normal oil.

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 17:07
by weber
HeadsUp wrote: and of course the gearbox has oil in it. just looking for sources of friction.
Squiggles wrote: Put auto transmission fluid in the gearbox instead of it's normal oil.
Why do you suppose car makers don't do that as standard? And hey, since oil is a source of friction, why not get rid of it completely. Image

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 17:21
by Tritium_James
They don't do it as standard because normally the gearbox runs hot (ie, oil gets thin) because of all the heat coming through from the engine. Since it won't get as hot with an electric motor running it, you can use thinner oil.

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 17:22
by lachlanmac
Hi and thank you all for the reponses.

I will check the brakes, thats a good idea. The transmission has Autotrans oil in it.

Maybe Im not doing so bad considering the journey.

I am going to try a different route - I have a choice of three - They all go up and down but my next choice has shorter up sections with some short recovery downs and flats.There are also fewer traffic lights etc. so fewer stop/starts but it is a little longer. I have another choice which goes up more but is physicall shorter - over the mountain rather than around the mountain. It will certainly be interesting to see the difference between up/down and length of trip.

It is also interesting on the choice of gear for uphill. I have only seen an efficiency curve for a lower voltage ADC motor and it was reasonably flat across the rev range. Id love to have more data about the ADC motors but I havent been able to find it.

I was thinking that the standard pot spring is not really strong enough for sensitive right pedal work. Slight changes on an uphill run makes a big difference to the amps.

Does anybody know if PWM controllers get rid of more heat at low speeds - more chopping - or high speeds - more current flowing through?

What does the Curtis Audible warning sound like? What happened with the power seems like a cut off. Again I dont know how hot is too hot for the cooling fins of the controller.

On a completely different note. The motor does get warm and its cold outside. has anyone heard of trying to duct the air blown through the motor into the cabin? It would be just like an old VW but with ozone not CO.

Cheers all

Lachlan

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 17:30
by HeadsUp
in case there was any misunderstandimications ........

i am not suggesting to remove the oil ... no

use the standard oil that will suit the aussie climate.

and look for any sources of abnormal friction like steering misalignment and brake binding.

a4x4kiwi suggestion about increasing motor RPM and using a lower gearbox ratio has merit here . it will reduce current load and heat.


Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 18:29
by lachlanmac
Thanks headsup and a$x$kiwi.
My reading of the motor graphs says that higher revs means lower torque and lower power - also less current. So the car will slow. The revs will fall and the torque, power and current will rise until equilibrium with rolling and air resistance. The only advantage seems to be that going slower means less of those resistances. I still have to overcome the potential energy of the hill. Going slower means I do that slower so the heat generated has longer to dissipate. Im guessing that the accerator may appear less sensitive in gear 3 than 4 as the higher rev range and lower torque means slower acceleration. Or am I talking just a whole lot of garble?
Driving an EV is a bit counter-intuitive.

Cheers

Lachlan

Toyota Corolla Conversion

Posted: Wed, 17 Jun 2009, 18:43
by Johny
I read from the graphs that the efficiency of a typical DC EV motor peaks at about 2500 RPM.
At 500 RPM and 4500 RPM it's about 10% lower - that's a lot of heat.

Edit: Added "of a typical DC EV motor".

Toyota Corolla Conversion

Posted: Thu, 18 Jun 2009, 00:11
by Squiggles
weber wrote:
HeadsUp wrote: and of course the gearbox has oil in it. just looking for sources of friction.
Squiggles wrote: Put auto transmission fluid in the gearbox instead of it's normal oil.
Why do you suppose car makers don't do that as standard? And hey, since oil is a source of friction, why not get rid of it completely. Image


Mostly because the viscosity of the usual oil aids the operation of synchromesh. Using ATF was (still is?) a common practice in racing cars where they were trying to get that last bit of speed. I figure the synchro issue is probably a minor consideration in the EV.

Edit: and what James said!!

Toyota Corolla Conversion

Posted: Thu, 18 Jun 2009, 00:32
by Electrocycle
some manual gearboxes specify auto trans fluid from the factory.
It's an extreme pressure lubricant just like normal gear oil, but much thinner so it works as hydraulic fluid as well.

Toyota Corolla Conversion

Posted: Thu, 18 Jun 2009, 00:34
by HeadsUp
good points there squiggles and james.

:)


Toyota Corolla Conversion

Posted: Fri, 19 Jun 2009, 05:28
by lachlanmac
Now Im getting cocky.
Two drives in a row and nothing broke.
Ive just driven tonight to my sons school - a 28km round trip - in the dark with the DC-DC convertor doing all the work. We have windy narrow tree lined roads and the car glided along them just like flying. I think it will be perfect for those trips. 10km to and from the supermarket etc. Go to school, return. My wife can charge it during the day if she is going to do longer Kms.

Cheers

Lachlan

Toyota Corolla Conversion

Posted: Fri, 19 Jun 2009, 14:04
by Johny
Sounding good Lachlan. Enjoy!

Toyota Corolla Conversion

Posted: Sat, 20 Jun 2009, 00:49
by Mark T
The Curtis in my Suzuki van was getting very hot, I can lift up the passenger seat while driving along and check it. It would give a painful squeal when loaded and only deliver half power. I mounted it on a 10mm thick aluminium plate with a heatsink in the air flow. Lots of heatsink compound between everything now it doesn't even get warm Image

Toyota Corolla Conversion

Posted: Sat, 20 Jun 2009, 04:20
by Squiggles
So is this indicating a design flaw with the Curtis or does it need more consideration of mounting position?

Toyota Corolla Conversion

Posted: Sat, 20 Jun 2009, 18:46
by Johny
Squiggles wrote: So is this indicating a design flaw with the Curtis or does it need more consideration of mounting position?
Not so much a design flaw as it is my understanding that most of these things (DC controllers) come from a fork-lift or light electric vehicle (golf buggys etc) backgroumnd. A road-going EV requires a more continuous rating so extra heat-sinking and heat-removal sounds a pretty likely cure.

Toyota Corolla Conversion

Posted: Sat, 20 Jun 2009, 18:55
by Squiggles
Johny,
This is a very valid point you make. It is the very thing that has my mind working overtime. It seems to me that most of the EV movement is about adaptation rather than design. I see this as a probable fault long term.

This is not a criticism by the way, you have to use what is available, no dispute with that. I think there is an alternate long term view required though.

Toyota Corolla Conversion

Posted: Sun, 21 Jun 2009, 02:12
by weber
Squiggles wrote:It seems to me that most of the EV movement is about adaptation rather than design.

I don't think you can say that about the Tesla Roadster. And what they came up with was a high speed version of a 3-phase induction motor.

Toyota Corolla Conversion

Posted: Sun, 21 Jun 2009, 04:17
by Squiggles
And a $200,000 price tag!

Actually is there any real data available on the motor? All I have seen is a few artists impression drawings.

Toyota Corolla Conversion

Posted: Sun, 21 Jun 2009, 04:21
by weber
The Tesla price tag is all the more evidence that they spent significant money on design, not merely adaptation.