Using Automatic Transmissions
 

Does anyone have any experience simply bolting a motor to the automatic transmission?

yes.

Why do you want to connect an electric motor (I assume) to an auto transmission if you want the most range possible out of an electric vehicle?

Surprisingly, bolting a motor to a transmission has been common for hundreds of years now, both professionally, amateur, and commercial manufacturing do it.

I'd say it could work.

Electric motor? I assume you'd want to leave out the torque converter.

Good point about the torque converter. However, it is the thing that makes for a smooth start up.

@Frank Lee, what is your experience?

This thread hereby nominated for the most ambiguous query and vaguest thread title of the month!

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Assuming you're talking about an electric motor, the thing that makes for a smooth start up is the motor controller. Wasting energy in a torque converter is not necessary. Nobody concerned with efficiency does it.

If you want a smooth starting transmission use a clutch and flywheel on a standard transmission.

Automatic transmissions have that pesky torque converter thingy that robs power most of the time, a hydraulic pump that zaps drive power all the time and it requires electrical power all the time to operate valves on the valve body and lock the torque converter.
You can replace the power robbing torque converter with a clutch and fly wheel and replace the parasitic hydraulic pump with muscle power from your left leg. Lastly the standard transmission will only draw power for the reverse lights when in reverse.

With DC systems you can keep the clutch or go with out.

Instead of being hyper vague why dont you pitch us a concept and we can set you on a direction to go with proven systems and designs and go from there instead of starting from nothing?

A guy in our local EV club has an automatic transmission in his Porsche 911, he's building a control box to make it shift so that it works properly, he said he thought about converting it to a manual but the cost would be in the $1000's and I suspect that in the end he will end up hunting down a manual transmission.

Yeah electric motors like to spin at much higher RPMs than piston engines.

When you are stopped idealy your motor RPMs should be 0. To keep an auto transmission operating "smoothly" you will need to keep the motor around 500 or more RPMs to make transitioning between stop and go nice and smooth.

Why pick the most difficult setup possible?
Transsitioning from 0 RPMs @ 0 MPH to slow speed with an AC motor and auto transmission would be the most difficult combo I could think of.
Where a DC motor on a standard transmission with clutch and fly wheel would be smooth/easy/cheap.

It would be like my camaro many years ago before I knew how to tune the carb. At one point when the tachometer wasn't working the idle speed slowly drifted down to about 300 RPMs over time. When I was stopped and started to press the gas to go again the car would jerk forward as the torque converter hit stall speed.

If you are looking for a easy to build smooth running setup, this ain't it.

Are we talking about a typical 4 speed automatic or a fancy tip tronic transmission complete with paddle shifters?

Most Ive seen are dc that use a stock manual tranny and no clutch that is shifted from time to time. Most AC setups are direct drive to the axles. I guess it depends on the rpms of the motor used vs axle speed at desired rpms rather any gear reduction is needed.

As a former electric wheelchair user I know the gearless brushless motors always had problems were as the 2 and 4 pole with worm and helesphere(SP?) cut gears had no problems at all. 4 pole had better battery life vs the 2 pole. :turtle:

Yes I believe most DC set ups are connected straight on to the transmission input shaft. Its cheaper, simpler and it works fine for most people.
I would go with a clutched DC motor to retain the ability to burn a little rubber and shift on the fly as needed.

Hey, oil pan 4, how's that regen braking working for you?

I would never use regen braking.
Electric golf carts, forklifts and floor tugs dont use it, why should I?
My plan is to scale up what I know works.
No need to reinvent the wheel...
I do occasionally blaze new trails, but not here.

Almost everyone must be missing the point here. I will simplify.

An electric motor has most of its torque right from the start, with hardly any reason to change speed. However, depending on tire rotational speed versus the top speed of the motor, there may need to be some sort of speed matching technology (a transmission) to keep things running efficiently. Changing tire rpm versus motor speed appears to signify a need for a go-between technology. Further, starting from a stop is better handled by a lower gear, especially if one is using a lower-powered motor and a heavier vehicle. Another factor involved in vehicle power is that even a tractor trailer might not use much power once it is moving.

So the obvious question is about bolting an electric motor directly to an existing transmission, and in particular, an automatic. And also obviously, what happens when one does so.

What happens when you bolt an e-motor to an automatic with a torque converter is: your efficiency (range, power to the wheels) goes down and complexity goes up.

That's the answer, simplified.

A manual gearbox is best.

Another guy in our electric car club tried using an automatic transmission, I think it was a Toyota Corrola and found that his range was 40% worse then the same set up with a manual transmission, he said his car was also pretty slugish.
If you want the vehicle to shift automaticly why not use something like an Arduino that can over ride the throttle, have a speed sensor on the motor shaft and the output shaft of the transmission and some solinoids to shift in to neutral, match the speed for the gear it needs to shift in to and shift in to that gear without the use of a clutch, that way you keep the driveline lighter weight and simple and you don't wear out the syncros in the transmission.

A lot of EV's like mine have a single speed gear box, others like my parents use the manual transmission but are driving in 2nd gear most of the time ad 4th gear on the highway.

Those are excellent pieces of information. It would therefore appear that some sort of electrically actuated shifting would be the best. That way one might get rid of the clutch expense and complexity, and still have an automatic shift based upon controller input.

By the way, what is the comparison of loss between an ICE and a motor? Did the suggestions take that into consideration? For instance, we know an ICE setup is pretty inefficient to begin with. Would simply swapping for a motor gain signigicantly?

I would run a GM T-5 (non-world class) on 4.10 gears with 30 or 31 inch load range C tires.

Also auto transmissions put off a lot of heat, they have external coolers.
Any heat produced by the system is just power that never made it to the rear wheels.
I have had several T-5 transmission vehicles, I could always drive them long distance and put my hand on the transmission afterwards, inferred temp gun never registered over 140'F on one. It also didn't have any kind of cooling system.
Dont try that with an auto transmission.

You don't need "some sort of electrically actuated shifting", you can shift a standard transmission with out the clutch as long as it has syncros. No one showed me how to do it, I read on the internet that it could be done so I tried it and it works.
I have never met one that I couldn't at least up throught the gears with out the clutch.

Still set on using an auto?

TheSGC in this forum is currently completing a 2001 Civic EV, but his first EV was a 1996 Civic with an automatic:
Civic Electric Car Conversion
He would have all the answers.

Powerglides make good transmissions for EVs. And the torque converter can be eliminated in many transmissions. Do some searching in DIYelectriccar.com.
Here's a good thread:
The Reasons why Automatic Gearboxes WILL Work with EV's & how to do it.. - DIY Electric Car Forums

Here is a possible scenario. I want more room; similar to my Town Car. In the decision-making process, the wife and I believe we still want the safety and space of a four-door sedan. That said, it must be at least a mid-sized car, and aerodynamic as much as possible.

A possible candidate is a late-model Lincoln LS with a bum motor. It can be had for a couple thousand, but comes with an automatic. Mechman600's post is helpful in this regard, along with Torque Converter Lockup in the wiki. And obviously, there is no inexpensive way to switch to manual. I have checked two-speed aftermarket trans with electric shifting; rare as hens teeth and I'm afraid to ask the price.

So far, the big issues are hydraulic pumping losses, heat and torque converter lockup mods. Once the clutches engage, it is direct connect, so I can't imagine any mileage loss to be significant at all.

Perhaps a very low-stall converter kit might do the trick, coupled with the lockup mod idea. Maybe an external hydralic pump with a small, presure-controled motor would work well. Just a couple thoughts.

If it's an electric Town Car you want and a manual gearbox isn't really a viable option, I say go with the automatic.
In your current town car, at what RPM does the torque converter lock up if you have the gear shift in third? As an EV this would likely be the gear you would use on the highway. Does the torque converter ever lock up when shifted into second gear?

If using an automatic kills 20-30% of your potential range, simply adjust the size of your pack accordingly. Besides, with an automatic doing smoky electric powered burnouts would be that much easier!

I was looking at a late model Lincoln LS; a mid-sized car. The automatic problem will probably be fixed with an aftermarket controller to allow a TC lock-up and remove all slippage. Therefore, from other forums about that issue which I've read, it appears that an automatic may actually become very efficient, and lower the cost of an electric conversion to boot.

BTW, I'm not really worried about burnouts. Fast acceleration is more important.

The '00-02 LS could have a 5 speed manual with the V6, so don't be too quick to settle for an auto.:thumbup:

I wonder how a giant (read: awesomely cool) warp 11 or warp 13 would suffice direct driving your driveshaft. A quick search reveals that a warp 11 is good for approx 300 ft/lbs @ 1000A. I would think that a warp 13 @ 1500A would be plenty for direct drive. Max continuous RPM is 3000, which equates to 60 mph (800r/mile tires, 3.90:1 ratio). Redline is 5000 - 100 mph. That will do.

192V*1500A=288kW. That will do.

The big advantage to rear wheel drive, direct drive, is a wide open engine bay to fit biblical amounts of battery, allowing full use of the trunk. Since viable wheel motors are not available, I see this as the best option.

I still like the idea of a couple gears forward plus reverse. Electronically operated would be really cool.

However, there are some really good ideas out there about using an aftermarket or custom transmission control module to make an automatic torque converter lock-up when needed (pretty soon after a little speed up) while allowing for decent shifts at optimum motor rpm range. Holding lock-up on coast would allow regen, too.

It is beginning to look very doable, as well as cost effective.

I honestly don't think regen is going to be an option in your Lincoln. The largest setup available (at a "reasonable" price) is the AC50/Curtis combo, which will not suffice when it comes to moving a whale like a Lincoln around at any speed for any length of time. I highly recommend going with a gigantic DC setup or you will end up disappointed. An AC50 will not provide the spirited acceleration you desire. And the "talk" out the is that regen braking really doesn't gain you more range vs simply spending that money on more lithium.

this is one of the cleanest AT installs I have seen...

Electric Vehicle Conversion - AC Project

it idles at 400rpm to keep the pressures up in the transmission.

oh... and the ride along test drive video...

http://www.youtube.com/watch?feature...&v=1ZmFNKamTQg

Considering the weight balance between the axles, I believe it would be better to leave some batteries closer to the rear axle. Well, after all there would still be some space under the front hood to mount a secondary trunk, just like a Volkswagen Square-Back :thumbup:
http://4.bp.blogspot.com/-EM88m4dY2d...Imagem1307.jpg
Also, the weight balance is important to keep the steering lighter.