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The “Automatic” Solution for EV Conversions

46948 Views 75 Replies 10 Participants Last post by  mizlplix, 
FB Performance Trans
5
Some time ago we were approached by a City Municipality that was in the process of doing a fleet conversion of their gas vehicles to electric. Their bottom line was to achieve vehicle performance and functionality that replicated that of the gas vehicle while of course providing long term energy cost savings. Their approach was to follow the lead of so many others by setting up the driveline with a “stick” type transmission.

Their first prototype proved to be very successful in all areas except one: Drivability. This unfortunate outcome was due to the use of a high torque electric motor in combination with repeated clutch engagements necessary during the normal gear changes. Numerous attempts to feather the clutch to prevent the sudden jerking of the vehicle and its passengers proved to be unacceptable.

They realized that the only solution would be to replace the stick with an automatic type transmission. On the surface this sounded easy enough, except that they discovered that throughout the EV industry most were skeptical about using an automatic for this type of application. So after much resistance to this idea, they decided to go outside normal channels and they contacted us. The result has been their complete satisfaction in achieving their “bottom line”.

Our objective here is to make everyone aware that the automatic transmission is absolutely a viable alternative. Let me start off by briefly acquainting you with our company. FB Performance Transmissions is a family owned and operated business. We’ve been successfully producing high performance and racing transmissions for a variety of automotive aftermarket applications since 1988. One of our specialties over the years has been the ability to adapt various transmissions to different types of motors. More recently of course we’ve been applying similar technology for Electric Vehicle purposes.

We’ve developed these transmissions and engineered the related equipment specifically for use in these types of applications. We now offer two 3-speed automatic transmissions. Both of these units are based on the original Ford AOD and AODE transmissions. We chose these transmissions because of the availability of a Low Gear Planetary set and the fact that we can build them to handle 1000+HP if necessary.

The AODE is fully automatic with a programmable Power-train Control Module (PCM) where all of the shift points can be varied and set as desired. The AO3 uses a Full-manual valve body where the driver always has total control over the transmission functions. The valve-bodies in both of these units are designed to eliminate the normal fluid bleed off, so that the transmission can react immediately to the input torque of the electric motor. They both have the strength and durability to handle the typical torque of these motors in conjunction with the weight of vehicles. Yet they provide a smooth transition when shifting from one gear to next, without the sudden jerking response typically found when using a clutch with stick type transmission.

We have also successfully engineered and fabricated the entire mounting interface between the Electric motor and the transmission. These components include the following and are listed as options on our spec sheets (See Links Below):
1) Motor to Transmission Billet Mounting plate – easily adaptable to a variety of electric motors that incorporate a surface mounting plate.
2) Motor shaft Rigid Steel Coupling – designed to fit a number of different motor shaft diameters and torque requirements.
3) Steel Flexplate – permits direct mounting of the Torque Converter (Fluid Coupler).
4) Torque Converter/Fluid Coupler – engineered for minimum stall and maximum coupling efficiency and fluid dampening.

The completed package of components provides for a very rigid assembly and permits a very simple installation into almost any type of rear-wheel drive vehicle. To better illustrate this I’m enclosing a series of assembly photos. (See Attachments below). The following links cover both of these transmissions:
Heavy Duty AODE (4R70W) Non Lock-up- Electric Motor Conversions
http://www.fbperformance.com/viewtrans.asp?TransmissionID=100

Heavy Duty AO3 (AOD) Non Lock-up - Electric Motor Conversions
http://www.fbperformance.com/viewtrans.asp?TransmissionID=101

If you have an interest or any questions about what we’ve developed, please contact us and we be glad to go over all of the details with you.

Contact: Mike or Fred
In NY: 1-631-242-0008
Outside NY: 1-800-769-1118
FAX: 1-631-243-3054
E-Mail: [email protected]
Web: http://www.fbperformance.com

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E
howdy neighbor,
Well, automatics aren't really new in conversions, many here have used them, in fact we have for 30 years. But since you are a stones throw from us, I'll stop by and talk about them...
Mike
www.EV-propulsion.com
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FB Performance Trans
EV-propulsion.com said:
howdy neighbor,
Well, automatics aren't really new in conversions, many here have used them, in fact we have for 30 years. But since you are a stones throw from us, I'll stop by and talk about them...
Mike
www.EV-propulsion.com
Click to expand...
Hi there Mike
You’re absolutely correct: Automatics have apparently been around for quite a while. Unfortunately most of the feedback we’ve been getting from various sources in the EV industry is that they’ve gotten a bad rap over the years. Based on what we’ve heard, it seems that there are many misconceptions about just how good they really are. We’ve heard everything from “lack of efficiency” to “lack of durability” and everything in between. All of these things couldn’t be further from the truth when you’re talking about a professionally built automatic designed for a specific application and installed properly.

The purpose of my earlier comment was simply to create awareness to the fact that with today’s technology the automatic transmission is without a doubt a viable alternative for EV conversions and will in fact replicate the drivability of a gas vehicle.

Fred and I look forward to meeting and discussing this further with you.
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C
Trying to figure out why it was so hard for them to learn to drive a stick trans on an EV.

It isn't even hard without a clutch and they had one!!!
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JRP3
Nice to have more off the shelf options. A few here have done autos quite successfully after some tinkering.
For GM solutions there is this Powerglide setup which eliminates the TC:
http://www.kansasev.com/evglide-powertrain.html
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FB Performance Trans
Coley said:
Trying to figure out why it was so hard for them to learn to drive a stick trans on an EV.
Click to expand...
Coley said:
It isn't even hard without a clutch and they had one!!!
Click to expand...
From what I’ve been told it wasn’t a question of learning how to drive a stick. It was trying to feather the clutch sufficiently during gear changes. Keep in mind that the vehicles being converted were intended for local street driving in stop and go traffic. Apparently because the electric motor produces most of it torque at low rpm that driving around town at speeds below 40mph became a real nuisance.

JRP3 said:
Nice to have more off the shelf options. A few here have done autos quite successfully after some tinkering.
Click to expand...
JRP3 said:
For GM solutions there is this Powerglide setup which eliminates the TC:
http://www.kansasev.com/evglide-powertrain.html
Click to expand...
It’s funny that you should mention that type of set up. Because one of the electric motor manufacturers that we’ve been dealing with let us know that some people that have tried using an automatic without a torque converter have not only had durability issues, but they run into the same problem regarding the harshness of the shifts at low speeds.

The torque converter is basically a fluid coupler and one of its primary functions is to dampen the transmission of torque through the drive line. In gas operated vehicles the stall rpm (or internal slippage) of the converter allows the motor to idle without stalling. In the converter we’ve designed for electric motors the stall rpm has been significantly minimized in order to maximize coupling efficiency. Stall is not an issue since the electric motor is turned off when the vehicle comes to a stop.

During start up when a gas vehicle first moves there’s a tendency for a normal converter to slip. This allows the motor rpm to increase in order to go deeper into its torque curve to improve acceleration. With an electric motor this additional slippage is not necessary because it produces so much bottom end torque at low rpm.
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toddshotrods
FB Performance Trans said:
From what I’ve been told it wasn’t a question of learning how to drive a stick. It was trying to feather the clutch sufficiently during gear changes. Keep in mind that the vehicles being converted were intended for local street driving in stop and go traffic. Apparently because the electric motor produces most of it torque at low rpm that driving around town at speeds below 40mph became a real nuisance...
Click to expand...
That makes absolutely no sense. Local street driving, in stop and go traffic, is where the electric conversion should shine brightest. Under 40mph, there really shouldn't have been a need for a lot of gear changes, if any.

Those people obivously weren't very adept at driving manual transmission equipped vehicles either. With an ICE you feather the clutch to get moving from a stop. There is absolutely no need to do this with a properly designed manual EV conversion. It should be in gear and the clutch all the way out before you start moving. It makes absolutely no sense to feather the clutch because the electric motor has torque from 0rpm.

Feathering the clutch during shifting makes even less sense. The vehicle is moving already and the clutch, if used, is just to allow the gear speeds to match more quickly. If there was harshness during shifting it was probably because the driver didn't realize that they didn't need as much effort on the accelerator pedal. It was probably liberal application of torque that was creating the "harshness"; i.e. a heavy right foot on the acclerator pedal.

In the short time I've been in this, and on this site, the biggest problem I have seen is people seem to insist on making the electric motor behave like an ICE. Poorly matched components and irrational expectations seem to be the real problems.
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correct Todd, or there was a dead zone at the beginning of the pot box range, or misadjusted ramp speed on the controller. Guessing as we don't know what other components were used.
Mike
www.EV-propulsion.com
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toddshotrods
EV-propulsion.com said:
correct Todd, or there was a dead zone at the beginning of the pot box range, or misadjusted ramp speed on the controller. Guessing as we don't know what other components were used.
Mike
www.EV-propulsion.com
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Whew! Was hoping I wasn't going to get a lashing! :D I realized after posting that I did it in my normal aggressive fashion, but left it stand to (hopefully) draw attention to the point. Thanks for backing me up with some ideas of other things that could be wrong. The moral of the story is, do some research, testing, etc, before giving up and labeling something a bad idea. If it was a bad idea find out why, before spending more money and time...
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FB Performance Trans
toddshotrods said:
That makes absolutely no sense. Local street driving, in stop and go traffic, is where the electric conversion should shine brightest. Under 40mph, there really shouldn't have been a need for a lot of gear changes, if any.

Those people obivously weren't very adept at driving manual transmission equipped vehicles either. With an ICE you feather the clutch to get moving from a stop. There is absolutely no need to do this with a properly designed manual EV conversion. It should be in gear and the clutch all the way out before you start moving. It makes absolutely no sense to feather the clutch because the electric motor has torque from 0rpm.

Feathering the clutch during shifting makes even less sense. The vehicle is moving already and the clutch, if used, is just to allow the gear speeds to match more quickly. If there was harshness during shifting it was probably because the driver didn't realize that they didn't need as much effort on the accelerator pedal. It was probably liberal application of torque that was creating the "harshness"; i.e. a heavy right foot on the acclerator pedal.

In the short time I've been in this, and on this site, the biggest problem I have seen is people seem to insist on making the electric motor behave like an ICE. Poorly matched components and irrational expectations seem to be the real problems.
Click to expand...
All of your points are well taken, and I've only been relaying the information that we were provided. We were not privvy to any information about the controller set up.

I will say this though, whatever drivability issues they had before with the stick have been completely eliminated by using the automatic.
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E
"Whew! Was hoping I wasn't going to get a lashing!" HaHa--not from me.....just cause I'm in the northeast don't put me in the same boat as some others in this end of the country! :) :) Don't get gun shy now!

"I will say this though, whatever drivability issues they had before with the stick have been completely eliminated by using the automatic"
I could see that happening to some degree..
Mike
www.EV-propulsion.com
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toddshotrods
FB Performance Trans said:
All of your points are well taken, and I've only been relaying the information that we were provided. We were not privvy to any information about the controller set up.

I will say this though, whatever drivability issues they had before with the stick have been completely eliminated by using the automatic.
Click to expand...
I was hoping you won't take that personally. I don't see any reason your product wouldn't work adequately, and you provided a solution that produced a happy customer - great. If the problem was a heavy right foot or, as EV-propulsion pointed, out the problem was with the pot box or controller settings the torque converter could be masking it. That's still not meant to be a negative reflection on your product, just noting the possibility that there could be other issues.

Also, in the interest of fairness, I don't see any reason why there should be any realiability or durability issues with a properly designed converterless system. I state that for people reading the thread and trying to make decisions. Manual/automatic, clutch/clutchless, transmission/direct-drive, etc - all have been proven to be good choices when they are properly designed and matched to the application. Do your homework...
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toddshotrods
EV-propulsion.com said:
...Don't get gun shy now!...
Click to expand...
No way! I always have my six-shooters on my side and ready! Notice the thought was more like "here I go again" instead of "I'm not going there again"? Any type of shyness is just not in my nature. :D
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JRP3
I'll agree that the problems either were a result of an improperly designed system or operators who were driving it like an ICE, or both. As for harder shifting without a TC, can't that be adjusted somewhat in the valve body?
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toddshotrods
JRP3 said:
...As for harder shifting without a TC, can't that be adjusted somewhat in the valve body?
Click to expand...
Should be. That's where performance/racing applications dial in firmer shifts, from snappy street cars to bone-jarring racers.
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FB Performance Trans
JRP3 said:
I'll agree that the problems either were a result of an improperly designed system or operators who were driving it like an ICE, or both.
As for harder shifting without a TC, can't that be adjusted somewhat in the valve body?
Click to expand...
That’s exactly the point. The people that we’re dealing with want to be able to drive these EV’s just like a vehicle with an ICE. The municipality apparently does not have the luxury or desire to train designated drivers just for using an EV. It seems that those who are building EVs for themselves can certainly tolerate any differences in drivability.

The valve body can certainly be adjusted for softer shifts but that will also compromise the holding capacity and life of the clutch packs. The purpose of increasing line pressure particularly with a “full manual” valve body (as shown in the link to the 2-speed Powerglide) is to eliminate clutch slippage and improve efficiency. Say what you will about those doing it, but the automatic transmission was never designed to operate without a torque converter. When built properly for any application it offers many advantages over a clutch, particularly when it comes to drivability.
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GizmoEV
So with your automatic transmission modifications would the electric motor need to be idled to properly keep the fluid pressure up? I think only the controller that has a built in idle solution is the Soliton1. Would this have to be added to other controller setups to get the transmission to behave properly?
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FB Performance Trans
GizmoEV said:
So with your automatic transmission modifications would the electric motor need to be idled to properly keep the fluid pressure up? I think only the controller that has a built in idle solution is the Soliton1. Would this have to be added to other controller setups to get the transmission to behave properly?
Click to expand...
No. From what we gathered when we first got involved in the EV market place was that many felt that the automatic was not suitable for these applications because the electric motors are normally not idled. When they’re turned off there’s a tendency for a certain amount of fluid bleed off in the transmission. As I mentioned in my opening comment regarding the (2) transmissions, we have been able to significantly reduce the bleed off:

The valve-bodies in both of these units are designed to eliminate the normal fluid bleed off, so that the transmission can react immediately to the input torque of the electric motor.

The fluid restriction and internal pressure readings were initially tested by simulating the “on and off” operation of the transmission on our Dyno. It was later confirmed in the actual operation of the EV vehicle itself. In fact, one the converted vehicles was a full size van weighing over 6,000 lbs. Even with all of this weight and the high low-end torque of the motor, the transmission and converter provided a very normal take-off after each stop.
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GizmoEV
Oh, I missed that line. That is good to know because it will make my build much easier. Do you know if those transmissions would fit rather easily in an S10? I ask because as I look around for a donor my options are much greater if an automatic is an option too. If the transmission isn't too big compared to a stock automatic in an S10 it would be just a matter of welding up the appropriate mounting brackets for your transmission setup.
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DIYguy
So with the recommendation to use a torque converter, and for...let's say, more performance oriented applications, ...do you do anything in particular to the converter? ICE applications that look for better hole shots, use stall converters with higher RPM connection points...to take advantage of the ICE torque curve. With a DC series motor having high torque at low rpm's, what do you recommend for the torque converter? Stock? Mods to lower hook-up rpm ...or????
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