Automatic versus Manual for EV

Technical discussion on converting internal combustion to electric
Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Sun, 21 Dec 2008, 03:22


G'day,
What is the advantage and disadvantage for using automatic transmission with 3000Rpm electric motor.

Using Torque converter the Auto transmission engages at 700rpm and hard at 1200rpm.(Possibly less with el motor) Instead of using Dead stop start torque @ 200 amp usage the torque converter will reduce the amp usage and work at best speeds 1200-3000rpm. estimated usage 100amp

Has anyone tried? I realise that auto cars use more fuel. would this history also apply and effect Electric motors?

Electric motors are best performing from 500 rpm up

The highest consumption of Amperage is at the start with manual G/box



User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Mon, 22 Dec 2008, 02:02

A torque converter would be really nice on an electric motor (you wouldn't even need the rest of the gearbox really) but the efficiency is very low so you'd waste a lot of power.

Most auto transmission EV conversions get rid of the torque converter.
The Engine Whisperer - fixer of things

antiscab
Senior Member
Posts: 2489
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Automatic versus Manual for EV

Post by antiscab » Mon, 22 Dec 2008, 04:50

Goombi wrote:
G'day,
What is the advantage and disadvantage for using automatic transmission with 3000Rpm electric motor.

Using Torque converter the Auto transmission engages at 700rpm and hard at 1200rpm.(Possibly less with el motor) Instead of using Dead stop start torque @ 200 amp usage the torque converter will reduce the amp usage and work at best speeds 1200-3000rpm. estimated usage 100amp

Has anyone tried? I realise that auto cars use more fuel. would this history also apply and effect Electric motors?

Electric motors are best performing from 500 rpm up

The highest consumption of Amperage is at the start with manual G/box



motor side amps will be lower for the same power under acceleration (since the motor will be spinning faster), but because you have added a lossy component to your drivetrain, battery side amps will increase (and so will total power drawn from the batteries for the same acceleration as with a manual gearbox).
The result will be a shorter range.

i dont see any advantage to having an automatic transmission, only disadvantages (unless of course you only have an auto licence).
If you had to have an auto transmission (say because the donor car is already auto) i would ditch the torque converter.

If you want lower battery side amps under acceleration, set the battery side current limit on your controller lower (if your controller supports this). If your controller doesnt support this, then just back off the accelerator to keep the battery amps (and power) down.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Mon, 22 Dec 2008, 05:40

Does it mean that removing the torque converter the auto bands are going to change gears without it?.... Hmm.. something is odd..

I was looking for smooth run up and when at stop the gear has already changed down to low
What has been presented here are theories.. not facts---
When driving with manual g/box the gear change is splintered where as with Auto it will be smooth and amps rising gradualy without them being erratic. The smoother the consumption the longer the holding charge.
Is there anyone that done a auto conversion?
I would very much like to have his opinion, but i thank the participants in this conversation.. and perhaps there could be some definite conclusion..

One more point. when driving auto in top gear and come across a rise , Auto will change down instantly.. by using manual it takes 2-3 seconds to change the gear down and in the mean time the EV loses monentum and starts pumping more power where as Auto would have dropped the amp consumption... I like to know why removing the Torque Converter. without effecting the smooth run and change over of gears. \Cheers

antiscab
Senior Member
Posts: 2489
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Automatic versus Manual for EV

Post by antiscab » Mon, 22 Dec 2008, 06:00

hmm, the auto bands would be built only to overcome the inertia of the torque converter, not the engine. but an electric motor has a much lower intertia than a petrol engine. This is something you might have to find out by trial and error.

the only auto conversion ive seen was rob masons, when he tested out a old ford 3spd in his mustang, without the torque converter.
went ok, but started with a *thud* whenever you would take off.

are your battery side amps erratic now?

i would assume in your example you are referring to a more modern auto transmission?
the one rob used had fixed motor rpm shift points, so wouldnt actually shift down unless the car had already slowed down, which didnt happen because the motor and controller combination (zilla 1k + 9"motor) was more than capable to attacking hills in top gear at full speed.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Mon, 22 Dec 2008, 16:42

the take off thud would be due to the auto box having no hydraulic pressure until it started spinning, so it would engage first without the cushioning effect of the torque converter.

Torque converters are inherently inefficient, which is the reason auto cars use more fuel than manual cars - and the effect will be the same for an EV.

An efficient torque converter on its own without a gearbox might be worth trying though, as you could run taller gearing than you normally would while still maintaining good take off performance.

A lock up torque converter setup without the rest of the auto box could actually work really well - giving extra takeoff grunt, but no loss of efficiency when cruising.
The Engine Whisperer - fixer of things

User avatar
Johny
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

Automatic versus Manual for EV

Post by Johny » Mon, 22 Dec 2008, 16:46

Someone on DIY electric cars did an auto with no torque converter. They ran a separate electric pump for the transmission pump but otherwise the transmission was untouched.

Rob M
Groupie
Posts: 88
Joined: Thu, 17 May 2007, 16:40
Real Name: Robert Mason
Location: Australia
Contact:

Automatic versus Manual for EV

Post by Rob M » Mon, 22 Dec 2008, 17:41

As Matt says, I did put an auto transmission in the Mustang for a while. The acceleration was outstanding and the energy consumption was only a little higher than with the gearbox, probably due to having to drive the oil pump.
Take off from stationary required a bit of care to prevent bumping but no more effort than engaging a clutch. An externally driven electric oil pump would solve the problem as Johnny suggests.
The other changes, first to second and second to third, were very smooth.
I did not connect the kick back lever to the throttle since electric motors have high torque at low revs anyway. In fact it would be a disadvantage.
I manually set the change revs (obviously controlled by tailshaft RPM) to about 2500 motor RPM. This worked very well.
The best solution would be to find an auto which did not require pump pressure to hold in top gear (for economy) and had an electric pump to engage first gear whilst stationary. I'm sure it would not be too hard to find something suitable. I didn't look very hard at all because I went on to other things
I would recommend an auto over a manual gearbox.

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Mon, 22 Dec 2008, 18:52

I felt that there was an advantage in Auto transmission with EV
Rob You made my day. I was affraid that i will be clobbered being too contraversial..
Do modern auto transmissions have inbuilt hydraulic pump? I shall make some enquiry. ""if there is no movement by the motor then the inbuilt Hyd. pump will not work""" More research

Have sent you e-mail ROB but it had to disapear into ether somewhere

Thanks again

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Tue, 23 Dec 2008, 02:06

yep, auto transmissions have an inbuilt pump, which is driven by the engine.
Replacing that with an electric pump means you can actually control the gearbox before the drive motor is running.
I think a power steering pump would do the job.
The Engine Whisperer - fixer of things

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Tue, 23 Dec 2008, 02:43

Auto is driven from engine through torque converter which drives the oil pump on a separate shaft the pump generally finished at the back of the auto. If a direct coupling had an adapter to lock on to the outer Oil Pump shaft It looks like a fork without the centre ) the pump would operate while the EV in moving regardless of revs. there fore it will hold the top gear in and can be manualy sellected when at stop.. Once the ev moves the Oil pump will activate the sellection since there will be preassure in the box. Question:By increasing amp input to the motor will the gearbox auto sellect up and when removing the power will it slip down? I think the trick will be to connect the pump shaft to the motor coupling. Torque converter is simply an Oil filled centrifugal clutch.

By using Torque converter you are adding 2 flywheels to the el motor bearing.. possible 25 kg so I feel the converter is OUT.

Rob M was your sellection to gears made manually or some auto?


Last edited by Goombi on Mon, 22 Dec 2008, 15:54, edited 1 time in total.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Tue, 23 Dec 2008, 03:31

the oil pump can be driven from the input shaft and will work fine (as has been done - mentioned above)
The thud on takeoff happens because as soon as there's hydraulic pressure the gearbox will engage first - but normally the torque converter gives a nice squishy coupling to smooth it out.

It's the same as manually going from neutral to drive with too many revs.

The torque converter works like a centrifugal clutch, but it also gives a virtual gear reduction.
It takes high rpm low torque in and gives low rpm high torque out.
It doesn't work over a wide enough range to do without multiple gears on an ICE, but with an electric motor it would probably do on its own.
It's not worth the extra efficiency loss if you use it with the auto box though, so it's better go ditch the torque converter and use the gearbox if you're converting an existing auto car.
The Engine Whisperer - fixer of things

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Tue, 23 Dec 2008, 05:41

The torque converter works like a centrifugal clutch, but it also gives a virtual gear reduction.
It takes high rpm low torque in and gives low rpm high torque out.
It doesn't work over a wide enough range to do without multiple gears on an ICE, but with an electric motor it would probably do on its own.
------------------------------------------------------------------------
Question: Can Torque converter be used like DIRECT DIFF DRIVE? without auto gearbox ( or manual box)to help propel the diff from start and lock up at higher revs, Its another subject but since we are on Torque Converters let explore all advantages.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Tue, 23 Dec 2008, 05:59

yep, that's what I've been saying.

I think a torque converter on its own, with a lock up mechanism, would work very well because you could get much more take off grunt without using huge motor current, and once you get up to speed you could lock the torque converter and have no extra losses.
The Engine Whisperer - fixer of things

Rob M
Groupie
Posts: 88
Joined: Thu, 17 May 2007, 16:40
Real Name: Robert Mason
Location: Australia
Contact:

Automatic versus Manual for EV

Post by Rob M » Tue, 23 Dec 2008, 19:03

"Rob M was your sellection to gears made manually or some auto? Goombi"
Hi Goombi
I connected up the selector handle so I had the usual range from 'Park' through to 'Low'. Therefore I could take off in "D" and let the auto change by itself or I could hold in low or second etc.
The "park"option was very useful meaning I didn't have to rely solely on the handbrake for parking.
I think if I did another conversion using an auto box I would go for a 2 speed with an external electric pump or mechanical shift.
The torque converter alone idea is interesting and worth a try.
Some of the energy losses of the motor at low revs would be compensated by allowing higer revs at start off but then lost again in the converter.
What I'm saying is that the losses might not be as bad as they seem at first glance.
Hmm! Interesting!

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Tue, 23 Dec 2008, 20:44



Hi Rob M,
The "park"option was very useful meaning I didn't have to rely solely on the handbrake for parking ----From Rob M --This part is going to become a big issue relying solely on handbrake we may have to carry some blocks in future. or use Auto..
When in park you had to isolate the start switch.### Once you took it out of Park the motor would run ??

The only 2 speed I know of was in cortina and 6 cyl ford . 70s Ford bought the gearbox from GM.
why not use all gears 3-4?. Small vehicled like Barina and charade auto ,the converter is quite small Running on 30-45 hp would be on par with 8.5 kW el motor at 2200rpm.
Your mustang gearbox came with V8 130-180Hp Mustang is a heavy car What sort of performance did you get out of it in distance and speed?
Last edited by Goombi on Tue, 23 Dec 2008, 10:00, edited 1 time in total.

User avatar
woody
Senior Member
Posts: 1715
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

Automatic versus Manual for EV

Post by woody » Tue, 23 Dec 2008, 22:09

hmm, this issue may be just the thing to push me into airbag suspension -- how can it roll when it's on the ground?

Is there anything passive electrical you can do to a motor (DC or AC) e.g. Short it out?

You can always turn your wheels so you don't go far...

Can you rig something up with the vacuum pump and the brakes so your service brakes are kept on?
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

fuzzy-hair-man
Groupie
Posts: 118
Joined: Wed, 12 Nov 2008, 16:40
Location: Canberra

Automatic versus Manual for EV

Post by fuzzy-hair-man » Tue, 23 Dec 2008, 22:39

woody wrote: hmm, this issue may be just the thing to push me into airbag suspension -- how can it roll when it's on the ground?

Is there anything passive electrical you can do to a motor (DC or AC) e.g. Short it out?

You can always turn your wheels so you don't go far...

Can you rig something up with the vacuum pump and the brakes so your service brakes are kept on?
I think you can get hydrolic hand brakes they use them for motorkanas and rally, but I don't think rego allows them because the hand brake has to be able to work independently of the hydrolic brake system, this probably doesn't apply if you are installing a second or backup hand brake though.

Which is making me wonder if there isn't something you could do inside a manual gearbox to lock it up so it wouldn't be able to turn in one of the gears you don't use.... Image

From what I know of gearboxes (very little cause they always looked complicated and I left them alone) the gears are all meshed and then slide with synchros etc to lock onto the shaft, if two gears were allowed to be locked onto the shaft at once the gearbox would lock up and you wouldn't be able to turn it disengage one of those gears and it would go back to being free. Would the two gears engage / lock on the shaft at once though? It might not be worth the effort though it'd probably be easier just to fit a hydrolic hand brake.

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Tue, 23 Dec 2008, 23:41

Carry couple chocks with you Image

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Wed, 24 Dec 2008, 07:24

you can get two gears to engage at once if the gearbox is worn enough :P
A friend of mine had it happen in the middle of a busy road in an old Charger.
It's surprisingly hard to move a car out of the way when its drive train is locked solid! (matters were made worse by a passer by stopping to "help", by yanking on the gearstick and breaking a selector!)

Induction motors and series wound DC motors can't be made to passively brake, but a permanent magnet motor can (although it still won't stop it moving completely - a bit like a manual car left in gear on a hill with the hand brake off. It'll still creep a bit)

Hydraulic handbrakes don't usually hold for long, and they tend to cause problems with seals. The mechanical drum type are the most effective, apart from the auto gearbox's "park" setting.
The Engine Whisperer - fixer of things

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Wed, 24 Dec 2008, 15:27

Good summery --Electrocycle
Question for Rob M:
When using neutral on auto g/box is it possible that after a short free run(spin) ---(without torque/c ) of el motor there will be enough preassure for the selector to operate? Or it only activates preassure valve when Pump is turning? Thinking of connecting the shaft that drives oil pump directrly to electric motor coupling. Would it be possible ,rather then building a new oil pump to add small preassure tank that holds enough preassure to activate the sellector --Once the el motor runs it does its own pumping.. One more problem,, When the el motor is in idle mode does the g/box generates its own preassure untill it stops? and the sellector will slip the high into low again.

User avatar
woody
Senior Member
Posts: 1715
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

Automatic versus Manual for EV

Post by woody » Wed, 24 Dec 2008, 16:00

just adding a further ingredient into the mix: some older (e.g. Early 60s Chrysler Torqueflite) autos had a second pump on the tailshaft -- this enabled you to roll start an auto ( at about 40 kph )
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Automatic versus Manual for EV

Post by Electrocycle » Wed, 24 Dec 2008, 17:26

yeah Jags had that too.

I think keeping the auto in neutral, running the motor, and then engaging drive would work, but it'll be hard to get it to engage smoothly.
Maybe it'd be possible to add an accumulator to the hydraulic circuit though, so you can pump up some pressure, stop the motor, select drive - and then take off as normal.

If you use a late model transmission (solenoid controlled) I'd just be inclined to use one with a lock up torque converter, and engage the lockup shortly after the car's moving.
The Engine Whisperer - fixer of things

Rob M
Groupie
Posts: 88
Joined: Thu, 17 May 2007, 16:40
Real Name: Robert Mason
Location: Australia
Contact:

Automatic versus Manual for EV

Post by Rob M » Wed, 24 Dec 2008, 19:33

I think it was easier to leave the lever in drive and crank up the electric motor slowly so as to minimise the bump.
It was harder to take off by spinning the motor in neutral and then engaging a gear because it was hard to tell how fast the motor was spinning. I guess this answers your question Goombi about the pump connection. All I did was connect the pump drive to the input shaft of the transmission so they turned together.
There is a damper on some boxes which slows the rate of gear change. This would help I think but I didn't get around to trying one.
I agree that a later model box would most likely be better on all counts.
I was impressed with the old Borg Warner 40 though.

Goombi
Senior Member
Posts: 532
Joined: Sun, 10 Aug 2008, 17:59
Real Name: Eugen
Location: Gympie

Automatic versus Manual for EV

Post by Goombi » Thu, 25 Dec 2008, 20:56

Thanks for your experience and explanation
What actually was the BUMP-- sellector or motor engaging or oil pump or lack of oil?--Engine mount?
In hindside--what would you do diferently? How would you solve most problems today? Or would you no longer consider Auto?

Post Reply