EV transmissions and Popular Science

[speedmd]

Interesting interview with Christian von Koenigsegg "regera". https://www.youtube.com/watch?v=sr1jylROsqQ Love the idea of the blend of torque curves. Wish F1 took more of this approach.

If doc gonzo can not stop with the personal attacks, he should be given a time out. This is not a place to be allowed to be abusive, even to ones self. :lol:

 

[JackB]

If you don't call a gear reduction and a differential a 'tranmission', then I guess Tesla engineers are really really clever.
What I have suggested in the past, which i think IS clever is direct drive from a dual shaft motor to wheels with two torque converters
between the shafts and wheels. They lock up at high speed just like they do today, and at low speed provide differential and torque multiplication.
This design was explored by Tucker, but torque converters in 1948 are not what they are today.

Are the OEM EVs that all use transmissions/gears, those guys are just not very clever?

Correct. Look at those that are definitely clever to see the way forward. Tesla, Zero, Lightning - even Koenigsegg with the Regera! Direct driven, no transmission and all market leaders in their segments.

Strangely enough all the companies that are in a position to do a 'clean sheet' design have arrived at this, those with the baggage of past experience where transmissions were crucial to success are not willing to adopt radical change and will eventually suffer for it.

As Luke has pointed out many times before a lot of the reasoning behind transmissions in EV's is due to motor limitations present only because of iterative change from the industrial roots of the industry. There are no limitations inherent with the technology, only the narrow implementation of it in mainstream EV components. This will inevitably change.

 

[Punx0r]

Hmm. It's an interesting potential alternative to 2 x fixed ratio reductions and then a mechanical differential. That Mercedes torque converter at 93% might be better than the two stages of mechanical reduction, although I'd guess somewhat a little larger and heavier. I'm also assuming that splitting your drive power between two sets of gears or two torque converters incurs similar loss as putting all the power through one twice the size.

There's a neat little quote from Christian von Koenigsegg talking about the new Koenigsegg Regera, which uses a twin-turbo V10 petrol engine

Its a V8 based on the ford 5.0

Quite right, my mistake.

 

[Ohbse]

I do not consider a reduction and a differential a transmission as its a single ratio between motor and wheels. It's clear from the photo a great deal of effort went into making the driveline simple and compact, the same results would be possible without the reduction, however things would need to be packaged quite differently to accomodate the motor radius necessary. Perhaps that will happen in future as tesla have experienced plenty of issues with even the single reduction holding up under the torque produced.

The koenigsegg v8 is actually 100% bespoke design and manufactured in house. Only the first couple of models carried the ford derived engine. They are a fascinating company and I expect we will see them pushing EV technology fast. The Regera battery discharges at up to 55c in a production vehicle!

 

[Arlo1]

The koenigsegg v8 is actually 100% bespoke design and manufactured in house. Only the first couple of models carried the ford derived engine. They are a fascinating company and I expect we will see them pushing EV technology fast. The Regera battery discharges at up to 55c in a production vehicle!

Yes it all started from the ford v8 and its still based on the ford 5.0 although Koenigsegg makes all of it custom to they needs.

And I Believe Rimac is behind the battery...

 

[h0tr0d]

Arlo

Rimac is behind the battery indeed. The battery is fully flooded in a liquid that boils at 34°C @ ambient pressure

 

[doctorGONZO]

Interesting interview with Christian von Koenigsegg "regera". https://www.youtube.com/watch?v=sr1jylROsqQ Love the idea of the blend of torque curves. Wish F1 took more of this approach.

If doc gonzo can not stop with the personal attacks, he should be given a time out. This is not a place to be allowed to be abusive, even to ones self. :lol:

I am terribly sorry if I in any way was abusive to you. Are you dyslexic, and, understand everything that you see, in the reverse, and then insist that YOU are right, and, then, insist that you are abused when someone tells you that you are wrong?

Oh, dear! That means that YOU are abusing ME when YOU accuse ME of being anti-social toward YOU if I complained that you were talking nonsense in the first place! But of course YOU are incapable of talking nonsense because, errr, well, just because, right?


GONZ

 

[doctorGONZO]

All of the recent balony has been obfuscative of an important issue.

On a race track, under a specific set of conditions, it can be most advantageous to eliminate a gear train. This can eliminate friction loss portrayed by a generic "Rule Of Thumb" 10%, or, in more specific conditions, such as NASCAR, about 5% .

On another race track, it can be most advantageous, under a different set of conditions, to have a gear train so as to maintain the electric motor in its "sweet spot" RPM. Just like when the motor is a non-electric combustion device. Electric motors are notorious for giving poor, perhaps 30% efficiency, when used in FREQUENT conditions of ACCELERATING. Does any party in this Thread deny this?

Does any party to this Thread claim that some kind of a Majicke Geometry Motor can give about 95% efficiency when it is required to frequently accelerate?

Does anybody here claim that a Majicke Geometry Motor, direct drive, can give 95% efficiency when used in commuter condition, gridlock, stop-and-go traffic?

I am willing to learn. Show me.


GONZ

 

[Punx0r]

Why not start by looking at that Leaf efficiency map Arlo posted for your attention on the previous page?

Then I would read the "Conclusive proof gearboxes are awesome" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=47930

Then read the "Field Weakening VS Gear Box VS Higher voltage battery" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=63467

 

[major]

Electric motors are notorious for giving poor, perhaps 30% efficiency, when used in FREQUENT conditions of ACCELERATING. Does any party in this Thread deny this?

I am willing to learn. Show me.

I'll deny that. Where did you get this 30%? You must have confused the electric motor efficiency with that of the ICE (Internal Combustion Engine). Here is the efficiency map for a typical ICE.

from: http://www.posterus.sk/?p=14577, 06. Február, 2013, Autor článku: Matej Juraj, Elektrotechnika

As Punx0r pointed out, there are 2 examples of electric motor efficiency maps posted on the previous page. You should study those. You are hard pressed to find operating points (RPM and torque or power) which show 30% or lower efficiency. Although we all know electric motors start at zero RPM and therefore at zero efficiency, the times and the power levels at efficiency of 30% or lower are so small in the typical drive cycle that it represents very little lost energy.

I also encourage you to search using the image option on google for _electric motor efficiency map_. If you are really willing to learn, that should show you a great deal about the efficiency of electric motors.

 

[Arlo1]

Why not start by looking at that Leaf efficiency map Arlo posted for your attention on the previous page?

Then I would read the "Conclusive proof gearboxes are awesome" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=47930

Then read the "Field Weakening VS Gear Box VS Higher voltage battery" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=63467

I see I can not PM him so maybe he added me as a "FO" trying to block all posts I have laid out. I don't think I have said anything harmful to him and I have not really said anything bad to anyone on this forum. IM here to Learn and share my learning's that is all.

 

[speedmd]

Who here has not taken some hard stances on subjects they know a bit about. Crapping on folks that are trying to help you see the path to better understanding is just foolishness. Best to just drop it or lock it for a few days, until one can digest the previous discussions on the topic. Some will remain fools regardless.

IMO this tranny topic will remain a hot button issue to anyone that loves shifting gears for some time. Inexpensive controllers / motors that can double or triple the rpm range of many current ebike motor/controller setups will help end this discussion for most.

 

[Teh Stork]

Why not start by looking at that Leaf efficiency map Arlo posted for your attention on the previous page?

Then I would read the "Conclusive proof gearboxes are awesome" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=47930

Then read the "Field Weakening VS Gear Box VS Higher voltage battery" thread: http://endless-sphere.com/forums/viewtopic.php?f=30&t=63467

As the OP of "Conclusive proof gearboxes are awesome" - I'd like to add that my main focus was performance (as in acceleration), not efficiency. The discussion is ok, even though it is a long read.

Direct drive > gearbox. A bigger motor will perform better than a smaller motor with gearbox. But I love my BBS02

Don't let Gonzo get under your skin with his CAPITALIZED writing style and faulty facts.

 

[John in CR]

Multi-speed gearboxes on electric vehicles are for people who can't let go of the past. ICE's have them because they need them, but unless an EV is really a dual use vehicle, eg needs to climb very steep hills with a heavy load and cruise efficiently at top highway speed, then they simply don't need them, especially with field weakening extending the top speed without a gear change.