GRA
Posts: 11497
Joined: Mon Sep 19, 2011 1:49 pm
Location: East side of San Francisco Bay

Vocis launching demo EV with 2nd gen multi-speed transmissio

Tue May 14, 2013 7:38 pm

"Vocis launching demo EV with 2nd generation multi-speed transmission; projected 15% improvement in vehicle efficiency"

Via Green Car Congress:

http://www.greencarcongress.com/2013/04 ... 30430.html" onclick="window.open(this.href);return false;
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

GRA
Posts: 11497
Joined: Mon Sep 19, 2011 1:49 pm
Location: East side of San Francisco Bay

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Thu Aug 01, 2013 1:30 pm

So, seeing another announcement of multi-speed transmissions for EVs,

http://www.greencarcongress.com/2013/07 ... .html#more" onclick="window.open(this.href);return false;

I'm wondering if this is something it's time to reconsider. Offhand, the original version of the Tesla Roadster is the only production BEV I can think of with a multi-speed transmission, and they pulled that owing to reliability issues and changed to single speed with some electronic magic. OTOH, lots of EV conversions in the '80s and '90s kept their manual transmissions.

ISTM that the efficiency gain at freeway speeds for cars intended for other than urban use, typically claiming 15% or so, may be worthwhile even allowing for the extra complexity. I suspect a multi-speed transmission is still far cheaper, lighter and smaller than putting in extra batteries for the same range gain, and acceleration performance for passing would also be improved (although Chevy seems to have found a work-around with the Spark EV). I don't think it's worth it for the city cars, but I could see a two-speed transmission, with low for 0 to say 50 mph, and high for 45+ with efficiency optimized for the 65-80 speed band as maybe being worth it for those BEVs with enough range to give them some road trip potential. Opinions?
Last edited by GRA on Thu Aug 01, 2013 1:35 pm, edited 1 time in total.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

User avatar
mwalsh
Posts: 9658
Joined: Thu Apr 22, 2010 10:10 am
Delivery Date: 05 Jan 2011
Leaf Number: 0213
Location: Garden Grove, CA

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Thu Aug 01, 2013 1:34 pm

^ Well, only to say that I agree entirely. Others may find the complexity not worth the gains (in the back of my mind, I think we've had this discussion before).
2011 Blue Ocean SL with 85,000 miles
2015 pack on 12/30/15
Tinted windows
Bosch AGM 12v
Ecopia 422+ tires
L1 EVSE upgrade
FIAMM horns
Superbright LED lighting
2013 sun visors
LED shifter
Heated seats
GT-R map lamp lenses
Altima illuminated door switches

Sublime
Posts: 120
Joined: Wed Jan 23, 2013 1:15 pm
Delivery Date: 23 Jan 2013

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Thu Aug 01, 2013 1:45 pm

If nothing else, I think its clever that they took the idea of a DSG and the advantages of an electric motor and rolled them up together.

The inverter would be interesting, because to take full advantage of this tech, it needs to be capable of sending full power to either motor and also be capbable of running both motors at different speeds. So you essentially need two motor controllers and two motors, both capable of handling full power.

GRA
Posts: 11497
Joined: Mon Sep 19, 2011 1:49 pm
Location: East side of San Francisco Bay

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Thu Aug 01, 2013 1:49 pm

mwalsh wrote:^ Well, only to say that I agree entirely. Others may find the complexity not worth the gains (in the back of my mind, I think we've had this discussion before).
You're right, but I missed it:

http://www.mynissanleaf.com/viewtopic.p ... =4&t=12364" onclick="window.open(this.href);return false;
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

User avatar
RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Fri Aug 02, 2013 4:38 am

GRA wrote:ISTM that the efficiency gain at freeway speeds for cars intended for other than urban use, typically claiming 15% or so, may be worthwhile even allowing for the extra complexity. I suspect a multi-speed transmission is still far cheaper, lighter and smaller than putting in extra batteries for the same range gain,...
I think calling this a "multi-speed transmission" is a bit of a misnomer since it requires two traction motors, much like the Chevy Volt uses two traction motors. So, really, they have added not just a transmission but also another traction motor and its inverter. All this to gain "up to 15% improvement" at highway speeds. Since the efficiency of the LEAF is above 85% at highway speeds, I do not think there is 15% to be gained.

My guess is that you may see this type of "transmission" in sports cars or delivery vehicles where the performance makes a difference, but not in everyday EVs.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

bowthom
Posts: 657
Joined: Sun Jul 18, 2010 12:22 pm
Delivery Date: 23 Feb 2011
Leaf Number: 307
Location: Portland Oregon

Re: Vocis launching demo EV with 2nd gen multi-speed transmi

Fri Aug 02, 2013 8:02 am

Hello,
I agree with pretty much all of what's been said. Before I signed on for the leaf in 2010 I had planned to build an EV out of a 1995 Toyota Tercel. My design included dual motors driving a reduction gear via a planetary gear set. Torque and efficiency figures were impressive, besting my 5.0L mustang at all speeds.
I decided on the leaf because it was only $5k more expensive and it saved a year or more of work. Would still be a fun project though.
Reserv Apr 20 - Ord Aug 31
Red - ETEC trim
BLINK inst 3/14/11 (rev 2.1.2B)
P1213 4/29/11 - Charger repl 6/8/11
P1273 2/15/12 - P32270 10/2/13
TCU upgrd 2/15/17
-1bar 11/14 -2bars 6/16 -3bars 7/18 -4bars 9/19

Deliver 2/23/11 - 75k+ mi

Return to “Engineering”