User avatar
TimeHorse
Posts: 999
Joined: Thu May 13, 2010 4:40 am
Delivery Date: 02 Nov 2011

Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 6:06 am

Why the heck don't any Hybrids or EVs use Ultra Capacitors for regenerative breaking? Surely these dense storage houses would be great for the short-term electrical input of the breaking system, non? I just don't get it, can someone explain?
RIP CO2 Fre, 27 months, 42,282 mi & 11 bars.
unAmerican Job & Nissan's Rapid Depreciation cost $20,000!
5 hours on the road daily w/o Charge at Work on 100%.

Long Live CO2 Fre, Maxed 2013 SL, 20,000 mi/yr lease.
http://aecn.timehorse.com/" onclick="window.open(this.href);return false;

User avatar
mwalsh
Posts: 9651
Joined: Thu Apr 22, 2010 10:10 am
Delivery Date: 05 Jan 2011
Leaf Number: 0213
Location: Garden Grove, CA

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 6:22 am

TimeHorse wrote:Why the heck don't any Hybrids or EVs use Ultra Capacitors for regenerative breaking? Surely these dense storage houses would be great for the short-term electrical input of the breaking system, non? I just don't get it, can someone explain?
I don't know anything about that, but there is a bus system that will use Ultra Capacitors. The capacitors themselves only give the bus a few miles of range (4 or 5 IIRC), but there is inductive charging at every bus stop and the capacitors recharge in the time it takes for the bus to board and disembark passengers.
2011 Blue Ocean SL with 84,000 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

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 7:28 am

TimeHorse wrote:Why the heck don't any Hybrids or EVs use Ultra Capacitors for regenerative breaking? Surely these dense storage houses would be great for the short-term electrical input of the breaking system, non? I just don't get it, can someone explain?
They are not "dense storage houses". They have very good power rating but very low energy density. EEStor is all about that - they promise both high power of capacitors and high ED of batteries. Alas they seem to contradict some basic physics ...
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

User avatar
EVDRIVER
Moderator
Posts: 6728
Joined: Sat Apr 24, 2010 7:51 am

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 8:19 am

evnow wrote:
TimeHorse wrote:Why the heck don't any Hybrids or EVs use Ultra Capacitors for regenerative breaking? Surely these dense storage houses would be great for the short-term electrical input of the breaking system, non? I just don't get it, can someone explain?
They are not "dense storage houses". They have very good power rating but very low energy density. EEStor is all about that - they promise both high power of capacitors and high ED of batteries. Alas they seem to contradict some basic physics ...

Please don;t mention that name here, it could get ugly:)

User avatar
johnr
Posts: 884
Joined: Sun May 02, 2010 2:08 pm
Delivery Date: 11 May 2011
Leaf Number: 2151
Location: Exeter, CA

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 10:14 am

For hybrids it makes sense - the short high-power bursts from regenerative braking can be absorbed by supercapacitors much more effectively than by any battery. For EVs, the battery pack is generally large enough that it doesn't have too much trouble absorbing the charge, but I think supercapacitors in tandem with the batteries would still help in absorbing the rapid power influx and then slowly transfer it to the batteries. Yeah, it makes sense - I don't know why they're not used more commonly.
My trip to Mineral King and the value of regen

Charging stations, electrical adapters, and portable CHAdeMO quick chargers

2011 upgrade: Fossil < Leaf. 2014 upgrade: Leaf < imiev. 2017 upgrade: imiev < tesla. Done upgrading.

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 11:08 am

johnr wrote:Yeah, it makes sense - I don't know why they're not used more commonly.
I guess they don't yet make economic sense ...

http://www.ultracapacitors.org/index.ph ... iew&id=252
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 12:20 pm

johnr wrote: Yeah, it makes sense - I don't know why they're not used more commonly.
One reason is that current lithium cells are capable of handling the surges. Caps made more sense (well, the promise of caps made more sense...) when the best batteries we had were lead-acid and NiMh.

Current retail lithium polymer has a 45C constant output, a 90C burst, and a 10C charge capability. A123 LiFePO4 round cells are about 30C discharge and 4C charge. Even older 4C charge-capable LiFePO4 delivers more than 8000 hybrid cycles with little capacity loss or internal resistance gain.

Maybe the cap folks could have some market share if they'd gotten products on the streets 5 years ago, but I think they missed the boat.

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 3:01 pm

evnow wrote:They are not "dense storage houses". They have very good power rating but very low energy density. EEStor is all about that - they promise both high power of capacitors and high ED of batteries. Alas they seem to contradict some basic physics ...
I don't know much of anything about this stuff, but trying to put this in layman's terms it sounds like "low energy density" means that to have a 24kWh capacitor system you would need something "as big as a house." Well, not literally, but something a lot bigger than the Leaf battery. Is that true? Any rough idea how much bigger? (I have this hilarious mental image of a Leaf jacked up three feet on huge tires to make room for the capacitors underneath.)
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Thu Jun 24, 2010 6:01 pm

Here's a guy in the DC area turning an EV1 into a series hybrid with supercaps: http://www.endless-sphere.com/forums/vi ... 34&t=15794

These supercap modules reportedly hold about 250Wh usable (about 450wH total).
Image

Image


A quote from a physicist and battery pro: "You can easily put more energy storage into the pockets of your pants, and not need a belt to hold them up still by using [lithium polymer]."

Andy

User avatar
TimeHorse
Posts: 999
Joined: Thu May 13, 2010 4:40 am
Delivery Date: 02 Nov 2011

Re: Why the heck don't any Hybrids / EVs use Ultra-Capacitors?

Fri Jun 25, 2010 6:09 am

Actually, the idea was keep the battery but since it can only load at, what, 90W or so, if the regenerative breaking produced more power than that, it would be wasted as heat. Of course, I will admit that if the LEAF has a 80kW motor and I assume for the LEAF the regenerative component would simply be turning the electric motor into a generator, I guess there's no way to recover more energy anyway, at least here. But if a higher-capacity generator was used for Regenerative Breaking, then Ultra Caps would definitely be wonderful at capturing the excess charge and releasing it back into the battery more smoothly. Anyway, that would be the idea. As someone said, this may be a better issue for the hybrids, depending on how their configured. It's really a question of how the Regenerative Breaking is configured.
RIP CO2 Fre, 27 months, 42,282 mi & 11 bars.
unAmerican Job & Nissan's Rapid Depreciation cost $20,000!
5 hours on the road daily w/o Charge at Work on 100%.

Long Live CO2 Fre, Maxed 2013 SL, 20,000 mi/yr lease.
http://aecn.timehorse.com/" onclick="window.open(this.href);return false;

Return to “Engineering”