Is there a supercapacitor sub-forum?

[gromike]

Ya' know, it's all an experiment for me. Maybe I can put together something that has some use, or maybe not. I have assembled very capable ebikes, and I have no need for more speed on a bicycle. So this tangent allows me to have something to chew on, so to speak. And, afterall, my initial investment in caps is only $90.

The plan is to have the battery and capacitor bank work in conjunction with one and another. That is if I can figure out how to harvest the cap banks energy in a useful way. I foresee the need of a robust and much more active use of regen than has be used in ebikes to date. The stumbling block for me will be in figuring out the "controller" for this. Advanced electronics is not my forte'.

Maybe, after this winter, I'll have constructed some sort of frankenbike as a test bed.

 

[neptronix]

VESC does what you're looking for with regen - strong braking to 0rpm.
I get really great braking power out of a 3C rated 19.5AH pack.

You have another problem with supercaps - the energy will flow into the supercap when doing regen, then want to flow back out into the battery at an uncontrolled spike. Your lithium battery has a maximum charge rate that will be greatly exceeded. Hopefully your BMS intervenes and cuts out, otherwise you are potentially damaging your lithium battery every time you brake.

The larger the supercap bank, the worse the problem.

I would not suggest running regen on this setup unless you are willing to design a circuit that limits current back into the battery from the supercaps.

 

[Chalo]

F1 cars use flywheels rather than supercaps. That's a hint as to how lame supercaps are.

 

[gromike]

They're evolving, and what didn't work in the past might work in the future.
I'm just a smuck living on technology's lagging edge. It seems great to be able to play with something that would of cost a small fortune a short while ago and is now junk, because in hi-tech, time quickly marches on.

 

[BlueSwordM]

There's no car that uses supercapacitors. They all use lithium batteries because of the ultra poor energy density of supercaps.
There's no use for supercaps in an EV because the lithium battery of today is totally capable of very strong charge and discharge.



I don't agree with this, certain ebike controllers can have powerful regen down to 0rpm, for example the VESC. This is not the DD's fault.

Geared motors lack the heat shedding capability to handle a lot of forward power & then also regen on top. Both create heat. DDs have tons of thermal mass and are also WAY better at heat shedding.

Good point, I didn't even think about heat dissipation. Without an adequate heat transfer path, a motor that is constantly heated will eventually fail...

Yeah, I also forgot you can phase shift and other things to get more regen out of motors as well, so pardon my somewhat ignorant statement

 

[neptronix]

Yeah, I also forgot you can phase shift to get more regen out of motors as well, so pardon my somewhat ignorant statement

Honestly i've never seen regen braking on any controller as good as the VESC until i tried one.
Other controller makers should take note!

 

[n00b]

I saw that a long time ago. In a very different context, too.

 

[Hillhater]

F1 cars use flywheels rather than supercaps. That's a hint as to how lame supercaps are.

Well, actually F1 cars all use Lithium battery packs.
The Williams developed electrical Flywheel energy storage system never made it into an F1 race, but it was used by Porche and Audi for endurance racing (Audi won Lemans several times using it).
Weight and technical regulations prevented the Flywheel’s use in F1.
weight and size/space prevent the use of supercaps/ultracaps also. ?

 

[Gruesome]

I agree it could still be a fun project to build, even if in the end it turns out to be overly complicated for little or no gain.

Some random thoughts: So, to make use of the very high current capability of your supercap bank, you need a motor that can exceed the current intake capability of your lithium ion battery when doing regen, AND a controller that can handle the current. I assume this would be a separate controller with extra powerful FETs/switches, in addition to the standard controller driving the motor normally from the Lithium ion battery. And of course you need to be able to actually use all that braking torque this extra strong regen operation generates. No point in building a 1000A regen unit if your wheel skids at a few hundred amps. It would be good to run some preliminary back-of-the-envelope numbers before buying more gear.

Maybe the caps are of better use in a battery welder, as power supply backend to to a KWeld or similar circuit?

 

[j bjork]

VESC does what you're looking for with regen - strong braking to 0rpm.
I get really great braking power out of a 3C rated 19.5AH pack.

Sorry for ot, is there some setting to get strong regen to 0rpm on vesc? I have rather weak regen at low speeds (like under 10km/h or something) but can lock the wheel at higher speeds with my 3shul cl1400. I think I have 250phase A and 80battery A limit setup for regen.

 

[harrisonpatm]

Found another build, this time a motorcycle. Their reasoning was that their battery wasn't quite powerful enough for their controller, and the controller would cut out during a high amp draw. They said that adding a supercapacitor bank fixed the issue.

 

[ElectroXa]

there had some experiments about using supercaps on some buses, who recharge themselves at each stop, like Watt System on Nice (FR) back in 2015
The RATP (Paris transportation) also use supercaps on 360 of their buses, all of them are hybrid with a diesel or CNG engine (RATP)

so a fully supercap EV would have very limited range

 

[Gruesome]

there had some experiments about using supercaps on some buses, who recharge themselves at each stop, like Watt System on Nice (FR) back in 2015
The RATP (Paris transportation) also use supercaps on 360 of their buses, all of them are hybrid with a diesel or CNG engine (RATP)

so a fully supercap EV would have very limited range

Years ago I saw a bus stop with overhead charging at the Geneva (Switzerland) airport, but I don't think they are using supercapacitors. Here is a link: TOSA: Geneva’s electrical bus innovation
According to the article, at the end stations and depot they are charging with 400 kW (if I read it correctly). At the bus stops the power must be even higher; the article says the 88 kWh capacity at the stops would be good for four minutes of charging, so that would be 1.3MW, transferring 7.3 kWh in 20s from the local Lithium Ion battery at the bus stop. 400 kW charging for four minutes at the end stations transfers transfers 27 kWh. That's apparently sufficient to keep the buses going until they fully recharge at the depot overnight.

 

[gromike]

Well, I received my order that contains 180 38F capacitors:

... and broke them down.

An evening's work, and I'm even saving money by not going out to my local watering hole. I'll need a couple of those to pay for these.
My first project will be to build a 12v string and see how that goes.
The caps are 10 x 45mm, so they will fit on an ebike. I'd like to find a 36v DD hubmotor wheel cheap for my experiment.

 

[Gruesome]

Well, I received my order that contains 180 38F capacitors:
View attachment 358878
... and broke them down.
View attachment 358879
An evening's work, and I'm even saving money by not going out to my local watering hole. I'll need a couple of those to pay for these.
My first project will be to build a 12v string and see how that goes.
The caps are 10 x 45mm, so they will fit on an ebike. I'd like to find a 36v DD hubmotor wheel cheap for my experiment.

Holy cannoli!

 

[harrisonpatm]

Very cool! Love the idea of using scrap for the experiment. Where did you find those?

 

[gromike]

Where did you find those?

Battery Clearing House.

 

[gromike]

So, with my 180 38F capacitors I'm thinking about building a bank of 20 caps in series and 8 of these strings paralleled.
Do you build it like using battery cells, with the paralleled cells connected in a group, and those groups tied in series for the output voltage, or do you just build the caps in a string and paralleling them at end of the strings?

 

[Chalo]

Do you build it like using battery cells, with the paralleled cells connected in a group, and those groups tied in series for the output voltage, or do you just build the caps in a string and paralleling them at end of the strings?

I think the opportunity for mischief would be less with mutually isolated series strings. You don't want any differences in resistance to cause a favorite path through the circuit that carries a disproportionate amount of the current.

 

[gromike]

I think the opportunity for mischief would be less with mutually isolated series strings. You don't want any differences in resistance to cause a favorite path through the circuit that carries a disproportionate amount of the current.

I guess that's way I'll go, series strings paralleled at the ends.
Of course, you want things "safe" when you have something like twelve thousand potentially instantaneous watts on the rear rack.

 

[riding_on]

I guess that's way I'll go, series strings paralleled at the ends.
Of course, you want things "safe" when you have something like twelve thousand potentially instantaneous watts on the rear rack.

Only if you're trying to survive and/or not damage any life that comes into contact with your product(s). Frankly, some people actually aren't overly concerned by either of those, in my experience.

It's worth remembering: some people are crazier than you can even imagine without being traumatized. That's just my opinion, I suppose, but my point is that "safe" is impossible. "Reasonably safe," however, is a requirement to do business with any business entity that I've ever interacted with.

Knowledge is power. And power lets you choose to not destroy things and other good stuff. (freedom of religion, ugh)