Ultracap Bike

[pwbset]

So don't think no one cares what your doing.

Yeah.. been reading this thread since the beginning.

[JCG]

Thanks guys. Things can be lonely on the low energy, high power side of the tracks!

Quick note: I have hooked up a 36V DeWalt "Nano" battery pack in parallel with the capacitor.



The pictures inside the toolbox would be messy, but here's a circuit diagram:



The lamp keeps the charging current to around 3 A max when the switch is open - used when there is a big (initial) difference in the cap and battery voltages, like when the cap is dead and needs charging. Then, I can close the switch and allow fast charge transfer between the two when they are at about the same voltage.

I rode home and back with it like this, the resting voltage is about 33.2 V now, and on the way home I got it to 33.6. Not much swing! Motoring up a longer hill on the way in today called on about 25 A or so for most of the time, but the voltage had only dipped from 33.2 to about 31.9 when I waited at the stoplight at the top of the hill, and it slowly climbed back to 33.2 while I waited there. Interesting stuff - but needs data acquisition and graphs to be discussed properly!

[tostino]

:lol: Thanks guys. Things can be lonely on the low energy, high power side of the tracks!

Quick note: I have hooked up a 36V DeWalt "Nano" battery pack in parallel with the capacitor.



The pictures inside the toolbox would be messy, but here's a circuit diagram:



The lamp keeps the charging current to around 3 A max when the switch is open - used when there is a big (initial) difference in the cap and battery voltages, like when the cap is dead and needs charging. Then, I can close the switch and allow fast charge transfer between the two when they are at about the same voltage.

I rode home and back with it like this, the resting voltage is about 33.2 V now, and on the way home I got it to 33.6. Not much swing! Motoring up a longer hill on the way in today called on about 25 A or so for most of the time, but the voltage had only dipped from 33.2 to about 31.9 when I waited at the stoplight at the top of the hill, and it slowly climbed back to 33.2 while I waited there. Interesting stuff - but needs data acquisition and graphs to be discussed properly!

From the looks of it, just the addition of one battery will increase the usability of your system greatly. I can see the Dewalt providing enough current for a long enough period of time to extend your hybrid pedal/electric range MUCH further than previously, while also retaining the abilities of the bike to regen TONS of current, and not need to always be plugged in to be used.

[JCG]

From the looks of it, just the addition of one battery will increase the usability of your system greatly. I can see the Dewalt providing enough current for a long enough period of time to extend your hybrid pedal/electric range MUCH further than previously, while also retaining the abilities of the bike to regen TONS of current, and not need to always be plugged in to be used.

You're right tostino; one interesting thing is that it seems to put me in the situation where I might keep an eye on long-term effective battery voltages( rather than amp hours spent and regened) to keep the battery off the charger as much as possible. The cap has (according to my rough observation) allowed dumping of about 35 A to the motor for a couple of seconds, and the battery sent only about 5 A to the cap over a longer period of time since the voltage difference between the two was not too much. If the A123 M1 cells (all 10 of 'em) give a resting voltage of 33.2 V now, then according to the 1A discharge curve here:

http://a123systems.textdriven.com/product/pdf/1/ANR26650M1_Datasheet_AUGUST_2008.pdf

and with the idea of staying somewhere in the 20%-80% charge range for the battery, I might be ok using regen to keep the voltage up to 34 V tops, and not letting it get below about 31 V. I noticed it does take an awful lot of pedaling to go from 33.2 V up to 34! I also realized (please correct me if I'm wrong) that the 2.3 Ah pack I've got in there is about 1/10 the capacity of most ebikes around here. It sure is pretty light compared to everything else in the toolbox.

[tostino]

Well it's probably not 1/10th of most ebikes, but it's close. That is truly a small pack, however, the cells that make it are such high quality that one could run a bike off one battery pack (with bypassing the BMS), which is something you just cannot do with almost any other cell/chemistry type.

[tostino]

I just thought about something... If you felt like it, you could tear apart 2 of those dewalt packs, and solder up enough cells (13s) to get you to a charge of 48.1 when the battery is full (assuming 3.7 is full charge resting voltage, I can't remember exactly what it is for A123).

You might as well try and increase the battery voltage so you can use it right away (without undercharging your cap to achieve this).

[deanz]

It kinda seems like the direction you may end up heading is higher volt caps [say 48volts] being charged by brakes/rapid regeneration, and a high amp hour lower volt battery [say 32volts] being recharged by either the caps or slow/pedal regeneration.

Normal acceleration is with battery, and Super acceleration is with caps or caps + battery.

Dean.

[JCG]

Interesting... and here I was thinking about tearing the cap box apart and removing a few of those to get it down to 36 V or so...

Maybe some kind of diode setup between parallel-connected battery (36V) and cap (up to 48 V) with the diodes preventing current going into the battery, but allowing it to come out if the cap voltage drops below 36V? Hmmm...

[tostino]

Interesting... and here I was thinking about tearing the cap box apart and removing a few of those to get it down to 36 V or so...

Maybe some kind of diode setup between parallel-connected battery (36V) and cap (up to 48 V) with the diodes preventing current going into the battery, but allowing it to come out if the cap voltage drops below 36V? Hmmm...

That would work too. I was just thinking about getting the battery voltage up so you could have a little higher performance constantly, rather than great performance to start, and then when the battery is able to help, only okay performance.

[yanwin]

Can i ride it for 3 hours?

[JCG]

Can i ride it for 3 hours?

Why, you certainly can. Come on over and take her for a spin.

I have finally got some data! I BIG thank you to Justin for doing a couple of things: 1st, making the new Cycle Analyst code (2.1 beta 4) do serial data output, and 2nd making this new firmware available to us for testing. Another BIG thank you to philf for walking me through the reprogramming of the microchip in the CA and giving instructions on how to pipe the data out of the CA and into a TTL-USB adapter which leads to the computer. More details have been posted by others elsewhere, but here are the data leads soldered into the CA board and going out:



I connected those two wires to two pins in this cable:



Black to ground (black wire) and yellow to data stream (red wire). The data stream comes out and is written into a text file.



I put the laptop on my back and rode out to the running track to get some zero slope data. I took a bunch of things but here is the data of me trying to keep a steady 20 kph without any pedaling. Look closely and you can see when I was facing in to the wind around the oval-shaped track.



I took the cap potential down to 36 V from the original 48 and went 2.24 km at an average speed of 20.6 kph, which took 393 seconds. Average power use was 200 W. Continue using 200 W to drain the capacitor down to 24 V, and it will take you another 453 seconds at the same speed to give you 2.6 additional km, for a total of 4.84 km, or right on three miles.

"How far does it go on a charge?" Now you have it! More work to do now (hills, etc.).

Thanks again to my Canadian friends J & P.

JG

[wanders]

The ride home (in the movies) has some fair downhills, so I expected a net recovery, but right now I don't even know the net elevation change... more work to do!

I am loving this thread. But regarding elevation mapping, you have to spend a few minutes at MapMyRide. It's a fantastic tool for cyclists.

Willie

[Grinhill]

You can also get distance and elevation data quickly from Google Earth.

[fechter]

I put the laptop on my back and rode out to the running track to get some zero slope data. I took a bunch of things but here is the data of me trying to keep a steady 20 kph without any pedaling. Look closely and you can see when I was facing in to the wind around the oval-shaped track.

We need a picture of that setup. Majorly geeky.
Outstanding on the data collection! That cap holds up quite a bit longer than I figured one would. I'm impressed. Now, if you mated it to an induction motor, your top speed wouldn't drop off much as you discharged. I suppose there are other ways to even out the power delivery (buck/boost).

[rgody]

Gentlemen :

I found some docs about ultracap vehicle.
http://www2.ing.puc.cl/power/paperspdf/dixon/tesis/PhDOrtuzar.pdf
http://www2.ing.puc.cl/power/paperspdf/dixon/58a.pdf
Could be usefull

Regards

Rodrigo
www.movielectric.cl

[JCG]

Thanks guys. Good stuff... Willie, that just might be the coolest website I've ever seen. I just mapped the route I've been taking to work every day for the past couple of years (after moving out of Chinatown - no Golden Motor outlets there though ) and it's like I can finally visualize what I've been doing all this time. Thanks!

Fetcher, I would love to learn more about the way an induction motor would do its business relative to what I see with this PM brushless motor. It's easy for me to get all wrapped up in this side-project (which has been a lot more fun than I imagined it would be) but in the end, we're supposed to learn something from this and use it to make an argument for getting the old EV-1 (with its awesome 103 kW AC induction motor) running again. I have bought some books and have been bothering people in the EE department, but we have more controls people than electromechanical types. There's also the question of trying to put a 25 kW genset onboard...!

The DC converter questions (in the large vehicle's case, maybe either boost or buck-boost) and the issues with the controller concern me the most. The Kelly controller I've been using obviously does a nice buck-boost job with the huge swings in voltage that I've put it through (18-48 V) and seems to be able to regen well too. The induction motor is the long-term answer to many larger problems with e-vehicles... no ruining your magnets by going up to the Curie temperature, maybe more efficient regen, etc... I'd like to bounce some ideas off some of the experts around here where it comes to true AC motors being used with a high voltage DC bus. Shoot me a PM if you'd like to hear more.

Rodrigo, thanks for the links. I have been following work similar to Dr. Dixon's and Dr. Ortuzar's for about a year now. I'm a firm believer in the serial hybrid approach vs. other types, which makes it too bad that my bike is a wimpy parallel, through-the-road hybrid I need to do something like E=IR has been doing:

http://www.endless-sphere.com/forums/viewtopic.php?t=6429

[JCG]

Another series of thoughts on AC induction vs. DC brushless in vehicle applications. I did some searching and came across an old thread where they discussed electric lawn mowers... and AC regen.

http://cosmos.phy.tufts.edu/mhonarc/elec-trak/msg00253.html

One item really interested me.

Regeneration: In industry commercial inverters are used to vary AC motor speeds by intentionally changing the frequency supplied to the motor. If you overspeed the motor, the motor is returning the power back to its power supply. When you use an inverter that has a variable frequency capability, you turn the frequency down and your motor is a generator, returning its power to the controller, until your new reduced speed is reached. Or you can have a over running load, like when you drive your AC motor powered tractor down a hill, and your motor is a generator.
Here is the problem in industry: Most AC inverters cannot return the excess power to the power line. There is a diode bridge that takes AC power and charges a capacitor bank. (There are a very few specialized AC inverters that use a bi-directional bridge of transistors to charge the capacitors or return power to the AC line.) With diodes that is strictly a one way trip. The capacitor bank is connected to the motor via a bridge of transistors or gate turn off SCRs. This bridge is bi-directional. So whenever the motor is a generator, the capacitor bank is charged up and potentially overcharged. Some drives turn off to protect the controller. Some drives switch on a resistor to dump the excess energy. Here we are not really regenerative, although the motor does not know any better.
If you were to replace the capacitor bank with batteries, like some electric cars, you now have the ability to absorb a lot of energy from the motor, and you can easily be regenerative over the entire speed range of the motor, whereas to regenerate with a DC motor you need to do tricks with field windings and still may not be regenerative over the entire speed range.

It seems that if the DC bus of an AC motor's controller is accessible, you can connect it to the DC source you like, and can regen without playing the winding switching games that limits you so much with a DC motor. I am working on a way to test this using an ultracap bank by the way. I'll eventually post something somewhere else about it, as it's getting a bit off of this build-specific topic.

[paultrafalgar]

Any news, JCG? Eagerly awaiting developments!

[JCG]

Any news, JCG? Eagerly awaiting developments!

Yeah, Paul... it has been too long. Mid-term and spring break can be a rough time. I have been spending experimental time dealing with a 290 V, 27.5 F capacitor setup (6 modules in series) that is powering an AC motor and have been extracting regen from it by spinning up a cast iron pulley (flywheel) and then slowing it down. As for the bike...

The weather is finally getting close enough to "good" so that I can start trying to build a propulsion model for the bike by taking certain types of data. It mostly comes down to speed and power (or current) vs. time, like what I posted a while back. I have been riding the e-bike back and forth from work quite often lately and it's holding up well. For the propulsion model, I'll need to get a handle on three main things (I think): rolling resistance, wheel inertia, and aerodynamic drag. From that (along with F=ma) I should be able to slap together a model which tells you how the bike will behave given a driving schedule. Regen braking might be estimated as a percentage of recoverable energy while slowing down.

Let me plan the next rounds of data acquisition by solicitation... what would you like to see? I have two base options for the bike to be tested.

1) Ultracap only.
2) Ultracap & DeWalt (A123) 36 V battery pack in parallel.

I've done an endurance run on ultracap only, posted earlier. I think some people wanted to see hill data, start/stop data, maybe all the data from one of my 15 or so minute commutes (round trip, I suppose). You guys let me know what you'd like to see (within reason!) and I'll take the data, post some graphs, and develop the model. Time for me to quit stalling!

[europa81]

Please the combination. I've enjoyed your experiment from the beginning and see a practical use of the Capacitor in efficiently buffering energy from braking to the next boost needed for acceleration. Question is how to combine battery & capacitor. There should also be a provision to feed overflow energy from Capacitor into the battery during a long descent. This is the closest no zero-loss energy-buffering and allows for charging during pedalling times if you feel like it. Great setup and thanks for your continued updates. Made me order a Cycleanalyst, too.

[liveforphysics]

I have been spending experimental time dealing with a 290 V, 27.5 F capacitor setup (6 modules in series) that is powering an AC motor and have been extracting regen from it by spinning up a cast iron pulley (flywheel) and then slowing it down. As for the bike...

Are you working on over-unity with that project? I love that stuff, and I've been a long time magnet motor tinkerer. Any neat photos?

Personally, I think you should buy 2 more packs of A123s, open them, and form them into a 2P13S battery. That would double your range, and enable you to make use of the full potential of the ultra-cap voltage storage.

[JCG]

Please the combination. I've enjoyed your experiment from the beginning and see a practical use of the Capacitor in efficiently buffering energy from braking to the next boost needed for acceleration.

I think you're right, this is probably the best setup for gathering power-speed-current data since it causes me to not be as concerned with the cap's voltage going all over the place. If I can make sure to get good items like cruising power draw, power for different acceleration rates, and I can try to fit a curve of some kind to the data points, so to speak.

[JCG]

Are you working on over-unity with that project? I love that stuff, and I've been a long time magnet motor tinkerer. Any neat photos?

I do indeed have some scary photos. It's a scaled down drivetrain. I'll post something tomorrow if I can get a few minutes in the lab. But, I'll post it in E-vehicles general discussion just so I don't distract too much from the bike here. I need to start a new thread... I have a bunch of questions to ask anyway!

[JCG]

liveforphysics, I've posted some of the photos/video you requested here:

http://www.endless-sphere.com/forums/viewtopic.php?f=7&t=9384

Enjoy...

[JCG]

Ok, I just finished making another strange modification to the ultracap bike. I mentioned in an earlier thread my annoyance at the fact that I was riding around with a through-the-road parallel hybrid arrangement, when all I talk to other people about is series hybrids and how great they must be. So, I converted the bike into a series hybrid.

The real inspiration for doing what I did came from a couple of places; first, fitek did a neat job here which illustrated the idea of non-traction pedaling, and E=IR had a nice thread here using an engine-driven generator. E=IR's thread introduced me to WindBlue Power, where they make permanent magnet alternators. One of their models in particular, the DC 540, is capable of generating an impressive range of unregulated voltages at low rpm. I thought that this would be perfect for a my application, since low rpms are all your legs can do, and I was OK in charging the capacitor with an unregulated DC voltage as long as I kept an eye on the total capacitor voltage. Here we go.

Here's the bike from the right side. Note the lack of a chain heading from the crank back to the rear wheel cassette. The only way to move the bike is with the motor. The 42 tooth crank now sends its chain up to a 13 tooth sprocket.



And here's the left side. The chain on this side heads from a 45 tooth sprocket to the alternator (fitted with an 11 tooth drive sprocket).



Direct connection of the crank sprocket to a small sprocket on the alternator wouldn't give high enough rpm to generate high voltages (and therefore acceptably large charging currents). So, I had to go about the dual reduction with a shaft fitted in a mounted roller bearing. I fixed it to the water bottle holder screw holes and kept it from twisting by bolting it to the lower part of the alternator.



So now, pedaling at 30 rpm should give about 400 rpm at the alternator. Here's a close up of the alternator's drive sprocket.



The back side of the alternator has two output connections from its internal rectifier. Here, I've duct taped the positive one to keep from shocking myself or creating a short to ground through the bike.



There's also a three phase AC output there which I don't use. One neat thing about this arrangement is that it gives me practical freedom from a charger, even if the cap goes all the way dead. In the old series arrangement, I couldn't send regen back into the cap unless the controller had at least 18 V to still be turned on. Today, after some time and a lot of sweat, I brought a dead cap up to 40+ volts by pedaling in place, keeping my balance by holding my hand up against the wall. It was exhausting.



At low capacitor voltages, the current draw from pedaling is around 8 amps and you feel significant resistance, but nothing overwhelming. As the voltage climbs, it's easier to pedal and you're forced to go faster to keep a 2-3 A charging current.

The alternator and gears don't stick out as much as you might think. The way I mounted it, I was able to keep my legs (and pant legs) clear.



I took the bike for a test drive this afternoon and it was a weird experience. It would take a lot of getting used to to pedal a bike without the expectation that it will help you move, and that messed me up a few times at low speeds. I was able to cruise at a moderate speed without observing a capacitor voltage drop, so that would mean that I was able to provide a the required electric power by pedaling the generator. Regen from the hub motor still worked as usual.

Overall, it was interesting, but it was pretty clear that this wasn't the best bike to try a series hybrid arrangement. With a two-wheel bike, if you're stopped at a light, your foot needs to be on the ground - not running the pedals to charge things up. This kind of thing might work best in a trike, I believe. You can just sit in one of those with the brakes clamped and charge things up while waiting somewhere. I'm not in the mood to install training wheels, so I'll go back to the parallel arrangement once I get some more time to work on the bike.