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teddillard
11 January 2011, 0539
So, racerboy watercooler talk aside, most of the people on this forum are interested in builds. At least I am. So, what exactly do we know about Yates' bike?

I know we've talked about the KERS system, I'm not sure if that has run successfully, does anyone know? The motor, I understand from his interview, is a custom design, do we know specifics there? Is it cooled? Controller?

I had guessed it was a dual motor- from that funky chain-drive thing on the open left side- is that just a reduction gearbox? What's that radiator on the front left?

The batteries- I just figured they're LiPo, has that been confirmed? Does anyone know the source? I believe you can see the motor manufacturer logo on the pack but not the battery manufacturer.

Finally, for me anyway, the million dollar question- why the hell is it so damn heavy? Specifically.

Square Wave
11 January 2011, 0659
I don't remember where I saw this, but somewhere I learned that he was using a UQM PowerPhase 145. They are based in Colorado. It's a rather big, heavy, powerful water cooled 3 phase AC motor. The controller is water cooled and rather large and heavy, too. Follow the link for full specs:
http://www.uqm.com/pdfs/PP145%20Spec%20Sheet%207.14.10.pdf

So far he's said that the supplier doesn't want to reaveal who made the batteries. But here's a quote fromthe MCM blurb:
"On our model the charge is held by 102 lithium ion polymer pouch cells"

Gene was working with them maybe he is allowed to share.

harlan
11 January 2011, 0913
Believe me I tried to get the battery info out of them this weekend but they would not disclose. I do know that they are LiPo pouch cells which does narrow it down quite a bit. About a quarter of the batteries are in the "gas tank" area and the rest are on the tail.

It is a single speed, single motor setup. KERS/regen is currently only running on the rear wheel and is activated and adjusted by pulling the lever on the left hand side.

I have a full spec sheet that Chip was handing out after the race. I'll post later.

DaveAK
11 January 2011, 0923
Now this is what I'm interested in. One question I have is that in one of the earlier pictures I saw not only did he seem to have what I believe was a gear reduction, there was also a chain going vertically towards the tank area. What's that all about?

My assumption is that he has a big heavy motor, and that's his biggest problem with regard to battery placement.

harlan
11 January 2011, 0931
The gear going to the tank area was for the front KERS system which was not used for this race.

Skeezmour
11 January 2011, 0933
Not allowed to share battery manufacture at this time. But almost everything else is wide open. That motor is a BLDC. If you go to the swigz site he has a build list for most of what is on the bike.

frodus
11 January 2011, 0939
There's a whole thread on Endless-sphere:
http://endless-sphere.com/forums/viewtopic.php?f=10&t=21080&start=45

The KERS is mechanically linked to the front. It goes up the forks and is combined and transfered to a chain. He said it only does regen, it does not drive the wheel, so there's a one-way bearing in there somewhere. Sounds like they disabled it for the race. Basically, both wheels can drive the motor in regen mode, but only the rear can drive. Its interesting, but I wonder what is gonna happen if he loses traction on that rear wheel for some reason.

Its a single UQM Powephase motor too, one big mother&^%@#$.

DaveAK
11 January 2011, 1042
Well I really can't figure a mechanical front wheel KERS system being worth the effort, but I'm not designing it. I just assumed that it was self contained within the front of the bike.

Nuts & Volts
11 January 2011, 1228
According to plugbike (http://plugbike.com/2011/01/10/are-electric-motorcycles-as-fast-as-gas-bikes-yates-proves-yes/) he is running 30 Ah cells and 102 of them that gives him a 377.4V nominal system at 11.3kWh nominal. at 30ah he may be pushing the batteries to about 10C it looks like.

Motor is as stated, UQM, at 194 HP at 110 lbs. The Controller is UQM at like 30 lbs I think.

Kyle

Frank
11 January 2011, 1230
A front-wheel KERS is very clever because of weight transfer. Assuming that motor can regen as much as it can (almost 200 HP IIRC) virtually all the braking can happen via regen. Rear wheels get very light under heavy braking and it's extraordinarily easy to lock up.

Whether or not the mechanical system is reliable, etc. is another question but I applaud their ingenuity.

DaveAK
11 January 2011, 1245
I don't disagree with the notion of a front wheel KERS - it's the natural place for it, I'm just not convinced in their ingenuity. But like I said, I'm not on the design team, so I don't know the processes they went through to come up with this particular implementation. I've not studied their system either, and going through a couple of designs in my head shows that they all suffer from one drawback or another. Maybe this is the best solution, it's just not obvious to me.

teddillard
11 January 2011, 1326
What is the frame he's using?

lugnut
11 January 2011, 1349
What is the frame he's using?

Suzuki GSX-R750

Nuts & Volts
11 January 2011, 1350
lugnut beat me. On his website http://www.chipyates.com/electric_specs
obviously the batteries have changed

teddillard
11 January 2011, 1401
lugnut beat me. On his website http://www.chipyates.com/electric_specs
obviously the batteries have changed

Crap, how did I miss that? Thanks!

frodus
11 January 2011, 1409
yeah, he forgot to update that, they're not Cylindrical Lifepo4.

Nuts & Volts
11 January 2011, 1620
I have a guess as to what the cells are, but no way of knowing for sure!!

Skeezmour
11 January 2011, 1624
The pack he had under his tank would sure make for a fun dirtbike.....:) 34x3.7x30ah= 3.7 kwh.

DaveAK
11 January 2011, 1634
I have a guess as to what the cells are, but no way of knowing for sure!!
Want to let us in on your guess?

Nuts & Volts
11 January 2011, 1722
Well, Ill say this; my guess is based on the fact that I only know of 1 battery that meets the specs we have seen. Those being LiPo, ~30Ah, min 10C discharge, and relatively lightweight.

I think Chip's cells are the Kokam 31Ah http://www.dowkokam.com/cell-specifications.php It seems you can no longer view the PDF on these cells, but I can check the one I have saved on my home computer. I think the continuous is 5C and max is 15C. Here is a datasheet that may be outdated - http://www.kokam.com/english/product/battery03.html

This is purely my guess based on the knowledge of cells I have.
Kyle

harlan
11 January 2011, 2211
Its a good guess. I don't think there are very many pouch cells to choose from. Kokam, A123, EIG, who am I forgetting?

frodus
12 January 2011, 0109
yeah, but aren't A123 still lifepo4?

Phantom
12 January 2011, 0649
Its a good guess. I don't think there are very many pouch cells to choose from. Kokam, A123, EIG, who am I forgetting?

Would pouch batteries from Leyden make your list? http://www.leydenenergy.com/index.php?page=pouch

Nuts & Volts
12 January 2011, 0758
Yea certainly any pouch is possible. I just only know of 1 pouch cell that is 30Ah in a 1p configuration. ie Kokam

DaveAK
12 January 2011, 0940
Yea certainly any pouch is possible. I just only know of 1 pouch cell that is 30Ah in a 1p configuration. ie Kokam
Does it specifically say they're 1P? Not that I'm doubting it, but it's as easy to say 30Ah to cover the configuration of cells as it is an individual cell.

Nuts & Volts
12 January 2011, 1034
no but i have seen it stated that the bike has 102 cells and 30AH. So 1p is 102 cells*3.7V*30Ah = 11322 Wh or 11.3 Kwh nominal. So it depends if he has 102 cells total or just 102 blocks of cells in parallel. The sources i have seen make it sound like 102 cells

Kyle

frodus
12 January 2011, 1135
I bave no doubt that they're running a very high voltage on this, the controller and motor are over 300V IIRC.....

Skeezmour
12 January 2011, 1214
Right off charge we are sitting at 420v.

Brammofan
12 January 2011, 1426
Skadamo tracked the batteries down. Chip says they're "NASA space batteries...the best you can get." See this post (http://electricmotorcycleforum.com/boards/index.php?topic=1557.0) about 1:30 into the video.

[insert "One small step for man" joke here]

teddillard
12 January 2011, 1438
i can haz nasa space batteriez?

Nuts & Volts
12 January 2011, 1442
Space batteries hmm... that means they weigh nothing right? :)

There are definitely better batteries. The problem is that the best battery is really a relative issue. I think he could have done better, if he has the right manufacturer connections.

Kyle, future battery astronaut!

edit: Ted=brilliant

DaveAK
12 January 2011, 1512
So he went for the lowest bid on the batteries?

Nuts & Volts
12 January 2011, 1529
So he went for the lowest bid on the batteries?

Maybe, because I believe he was going over budget on the bike and he probably had a price limit. But I would say he got the best batteries available to him. I know some manufacturers wont sell certain cells to you unless you are an OEM or something. Or you need to order a bunch to make it worth it to the manufacturer.

teddillard
12 January 2011, 1539
(psst. it was a joke. nasa. lowest bid. get it? hahaa)

DaveAK
12 January 2011, 1543
Ted. You complete me.

(Also a joke!)

dice23
12 January 2011, 1553
he says 194hp @ 8000rpm? the video i saw of this sure sounds like 10,000 plus rpm. the pitch that that motor makes is awesome...nice how he has avoided specifics on most everything. i think he is sandbagging big time! that bike is really fast! i tried to get a deal with uqm 3 years ago..just could'nt afford to meet them half way. would love to see that run a 1/4 mile blast just for the hell of it. the ice guys will all cry foul very soon if he get more top places. hope chip sticks with this project! dice

Nuts & Volts
12 January 2011, 1600
oops. Damn you dave! :) Use some smilies or something, I got my serious hat on!

DaveAK
12 January 2011, 1602
Yeah. My bad. :D

cycleguy
12 January 2011, 2036
For some reason the term "NASA space batteries" doesn't impress me considering CALB
(China aviation lithium battery) and Thundersky's were developed and used in China's space/satellite programs too. I guess we can all say we're using "space batteries".

Brammofan
13 January 2011, 1007
So he went for the lowest bid on the batteries?
As an employee of your federal government, I wanted to let you know,
http://www.alternate-reality.net/wp-content/uploads/2009/10/i-lol-d.jpg

obama6493
24 February 2011, 1008
Believe me I tried to get the battery info out of them this weekend but they would not disclose. I do know that they are LiPo pouch cells which does narrow it down quite a bit. About a quarter of the batteries are in the "gas tank" area and the rest are on the tail.

It is a single speed, single motor setup. KERS/regen is currently only running on the rear wheel and is activated and adjusted by pulling the lever on the left hand side.

I have a full spec sheet that Chip was handing out after the race. I'll post later.

Now this is what I'm interested in. One question I have is that in one of the earlier pictures I saw not only did he seem to have what I believe was a gear reduction, there was also a chain going vertically towards the tank area. What's that all about?

My assumption is that he has a big heavy motor, and that's his biggest problem with regard to battery placement.

teddillard
24 February 2011, 1016
^ yep, smarter and smarter. Now that one is almost as smart as Dave!

(ahh, I remember the good ol' days, when Terry was a moderator, and he'd try to talk to the bots first before vaporizing 'em. )

DaveAK
24 February 2011, 1133
Watchu talkin' 'bout Willis? :mad:

electriKAT
24 February 2011, 1206
Possible spambot in post #41. Ted - have reported the post to a moderator using the little triangle button?

teddillard
24 February 2011, 1230
Possible spambot in post #41. Ted - have reported the post to a moderator using the little triangle button?

there is no moderator. just us inmates. what button? hold on, lemmee ask the bot...

electriKAT
24 February 2011, 1458
What about Mike? Someone has to be running this place. I think Ed also zapped a few spammers for me.

I notated the button in this picture.

869

teddillard
24 February 2011, 1510
Last I knew, Mike dumped the moderator idea, and yes, he's running the place. I usually message him directly, but thanks.

I was, you know, making a lame joke, right?

MikeB
25 February 2011, 0736
One question I have is that in one of the earlier pictures I saw not only did he seem to have what I believe was a gear reduction, there was also a chain going vertically towards the tank area. What's that all about?

Working from memory of the picture, and a discussion at E-S, I think that chain was part of the KERS system, mechanically bringing power back from the front wheel to the main motor where it could be converted back to electricity.

BoneFire
25 February 2011, 2026
Here is a picture of the KERS shown in Chip's new "History Made" poster. http://i51.tinypic.com/142d2yh.jpg

Nuts & Volts
25 February 2011, 2150
^^^ i ccccs no pitcha' ??

lugnut
20 May 2011, 0547
One question I have is that in one of the earlier pictures I saw not only did he seem to have what I believe was a gear reduction, there was also a chain going vertically towards the tank area. What's that all about?

I believe this was the mechanical connection to the KERS system which was on the front wheel. It used a chain up to the tank area and then a shaft to the forks. I'm pretty sure he has removed all this and devoted the tank area to battery.

ZoomSmith
20 May 2011, 0612
Akira12 was a spammer. He's gone now.

DaveAK
20 May 2011, 0836
Still, since this thread has been bumped here's something I've wondered. Why all the chains? Why not replace the whole system with a separate electric motor in some fashion? I'm guessing there's a reason they did it this way, but it looks overly complicated to me.

Nuts & Volts
20 May 2011, 0847
Still, since this thread has been bumped here's something I've wondered. Why all the chains? Why not replace the whole system with a separate electric motor in some fashion? I'm guessing there's a reason they did it this way, but it looks overly complicated to me.

First thing I want to say is that those chains are no longer there and Chip Yates has never run a front wheel KERS on a track.

To answer your question
The separate motor would need to be able to generate about 40-50kW of power and would require a second controller. Since he already has a motor and controller not doing anything during braking that can handle that power it is easier just to add chains. The extra motor would add too much weight that would be doing nothing anytime the motorcycle is not braking.

lugnut
20 May 2011, 0855
Still, since this thread has been bumped here's something I've wondered. Why all the chains? Why not replace the whole system with a separate electric motor in some fashion? I'm guessing there's a reason they did it this way, but it looks overly complicated to me.

To stop (or slow down) the bike in the same time as it takes to accelerate it, takes about the same power (or torque), so a dedicated motor for regen would be about the same size as the primary drive motor. Maybe a bit smaller because it would not be used as long. But to get effective regenerative braking, it would require a quite large motor and controller, so his drive shaft, clutch and chains are considerably less weight, although complex, IMO.

DaveAK
20 May 2011, 0921
To stop (or slow down) the bike in the same time as it takes to accelerate it, takes about the same power (or torque), so a dedicated motor for regen would be about the same size as the primary drive motor. Maybe a bit smaller because it would not be used as long. But to get effective regenerative braking, it would require a quite large motor and controller, so his drive shaft, clutch and chains are considerably less weight, although complex, IMO.
We're not talking about stopping though, we're talking energy recovery. I'm guessing he's going to still be using his brakes. Still, I follow your argument, I was just envisioing a smaller motor for a smaller amount of energy. Do you know how F1 cars implement their KERS?

DaveAK
20 May 2011, 0924
The extra motor would add too much weight that would be doing nothing anytime the motorcycle is not braking.
And what does his current system, (if he were using it), do when he's not braking? :) My thinking is that an electric motor system could replace all of that and not be any heavier. Of course, it's all dependent on the power requirements which could be the reason they did it this way. The other arguments don't necessarily hold water.

frodus
20 May 2011, 0947
one way bearing, the front wheel is only for regen, not for drive....

Nuts & Volts
20 May 2011, 0949
And what does his current system, (if he were using it), do when he's not braking? :) My thinking is that an electric motor system could replace all of that and not be any heavier. Of course, it's all dependent on the power requirements which could be the reason they did it this way. The other arguments don't necessarily hold water.

The front wheel KERS would just be spinning or sitting there, but on a race track you brake a lot so it would be used a lot, but Chip would need over 100HP of KERS braking power if he wanted to use it eliminate some batteries which was his original goal. My guess is all his mechanical KERS (gears, chains, shafts) weigh no more than 20 lbs. A 100HP motor and controller to replace this would weigh at least 50lbs. So yes the power density levels is the issue with making an effective front wheel KERS.

Chip does use a rear wheel KERS, or what we call simple regen, on his bike.

DaveAK
20 May 2011, 0958
My point was that his current system is a weight penalty just like a motor would be when he's not braking. It would be sitting idle just like a motor would be, i.e there's nothing to the argument that Kyle introduced about adding "weight that would be doing nothing anytime the motorcycle is not braking".

I guess it just comes down to the numbers and the goals.

Nuts & Volts
20 May 2011, 1006
My thought is this. If you add a motor for braking and keep your original motor for driving. Then in both instances (braking and driving) you are not utilizing/wasting a power source. Your braking motor could help you drive and your driving motor could help you brake. You also have to add the weight, cost and complexity of another motor controller. So if you want to us an electric motor for driving and braking then it makes more sense to just use one. Now you must use a mechanical linkage that will not be used under driving. When you are braking thou you are not wasting any power sources like in the 2 motor setup. You are also accomplishing this with less weight, less cost, and about the same complexity (IMO).

This is all referring to front rear KERS. rear wheel comes for free with your drivetrain ;)

DaveAK
20 May 2011, 1018
Of course I would use the UQM for regen braking, that's a given and it's free. But what's the difference in replacing something that doesn't drive either wheel with something that doesn't drive either wheel? It's a false argument to say that just because you have an extra motor you're wasting a power source. We're only talking the front KERS system here, not the rear.

My only thought was that an electric motor KERS could be smaller, lighter and less complex than his current system. I wouldn't suggest replacing it with something larger, heavier and more complex, 'cause that would be stoopid. :)

Nuts & Volts
20 May 2011, 1051
My only thought was that an electric motor KERS could be smaller, lighter and less complex than his current system. I wouldn't suggest replacing it with something larger, heavier and more complex, 'cause that would be stoopid. :)

I'm not stupid, you are! Oh. Anyways, your thought here is incorrect. :)
Chips has said that his pack can take 150-200 Amps of regen. His pack is 102 cells, so that is (377.4 V nominal), lets call it 390V nominal on regen to optimistic.
So that is 59-78 kW*80% efficient regen = 47-62 kW (63-84 HP) of recoverable power

I am guessing his front wheel KERS was 25lbs or less.

Comparision
Chips Old Front Wheel KERS
25 lbs
70HP of braking power
$2,000 in engineering and parts

Additional Motor and controller and wiring
(using this motor (http://www.enstroj.si/Electric-products/emrax-motors.html) at 26lbs and 83HP, $4000 and this controller (http://www.tritium.com.au/products/TRI74/index.html) 20lbs, 200HP, $6000)
50lbs
83HP of braking power
$10,000 in parts

Those are the most power dense and available to buy parts I can find.

So I think his system wins with less weight and cost. Does my argument make sense now?




for more info see the last page of this thread (http://endless-sphere.com/forums/viewtopic.php?f=10&t=21080&p=357079&hilit=Yates#p357079)

DaveAK
20 May 2011, 1106
See, now you're using numbers. I like numbers. I'll happily agree that the numbers you show support your argument. But there are just too many assumptions for me to discount the practicalities of a small motor system, not one that produces 150amps of regen or 70hp of braking. Right now he has zero front wheel KERS, for whatever reason that might be. With that in mind any small system would be an improvement, but might not give enough benefit to be worth the cost.

I think hidden in your post might be the answer though - 390V. To generate this kind of voltage would be where my suggestion starts to fall apart.

podolefsky
20 May 2011, 1114
F1 uses two kinds of KERS (http://www.formula1.com/inside_f1/understanding_the_sport/8763.html), mechanical or electrical. Mechanical just spins up a flywheel (e.g., Flybrid (http://www.flybridsystems.com/)) the energy is stored mechanically. Electrical is usually a BLDC motor/generator and batteries.

Reportedly, mechanical can be more efficient because spinning up the flywheel is much more efficient than charging a battery, especially at high current.

Nuts & Volts
20 May 2011, 1122
See, now you're using numbers. I like numbers. I'll happily agree that the numbers you show support your argument. But there are just too many assumptions for me to discount the practicalities of a small motor system, not one that produces 150amps of regen or 70hp of braking. Right now he has zero front wheel KERS, for whatever reason that might be. With that in mind any small system would be an improvement, but might not give enough benefit to be worth the cost.

I think hidden in your post might be the answer though - 390V. To generate this kind of voltage would be where my suggestion starts to fall apart.

I agree I am making assumes and you can discount my argument for that reasong, but i will still back it :)

I believe the weight of added front wheel KERS system will only improve your performance 5% or less. I dont feel like doing any more math but I think a mechanical system has a better yield than an electrical system.


It all has to do with F=m*a where F is wheel torque, If you can increase m without decreasing a then you should do it. Thats my design principle :cool:

podolefsky
20 May 2011, 1149
Just to be picky, torque = F*r, where r is the length of the lever arm (e.g., the wheel radius).

I think an important equation here is KE = 1/2 mv^2. And delta_KE = 1/2 m*(v_final^2 - v_initial^2).

If a 200 kg bike slows from 150 to 100 mph (67 to 45 m/s), it loses 250 kJ. If Chip's bike can soak up 50 kW, then he could recover all of that energy if he slowed from 150-100 mph over 5 sec (250 kJ/5sec = 50kW). If he slows in 1 sec, then he can put 50 kW to the batteries and has to take up the other 200 kW with the mechanical brakes.

podolefsky
20 May 2011, 1204
So just thinking about this some more - the usable regen is, say, 50 kW for however long Chip is braking. In racing, that's probably less than 1 sec at a time before getting back on the throttle. If he slows from 150-100 mph in 1 sec, he captures 50 kJ. Then he speeds up again, which takes 250 kJ. So he can get back about 20% (assuming he actually gets 50 kW back into the batteries).

Compare 20% regen to the weight and size of 20% more batteries.

Nuts & Volts
20 May 2011, 1304
Just to be picky, torque = F*r, where r is the length of the lever arm (e.g., the wheel radius).

I think an important equation here is KE = 1/2 mv^2. And delta_KE = 1/2 m*(v_final^2 - v_initial^2).

If a 200 kg bike slows from 150 to 100 mph (67 to 45 m/s), it loses 250 kJ. If Chip's bike can soak up 50 kW, then he could recover all of that energy if he slowed from 150-100 mph over 5 sec (250 kJ/5sec = 50kW). If he slows in 1 sec, then he can put 50 kW to the batteries and has to take up the other 200 kW with the mechanical brakes.

Haha I was using F=m*a to make it simple for everyone, your equations are more detail than most care to use (I like them thou :)). And as i said "torque at the wheel" is actually the "F" in this case :) Its the force that is making you go


Anyways here is the calculation I did on ES a couple months back- I got 11% max from regen, your 20% is assuming he accelerates the same amount of time that he brakes.
"Chips said that his pack can take 150-200 Amps of regen. His pack is 102 cells, so that is (377.4 V nominal), lets call it 390V nominal on regen to optimistic.
So that is 59-78 kW*80% efficient regen = 47-62 kW (63-84 HP) of recoverable power. His battery pack is 377.4V X 30Ah= 11.3kWh.

Lets say he brakes for 10% (total guess, any better ideas?) of a 15 min race. So from 1.5 minutes lets say he puts 50 kW back in his pack. That is adds 50kW* 1.5min* 1hr/60min = 1.25kWh of energy that would add (2.5/11.3) 11% to his race distance.

1.25kWh does not =130 lbs, it equals 20 lbs 0.11*180lbs(his battery weight)

So wouldnt really mean he would have to cut power by as much as he said.
I only did the calculation because I wanted to see how the numbers worked out.

Am I overestimating things too much anywhere?? Cuz apparantely he thinks he can get more out of the KERS.

Kyle"

podolefsky
20 May 2011, 1314
Whatever makes more sense to you. I like working in energy, since with force or torque you have to convert to energy used anyway.

My calculations don't assume he brakes for the same time he accelerates. I'm just looking at the total energy slowing down and the total energy speeding back up. It's the difference between kW (energy / time, a rate) and kJ (energy, an amount).

If he saves up 50 kJ by braking for 1 sec, then has to add back 250 kJ to get up to speed again, that's a difference of 200 kJ. Doesn't matter if he accelerates over 1 sec or 5 minutes, it's the same amount of energy that has to come out of the batteries (actually more since there are efficiency losses).

11% could be...all depends on the assumptions you want to make. We're both guessing about that.

DaveAK
20 May 2011, 1314
I should add something, just to stir the pot up :), I only brought this subject up because the chains seem to take up some valuable battery space. Overall I think front wheel KERS isn't worth the effort, whatever system you use. Would love to see Chip get it working to the point where he could provide data as to its actual value.

podolefsky
20 May 2011, 1339
Sorry if this was already posted - this explains how the front wheel KERS works (http://startqq.com/ducati/the-energy-harvesting-gadgetry-of-a-ducatibeating-superbike/). It uses a bunch of shafts and crap to turn the main motor. Doesn't appear to take up much room.

http://startqq.com/images/201103/20110325ducati2.jpg

Looks like it is basically a Christini AWD system (http://www.christini.com/index.php) used in reverse. They're about $4500.

Front wheel KERS would be worlds better than rear, since 90% of braking is front wheel (hard braking at least). It's only going to be limited by how much regen current the batteries can take, and the regen efficiency.

lugnut
20 May 2011, 1341
We're not talking about stopping though, we're talking energy recovery. I'm guessing he's going to still be using his brakes. Still, I follow your argument, I was just envisioing a smaller motor for a smaller amount of energy. Do you know how F1 cars implement their KERS?

I believe that F1 has the motor (which is also the generator) or the flywheel (for mech KERS) coupled to the engine crankshaft. They are limited to 60kW of power when they use it as boost, but I have never heard of a limit on power in the braking mode. It is probably the about the same. The actual power level to slow the F1 car during a hard braking event can exceed 2 Megawatts. So obviously, the KERS goes practically unnoticed during "charging" and I wonder if they actually even bother to implement it during braking or just use engine power during periods where they have it available. When you watch an F1 race on TV, the KERS icon is magically refilled at the instant they cross the start/finish line each lap :-)

KERS on a race bike is an interesting application. The weight transfer during hard braking makes strong regen impractical on the rear wheel. And the braking torque applied to the front wheel wouldn't care if it came from regen or friction. I suspect that the propulsion system (motor/controller/battery) which Chip has could regen at the same torque level as it has available for acceleration. It makes sense to use it and not a separate generator. However the mechanical linkage to accomplish this is more trouble than it is worth in my opinion. I am not surprised he dropped the idea and think he will never use it, although I'd like to see him try.

DaveAK
20 May 2011, 1403
Doesn't appear to take up much room.
I disagree. I know from my bike that any chain going forward from the motor is going to cut in to my batteries. It looks like in that picture that the chains are outside of the frame, but take them away and you could widen the frame. Of course my bike isn't a race bike and I'm using large prismatics. I think that while it may not appear like a lot it's still significant on a race bike.


However the mechanical linkage to accomplish this is more trouble than it is worth in my opinion. I am not surprised he dropped the idea and think he will never use it, although I'd like to see him try.
100% agree with this.

I understand Chip's philosophy is go big or go home, and there's nothing wrong with that. All I'm trying to say is that maybe trying to capture all that braking energy is making the problem that much more difficult. If there was sufficient payback in capturing just 10% then maybe a smaller system might be more workable. I'm not trying to suggest that another solution, such as with a small generator, would give the same results. Why bother to go for 10% rather than 100%? Because this is racing and if it gives you a tenth of a second advantage it might just be worth the cost.

teddillard
20 May 2011, 1409
jeesus christ. It's the last day before the End of Times and all you guys wanna yabber about is frikkin KERS.

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/231189_2131977898527_1218396040_32647227_8052339_n .jpg

ima go have a drink. :rolleyes:

DaveAK
20 May 2011, 1419
You go drink Ted. I'm staying sober so that I can get a good start on my post-apocalyptic looting spree.

Or are you just jealous 'cause no one's talking about transmissions any more? ;) What can I say. We're a fickle bunch. :)

DaveAK
20 May 2011, 1431
Better get busy Ted, apparently you've only got until 2AM EST tomorrow!


He told me that the rapture would technically be May 21 at 6 p.m. New Zealand time, which is actually 10 p.m. Friday, Alaska time. He made me promise my column would run by then.

(If it's in the Anchorage Daily News it has to be true.)

Nuts & Volts
20 May 2011, 1503
Noah - Yea energy is more accruate/correct than using forces/power, just involves more brain work and time.
and yes it's all assumptions, but i believe my assumptions are good enough for me to make a design decision on...young and niave I am :)

Ted - youre crazy, but you got some good taste ;)

Lugnut - I agree the best way to do KERS is not with mechanical linkages, now for acceleration I think differently (topic for the threads we already have). I am very dissapointed that he never tested or recieved any data from the KERS before he removed it.

Dave - Yea I think it takes up a lot of room for batteries, but I also think his motor takes up so much room that he cant really fit anything except those KERS parts in there

podolefsky
20 May 2011, 1808
solution to the question of whether to do front or rear wheel regen

http://www.smorgasbord.net/wp-content/photos/uno.jpg

Nuts & Volts
20 May 2011, 1811
solution to the question of whether to do front or rear wheel regen

http://www.smorgasbord.net/wp-content/photos/uno.jpg

I'd **** my pants trying to race on that thing. I would **** my face trying to brake on a racetrack on that

podolefsky
20 May 2011, 1820
I'd **** my pants trying to race on that thing. I would **** my face trying to brake on a racetrack on that

you would what your face?

Nuts & Volts
20 May 2011, 1826
you would what your face?

bahaha I needed something stronger than "s-h-i-t my pants" so I decided s-h-i-t-ing my face sounded right. It's a figure out speak common to idiots like myself :)