DIY Electric Car Forums banner

1000 HP dragbike with Ultracapacitors

15342 Views 35 Replies 8 Participants Last post by  Karter2
i want to split out the discussion from the other thread to focus on the technical details of the dragbike project.

Sifting thru their blog pages seems to be the only way to find little bits of info about the details.

Their goal is to do 1/4 mile in 6 seconds at 200 mph, and they call out 1000HP. The electric power supply will come from ultracapacitors, looks like the Ioxus Titan 60 x 108mm axial cells, 2.7/2.85V-2000F, weighing 390 gms each. The drawing indicates 3px210s, so it's ~600V pack (somebody double check my count on that). 630 cells x 390 gms = 540 lbs per dcb.

No word on the motor, but some about the gearbox:
a single speed reduction gearbox, using two sets of 31:59 gears to give an overall ratio of 3.81:1. This reduces the motor's peak speed from 22,000 rpm down to 5,750 rpm, after which a standard motorcycle chain/sprockets set gives us 2.5:1 reduction to the rear-wheel rpm of 2,300.


See less See more
21 - 36 of 36 Posts
Another tech article on the BYU ultracap EV1..
With the decision made to use ultra capacitors in the race car, design and construction of the storage pack was begun. A preliminary estimate of the energy needs for the race, combined with the maximum voltage rating of the motor and controller, indicated that the car would need a storage pack consisting of 160 capacitors where each capacitor was rated at 2700 farads and 2.5 volts.

The capacitors were connected in series using copper bars for conductors. They were mounted in six sets of twenty-five plus two sets of five. This allowed the use of the original, "T"-shaped battery storage box which came with the EV1.

The capacitor mounting arrangement is illustrated in Figure 1. Students designed the capacitor bank using a solid modeling program and machined the copper bars and ABS plastic structural frames on a computer-controlled milling machine. The completed pack, including the connectors and mounting hardware, weighed 370 lbs compared with 1310 lbs for the original GM lead-acid battery system.
Race weight was 1801 lbs...1/4 mile was 15.94 Using a 400v, 400amp modified EMS controller.
So , max 160kW at the start line , and nothing left at the finish line !
re: ev1
it sounds like about stock 1/4 mile performance after drastic weight reduction and cutting the range from ~100 miles to 1/4 mile...
At 1/4 Mile: 78.9 mph
At 1 Mile: 80.4 mph

a couple more data points (and variants)

They say it is "electronically limited" to 80mph, but I wonder if it is really BEMF limited, which would give you a KV approximation, i.e. the supercap version was still above ~300v at the end of 1/4 mile.

And 2.5v * 160 = 400v, and 2700F * 160 in series = 17F. So fiddling a bit with the simulation I get an average of 37KW (50HP) discharge, ignoring losses. Given that the byu car only gained 8mph in the last 1/8 mile, it was probably current limited by BEMF.

Note, I don't necessarily agree with the BYU conclusion (especially since it is from the lead age, it would have been closer to 100mph with an even lighter 400v lithium pack), though I imagine the PI probably felt like they had to say something encouraging for their capacitor sponsor or something. Also it looks like they just took an inverter and IGBTs ( for a controller.

edit, looking at that manual, 300VDC bus volts is the lowest undervoltage detection setting for the 460v unit, and they mentioned getting undervoltage warnings at the end of the race, so that is probably how it went down.
See less See more
BYU EV1 Drag racer

I did the controller modifications on the EV1 power module for BYU. All the power electronics stayed OEM. It just involved the installation of an Yaskawa G5 control card and other bits. GM removed all the control electronics to disable the car prior to the donation. The resulting DC bus range was 400 to 170V. OEM adverstised power was 100 kW. After the mods I think we exceeded that but don't recall the number.

Hi Major, hokey smokes, you've been at this a while! I recall you mentioning using a regular inverter in a car, but didn't put it together.

So what do you think in 2016? a lot of folks are speculating about future capacitor improvements, meanwhile the NEDRA folks cut hundreds of pounds off a lithium pack and get under 7 seconds.

despite the improved cycle life, do you see supercaps competing in drag racing (without some handicapping system)?

edit: here's a breadcrumb trail of Major's ultracap experience ultracap
found an online version with pictures (sorry if it is pirated...)

you can see they hit the knee 3 seconds into the run (or it is a controller artifact) and its down to nearly 300v already, making ~116kw at the capacitor bank. And they are at 1/8 mile at ~ 10 seconds, where distance/time goes nearly linear (speed goes fairly constant) at about 50kw pack power. Finally down to about 22kw at 1/4 mile. ev1 takes maybe 17kw to hold 77 mph, less if you cut out 1000 lbs.

nice to see some actual data.
See less See more
So i guess we have to see how far off the mark the "Fast Charge" system is.
Sounds like they wont make the 6 sec target, but should we start a book to guess what time they get after say, the 3 rd full timed run ? :)
..I will take 9 secs .
I'm not sure what advantage the caps would really have over modern LiPo's, other than the cool factor that is.
The Caps are no advantage,.
Infact a definite disadvantage, in power , size , and weight.
...That is the big mystery .
That is the big mystery .
Not really, I mean if it looks like a scam and smells like a scam...

There are so many things they have pushed out to the web that are misleading or flat out wrong, and nothing demonstrating ANY scientific rigor, and they hide behind the "kids in STEM" angle.
it should be a fast bike with those capacitors
Why do you say that? - they are heavier with much less energy than batteries
The capacitors can deliver the power, lipos struggle to provide 2000A
The capacitors can deliver the power, lipos struggle to provide 2000A
big difference between power and energy, a race of length > 0 requires energy (power * time), and lipos don't appear to be struggling at making power while having much greater energy density. I'm not sure it matters how much >0, but it looks like in this instance the caps would be much heavier for less power and much less energy.

heavy bad.
The capacitors can deliver the power, lipos struggle to provide 2000A
I can assure you that modern LiPo's have no problem at all delivering current!
The capacitors can deliver the power, lipos struggle to provide 2000A
For power you need amps, and volts
Lipo can deliver the 2000amps
Capacitors cannot maintain the voltage
21 - 36 of 36 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.