EV Power vs Speed

[John in CR]

I'm really interested in aero moding either a scooter or full suspension bike to bring those high watt draws down considerably. I just hate how there is such a big penalty for going a quick safe speed (keeping up with traffic).

You and me both. In the not too distant future I want to be commuting 50 miles to the beach several days a week. All aero gains I can make will pay significant dividends. My favorite thing on the table is a tailbox with lots of solar cells, because cargo space and the potential for recharging without plugging in has great appeal. I take that back, it's extremely appealing to me.

I'll also address the little stuff like minimizing handlebar width and eliminating exposed cabling to the extent possible. I even carved some pieces of balsa to epoxy to the back of my front suspension forks, so instead of round the taper at the back will give them a much more efficient air foil shape. Every little bit helps, though I doubt I'll ever give up my cotton t-shirts in favor of some plastic on my skin.

John

[FMB42]

Oatnet writes:

Welcome to E:S FMB42, Boy are you visiting the wrong site if you are preaching street-legal speeds!

Ya, I guess I sounded a little on the preachy side...sorry about that...

The truth is that I used to be one of the "there is no such thing as going too fast" crowd for many of my 19 or so motorcycle riding years (plus another 5-6 mountain biking years). However, at age 50+, I've become less addicted to speed and more into less "demanding" riding styles due to the fact that my eyes/depth perception, reaction times, and balance are nothing like they were 30 years ago.

I'm just trying to suggest that doing 45+ on a bicycle based machine can require both advanced riding skills and a properly setup bike. I say this because I've owned and ridden some pretty fast (in their day) motorcycles (both on and off road) of which most had adequate or better brakes, tires, suspension, and frames (i.e. good or better handling). However, I've also ridden and/or owned a few motorcycles that had absolutely terrible handling traits ( '74 Kawasaki 500 two stroke (spit you off) triple, '82 Yamaha (rubber framed) 650 twin, etc).

Anyway, I trust what you're saying. I'm also convinced that both you, and now Vanquizor, have the skills required to operate and setup the higher speed machines that you ride.

[mylittlepony]

Hi,
I was wondering what sort of power people were pulling at various speeds. I found this topic but I found the results a bit hard to digest. I figured Google Forms would enable me to gather really cool data for the benefit of everyone. All data gathered is public, click here for the spreadsheet(s).

Click this link to complete the Power vs Speed Survey. You'll need technical data about your bike and some Wattage figures at various speeds in either MPH or KPH.

The dynamic chart below shows the results so far. Be sure to return to this page after you take the survey to see your data added to the plot.







I've entered my own data to get the ball rolling. I'll try to do more with the data when time premits.

Here's a link to the Summary Page. I'm looking forward to some interesting results.

[mylittlepony]

Hey congrats to dennyt for making the 1st entry. Cheers mate

[veloman]

OKay, I filled it out. Nice survey, very easily.

[oatnet]

I was wondering what sort of power people were pulling at various speeds.

This topic has been beaten to death in a billion threads, so you will get a larger pool of data with the SEARCH button.

Because of the wide range of variables - drag/weight/body position/speed/wind/hills/leadfoot/accuracy of the measuring device/temperature/amount of pedalling etc/etc/etc, not to mention the wide range of efficiencies - the data can't be normalized for comparison. There is a calculator that will let you model many of these variables to satisfy your curiousity.

[mylittlepony]

Thanks Oaty - now leave us alone please.

Hey Veloman, thanks for the data. You were right in the streamlining thread, you are super efficient. Cheers! I'm going to create efficiency plots next, I'm sure you'll be near the top. Oh, yeah and this will really annoy Oaty but you're currently placing 3rd in THE FASTEST, MOST POWERFUL EBIKE LEADERBOARD too! It all comes from the same data you see.

[Kingfish]

I actually don’t know precisely what the wattage was for my trip because I didn’t set the RShunt value; there wasn’t a practical way to make the measurement with the tools at my disposal. However, I did set the battery and phase amps in the controller and one can conclude that at WOT what these values ought to be. The stats remitted represent my cross-country configuration wherein I was pulling a trailer and carrying 100 lbs. of LiPo.

Seen from the graph (if read correctly) it appears I was the least-efficient leader of Wh/mile: Such is Life; now onward to improve.

Thanks for the fun! KF

[mylittlepony]

KF: Haha! Yes you are 'least efficient' but that's because you were only able to enter a single power vs speed figure at WOT so your lowest figure = your highest figure = your worst figure. If you could come up with a power figure at say 15mph I'm sure you're standing would be much improved. Please feel free to add your data again if you can get that lower speed wattage - I can just delete your earlier entry for you.

I'm blown away by Voltron's efficiency given its #1 by a long way for power and speed.

[SamTexas]

I just entered the data for my 2 bikes. Good survey.
Suggestions: To make better sense of the survey results, more detailed info are needed: Weight (rider & bike), terrain (flat, hilly and how hilly), route (city or country), tires (slim or fat, smooth or knobby). On the power vs speed, let the user both speed and watts, not just watts. I happens to have data at 22mph, so I had to extrapolate to arrive at power at 20mph. Need to specify whether the power used is pedal assisted or not.

[Kingfish]

Min & Max range for me needs to be reset:
Min likely is 125 miles in all conditions, and max is unknown cos I never found out - but we can use the 165 miles that I did in one day without recharging

Cheers, KF

[mylittlepony]

Hi KF. I've read your California thread and you're right. The figures don't reflect the range we all know you can achieve with your MONSTER battery pack. Range is calculated from the Wattage and Speed figures you supplied. As you say you struggle to make the measurements but I think we can come up with something.

So far you've entered a figure for WOT and it should be fairly accurate - you've got 3024W(48A) to do 40mph. So if you drain your 130Ah battery at 48A it'll take 2.7hrs. In that time you'd cover 108.3miles. Which I have to say if very impressive mate. So this would be your minimum range figure.

You say to use 165miles as your max, what kind of average speed do you want me to use? That would equate to 49.6W.hr/mi which is quite high consumption e.g my bike has a similar figure doing 42mph at WOT. Hmm so I guess that means that your pack must have still have quite a bit of charge left in it after your 165mile ride! Lets say you pootled along at 20mph, you'd hopefully get a figure of maybe 20Whr/mi which would equate to an insane range of maybe 400miles Which is absolutely nuts!

If you can't measure Watts is there any chance you could hook up a small pack and ride around the block at 20mph until you hit LVC? Just to get a nice figure for the range you get on say 5Ah at a moderate speed. With that info we can put you where you rightly belong - at the top with about 350miles more range than anyone else

[Kingfish]

Hi KF. I've read your California thread and you're right. The figures don't reflect the range we all know you can achieve with your MONSTER battery pack. Range is calculated from the Wattage and Speed figures you supplied. As you say you struggle to make the measurements but I think we can come up with something.

So far you've entered a figure for WOT and it should be fairly accurate - you've got 3024W(48A) to do 40mph. So if you drain your 130Ah battery at 48A it'll take 2.7hrs. In that time you'd cover 108.3miles. Which I have to say if very impressive mate. So this would be your minimum range figure.

You say to use 165miles as your max, what kind of average speed do you want me to use? That would equate to 49.6W.hr/mi which is quite high consumption e.g my bike has a similar figure doing 42mph at WOT. Hmm so I guess that means that your pack must have still have quite a bit of charge left in it after your 165mile ride! Lets say you pootled along at 20mph, you'd hopefully get a figure of maybe 20Whr/mi which would equate to an insane range of maybe 400miles Which is absolutely nuts!

If you can't measure Watts is there any chance you could hook up a small pack and ride around the block at 20mph until you hit LVC? Just to get a nice figure for the range you get on say 5Ah at a moderate speed. With that info we can put you where you rightly belong - at the top with about 350miles more range than anyone else

3024W(48A) to do 40mph: Actually that was the wattage at 42 mph

The pack was designed for 225 miles on level ground with no wind - but of course I never saw level ground for any length of time, and I was making my own wind. The farthest I went in a single day was 186.6 miles and climbed 11,000 feet (and yes - I picked up 1 volt charging while I ate breakfast) - but that at least is an indication what the pack could do. The fact is - I never did let that pack get to 53V. However - I would accept 165 miles because that is a real value and anything else would be perhaps unfair speculation.

My average speed (from the trivia section) was about 26.2 mph for the entire trip.

Best, KF

[mylittlepony]

I've put down 1200W @ 25mph which works out at 170miles range. I still think you could do more. You're efficiency isn't great at 48Whr/mi. I don't know if its your 2WD setup, weight or just the mountains! Lets say you could get your efficiency up you'd be able to carry less battery. Less battery = less weight = even higher efficiency. Especially on those long climbs. Lets say you could manage to improve it to 900W @ 25mph like Ebike4life and Drunkskunk. Then you'd be doing 36Whr/mi or 228mi on a pack which is actually about the range you say you were originally shooting for. Put another way you could reduce your pack size by 75% to 6120Whr and still do 170miles on a single charge. I'm looking forward to your next adventure!!!

[AussieJester]

Please remove my information it is not even close to accurate anymore as I have changed my gear ratio....if I remember I will input new data...Thankyou.

KiM

[jonescg]

Haha yeah, my data is definitely wrong. I would imagine at 50-60 km/h I could get a range of about 100 km (60 miles). And possible less than 30 km at WOT. Trouble is, I don't have my bike with me to make these calculations / observations. And if I did try, I'd probably get picked up by the local constabulary for riding an unlicensed bike

[AussieJester]

I gather your bike is being kept in the eastern states now CHRiS? Making you a fly-in-flyout rider hehe..must be a large savings for you not having to ship it for each race from West to eastcoast.. You will fly it home after the last ttxgp race I imagine?....


I forgot to mention with the gear change I also upped the power, another ~ 2000Watts on tap need to take it for another run today and download the hv160 datalogging to confirm the exact increase, still has more but for reliability I shall likely leave it as is
Now, its already 20km/he over the local speed limits, and I don't want to be the first e-biker to have his bike confiscated/crushed for hooning (law here in WA)

KiM

[jonescg]

Yeah KiM, I keep it at SplinterOz's place in-between and fly over just before the race. I hope to have it back here soon after the last race though. I want to show it off to all my friends! It's actually more expensive to ship it from Sydney to Canberra (300 km) than it was to ship it from Perth to Sydney (4500 km)!

And even if you let someone else take it for a spin, it would get crushed into a cube and you would have to wear the consequences! Fuggin unbelievable! Since when did the innocent get punished for someone else's stupidity? The Libs have no intention of repealing such stupid laws either.

[amberwolf]

You're efficiency isn't great at 48Whr/mi. I don't know if its your 2WD setup, weight or just the mountains!

That's the problem with any kind of efficiency comparison--it's nearly impossible to make one unless all the vehicles are run on the same course at the same time under the same conditions, as there are so many variables that affect this. A little for this variable, a little for that, a lot for another here, even more for yet another, some cancel out, some add, and it just becomes a mess trying to figure out which comparisons are meaningful.

[mylittlepony]

Please remove my information it is not even close to accurate anymore as I have changed my gear ratio....if I remember I will input new data...Thankyou.

Done. Would love to see your new figures.

Suggestions: To make better sense of the survey results, more detailed info are needed: Weight (rider & bike), terrain (flat, hilly and how hilly), route (city or country), tires (slim or fat, smooth or knobby). On the power vs speed, let the user both speed and watts, not just watts. I happens to have data at 22mph, so I had to extrapolate to arrive at power at 20mph. Need to specify whether the power used is pedal assisted or not.

the problem with any kind of efficiency comparison--it's nearly impossible to make one unless all the vehicles are run on the same course at the same time under the same conditions, as there are so many variables that affect this.

You're both right. I was limited to the way I could build the survey. Being limited to only a few speed selections is not ideal but I was limited by the tools and my skills. Just allowing MPH and KPH figures was tricky I didn't want to make the survey too long to complete by asking for every minute detail. I'll bet atmospheric pressure plays quite a big part in air resistance and would be just as valid as tyres or even tyre pressure but asking for atmospheric data would likely have drawn a blank. So really what I'm saying is that yeah there are loads of variables, so many we might as well just think of them as white noise. As we get more data we can already see that there is a middle ground developing where most bikes lie, and only a few bikes on the extremes. Some bikes will be extreme in performance (like KF and Doctobass), others will be extreme due to poor setup. It allows people to see which they are and maybe help them find ways to improve. Already it has been useful for me when looking at my own bike's performance.

To be honest I'm more interested in the larger trends such as:

How big are people's batteries?
How fast can people go?
Can we see if higher pack voltage results in better efficiency?
Are DD Hubs more efficient than RC?

[NeilP]

In tthe goolge doc survey, can we come back edit and add data as we get new figures or is it a one off entry ?

[mylittlepony]

Hi Neil,
I could share the spreadsheet with you if you want to edit your entry. Alternatively I could delete your old entry for you and you could just resubmit the new data. PM me with your gmail username if you want me to share it.
atb,
Dave

[Kurt]

Looking over some of the numbers posted on the forum I am shocked at the Power required to hold a a set high speed on a e bike. Looking at some data from full size 4000lb but efficient EV you only need 15kw to hold 100kmh - 60mph.

Most e bikes particularly hub motor driven that can do 80 - 100kmh have 80 - 100A or more of controller and 100v or more of battery. So if a car can hold 60mph on 15kw why are we pumping 10kw into our bikes to come close to the same thing. The only thing I can think of is we are pumping 10kw and receive 5kw or less at the wheel ?

Or the question is to the people with very fast ebikes whats the controller doing at full speed say speed over 80kmh are you seeing the full 100A or so due to wind drag or less?

I guess I started this thread as a spot for people to post level ground speed and watts consumed at that speed. Particularly speeds over 40mph. I know this is the e bike section but even some with e- motorbike or scooter data would be good to.

Kurt

[amberwolf]

THere is already a thread "Post your watts at speed" or similar, with such data, if you want to contribute to it.

EDIT: it's this one:
http://endless-sphere.com/forums/viewto ... =5&t=14786

And another thread doing the same thing:
http://endless-sphere.com/forums/viewto ... =5&t=32295

[Kurt]

Thanks for that after a quick read It was interesting that Docs 75kmh took 4300w on his MTB and only 2800W to do the same speed on his recumbent trike. That's a HUGE differences just from the wind drag advantage of a trike.

I noticed it took 8000w for him to do 100kmh. It seams like a lot. i take it thats at the battery and not at the wheel.

Kurt