# SURVEY: Your watts at various speeds

Some rough numbers. 26" 9c at 66.6v lipo. I am using the ebike calculator for these predictions, and they seem pretty accurate.

Watts at:
10mph - 75w
15mph - 150w
20mph - 280w
25mph - 500w
30mph - 800w
35mph - 1225w
----------------
40mph ~ 1750w
45mph ~ 2450w

The numbers are all estimates from the e-bike calculator. I can almost always hit 35-36mph with a my 20a, 1500w power limit.

I got a graph out of the ebike calculator.

Watts at:
10mph - 75w
15mph - 150w
20mph - 280w
25mph - 500w
30mph - 800w
35mph - 1225w

interesting.
i specialize now (in retirement) with mobility scooters
24 v at 6km/h =6 amps 144 watts
24v at 12 km/h =12 amps 288 watts

total weight approx 150 kg 4 cross ply tires all independent suspension and wind shield
combination of cog belt and chain drive.
so although i cant have 26 inch wheels there would be lot of potential improvement here for this sort of transport
much of scooter design is 100 years behind the times

Crossposted from the DayGlo Avenger MkII build thread:
http://endless-sphere.com/forums/viewtopic.php?p=292010#p292010

There was some slightly gusty breeze that varies in direction, so I rode in all four cardinal directions with the streets around here and get these readings, using the 9C, 36V 13Ah NiMH, and Lyen 6FET. I forgot to look at the Watts reading but was instead looking at Amps, so that's what I've written down below:

5MPH = 3-4A
10MPH = 4-6A
15MPH = 5-7A
20MPH = 11-13A

To get to the desired speed for steady reading, I rode for at least 3 seconds at that speed with no spedometer variation before glancing at the WU readout. Would've been longer, but there is too much traffic this time of day in the neighborhood and the roads are too short in some cases, before coming to stop signs or other speed-altering situations.

Since the voltage for 5-15MPH is around the same, at 38-40V, and at 20MPH is around 33-35V, that puts calculated watts-at-speed at these numbers:

5MPH = 114 -160W
10MPH = 160 -240W
15MPH = 190 - 280W
20MPH = 363 - 455W

Accelerating up to those speeds takes a lot more power; the peak watt reading was 841W, and the peak amps were 24.63. Minimum voltage was 32.44, resting voltage after return was 38.5. Total of 1.544Ah used up.

Total mileage doing these tests was 3.396 miles, and total Wh was 56.3, giving a Wh/mile of 16.58. Surprisingly low given that I was not pedalling at all, and the heavy accelerations I did for extended periods for the 20MPH runs (which were interrrupted multiple times due to heavier traffic out on the faster longer roads).

Less-scientific post this time, but a probably more accurate reading:
http://www.endless-sphere.com/forums/viewtopic.php?p=334613#p334613
CrazyBike2 using a Vpower/CammyCC 48V20Ah pack, running a 12FET Infineon generic with a 9C front 26" wheel. Total bike weight (including battery packs/etc) is probably 185lbs right now plus my own 155lbs.

I failed to remember any data other than 20MPH took 260-290W, consistently throughout a 2.9-3mile trip, with varying directions and very slight slope changes (nearly completely flat for all intents and purposes).

I'll have better and more data at some point soonish, now that I have the large-screen CA to make reading this stuff while riding possible. I may also be able to log the data once I make the cable and rig up an old laptop with serial port in the cargo pod.

Then I can also take the pods off and compare readings, to see if it is much lower without them.

As an aside, it is interesting to note that CrazyBike2 (semi-recumbent) is so much lower than DayGlo Avenger (regular fully-upright riding) for power for the same speed, using the same motor and wheel, even with a slightly higher voltage battery pack (about 4V) and that CB2 is MUCH heavier than DGA, at least twice as heavy right now.

Hunh. When I tested same conditions but using the NiMH (~4v less total pack voltage), I got 360-390W for 20Mph. :?

Why *more* power needed for less voltge at same speed? More current, sure, same power total expected.... kless, actually, since the heavy vpower pack was not on the bike .

44km/h = 820w input upright on the bike this is 18.6 wh/km
70km/h = 2400w input crouching on the bike this is 34.3 wh/km

Hi everyone,
I found these results useful but I thought it would be nice if they were collated better. I've made up a survey thing that will collate and graph all the results automatically. Anyone fancy entering their data into it here?

20mph = 250watts
25mph = 450watts
28mph = 650watts

I don't have the typical ebike.

GIANT DH motocross style ( NOT EFFICIENT. BUT BRUTE !! )

0km/h 60W (DC-Dc, controlle and LED)
32km/h 550W
75km/h 4300W
100km/h 8000W
113km/h 11500W
140kmh/h ??

at up to 75kmh it's with my 20 x 3.00 moto tire and 5305

at above 75km/h it's with my 24 x 2.5 maxxis wookworm and 5303

KMX e-trike

5304 on 20'

0km/h 30W (DC-Dc, controlelr and LED)
32km/h 450W
75-80km/h 2800W

Doc

I didn't mean put the data in this thread - I meant HERE

Watts at:
10mph - ~150
15mph - ~250
20mph - ~300
25mph - ~400
30mph - ~ 850
35mph - 1.5k
40mph - 3.6k
45mph - 4.5k
50mph - 6k
>50mph - @ 70mph, 11.2kw (120A @ 94V)

I did some riding with the watt meter on some dead flat stretches. There was a strong sustained wind, so I averaged the two below:

22mph with tailwind 350watts
so, that would give about 460watts at 22mph. With no wind, it should actually be less, like 400watts I'd say. Introducing wind with make things slower overall.

Not very scientific, but the best I could do without uploading data into a graph or excel.

BTW, my no load wattage at 38mph is 145watts. (52v on Mac 8 turn). I think this is kind of high, but not sure.

Farfle said:
Watts at:
10mph - ~150
15mph - ~250
20mph - ~300
25mph - ~400
30mph - ~ 850
35mph - 1.5k
40mph - 3.6k
45mph - 4.5k
50mph - 6k
>50mph - @ 70mph, 11.2kw (120A @ 94V)

If you were to chart these numbers, I think you'd see they don't look right. How do you get a 2.1kw jump from 35 to 40, but only a .9kw jump from 40 to 45? I guess it's possible if a setup has a weird torque band.

I may have my data a bit messed up, it was taken on the fly. Ill try it again with the new motor. hopefully should get some more accurate numbers up to the 90 mph mark

Tested tonight with light wind on the same flat stretch as before, but on my 2806 9c. Averaged 480watts at 25mph, no funky aero tuck or anything. The 9c should be more efficient at this speed than my macs. I seem to average slightly less wh/mile overall.

25mph - 480watts - standard 9c wheel, 48v battery 4110 fet controller
20mph is 300ish, but I didn't do a real test of it.

31mph
20in rims and tires inflated to 58psi
15ah @ 36v LiFepo4
Currie 36v 750w motor
36v 30a 1000w controler
15t front sprocket 90t rear
Total weight with rider 362 Lbs

It’s not what you know, or don’t know. It’s what you know that isn’t so that can hurt you
Roy Rodgers – circa ( 1939 )

I get 67wh per mile @ 44.6 mph @ 2100 watts

veloman said:
20mph = 250watts
25mph = 450watts
28mph = 650watts

I don't have the typical ebike.

I did more testing with my new low/stretched out seat position. This time at 28mph, I averaged 570watts. Same road. I tested both with a tail box and without and saw no difference. Tailbox is coming off as it adds 3-4lbs.

It seems the only thing that really drops consumption is reducing frontal area. When it gets cooler I will experiment with front fairings.

Unassisted, on an efficiency optimized recumbent. (Low rolling resistance tires@100psi, 9c wheel, making sure everything is streamlined - i.e., battery pack goes right behind the seat)

@24 volts
10 mph = 70 watts
15 mph = 120 watts

@48 volts
25mph = 420 watts

With pedaling, I use about 65ish watts on average and about 5wh/mi (It's just a gentle pedal). That allows for my 500wh pack to be usable upto 100 miles or so.

veloman said:
veloman said:
20mph = 250watts
25mph = 450watts
28mph = 650watts

I don't have the typical ebike.

I did more testing with my new low/stretched out seat position. This time at 28mph, I averaged 570watts. Same road. I tested both with a tail box and without and saw no difference. Tailbox is coming off as it adds 3-4lbs.

It seems the only thing that really drops consumption is reducing frontal area. When it gets cooler I will experiment with front fairings.

I've always been dubious about front fairings because whatever improvement in Cd would seem to be offset by increases in the frontal area. I've also noticed that none of the HPV finals guys have front fairings; only tailboxes, and typically with the guy in an extremely reclined seat.

Also, you can just imagine the air bouncing of the windshield and some of it going back in to hit the rider (air molecules bounce around, some getting "sucked" into low pressure areas right behind the windshield), increasing the total air resistance. That is, possibly increasing Cd.

What would probably help is a kamm-shaped tailbox, though it might be marginally helpful on a regular recumbent.

It could be just that my tailbox was too short at about 22" long. I won't bother making it longer as it will be way too obtrusive for practicality.

I did find that lowering and pushing my seat back helped noticeably. It really did reduce frontal area and made a difference.

hydro-one said:
Come on guys, can we get with the TWENTIETH CENTURY HERE !!!! A LITTLE SI UNITS PLEASE!!!! WTF IS A MPH?????

Can I get my power units in electronvolts/microsecond?

I tested one of my Speed pedelecs on a flat road during summer, wearing a T-Shirt.

Made the test in both directions at varoius own power Input at mostly constant speed.

Flat handlebar and upright position.

If you look at the graph you can see total watt needed on the wheel in relation to speed. This is a calculation made in reality and compared to theory. (for the graph another Kreuzotter2 calculation was used with a racing bike which matched much better than the Kreuzotter estimation from the table)
Weight of the bike is 19-20kg, weight of rider incl. clothes is around 80kg, size of the rider 1,82m.
Tires are Schwalbe Marathon Deluxe 40-622 at rather low 3.5 bar to 4 bar for comfort (picture shows a different 32-622 Marathon Durano-E tire)
Motor is a BionX D. Measurement of V and A at 0,25s intervalls between BionX battery and motor

Own power input is an estimation. Very easy pedaling should be something like 70W and normal pedaling around 150W.
Efficiency of the electric drive system was estimated at 80%. (i.e. 300W measured electric consumption = 240W mechanical power output at the rear wheel)

In reality I need around 10Wh/km for driving at 40km/h. Clothing has a significant impact on air resistance and consumption as has the own human power input.

My goal is to build efficient electric bikes to go longer distances on smaller batteries and becaue as an engineer I think efficiency is technically much more elegant than just power.

Reason for the test was to have a reference for further tests with aero handlebar, bike packing vs. pannier and a (solar)-Trailer.

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30kph - 88W ~3Wh/km, 4.8Wh/mi
35kph - 201W ~5.8Wh/km, 9.3Wh/mi
40kph - 341W ~8.5Wh/km, 13.7Wh/mi
45kph - 500W ~11.1Wh/km, ~17.9Wh/mi
50kph - 740W ~14.8Wh/km, ~23.8Wh/mi
53kph - 880W ~16.6Wh/km, ~26.8Wh/mi

rider: 160cm, 62kg, power output ~130W
platform: Juiced CCX, M size
mods: -30° 130mm stem, 38cm wide drop bars, Schwalbe G-One Speed 40-622 front @ 3.5bar, 50-622 rear @ 4bar

these numbers were with an Ortlieb rear bag on, whereas i had measured CdA and Crr at about 0.37 and 0.007 using the RChung method without it on a few months ago