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What is your watthours per mile?

Posted: Aug 06 2013 6:00pm
by swbluto
I'm trying to figure out whether my bike is as efficient like I'm expecting, so I'm doing testing. I'm wondering if my squeaking wheel is affecting efficiency and whether that warrants servicing it?

I was doing some testing on my bike recently, it's a Bike-E recumbent like this.

Image

UNASSISTED:

Normal riding position
Voltage: 24v
avg-speed: 13.5 mph
Rear tire: 40psi Knobby
Wh/mi: 15.5

Normal riding position
Voltage: 48v
avg speed: 12.5 mph
Rear tire: 100psi comet primo low rolling resistance tire
Wh/mi: 11.7 wh/mi

Draw legs close to the body, bring in head. (Curl up into a ball) [To minimize frontal area]
Voltage: 48v
avg speed: 12.5 mph
Rear tire: 100psi comet primo low rolling resistance tire
Wh/mi: 10.5 wh/mi

One time, I was trying to maximize my range because I had no idea how far my bike could go and my derailleur was busted so I couldn't pedal, so I went 10 mph and coasted wherever possible and minimized braking (To conserve energy).
Normal riding position
Voltage: 48v
avg speed: 10 mph
Rear tire: 100psi comet primo low rolling resistance tire
Wh/mi: 9.2 wh/mi

A neat way to figure out your watthours per mile, without relying on a CA to do it for you, is by dividing your power output by your speed.

So, this one time I was going 26 mph and my motor was consuming 450 watts, so my wh/mi at 26 mph was (450/26)=17.3 wh/mi. (I had my 40psi knobbies on at the time)

On my older upright bike like this:

Image

It was consuming 770 watts to sustain 25.5 mph, so my wh/mi. was (770/25.5) = 30wh/mi which is a figure I remembered seeing on my CA.

Re: What is your watthours per mile?

Posted: Aug 06 2013 6:29pm
by davec
that is a clown bike
i will measure my consumption tomorrow
i do about 70km and consume about 20ah
we're talking a cargo bike though- 310lbs with me on it...and going 20-25mph
tire pressure does make a super difference....
i am still working on improving my efficiency- im sure i can upgrage bearings and do a few things

Edit- my voltage is 48V - so about 52v nom -
Edit2- generally on an efficient cycle going @ 20-21mph 13 to 15wh/km is normal
10 is also possible if your rig is really efficient possibly with skinny tires/small weight etc....
mine is probably 20wh/km or close as my rig is heavy and i go fast

not bad looks like im using 15wh per KM
70KM * 15WH/KM / 52 = 20ah
Edit: new record did 140km trip used up 24AH
this is on a 60v battery (added 2 cells my my 16s to make it 18s) and i wasnt going fast this time

Re: What is your watthours per mile?

Posted: Aug 06 2013 6:32pm
by swbluto
davec wrote:that is a clown bike
i will measure my consumption tomorrow
i do about 70km and consume about 20ah
we're talking a cargo bike though- 310lbs with me on it...and going 20-25mph
tire pressure does make a super difference....
A super comfortable, highly efficient and fast clown bike at that! (Also, just about the only recumbent with a suspension for under $500. :roll:)

Essentially, perfect for long-distance trips over 60 miles. Doesn't have the usual burning urethra sensation that follows riding on a lycra's bike for more than 10 miles.

Do you have the voltage? With that info, I could calculate the wh/km.

Re: What is your watthours per mile?

Posted: Aug 06 2013 6:45pm
by Drunkskunk
On my monster bike, running 20lbs in some extra fat knobby tires, I get about 10wh/mile at 10mph, and thats with the aerodynamics of a brick wall wearing a parachute.

My Kona gets sbout the same with it's Clyte. I think my last bike with a 9C got slightly better. 9-point-something at 10mph

If youe wheel is making noise, it's burning watts. 30db measured at 1 meter is 1 watt. And it doubles for every 3db increase. 33db is 2 watts. 36 is 4 watts.

Re: What is your watthours per mile?

Posted: Aug 06 2013 6:46pm
by Farfle
Typically between 90 and 110 wh/mile on the race bike commuting. At laguna seca we were averaging about 280 wh/mi.

Re: What is your watthours per mile?

Posted: Aug 06 2013 7:02pm
by John in CR
Farfle wrote:Typically between 90 and 110 wh/mile on the race bike commuting. At laguna seca we were averaging about 280 wh/mi.
wh/mile like that is some FUN riding.

Re: What is your watthours per mile?

Posted: Aug 06 2013 7:12pm
by Tommy L
On my Catrike 700 with Bionx @36v (41v hoc) Tadpole Trike I'm using 7-9wh per km speeds between 35-40kph.
And I'm pedaling for a workout as well.

Tommy L sends.....Image

Re: What is your watthours per mile?

Posted: Aug 06 2013 7:14pm
by swbluto
Drunkskunk wrote:If youe wheel is making noise, it's burning watts. 30db measured at 1 meter is 1 watt. And it doubles for every 3db increase. 33db is 2 watts. 36 is 4 watts.
Oh interesting. Didn't know one could directly infer power levels from volume, but makes sense.

It seems that wikipedia thinks that 90 dB is .001W. Wiki's Sound power
Chain saw 0.1 W 110 dB
Helicopter 0.01 W 100 dB
Loud speech 0.001 W 90 dB
But it's not necessarily the energy wasted on sound that I'm worried about, it's the energy wasting on the rubbing in the form of heat, the squeak just lets me know something's rubbing.

It seems that the wheel started squeaking after I changed out my 40psi knobby tire for a 110psi comet primo tire and pumped it up to 100-110 psi. So, I'm not sure if the high air pressure is causing the inner tube's rubber to rub against the casing or against the Mr.Tuffy Tire Liner or what, or if some problem with the hub bearings suddenly arose after changing out the tire. (Seems unlikely, but possible, I suppose.)

If it's the inner tube, like I suspect, not entirely sure what I can do about that that doesn't involve deflating the tire... (Deflating the tire would presumably cause me to lose precious watts)

Re: What is your watthours per mile?

Posted: Aug 06 2013 7:29pm
by Tommy L
Switching to a 100 psi front tire passes the bump shock to the wheel bearing harder than with a 40psi tire.
If you can, replace with a high quality ceramic bearing :)
I will help reduce wh too ;)

Tommy L sends......Image

Re: What is your watthours per mile?

Posted: Aug 06 2013 7:50pm
by SamTexas
Farfle wrote:... At laguna seca we were averaging about 280 wh/mi.
What were your average speed?

50mph only requires about 3,500W. At 50% efficiency, that's still only 7,000W or 140Wh/mi.
Using the same calculation, 62mph only requires 12,400W OR 200Wh/mi.

4,000+ lb electric cars consume less than 280Wh/mi on flat at 60mph.

Re: What is your watthours per mile?

Posted: Aug 06 2013 11:27pm
by Farfle
Our fastest lap was 2:09 , and iirc the track is 2.3 miles long. So somewhere around 65mph average speed. We were hitting the rev limiter often, and that happems around 88mph.

Re: What is your watthours per mile?

Posted: Aug 07 2013 1:30am
by Toorbough ULL-Zeveigh
swbluto wrote:just about the only recumbent with a suspension for under $500. )
actually it's more like a heavy-duty glorified thudbuster than any real sort of suspension. :P

is this like the 6th or 7th energy per distance thread?
half of them started by swb it seems.
there's a sticky & everything for this.
why didn't you use it?

i sense moderation in your future.

Re: What is your watthours per mile?

Posted: Aug 07 2013 1:40am
by swbluto
Toorbough ULL-Zeveigh wrote:
swbluto wrote:just about the only recumbent with a suspension for under $500. )
actually it's more like a heavy-duty glorified thudbuster than any real sort of suspension. :P
If it's a glorified thud-buster, thud busters must be really NIIIIICCCE... :mrgreen:
is this like the 6th or 7th energy per distance thread?
half of them started by swb it seems.
there's a sticky & everything for this.
why didn't you use it?

i sense moderation in your future.
Please link to the sticky. I didn't spot it. Even googled and everything, and got anything between flamewars from 2007 and craptastic "wh/mi/lb" threads, but didn't see much in the way of wh/mi.

It's be nice if you linked to my "energy per distance" threads as I have no idea what you're talking about. I like energy efficiency concepts, but started very few to no threads around the "Wh per mile" concept, specifically, AFAIK.

Re: What is your watthours per mile?

Posted: Aug 07 2013 2:05am
by swbluto
Toorbough ULL-Zeveigh wrote:
swbluto wrote:just about the only recumbent with a suspension for under $500. )
actually it's more like a heavy-duty glorified thudbuster than any real sort of suspension. :P
Oh interesting, it appears Cane-Creek made the air-suspension to my recumbent and it also makes the thud-buster. Maybe it IS the exact same technology. (Actually, just checked; it uses elastomers instead of air for cushioning.)

Re: What is your watthours per mile?

Posted: Aug 07 2013 9:57am
by parajared
A 25mph commute drains about 45 wh/mi from my upright off-roader bike. Actual off-roading drains quite a bit more energy.

On my recumbent tadpole I can drain as much as 70 wh/mi when I go on little 3500 watt joy rides and as little as 7wh/mi when I go on energy save runs. A realistic good clip commuting to work puts me in the 25-30 wh/mi range amperage set to 2000watts maxout.

Re: What is your watthours per mile?

Posted: Aug 08 2013 4:00am
by bobc
My commute around 21mph drains a 20Ah 6s Lipo in about 20miles. I make that 23Wh/mile. It's the world's cheapest old mountain bike with the knobblies replaced by "city tyres" (that was worth about 10% more range thankyou very much). goodish roads, no big hills.

Re: What is your watthours per mile?

Posted: Aug 08 2013 7:19am
by dogman dan
Wh/mi will vary wildly with speed, and if you pedal or not at the slower speeds.

My super un aerodynamic longtail can get 12 wh/mi, at about 12 mph. But at 30 mph, 40 is more like it. I aim for about 25 wh/mi as a compromise between speed and efficiency. That's about 20 mph max.

On a slightly more aero commuter bike, I'd get closer to 20 wh/mi at 20 mph.

Dirt riding could easily get as poor as 60 wh/mi. Without going fast too. Just lots of brake, corner, throttle, brake corner throttle. Just like stopping every 50 feet or so would be.

Re: What is your watthours per mile?

Posted: Aug 08 2013 8:30am
by Ykick
33 Wh/mi city commute averaging 17MPH running 26" wheel 9C, 9FET Lyen, 30A, 60V hot off charger.

17MPH is mostly due to frquent stop lights. My average traffic speed is around 20-25MPH.

Re: What is your watthours per mile?

Posted: Aug 08 2013 3:52pm
by swbluto
Now, talking about with assistance, I can go 13 mph no matter how windy it is, with somewhat hilly terrain, and get 3wh/mi. comfortably.

But, it seems silly to compare "with assistance" stats, as how much assistance varies from rider to rider and ride to ride.

Re: What is your watthours per mile?

Posted: Aug 08 2013 8:19pm
by StudEbiker
I have tried to think up a way for everyone to realistically and honestly compare wh/mi numbers. So many variables to try and keep consistent.

The best thing I have come up with is probably most people on this forum (at least in the states & Canada) live somewhat close to a football/soccer field that has a track around it for track events. These are consistent in length, always dead level and are very common. Usually they are open for people that like to walk them for exercise too.
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I think a comparison of like five laps on the outside track at as consistent speed as you can maintain (probably around 15mph because of the turns) would give a nice real world comparison of the figures.

I have a track at the end of my block. If there's any interest in doing something like this I'll put up my numbers.

Re: What is your watthours per mile?

Posted: Aug 08 2013 9:03pm
by swbluto
StudEbiker wrote:I have tried to think up a way for everyone to realistically and honestly compare wh/mi numbers. So many variables to try and keep consistent.

The best thing I have come up with is probably most people on this forum (at least in the states & Canada) live somewhat close to a football/soccer field that has a track around it for track events. These are consistent in length, always dead level and are very common. Usually they are open for people that like to walk them for exercise too.
1.jpeg
I think a comparison of like five laps on the outside track at as consistent speed as you can maintain (probably around 15mph because of the turns) would give a nice real world comparison of the figures.

I have a track at the end of my block. If there's any interest in doing something like this I'll put up my numbers.
I used to have a track like that, but they tore it down for the summer. :cry:

You can't imagine what affect that had on my budding running exercise plans. (And, wh/mi testing)

There's another one around here, but it feels all sorts of weird since it's hidden from view (Recessed below ground level) and there's only one way in and out.

I used, instead, a relatively flat middle school parking lot that has a half-mile loop and no stops. Does the trick. :D

Re: What is your watthours per mile?

Posted: Aug 09 2013 2:25am
by mvly
Normally 35-50Wh/mile on my fast DD mountain ebike

On my hybrid with heavy pedal assist for highest range: 9.8wh/mile otherwise normally @ 35wh/mile

Re: What is your watthours per mile?

Posted: Aug 11 2013 7:25pm
by swbluto
Just did some trip where I was trying to ride at 20mph along those busy 25mph roads and found that it took about 150 watts on average to sustain 20mph with my weak, untrained muscles (My bikes have been too broke this summer to train. :roll:). That implies the wh/mi is (150/20) = 7.5 wh/mi at 20mph with assistance on my recumbent.

With the addition of 100 watts of solar panels on a rear rack, that implies that I could potentially cut my power usage of the batteries from 150 watts to 50 watts, thus tripling my effective range of 133 miles@20mph with 1kwh of batts to around 400 miles. In practice, I'd probably get around 200-300 miles in a day and the battery would never fully deplete.

Re: What is your watthours per mile?

Posted: Aug 11 2013 7:44pm
by mvly
swbluto wrote:Just did some trip where I was trying to ride at 20mph along those busy 25mph roads and found that it took about 150 watts on average to sustain 20mph with my weak, untrained muscles (My bikes have been too broke this summer to train. :roll:). That implies the wh/mi is (150/20) = 7.5 wh/mi at 20mph with assistance on my recumbent.

With the addition of 100 watts of solar panels on a rear rack, that implies that I could potentially cut my power usage of the batteries from 150 watts to 50 watts, thus tripling my effective range of 133 miles@20mph with 1kwh of batts to around 400 miles. In practice, I'd probably get around 200-300 miles in a day and the battery would never fully deplete.
Only one way to tell! Try it out! I suspect you won't get 100W out of the solar panels. I mean there will be clouds. Also carrying solar panels will increase weights and probably kills your aero. Then the hills and wind will cut down your range significantly. Finally keep in mind you only get x number of sunlight. 200/20mph = 10 hours. You will have to take breaks. Overall, I think when you do take the long trip. You find you will get around 150-200 max per day even with heavy assist. Unless you go and charge and go and charge by doing opportunity charging with high power charger.

Re: What is your watthours per mile?

Posted: Aug 11 2013 7:54pm
by swbluto
mvly wrote:
swbluto wrote:Just did some trip where I was trying to ride at 20mph along those busy 25mph roads and found that it took about 150 watts on average to sustain 20mph with my weak, untrained muscles (My bikes have been too broke this summer to train. :roll:). That implies the wh/mi is (150/20) = 7.5 wh/mi at 20mph with assistance on my recumbent.

With the addition of 100 watts of solar panels on a rear rack, that implies that I could potentially cut my power usage of the batteries from 150 watts to 50 watts, thus tripling my effective range of 133 miles@20mph with 1kwh of batts to around 400 miles. In practice, I'd probably get around 200-300 miles in a day and the battery would never fully deplete.
Only one way to tell! Try it out! I suspect you won't get 100W out of the solar panels. I mean there will be clouds. Also carrying solar panels will increase weights and probably kills your aero. Then the hills and wind will cut down your range significantly. Finally keep in mind you only get x number of sunlight. 200/20mph = 10 hours. You will have to take breaks. Overall, I think when you do take the long trip. You find you will get around 150-200 max per day even with heavy assist. Unless you go and charge and go and charge by doing opportunity charging with high power charger.
I'm assuming I'd be using "150 watts worth of solar panels" to get 100w average and for a longdistance trip, I'd probably be willing to sink in the $3/watt for the ultra-lightweight and high efficiency panels on ebay (1.5 pounds per 50 watts, so 150 watts would be 5 pounds). Since you can design it so that the panels lay flat on the back of the bike on a custom rear rack, the affect on aero should be negligible (Since flat panels have a very low drag coefficient and obviously very low frontal area). Would probably become significant at 50+mph, sure, but I wouldn't suspect it'd be significant at 20mph.

I'm assuming one would take such a hypothetical long-distance trip during the summer time when cloud cover is minimal and the days are long. Even in the case of cloud cover, the data shows that power output is usually cut in half, so it's still producing a useful amount of energy -- i.e., might end up merely doubling your range instead of tripling. There's one welcome affect in any case, however - it could negate the need to stop somewhere to charge.

This is all hypothetical, however. There's no place in the United States, AFAIK, I'd be willing to bicycle for 1000s of miles -- highways are too dangerous with people whizzing by at 80 mph. Maybe when they get that eastern coastal interstate bikepath done, there'll be a reason to try it out.