Comparisons? WattHrs/mi/lb. @ speed

[TylerDurden]

With so many different setups, I'm wondering how to get a reasonable idea of performance/efficiency comparisons.

It takes my setup 12ah@24V =288Wh to travel 10mi @ 10 mph. Total weight of bike, rider & cargo = 250lbs.

28.8/250 = .115 Wh/mi/lb. @10 mph


Anybody?

[patrick_mahoney]

Tyler, what is your setup again?

I should be able to collect this data with my GPS and my Hyperion e-meter. I'll see what I can come up with.

[Lowell]

With so many different setups, I'm wondering how to get a reasonable idea of performance/efficiency comparisons.

It takes my setup 12ah@24V =288Wh to travel 10mi @ 10 mph. Total weight of bike, rider & cargo = 250lbs.

28.8/250 = .115 Wh/mi/lb. @10 mph


Anybody?

35Wh/km and 280-290lbs total weight. Average speed 35mph, top speed 55mph downhill.

[TylerDurden]

My bike is a stock currie/mongoose cx 450: http://endless-sphere.com/forums/viewtopic.php?t=122

Unite 24V, 250W motor

12Ah 24V (4 Ridgid emoli drill packs)

Bike & batts: 70lbs, rider: 160, cargo: 20lbs

Estimated speed 10-12 mph

[xyster]

It takes my setup 12ah@24V =288Wh to travel 10mi @ 10 mph. Total weight of bike, rider & cargo = 250lbs.

28.8/250 = .115 Wh/mi/lb. @10 mph

My setup, 33ah@80V and 270 lbs with me on it draws 5 amps to sustain 20 mph on level ground no pedaling, and 10 amps to maintain 26mph. It's pretty hard to tell on my analog ammeter how much it takes to sustain 10 mph -- looks like 1 amp. So I'll calculate it at 20 mph instead.

5 amphours (@ 20mph) X 80 volts = 400WH to travel 20 miles at 20mph.

20WH per mile / 270lbs = 0.74 WH/mi/lb @20mph.

Stopping at 80% DoD, the pack is about 2kw-hr, so it can go 20mph for five hours or 100 miles.

[TylerDurden]

20WH per mile / 270lbs = 0.74 WH/mi/lb @20mph.

As I recall from an earlier chart, you peaked greater efficiency (14Wh) at 10mph.

.05 WH/mi/lb. !

Kinda funny tho, motor efficiency drops but overall efficiency rises...

[xyster]

20WH per mile / 270lbs = 0.74 WH/mi/lb @20mph.

As I recall from an earlier chart, you peaked greater efficiency (14Wh) at 10mph.

.05 WH/mi/lb. !

Kinda funny tho, motor efficiency drops but overall efficiency rises...

You recall correctly, TD. I missed a decimal place on the quoted calculation. It should be 0.074WH/mi/lb @ 20mph and so 0.05 WH/mi/lb at 10mph. Here's that chart to which you refer, derived from real-world observations of my ammeter/speedometer, showing that at speeds above ~10mph, wind resistance considerations easily trump motor efficiency considerations. I recorded drawing 1 amp to go 5 mph, but the precision of that observation is lousy because it's so hard to maintain that slow of a speed!

[EbikeMaui]

20WH per mile / 270lbs = 0.74 WH/mi/lb @20mph.

As I recall from an earlier chart, you peaked greater efficiency (14Wh) at 10mph.

.05 WH/mi/lb. !

Kinda funny tho, motor efficiency drops but overall efficiency rises...

You recall correctly, TD. I missed a decimal place on the quoted calculation. It should be 0.074WH/mi/lb @ 20mph and so 0.05 WH/mi/lb at 10mph. Here's that chart to which you refer, derived from real-world observations of my ammeter/speedometer, showing that at speeds above ~10mph, wind resistance considerations easily trump motor efficiency considerations. I recorded drawing 1 amp to go 5 mph, but the precision of that observation is lousy because it's so hard to maintain that slow of a speed!

At 37 wa per mile to maintain 30 mph you are in a FANTISY ZONE. Try it on a round trip a few hundred times with NO pedaling and give us a REAL average for a update!

[TylerDurden]

At 37 wa per mile to maintain 30 mph you are in a FANTISY ZONE. Try it on a round trip a few hundred times with NO pedaling and give us a REAL average for a update!

What figures have you got Randy?

[EbikeMaui]

20WH per mile / 270lbs = 0.74 WH/mi/lb @20mph.

As I recall from an earlier chart, you peaked greater efficiency (14Wh) at 10mph.

.05 WH/mi/lb. !

Kinda funny tho, motor efficiency drops but overall efficiency rises...

When you do a average speed test try to just compute your fugures over a round trip WITHOUT pedaling for 20 miles.you may hit any top speed you like and just try to get a AVERAGE ROUND TRIP SPEED off your cylometer and ah meter for the complete distance.

[TylerDurden]

What figures have you got Randy?

[EbikeMaui]

What figures have you got Randy?

I quit posting them because everyone tries to 0ne up me on there figures. But my WORST figures are on the Volcano trip with a elevation climb of 10,005 feet.Up The Volcano using four 12 volt, 20 lb batteries rated at 33ah @48 volts I climbed the Volcano in 36 miles at the average speed of 12 mph in 3 hours.The Trip back down I can average 32 mph coasting for 36 miles using ZERO power= total power used on the 72 mile trip. = 1584 watts to DOA.or DOD lol
This standard I set was four years ago.Since then everyone Thinks they can beat it.
All of these Videos (except for the CycleToTheSun video) on my Huffy ebike are carrying 14 lbs of batteries that usually cut off after 7 ah of use.My normal routes are from 15 to 20 miles on round trips the way I rode in these videos.If you have bothered to watch any I tell the milage and amp hours used at many points of the trips.One trip only using ONE 7 lb battery @ 36 volts just made for a slow 20 mph trip in 20 miles using 6 ah.The faster 72 volt runs for 20 miles was much more fun to have more power and speed but used more watt hours at the same 6 ah figure but using 72 volts.
http://tinyurl.com/y9hh8s

[CGameProgrammer]

I wouldn't factor in the weight of the system because it does not affect things linearly. When I turn my bike upside-down and run the motor (where the weight of the system is just the 23 lbs of the wheel), it reaches 54 mph. When I ride in the actual street, with 260 lbs, air resistance, and tire resistance, the max speed is 34 mph. I don't yet have a multimeter connected so I can't measure that, but obviously it's a bit complicated.

More useful is power at a given speed. ...In loaded real-world results, as opposed to the simulator. W @ mph. Then of course you can divide W by mph to get Wh / mile, but that value will differ depending on the speed at which the value was read, I expect.

[TylerDurden]

OK,

Well it looks like Randy's bike is in the ballpark...

36V x 6ah = 216Wh / 20mi = 10.8Wh/mi / 210lbs = .051

.051Wh/mi/lb. @ 20mph

(approximating 150lb rider, 50lb bike, 10lb battery)


*** OR ***


1584W / 72mi = 22W(h) / 280lbs = .078 Wh/mi/lb. @ 12mph
(uphill then down, fully loaded on the volcano ride)

[EbikeMaui]

OK,

Well it looks like Randy's bike is in the ballpark...

36V x 6ah = 216Wh / 20mi = 10.8Wh/mi / 210lbs = .051

.051Wh/mi/lb. @ 20mph

(approximating 150lb rider, 50lb bike, 10lb battery)


*** OR ***


1584W / 72mi = 22W(h) / 280lbs = .078 Wh/mi/lb. @ 12mph
(uphill then down, fully loaded on the volcano ride)

But even on a round trip to 10,005 feet and back down my total average speed was pretty dam close to 20 mph carrying a 300 lb gross weight.=In The Worst Conditions with the heavy batteries and the hill.When using lithium batteries I can usually just count on 6ah at the WORST! for ANY conditions on complete ROUND TRIPS of 20 miles. WITHOUT ANY PEDALING if I am lazy or surfed out.You do have to have a ebike that FREEWHEELS FREELY to get these results.Just the coggong in any hub motor will offset the coasting factor and the power usage quite a bit while going down hills.= Motor Drag without regen.If regen were applied it would just stop you.

[xyster]

Just the coggong in any hub motor will offset the coasting factor and the power usage quite a bit while going down hills.= Motor Drag without regen.

Hardly. Hubmotor cogging torque is negligible compared to other losses -- as Justin from ebikes wrote, about the same as the extra rolling resistance from using a wide tire versus a narrow tire. Mine pedals just fine. I don't notice the motor until I go to pick the bike up and move it somewhere.
Including the cogging torque, efficiency of large BLDC hubmotors is still around 90% max. This is far better than the efficiency smaller external motors (that'll fit on the bike frame somewhere) like yours' can achieve, and with a much wider powerband too. *
http://www.ebikes.ca/simulator/
And of course there are hubmotors like the BMC Puma with the freewheel built inside already.



*Plz Safe, don't ruin my fun just yet!

[patrick_mahoney]

The cogging on my 5304 motor is pretty minor. I went for a ride without the batteries with my daughter (no e-biking because she complains that it's not "fair"). We rode for about 6 miles and I didn't even notice the motor at all - until, as Xyster pointed out, I had to pick the bike up to lift it up a curb. The weight of the 5304 motor seems to have a larger effect on riding than the cogging which is pretty minimal.

[CGameProgrammer]

The motor resistance is definitely almost nonexistent at normal bike speeds. On my bike with 28" diameter tires, at 15 mph the wheel is spinning exactly 3 times per second (180 RPM). That's very slow for a motor.

[EbikeMaui]

The cogging on my 5304 motor is pretty minor. I went for a ride without the batteries with my daughter (no e-biking because she complains that it's not "fair"). We rode for about 6 miles and I didn't even notice the motor at all - until, as Xyster pointed out, I had to pick the bike up to lift it up a curb. The weight of the 5304 motor seems to have a larger effect on riding than the cogging which is pretty minimal.

Hub motors DO have weaker magnets and a squed arangement also a larger airgap to minimise cogging at the cost of low end torque and some efficiency. Compared to much stronger torque motors with tight airgaps and stronger streight across magnet design that CAN put out 10 KW efficiently in the same size as hub motors for bicycles. Hub motors are rather Whimpy for there size and NEED a high semi unloaded RPMs to be efficient (Hard Pedaling Helps)
About the Coasting, see how fast a freewheel bike with the same weight coasts from a dead stop to 20 mph down a hill compared to a hubmotor ebike that is off.There is some cogging on any induction motor.= unneeded drag. How ever minor the cogging is, it all adds up on free coasting in which adds up to many miles on most of my trips.Negiitive cogging effects are less when running the hubmotors constantly on leval ground.
This part gets interesting! A lithium battery rated at 12 ah with a .2 C rating discharged to 80% =9.6 ah.With a capacity of 691.2 watt hours.Discharged at thr RECOMENDED HIGHEST Rate for the expected cycle life of 200 cycles (for Chineese batteries) would be a 2.4 ah or a 172.8 Wh discharge rate.I have done many tests averging 13 to 14 mph for 52 miles of range in 4 hours with 14 lbs of batteries.Two 36 volt packs in series or each 36 volt pack used up one at a time it makes no difference.Same results.Now if I were to paralell the two packs it just makes the batteries get just a slightly better range and speed. Any Hub motor guys just need more and LARGER ah packs like 30 ah rated to feed there need.Another thing to remember is that the more cogging you have maked mote efficient torque at low end.High end is stronger too! In Fixing cogging you loose out on some motor efficiency.IBut hub motors ARE easy to get cheap. You just need to pay more for more batteries is all..
At some point as most of you will figure out (the batteries most ebikers love to have) That the batteries will cost more than your bike just for a minimal battery (such as equal ah of a SLA that works good). Once someone makes a COMPLETE motor sysyem that proves that there is NO DOUBT that a 50% battery savings COULD be seen just by purchasing a more efficient longer lasting ebike component that is 1/3 of the weight of a hub motor and isn't so hard on batteries. Optibike hasn't proved SQUAT either LOL Bear in mind No one cares since there is no lithilm ebike market to speak of.... YeT ?
Happy Hub MOTOR PEDALING ... Aloha RD
http://tinyurl.com/y9hh8s

[Lowell]

While hub motors are far from perfect, the results speak for themselves. Even though I have machining, welding and fabrication equipment at my disposal, clearly no special equipment was used in the construction of my bike.
I'm talking about here and now. What's on the shelves and in stock. Some ideas are great, but will never see mass production by the container load. The average ebike commuter is going over city streets not mountains and I'm sure they could care less if it can make it up a 5000ft climb. They want to get from point A to point B quickly and reliably.

[CGameProgrammer]

Quietly, too. From the videos I've seen, chain-driven e-bikes, using high-RPM motors, sound as loud as many motorcycles. Hub motors are somewhat quiet at a distance. Actually I wish there were more videos taken by pedestrians as an e-bike passed by.

[Lowell]

Quiet is a big plus, so as not to attract attention from cops. Much like a fart-can muffled Honda Civic, even a slow POS can get unwanted attention if it's noisy.

[TylerDurden]

Back to the numbers...

172.8 Wh / 52mi = 3.32Wh/mi

3.32WhMi / 210lbs = .0158WhMi/lb @14mph


The results seem inconsistant with Randy's previous results of .051(WhMiLb) @20mph. That's a 25% reduction in speed, but more than double the overall efficiency.

Randy, are you quite certain that the 172.8Wh is for 52mi, and not 26mi?

[fechter]

Perhaps he was pedaling.

[Matt Gruber]

Quietly, too. From the videos I've seen, chain-driven e-bikes, using high-RPM motors, sound as loud as many motorcycles. Hub motors are somewhat quiet at a distance. Actually I wish there were more videos taken by pedestrians as an e-bike passed by.

HUH?
after break in my PSEV is silent.
my mbike tensioner rattles a bit, but it disappears at 20mph.
new it was annoying i'll grant u that. like loose change in my pocket, NOT LIKE ICE!

.
Tyler
my psev is11 amps @24v 15mph 62#+144
my mbike is 10a@17mph36v 132# +144.
but 20a @25mph @53v