Mileage trouble shooting

[bandaro]

Hey guys, so a few months ago I finally got around to modifying a kids electric scooter as a temporary means to get around, primarily to a mates place for beers or similar trips. Works great, cheap and easy, but uses about 25wh/km (35-40wh/mile). So yeah, way too much.



The setup:
Schwinn s-150 scooter
5s 10ah lipo
6354 sk3
turnigy d-lux 100A esc
mechanical brakes
hall effect throttle through a servo tester
Various wires/plugs/switches
70kg rider
32km/h gearing

Obviously I jump on, gentle kick, then motor to my destination with no extra input at full throttle (max speed it about the 32km mark). Recent rides have got me 8km with 14m variation in elevation, so essentially pancake flat. The motor can get hot, but if I'm riding in cooler temps, the motor only gets warm (can hold it). The wheels spin ok when I take the belt of, and the belt is correct tension. So yeah, little confused as to why it uses so much power, it's not going extreme speeds or anything. Anyone else have terrible efficiency with a similar setup? Makes me more determined to finish my skate build...

Side note, I'm generally squatting down to improve my air profile, and haven't noticed a difference between full/half throttle range. Esc stay ambient temp, no stress there.

 

[xenodius]

Yikes, I get that efficiency with steep seesaw hills, a 100lb bike, and 30+mph speeds! I don't know what's typical for escooters, but that's definitely high-- I can hardly believe that nothing is getting suspiciously warm. The alternative, of course, is what you've already tested-- your setup is efficient, and aero or rolling resistance is dragging you down.

Do you know your no-load consumption/rpm/speed?

 

[amberwolf]

I'd say something is either configured wrong, or there's a lot of friction in something (though that ought to have overheated by now).

Even me on CrazyBIke2 with hard starts up to 20MPH isn't that bad except on realy windy days or if my tires are really low, or I"m pulling a heck of a load.

 

[bandaro]

Yeah I thought it was pretty crazy, even for the zero self input...

I guess the next step is to skip the on/off switch and hope it was there? but one would think if that was the problem the inbuilt fuse would blow at the very least... I imagine an escooter would sit at about the same consumption as a board/bike, the weight would be in between the two with similar rolling resistance... I'm getting some fvt esc's for a board so I can try swapping in instead of the dlux too, don't expect that to change anything though as the esc is never stressed.

 

[torqueboards]

40wh/mile if I read that incorrectly. Supposedly due to your lower voltage at 5S the setup is working harder. Also depending on your gearing. Use a 8S/10S ESC and pop in a 8S/10S pack and it should do better.

 

[amberwolf]

I guess the next step is to skip the on/off switch and hope it was there?

A switch woudln't cause excess power usage, unless it was shorted to something else leaking current thru it to the other battery pole. Probably that would result in your battery dying quickly while jsut sitting there, no motor usage, and you'd also be able to see that on the wattmeter if it's wired before the switch. (if it's after the switch, you wouldn't).

I imagine an escooter would sit at about the same consumption as a board/bike, the weight would be in between the two with similar rolling resistance... I'm getting some fvt esc's for a board so I can try swapping in instead of the dlux too, don't expect that to change anything though as the esc is never stressed.

It could be settings in the ESC allowing very high usage during starts from a stop, but youd see that on the wattmeter then, too.

If the motor is not running in it's efficient zone for hte voltage/current it's getting vs RPM, that coudl be quite a waste of power. YOu can see how this works by plaing with the hubmotors in the ebikes.ca simulator.