My bike uses less electrical power at fast speeds

[steve marino]

This may not make any sense to anyone here, but that's OK, it doesn't make much sense to me either. I've monitored this repeatedly, and if I go easy on the throttle and pedal a lot at slow speeds, I have less batter power left than if I go fast and use the throttle a lot. Probably a dozen times I've measured this on my daily coffee-in-the-park run of 12 miles round trip, and it's always the same outcome, assuming wind isn't a factor.

The only two things I can think of that might account for this is, A- I get where I'm going much faster if I go fast, so the battery is used less time than on the slow runs, and B- when the bike is traveling fast, I have a good cadence going w/ the pedals, so even though the throttle is open it's not really being used much, my legs and the bike's momentum are more in play.

Now this is using the bike the way one would normally use it. The battery usage could be almost zero if I pedaled 90% of the time and used the throttle the remaining 10%, but this is riding the bike like most anyone would ride it. It's been checked w/ a volt/ohm meter as well as with the LED readout on the handlebars too.

 

[TMH]

I suppose it could also have something to do with where the motor is the most efficient. Perhaps the increase in efficiency at a certain power or RPM exceeds the increase in aerodynamic drag at higher speeds.

Or maybe what you've got yourself there is some kind of newfangled perpetual motion machine. How warm does the flux capacitor get on normal rides?

 

[Deacon Blues]

I suppose it could also have something to do with where the motor is the most efficient. Perhaps the increase in efficiency at a certain power or RPM exceeds the increase in aerodynamic drag at higher speeds.

Or maybe what you've got yourself there is some kind of newfangled perpetual motion machine. How warm does the flux capacitor get on normal rides?

Hold everything. Are you saying that he's getting his ebike up to 88 mph on his daily rides?

 

[rich c]

You'll need to have a meter that measures current draw at the motor. If at slow speed and a high gear, a torque sensor will send more current to the motor at low road speed. I assume the same with a PAS sensor if the gear is wrong. Using the throttle at a higher speed will draw less current. I can max out the current draw on my Haibike if I stand up on the pedals and go 5 mph in the highest gear. Drop it to the lowest gear and the current draw is minimal.

 

[FullyCharged]

It makes sense if you don’t think about it.

 

[legsofbeer]

Depends on what kind of PAS you have. If your bike is giving a constant-watt PAS while you are cranking the pedals, then the quicker you finish the fixed-length ride the less time the battery has been draining, though stops and coasting mess with the simple math. If it's a mid-drive with torque sensing then things are more complicated.

 

[legsofbeer]

What kind of motor do you have?

I've read somewhere that bikes with gearless direct drive, like Stromer are more efficient at higher speed.

I think that is true, having chased my buddy riding a 500w stromer.