Which scenario drains the most battery?

So there's a steep hill coming up.

 

1. You put it on a low assist (1-2) and get pedalling, but at this assist level, even with pedalling you can't get the bike up to 15mph so the motor is working fully until you reach the peak.

 

2. You put it on the highest assist, with the same pedalling effort (or slightly less) and the bike reaches 15mph (or whatever you have the limiter set at for illegal bikes)

 

Which would drain more battery and reduce overall range from one charge?

most likely scenario 2, but the difference would be small at equal user contribution.

Higher assist will almost always produce higher acceleration thus burning a bit more.

Interestingly I have just been experimenting with this.. I have found that a mid power setting gives me the best range and overall e-biking experience

Who cares...do you really go into it that deep as your peddling up steepest hills..ooh.. am I doing 15 an half miles an hour now??.......lowest gear..highest setting....way to go..

Get true values with a Turnigy watt meter in line..

Who cares...do you really go into it that deep as your peddling up steepest hills..ooh.. am I doing 15 an half miles an hour now??.......lowest gear..highest setting....way to go..

I can't take anyone seriously who doesn't know when to use your and you're.

I can't take anyone seriously who doesn't know when to use your and you're.

just paddle faster

Most likely the second scenario will use the least battery because the motor will be running more efficiently. It will consume battery charge more quickly, but it won't be doing it for as long. This assumes that climbing speed is not too fast - say less than 15 mph - so that air resistance isn't a big factor.

I can't take anyone seriously who doesn't know when to use your and you're.

Doesn,t know...or doesn,t care...I can,t take anyone seriously who takes things so seriously...

Doesn,t know...or doesn,t care...I can,t take anyone seriously who takes things so seriously...

And has fallen apostrophes.

Most likely the second scenario will use the least battery because the motor will be running more efficiently. It will consume battery charge more quickly, but it won't be doing it for as long. This assumes that climbing speed is not too fast - say less than 15 mph - so that air resistance isn't a big factor.

 

the calculation of the required energy to accelerate the bike to 15mph is similar to calculating the critical damping in physics. The smoother the acceleration, the less waste you are going to get. Higher assist level will likely produce more oscillations, therefore is less energy efficient.

And has fallen apostrophes.

I have falen appostr, aphostro, thingies as well!

I can't take anyone seriously who doesn't know when to use your and you're.

dont text a teenager then!

And has fallen apostrophes.

..yes... I,ve had many a sleepless night over my fallen apostrophes..

..yes... I,ve had many a sleepless night over my fallen apostrophes..

Oh I don't loose any sleep over them, at least not since I bought some insoles [emoji102]

Most likely the second scenario will use the least battery because the motor will be running more efficiently. It will consume battery charge more quickly, but it won't be doing it for as long. This assumes that climbing speed is not too fast - say less than 15 mph - so that air resistance isn't a big factor.

Seems to have made little to no difference on my way home yesterday. Just my usual ride, the way home is always mainly up hill. I struggled on assist 2 on a mid charged battery and it wasn't helping much, thighs starting to burn after about half an hour of doing this. Said sod it and used assist 5 and throttle for the remaining 5 or so miles and got home having not saved any more power than if I did the whole return trip on assist 3-5

the calculation of the required energy to accelerate the bike to 15mph is similar to calculating the critical damping in physics. The smoother the acceleration, the less waste you are going to get. Higher assist level will likely produce more oscillations, therefore is less energy efficient.

Acceleration would be negative going up a hill, so does that mean that your conclusion from your theory is the wrong way round?

Acceleration would be negative going up a hill, so does that mean that your conclusion from your theory is the wrong way round?

I don't think the gradient would change the basic calculation as long as the motor is required to provide assistance. You integrate the battery usage over the distance, oscillations will automatically add to waste.

Were ever yous think yous where going with this post, I think the pacific point off it has bin lost on the way. It could of bin so different........never mind - there their they're......

And the only thing I loose any sleep over is a wheel coming lose.

Edited June 24, 20178 yr by Euphony

So there's a steep hill coming up.

 

1. You put it on a low assist (1-2)

..

2. You put it on the highest assist

 

A couple of technical questions if I may:

 

1. What EXACTLY does changing the assist level do (in terms of what gets delivered to the motor)?

 

2. Does changing the assist level shift the zone of maximum efficiency of the motor (and thus change the heating losses at a given motor rotation speed)

 

??

Good questions.

1. There are basically two types of system that respond to the PAS setting. Speed control allows full power for accelerating but limits the speed in each level to a different value. Current control limits the power (current) to a different value in each level, but it allows full speed. Oxygen bikes use both. They have three levels of power and 6 of speed, so 18 combinations.

 

2 Yes it does. Everything becomes more complicated when you reduce PAS or the throttle. Generally, the efficiency curve gets shifted down the RPM range. I haven't yet figured out what happens with current control controllers, but basic logic says to me that efficiency would be lower than a speed control one; however, in practice, there's no noticeable difference. I guess that it gains in some circumstances and loses in others.

Also another variable is that once the motor starts turning, back emf enters the equation apposing the current from the controller.

Good questions.

... Current control limits the power (current) to a different value

...

Everything becomes more complicated when you reduce PAS or the throttle. Generally, the efficiency curve gets shifted down the RPM range.

 

Ok, thanks for that. That's what I imagined would happen (the max efficiency zone seems to be related to the voltage. Some graphs I came across indicate you lower the voltage, and thus lower the zone).

 

So when you say 'Current control limits the power', what is actually happening here? On a typical ebike with a simpler control setup compared to the Oxygen, when you change assist settings (eco, tour, turbo etc), and I guess also when you introduce a torque sensor into the equation, is it actually varying the voltage (which would determine the current). And if so, how do they typically do this. Is it some kind of PWM setup?

All sounds like it's getting complicated,I usually ride in level 2 (of5) and use the throttle(still can't get used to calling it a throttle)whenever I need it and I need it constantly,sometimes to get up a hill or get me up to speed to keep up with other riders or just to get a wee rest from peddling.

You can't vary the voltage. The battery is connected directly to the motor, but it's blocked by the mosfets. all the controller does is open and close the mosfets in the right sequence in short pulses. you have to see the power provided to the motor as pulses of energy that have a height (voltage) and time. You could argue that there's an average voltage and/or an average current.

 

That's it in simple terms, but you have to add in the effects of capacitance and inductance in the coils and the help from any output capacitors.

 

The torque sensor is only a sensor. The controller reads it and regulates power to whatever algorithms are programmed into it. Basically, the controller is a tap. the CPU reads sensors and opens/closes the tap accordingly.