Range Anxiety?

[apctjb]

Recently purchased BMC Roadmachine Amp for my wife and I, our first foray into ebikes. So far they have been a ton of fun but we were having some range anxiety about doing some longer rides in the mountains near where we live. Searching online I could not find a good range estimator for TQ equipped bikes so decided to build one. So far its proving to be accurate and last weekend my wife did a 110 mile / 7600 ft elevation ride and used the app to verify the range. The app predicted she could make it with 11.3% battery remaining, she rolled in with 13% SOC showing on the display. Not bad. Here is a link for the app if anyone wants to check it out. Upload a .GPX file of a ride you are planning, input your motor settings and the app will estimate range and ending SOC.

TQ HPR Ebike Range Estimator

 

[djward43]

That's pretty cool. You seem to be enjoying the time on your bikes. My trouble with range anxiety was pretty much under control until I dropped one of my Lectric Xpress 750's batteries... The one out of the box design flaw I recognized was how slick the coating on the battery housing is; I actually scuffed one of them up with sandpaper. Obviously not the one I dropped. Now I'm pulling a trailer with a 1.somthing kwh battery I bought from a guy who changed his mind about how much fun living off grid powered by the sun was going to be. I have been making it to work and back 5 times a week opposed to 2 with both batteries.

 

[kristian92]

That's a useful way of looking at range. I think elevation is one of the things that makes a simple "miles per charge" number pretty misleading.

Being able to plan around the actual route seems much more useful, especially for longer rides where the last part of the route might include a big climb.

It would be interesting to see how accurate it stays across different temperatures and rider weights.

 

[apctjb]

It would be interesting to see how accurate it stays across different temperatures and rider weights.

Thanks for taking a look. Assuming the user correctly inputs bike and rider weight the physics engine behind the calculations should account for heavier riders accurately. Temperature is an interesting one as it impacts air density (you can adjust by changing headwind assumption) but also motor efficiency which is baked into the model.

 

[4πr^2]

Nice bike! Interested to hear any more input on the X20 system. Will also be interesting to see how the app/predictions hold up over time. As they say...even a broken clock is right twice per day.

Just penciling in some numbers, I see at least one reference that the bike has a 350Wh battery. She used 87% or 304Wh on a 110 mile ride. ...or about 2.7Wh per mile - which is stunningly low. I'd have to think a well lubed or poorly lubed chain could make a few watts difference. Certainly +/- a few psi in the tires could be a few watts, and we won't even get into headwind/tailwind. So any one of these could double, or half that consumption and make the prediction wildly off base.

Really, I would almost wonder, at an average of 2.7Wh/mile, she might be better off to cut the 3-4kg of 'electric' bike and just get a nice, light normal bike?

 

[apctjb]

Really, I would almost wonder, at an average of 2.7Wh/mile, she might be better off to cut the 3-4kg of 'electric' bike and just get a nice, light normal bike?

On this ride she contributed about 75% of the input energy, the battery the remaining 25%. What I have found is it does not take much assist to dramatically change the fun factor of a ride. 30W of motor input in addition to the 150W I am able to maintain and I feel 10 years younger and increase my average speed by 1-2 mph, 60W and I can keep up with just about any of my younger and fitter friends. 30W-60W makes these longer rides much more enjoyable especially on the steeper climbs at the end of ride when the legs are getting tired. I was skeptical about e Road bikes , but now I am hooked and regret that I waited until 70 to get one.