The truth: How far can an electric bicycle really go on a single charge?

FlatSix911

Well-Known Member
Interesting article on how to understand and calculate realistic range on an EBike.


One of the biggest benefits of electric bicycles is that they can help riders go farther with the same amount of leg power. But with manufacturers citing wildly different range ratings for seemingly similar e-bikes, how can you know what an e-bike’s true range is? It’s actually easier than you’d think. And after spending more than a decade working in the electric bicycle industry, I’ve gotten decently good at it, if I may say so myself. Here are my tips to get a true, honest range rating out of an e-bike.

What are the factors in e-bike range? First things first: One of the reasons e-bike range ratings seem to be all over the place is because they can be affected by a number of factors.

  • Everything from speed to rider weight to terrain style to wind conditions and even tire choice can impact an e-bike’s effective range on a single charge.
  • The second major factor is the presence (or absence) of a hand throttle. Most European riders won’t have to consider this since e-bike throttles aren’t common in EU countries.
  • But for Americans and riders in other countries that allow hand throttles in addition to pedal assist, a hand throttle can be a quick way to drain the battery and reduce range.
How to estimate e-bike range
To determine an e-bike’s approximate range, you first need to start with the battery capacity. It is usually measured in Watt hours (Wh). Sometimes you’ll see a battery rated in volts and amp hours, such as an e-bike with a 48V 10Ah battery. To convert to Wh, simply multiply the volts by the amp hours. A 48V and 10Ah battery is therefore a 480 Wh battery.

Next, you can calculate effective range by simply dividing the watt hour capacity of the battery by an average efficiency number in Wh/mi (or Wh/km if you prefer kilometers).

This is the slightly fuzzy part of the math since efficiency numbers will vary based on the factors listed at the start of this article. But speaking generally, I find that most 500-750W throttle e-bikes ridden at an average speed of 20 mph (32 km/h) on only slightly hilly terrain get me around 25 Wh/mi (or 15.6 Wh/km). Thus an e-bike of this style with a 480Wh battery would provide me with around 19 miles of range (480 Wh ÷ 25 Wh/mi = 19.2 miles).

Pedal assist will always be more efficient. I find that most pedal assist e-bikes ridden around 15 to 18 mph in medium levels of pedal assist will get me around 15 Wh/mi (or 9.4 Wh/km). Thus the same 480Wh battery on a pedal assist e-bike will provide me around 32 miles of range (480 Wh ÷ 15 Wh/mi = 32 miles).
 
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FlatSix911

Well-Known Member
I have found that the formula for calculating range is accurate within +/- 15% for the average rider. YMMV ;)
 

sed6

Active Member
So, 50% further if you pedal? Seems logical. I bet you could double your range if you went half as fast also.
 

CdnShaun

Active Member
Great article FlatSix911 - appreciate the link and insight shared.

I'm new to the forum (just signed up today and this is my first post) and I have been an ebike rider for a few years getting quite active last year and thankfully into this year. I have several Bionx setups with a collection of 557wh (48V) batteries and the calculations are spot on for real world experience.

I did want to add a few thoughts. Nothing better than a fresh off the charge battery and it's easy to let the motor do most of the work. When I go out looking to stretch my battery life I have to remember to ride the lowest assist level and put in as much pedal power as I can to 'sip' on the battery to make it last.

With a lot of OEM bikes/conversions I have found (test ride of others and my own) the assist level drops over the life of the battery as the voltage reduces. there is also the golden rule I have read about and learned to live by of not draining your battery/batteries below 10% capacity if possible (and charge only to 80-90% if possible, for extended charge cycle life) so when I do calculations I base it on using 80% of the available Wh's (from 90% to 10%, or in the case of Bionx since they only can be shared to full - 100% to 20%) and the real world experience matches up within 5-10% of my calculations.

A useful tool I have used and surely has been shared often before is Grin's motor simulator - https://www.ebikes.ca/tools/simulator.html

While the default list is the motors they currently sell, you can scroll down and access many more motors and configurations they have in the tool's database. I discovered this for the Bionx D500 motors I have for example and when setting the variables such as overall rider weight, grade of hills and rider power inputs - helped me confirm a lot of what I saw in real world riding. Specifically when you run the simulator it will be you the Wh/Km estimates like shared in this thread so you can compare different equipment and riding situations.


My last bit to share - since I purchased multiple bikes last year (all Bionx D500's) I ended up with multiple batteries. I then purchased additional used 557wh batteries when they came available to expand my collection - mostly to have them as we all know Bionx is gone (for now) as they went bankrupt in 2018 - having extra batteries gives me a better chance of having usable batteries for years to come.

That said, I did mount up pannier's on my road bike last fall and while my first ride last summer at 305lbs in June with a single battery was a whopping 17kms, by September I had built up to as a rider and with 6 batteries (feel free to laugh, I do everytime I put 55lbs of batteries on my bike with me) to complete a 163km ride with over 1,300m of elevation - and I was still 265lbs as a rider at the time.

With multiple batteries and enough stamina to stay in the saddle for the hours needed -100-200kms (60 to 120 miles) in a single day ride is very much possible. Just wanted to share for a smile.

Cheers
 

CdnShaun

Active Member
So, 50% further if you pedal? Seems logical. I bet you could double your range if you went half as fast also.

First part of your statement is absolutely correct. Adding even 80-150watts of pedal turning to a ride versus just holding the thumb throttle and having the motor do all the work will roughly double your ride distance in most cases.

As for speed, each motor has an ideal speed, rpm's in particular that it is most efficient operating at. This is why you will find (as I am learning as I get into fully custom conversions of my bikes this year) different 'wind' speeds of the same motor - technically the winding measurement also dictates maximum rpm (and therefore top speed) the 'sweet spot' for the most efficient Wh/Km does vary from motor to motor based on what voltage (36, 48, 52, 72, etc) you are supplying it as well.

As per my post above, the motor simulator from Grin (https://www.ebikes.ca/tools/simulator.html) helps calculate these estimates. A quick example of a couple motors I am looking at have the 'standard' wind configuration most efficient speed at 38kmph where as the 'Fast' wind is up around 46-48kmph and about 20% shorter distance per ride based on the same battery choice.

Finding your optimal speed for lowest Wh/Km (or Wh/Mile for my American friends) is a great exercise to complete as it helps you get the most out of your rides each time you head out.