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

[FlatSix911]

Interesting article on how to understand and calculate realistic range on an EBike.

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

One of the biggest benefits of electric bicycles is that they can help riders go farther with the same amount...

electrek.co

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).

 

[FlatSix911]

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

 

[sed6]

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

 

[CdnShaun]

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]

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.

 

[kevinmccune]

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

you might even do better then that,however beware of ET.I ran a 15 ah equipped bike shamefully low on charge one and paid the price had to get real creative to get back home.

 

[GAJ]

Zero range anxiety on my 33lb Turbo Vado SL1 5.0 as it pedals as easily as a regular bicycle.

 

[kevinmccune]

Zero range anxiety on my 33lb Turbo Vado SL1 5.0 as it pedals as easily as a regular bicycle.

and the tires you are using have an effect also,I test drove a "specialized" and it pedaled easy,careful engineering and attention to details makes a difference!

 

[harryS]

At 12 mph, using wattmeters, I get I 8-10 Wh/mile for a 200 lb rider and 6-8 Wh/mile for a 135 lb rider. Measured over a half dozen hubmotors. Motor size isn't a big factor, Figure 10% less with torque sensor mid drives.




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[Stefan Mikes]

I've just noticed it is a five year old thread that died in 2020

Anyway, I'm getting the best range in the summer when I am fit and can afford low assistance. Typical battery consumption factors for me with the rider's weight of over 100 kg:
Vado SL: 6.4 Wh/mi (4 Wh/km), a 70 mi trip with 900 ft elevation gain, summer
Vado 6.0: 6.6 Wh/mi (4.12 Wh/km), a similar trip as above
Important: I'm setting the assistance the way either of these e-bikes (despite its weight) provides similar assist. Also, the degraded Vado battery holds the same charge as the degraded main battery + Range Extender for Vado SL.

Just recently, a 60 mile ride, Vado 6.0 ride, 4.77 Wh/km or 7.7 Wh/mi.

Whenever I use high assistance, the battery consumption factor is skyrocketing.

 

[Jeremy McCreary]

Everyone willing to base real-world charging and backup battery decisions on a generic battery mileage of 15 Wh/mi, determined who knows how, raise your hand!

 

[Stefan Mikes]

Everyone willing to base real-world charging and backup battery decisions on a generic battery mileage of 15 Wh/mi, determined who knows how, raise your hand!

Could you be more specific?

 

[Jeremy McCreary]

Could you be more specific?

Don't know about more specific, but I could probably be more sarcastic about the article if you like.

YMMV applies as much to ebikes as cars. A carefully determined personal, ebike-specific mileage might be of limited use in range prediction. But it'd be unwise to rely on any battery range projected from a generic mileage figure pulled from an unspecified sample of ebikes, riders, use cases, and terrains.

 

[Stefan Mikes]

YMMV applies as much to ebikes as cars. A carefully determined personal, ebike-specific mileage might be of limited use in range prediction. But it'd be unwise to rely on any battery range projected from a generic mileage figure pulled from an unspecified sample of ebikes, riders, use cases, and terrains.

Now I get it. (Sometimes, I can understand any single word in an English sentence but miss the message!)
The most asked question of any cyclist related to my e-bikes is "how far can you ride on the battery?" I make a worried face and reply "I cannot answer this question as the answer depends on too many factors. I could ride for 116 km on the single battery set in the summer but I estimate today's range to seventy kilometres", or so.

 

[Jeremy McCreary]

Now I get it. (Sometimes, I can understand any single word in an English sentence but miss the message!)
The most asked question of any cyclist related to my e-bikes is "how far can you ride on the battery?" I make a worried face and reply "I cannot answer this question as the answer depends on too many factors. I could ride for 116 km on the single battery set in the summer but I estimate today's range to seventy kilometres", or so.

Exactly. Just checked 4 very different 20+ mile rides. Averaged 5, 5, 7, and 8 Wh/mi. Not a small spread in relative terms.

And any experienced ebiker will immediately ask what ebike, what assist levels, what rider inputs, what elevation gains per mile, what ambient temperatures and winds? Because these things really matter in the mileage biz.

Reserving the 320 Wh battery's last 10% for emergency use only, these mileages project battery ranges of 58, 58, 41, and 36 mi. Again, not a small spread, with the same factor of 1.6 between extremes as before.

So which of these rides best matches tomorrow's planned ride? Do I really need to lug around that heavy range-extender? Very hard to say with so many independent variables mixing it up from ride to ride. And that's just for a single rider+bike combo.

But that's recreational riding with a taste for exercise and variety. Utility riding could well be less variable and therefore more predictable WRT both mileage and range. That's the best-case scenario for the article's approach — but only with a personal, ebike-specific mileage figure already in hand.

 

[Stefan Mikes]

what ebike, what assist levels, what rider inputs, what elevation gains per mile, what ambient temperatures and winds?

+ rider's and cargo weight, is the ride continuous or does it involve many intersection stops? etc. What is the terrain? What tyres and under what pressure?

So which of these rides best matches tomorrow's planned ride? Do I really need to lug around that heavy range-extender?

We are lucky Jeremy that we own Specialized e-bikes. Precise assistance setting, Smart Control, (and MicroTune as well as Range prediction in your case!)

 

[6zfshdb]

Another factor that is often overlooked when calculating miles per charge is battery age.
Just because your fully charged battery is rated at say 420wh, doesn't mean it actually contains that much energy.
A battery can loose capacity due to age, temperature and the way it is treated.
Occasional bench testing is the only way to know its true capacity.

 

[Stefan Mikes]

Occasional bench testing is the only way to know its true capacity.

Unless you own an older Specialized e-bike

This battery was originally rated at 604 Wh.

 

[Jeremy McCreary]

Good demo of the relationship between climbing and battery drain from a recent ride:

The slope of the gray elevation profile at any point X along the ride approximates G, the rate of elevation gain (EG) at X in vertical ft per mile. The slope of the orange battery level profile at X is formally the discharge rate P in %/mi but for our purposes can be read as the discharge rate D in Wh/mi, as P and D are approximately proportional.

A constant D (like the 15 Wh/mi suggested by the article) would show as a straight orange line descending to the right. But as you can see, D is far from constant here. The gray and orange slopes corresponding to G and D are strongly correlated, with generally faster discharge rates on the way up, especially near the summit.

This ride climbed Double Peak (1,646 ft) from a start at 140 ft with lots of up and down in both directions. Average EG rate was 110 vertical ft per mile — a hilly ride by most standards. The adjusted rider power shows some effort on my part.

Result: D = 7.0 Wh/mi overall, but the battery drain was much faster than that on the final 15-18% grades to the summit. Reserving the 320 Wh battery's last 10% for emergency use only, the overall D projects to a battery range R of 42 mi. In contrast, D and R are more like 5 Wh/mi and 58 mi on rolling coast rides.

Since this is a power-sensing ebike, the more rider power in, the more mechanical motor power out up to a ceiling set by assist level. The motor and I both got workouts on this one.

Assist level was generally the lowest allowing a steady cadence of 80-90 RPM — the happy place for both the mid-drive motor and my knees.

 

[Roamers]

It's great having a riding partner that weighs 110# less, doesn't tow the trailer (yet), and has virtually identical bike (only frame size differs. Although we haven't had to do it yet, keeping an eye on estimated range, we can just exchange batteries. Love a simple life!