Why Do E-Bike Companies "fib" About Distance?

22.02.22 04:10 PM By John

"Your New E-bike Goes 80+miles per charge!", in Bizzarro World!

     It doesn't take long for someone looking to buy a new E-bike to quickly realize that these machines boast great distances per charge!  They are amazing and why would you ever step in a car again?!?!  Well, there's a common downside to those wonderfully high 40/60/80/100+ mile per charge rating from most companies...... they're NOT REAL!  That's right, that's what I said, they are at best a guesstimated calculation to present a favorable number to you.  Because who wants to spend $1500+ on transportation that won't even get you down the street let alone across town.  But we at E-powersport.com don't believe in over inflating our numbers, much to the happiness of our investors too.  


       In the rest of this Blog Article we'll discuss how you, yes you, maybe even you, but I'm not so sure about that guy, can easily tell how much distance you can realistically expect.  There is some basic math involved and we're going to look at it from 2 different number calculations, but in the end, you'll be able to confidently go into any bike shop and tell them the realistic #s and if they're full of shit or not.  Which is your right as a consumer and potential customer.


First, let's explain why companies label their E-bikes with such high numbers as to lead you to disappointment.  I'm going to be a little absurd here, but you'll get the point.  When other E-bike companies test an E-bike's distance capability, they first go through the company and poll their staff to see who has the smallest and lightest 13 year old.  Thirteen as that's about grown up enough to handle a motorized vehicle.  This 98lb Tween is then told they will get a pony or go-cart if they pedal the E-bike on level 2 until their little legs fall off.  Sometimes they get to take a break to use the bathroom, but normally they make them wait till the battery runs out.  Luckily, the components are waterproof incase of an accident.  They then chase the child with small dogs to help keep them pedaling and when done, they round up to the nearest Tens place, yielding those wonderfully high milage numbers we're all used to seeing.  

*This is an absurd joke to demonstrate the absurdity of what is actually done in testing*


     Now, I don't know about you, but the last time I weighed 98lbs I was 10 years old.  Yeah, I was, still kind of am, the chubby kid.  Which works for you, since we rate our units on being able to move my 210lbs around.  So, when you see a distance rating on our website, you know some chunky guy was able to get 60+ miles out of it and your waifiness should be able to go a bit farther.  All that is great when it comes to buying from us, but what if you did the dirty deed and bought from someone else.  Well, I can't fault you for it, not everyone knows about us yet.  But here's how you can do a little math and make sure you know, for sure, what you're buying vs. what's being said on the marketing flyer:


To give things more context, let's look at a competitor's E-bike, the Himiway Zebra.  Himiway claims that it's 750w motor and 960wh battery will get you 80+ miles per charge.  Poppycock!  Maybe with Bob's kid riding it with those dogs at his feet, but not my fat butt.  Let's break it down and see what you can really expect.


The motor is 750w.  That means at full speed, it runs 750w average per hour.  The wattage per hour for the battery is 960wh.  If we divide 960/750 we get 1.28.  This means if you run the motor at full speed for an hour and 20 minutes you will have run the battery out of juice.  Since most E-bikes running at 48v stay around 28-30mph, we'll call it 28mph.  At 28mph for 1.28 hours you would travel 35.84 miles total distance per charge.


Taking the word problem out of it:

(Total Battery WH) / (Total Motor Wattage) = (Total Runtime per Charge) x (Avg MPH) = Realistic Expected Distance Per Charge


Now let's look at this from my favorite factor in this electrical burrito, the Amp.  If you read our previous blog entries you'll know that Wattage is a rating comprised of multiplying Voltage by Amps.  For me, since I already know what the Voltage rating is and voltage generally runs at a constant, if it's a 48v system, it's 48v going through it when on.  If it's 72v there's 72v and so on.  What changes is the applied Amperage.  The changing of the amperage is what allows companies to say a motor operates at one speed, while being able to "Burst" to a higher speed.  This is why I prefer to focus on Amps and amp hours.  It works the same, but for me a little cleaner as it take some of the guestimate work out of things.


Amps:


First, let me preface this by saying, not all companies disclose their amp ratings.  Most use Wattage because it's a rating most people are familiar with due to light bulbs.  

If you want to break it down, you can reverse factor by dividing the rated wattage by the voltage, in most cases 48v or 72v, but check your specs to be sure.  What you'll find is most of your E-bikes at 48v are running 12amps.  This means that at the highest point, when your riding up that big hill, the motor is drawing a maximum of 12amps charge.  Here's the funny thing, though your motor might be rated for a certain wattage, most will accept more amps and hence increase the wattage, as mentioned before, burst mode.  Now there are some, well most motors actually, where if it runs nominally at 12amps, it usually means it can range up to about 15-20amps, let's say 20amps multiplied by 48v equals 960w.  This is how and why there is a peak and a nominal rating for most E-bike motors.  Now, let's look at how this would effect distance per charge of our example unit, the Himiway Zebra.


Battery rated Capacity : 20AH

Now there's no Amp Rating, but I know it's 48v @ 750w so well, divide, 750w/48v = 15Amps

Meaning if we run at full draw of 15amps on a battery that can provide 20Amps per hour, we'll end up with 1.33 hours of runtime @28mph for a total distance of 37.24miles per charge.  


Now, that's not bad for the Himiway Zebra, considering our estimates are pure throttle usage and don't impart any human efforts applied.  But I'm still not convinced you'll get 80+miles, more like 60+ if you pedal along too, which is still a respectable DPC(distance per charge).  We prefer to use the "Scotty Principle" in our ratings.  For those that don't know, it's from Star Trek and means, we under promise and over deliver.  It's what made Mr. Scott the best Chief of Engineering Evva!


Looking at the difference between the two calculations you can see that they're relatively close, but not the same.  This is why I take the Amps calc over the Wattage.  Though Wattage is more conservative, Amps are a direct calculation without adding another variable, ie voltage.  But either way you can easily see that you're not going to get 80+ miles out of a charge on that E-bike.  


     I mean anything IS possible.  If they throw someone's Jockey sized kid on it, or maybe just hire some Jockeys.  I mean, Jockeys are literally hired based on height and weight for the exact purposes of extending the horses speed and distance.  Something for the retired Jockeys to do now!  But when it comes to E-bikes, e-Enduros, e-Motorcycles and any other electric transportation we sell, you can be assured we've tested them, we've rated them and we stand behind them.  Because if you stand in front of one you're likely to get run over!  LOL, thanks for reading!

~John 

John

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