Not All Riding Conditions are Ideal
The purpose of an electric scooter (or escooter) is to get you from place to place. Naturally, how far the scooter can go is an important feature. However, the range is often the feature most often complained by riders less to be than advertised. Why is that consistently so?
The range of electric scooters is affected by more external factors than any other performance feature.
The short answer is that the stated range of an escooter is usually the range achievable in IDEAL conditions. This is not a ploy to over-market or short-change the scooter buyer. The manufacturer has to control the conditions for range testing and specify them in order to publish range information that is meaningful.
A responsible manufacturer will clearly state the conditions and circumstances which result in the range they specify. A good example is the recently released Inmotion V10 electric unicycle(EUC). The published range of the V10 is “~70km”. The manufacturer is even careful enough to use the “~” symbol to indicate that this is an approximation. This range is said to be achievable under these conditions:
- while riding under full power;
- with 75kg load
- at temperature of 25°C
- riding at an average speed of 15km/h
- on a smooth pavement
They have even gone as far as to declare in advance that “riding habit, environment, temp, road condition, load and other factors will affect the range”. This careful and clear treatment of range may have something to do with the intense competition between EUC manufacturers at the time this article is being written. EUC makers are launching a number of new high-end machines at this time and are vying for attention from riders who care very much about performance.
Many electric scooter manufacturers spare the consumer such details, and simply publish a single figure for the range. This can lead to customer dissatisfaction when customers take the range at face value.
In this article, we will show you how battery range can be calculated, and more importantly, what factors suck the life out of your battery, so you can avoid them and maximize your range.
The battery capacity of your scooter is analogous to the size of the fuel tank in a car. The more fuel you can carry, the longer the drive you can get. The motor will be like the engine displacement of a car: the larger it is, the more powerful but power-hungry it will be.
With some basic arithmetic and high school physics, we can calculate the theoretical range based on the specifications of the battery and motor.
Above: It is possible to calculate the range once we know the scooter specifications like battery capacity and motor power.
Let’s say we want to calculate the range of a typical medium-sized electric scooter with these specifications:
- Battery: 36 Volts (V) 10.5 Amphere-hour (Ah)
- Motor power*: 250 Watts (W)
The first formula is something we all know:
DISTANCE (Km) = SPEED (Km/hr) x TIME (hr)
This formula says that if we know the speed we ride at, (let’s assume we ride at a consistent speed,) and the duration the scooter can sustain this speed until the battery runs out, we can calculate the distance it can travel.
For the SPEED, we will use the highest possible speed at which we can ride the escooter. The speed limit for Personal Mobility Devices (PMD) in Singapore, where this article is written, is 25km/hr. So let’s use this figure for speed.
For TIME, we can calculate it from the battery capacity and motor power.
To do this, we need to figure out the battery capacity. This is measured in Watt-hour (Wh), the energy (in Watts) it can deliver in one hour.
Watt-hour (Wh) = Ampere-Hour (Ah) x Voltage (V)
So the capacity of our battery is 10.5Ah x 36V = 378Wh
Knowing the amount of energy in the battery, and knowing the power (and hence consumption) of the motor, we can now calculate how long it will take for our motor to burn through this energy:
TIME (hr) = Battery capacity / Power consumption = 378Wh / 250W = 1.512 hr
Now we have the SPEED and TIME to put into our first formula:
DISTANCE = SPEED x TIME = 25 Km/hr x 1.512hr = 37.8 km.
So in theory and on paper, your scooter can carry you for 37.8 km before its battery is fully depleted.
* Note: some manufacturers indicate peak power instead of nominal (average) power. If both figures are indicated, use nominal power for a conservative calculation.
Above: understanding your escooter’s range and knowing what affects it reduces the chances of you running out of battery and getting stranded.
In practice, however, the range story doesn’t end here. Because the calculation so far has only considered the characteristics of the battery and motor. We have not taken into consideration the rider, riding conditions and other factors in the calculations.
Let’s find out in detail the factors that have a negative effect on range, and what you can do about them to squeeze the maximum mileage out of your e-scooter.
E-Scooter Range Killers
Broadly speaking, these conditions or actions compromise range:
- Insufficient tyre-pressure
- Riding uphill
- Riding aggressively
- Riding or storing escooter in high temperatures
Let’s look into each one in detail.
It is common sense that an electric scooter will have to work harder to move a heavier rider compared to a lighter one.
All electric scooters have an indication for the maximum safe payload. Most are rated at 100 Kg, with some larger models at 120 Kg. Some high end or heavy duty models carry as much as 150 kg. The maximum load is not the same as the optimum load. It’s a common practice for electric scooters makers in the market today to use a rider weight load of about 75 Kg for performance tests. This is understandable because 75 Kg is roughly the weight of an average healthy adult male.
In other words, most of the time, any rider heavier than 75 Kg can immediately expect the range achievable to be lower than the published figure.
Problems with overloading tend to happen when large riders buy lightweight scooters for the sake of portability.
These scooters may be underpowered for the big riders, but it is alright if the rider understands there is a trade-off and is willing to give up some range for portability.
Post time: Apr-25-2019