How to Figure out Electric Bike Range
The range of an electric bike is how far you can ride on one charge. The problem is how to assess electric bike range. All electric bikes are advertised as having a particular range. However, these advertised ranges are usually inaccurate. In fact, sometimes they are downright exaggerated, and may even be four times higher than the reality. It is nearly impossible for electric bike range claims to be totally accurate. There are too many factors that make it different from person to person.
Factors to consider:
- how much the rider weighs;
- what level of assistance the rider chooses;
- the terrain they’re cycling over;
- the amount of luggage they’re carrying;
- how fast they go (1/3 faster = 1/2 the range);
- how hard they’re pedaling;
- how many times they stop and start (hill starts in particular will drain power);
- wind conditions;
- temperature (they will get about 15% more range from a battery on a warm sunny day than they would in winter);
- tire pressure (as with regular bikes, soft tires = less efficiency = less distance for power expended);
- what kind of battery they’re using;
- how old their battery is (batteries lose power over time);
- size of their bike motor (big motors are fun, but obviously they drain more battery power); and
- how fast they’re going.
Battery Capacity is the Most Important Factor
Most people will want to have the most powerful bike motor they can afford. But in fact, motor power only impacts how fast you can pull off, and how well you can get up hills. It does not necessarily impact how far you can go. The most important variable to look at in terms of electric bike range is battery capacity.
The size of the battery is directly analogous to the size of a car’s gas tank.
Battery capacity is usually measured in Watt-hrs. Watt-hrs = amp-hrs x volts.
Note: when you are looking at adverts for electric bikes, you may find some where battery capacity is simply stated in amp-hrs. This is insufficient, as it does not include the voltage, so it does not reflect the true energy capacity. So if a bike is advertised with a 36 volt battery, with a capacity of 9 amp hrs, then the true capacity of the battery is 9 x 36, that is, 324 watt hrs (written as 324 Wh).
Watt-hrs is important, because watt-hrs determine the range of your bike, that is, how far you can go.
- Bike A has a 24 Volts and 20 AH battery = 480 watt hours.
- Bike B has a 48 Volts and 10 AH battery = 480 watt hours.
- Bike C has a 24 Volts and 6 AH battery = 144 watt hours.
Bikes A and B have a similar amount of energy. If Bike A and Bike B have equal motors and riders, they will perform in a very similar fashion. The bike with the higher voltage battery will accelerate faster and climb better – but that will be at the expense of some of that energy. On the other hand, Bike C will not take you nearly as far.
Simply put, if you want an ebike that accelerates fast, climbs well, and can travel long distances on a single charge, then buy one with a battery that has high voltage and high amp hours. A battery with high voltage and low amp hours will shorten the distance you can travel on a single charge.
Also consider the issue of range with regard to the type of motor you are buying. For example, there is a good argument that mid drive motors get a better range than hub drive motors because they work synergistically with the gears.