How to manage the autonomy of an electric bike?

The management of the battery life of an electric bicycle is a particularly abstract element for the majority of the beginners of an electric bicycle. Indeed, learning is generally done on the job, in the absence of technical knowledge specific to electric batteries, their capacity, their consumption and their autonomy.

As we will see in the rest of this page, a few simple tips to apply will allow you to gain autonomy, for everyday trips in town, as well as for long rides on the road.

This guide is also intended to help you understand how the motor and the battery work together, so that you can make the best possible choice when buying an EV.

Apprendre à bien gérer l’autonomie de la batterie d'un VAE-1

The technical characteristics of the batteries of VAE

Nowadays, the majority of electric bicycle manufacturers use lithium batteries, known for their high energy storage capacity . Lithium batteries also offer the advantage of a reasonable weight and volume, an improved lifespan and the absence of memory effect. As a reminder, the memory effect of an electric battery is a constraint that forces you to wait until it is completely empty before you can recharge it.

Miniaturization and weight saving are two very important criteria in the world of electric bikes, with a generally observed rule: the lighter the material, the higher the price.

The capacity of an electric bike battery

To determine the storage capacity of an electric battery, we must first refer to its voltage, expressed in volts. The electric bikes available on the market have voltages of 24 V, 36 V and 48 V.

You also need to look at the maximum capacity of the batteries, which is expressed in ampere/hour (Ah). To simplify the understanding of this data, it is possible to make an analogy with a car, comparing it with the capacity of the fuel tank.

Thus, by multiplying the voltage by the capacity in Ah, we obtain the quantity of energy available in a battery, in Watts/hour (Wh). For example, a 36 V, 8 Ah battery gives a result of 288 Wh. This calculation is the one that allows to determine precisely the capacity of a battery to store electrical energy and, consequently, to be able to compare two battery models.

Be careful not to confuse the Watts/hour indicating the capacity of a battery with the Watts associated with the nominal power of the motor of the EAB. For information, the nominal power of an electric bike motor is limited to 250 W in Europe, which is the most obvious choice when buying an EAB.

What is the link between capacity and range?

In theory, the capacity of a battery determines its autonomy. Some manufacturers give figures in hours of use or in kilometers covered. However, these figures are only theoretical, as the actual range of a battery is affected by many factors.

The main elements that can impact the autonomy of an EV battery are the following:

  • the weight of the bike, the weight of the rider and his position on the saddle;
  • the type of EAB (city bike, mountain bike or VTC);
  • the relief of the route;
  • the type of road used (asphalt, trail, gravel, etc.);
  • the level of tire inflation and the diameter of the wheels;
  • The quality of the bike's transmission maintenance and the location of the motor (in the crankset, front wheel or rear wheel hub);
  • the cyclist's habits (power of action on the crankset, speeds used);
  • the type of electric assistance chosen (eco mode, standard mode or sport mode);
  • the traffic environment (numerous stops and restarts when used in the city);
  • the outside temperature (the electric batteries have an optimized capacity between 5° and 25°).

As it is easy to see, the number and diversity of these different factors make any estimation very fluctuating, from one trip to another and even from one day to another.

Therefore, for a cyclist who needs to know precisely his or her available autonomy at any given time, it is recommended to opt for the solution of the connected VAE, or smart bike. A connected electric bike model offers the possibility to benefit from a screen acting as a real on-board computer.

Combined with several sensors and controllers, the connected EAB is able to display the remaining autonomy by taking into account multiple factors, such as the battery charge level, the terrain and the type of road of the last kilometers covered.

Apprendre à bien gérer l’autonomie de la batterie d'un VAE-2

Our tips and tricks to increase the autonomy of an electric bike

The autonomy of an EAB is therefore determined by technical elements and factors related to the type of use. This autonomy can also be improved by the way the cyclist manages the use of his electric bicycle.

First of all, it is possible tooptimize pedaling habits and gear changes, by adopting a flexible driving style and avoiding forceful pedaling. Moreover, in the city more than anywhere else, stops and starts are frequent. It is advisable to use the minimum level of assistance offered by the EAB during these phases, with a potential gain of 20% of autonomy on the same journey.

The choice of the level of electric assistance being a key element of the autonomy of the battery, it is thus recommended to reserve the maximum assistance for the roads in rise or the passages against the wind.

The gain in autonomy also depends on well inflated tires, because tires with insufficient air pressure increase the friction forces, resulting in a higher energy requirement for the same speed.

The user of an electric bicycle can improve the autonomy of his EAB by modifying his route. For a typical commute to work, it may be possible to avoid taking a road or street uphill, or to find a bike path nearby. Riding on a bike path is generally less energy intensive than riding in the middle of car traffic and pedestrians.

Finally, the choice of the type of bike remains a determining criterion, with, for example, the possible presence of a sensor in the pedals. Such a system allows the bike's computer to offer the best assistance mode and the necessary motor power at the right time, according to the data collected in real time. Electronic management of the level of assistance and the power of the motor action are an effective source of gaining autonomy without having to pay attention.

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