Lithium-ion battery

Structure and function of the batteries.

Electric scooters and e-scooters get their drive energy from a rechargeable battery. All of our eaventura electric scooters are equipped with so-called lithium-ion batteries because they are very light for their energy density and make it possible for the scooter to have a very low weight.

Anyone who thinks that the wattage of a battery is the only indicator of performance and driving time is not entirely correct. The voltage numbers are also important. If you divide watts by volts, the result is the battery's current in amperes.

Ampere is the unit in which current is measured.

The capacity of a battery is given in ampere hours. It indicates the amount of electricity stored in a cell. The more ampere hours (Ah) a battery has, the longer it can be used. Ampere hours are also known as the nominal capacity.

An example: A battery has a capacity of 10 Ah hours. This means that you can draw 1 ampere per hour from the battery for 10 hours.

Watt is the unit of measurement for electrical power.

The energy that a battery cell can deliver under certain conditions is measured in watt hours (Wh). Watt hours are also referred to as nominal energy. If a battery provides 1 watt of electrical power for 1 hour, the battery delivers 1 watt hour. The watt hours of a battery are calculated from voltage * capacity.

An example: The description of a battery states 25 volts with 18 Ah. So 18 Ah x 25 V = 450 Wh.

Average range of an electric scooter.

The range of the e-scooters naturally depends on the driving style and the weight of the driver, as well as the road surface, the temperature and the speed driven. So when purchasing, it is worth considering whether the range is one of the decisive factors for you when choosing a particular model.

Structure of the lithium-ion battery.

A lithium-ion battery contains many small battery cells. Each cell consists of two conductive layers of aluminum or copper. In between are the cathode and anode, the two electrodes of the battery. The cathode is the positive pole of the battery and is made of lithium metal oxide. The anode, the negative pole of the battery, is made of graphite.

The charge carriers in the battery are lithium ions that move back and forth between the cathode and anode. To make this possible, there is a liquid between the two poles, the electrolyte. It consists of an organic solvent and a conductive salt. This electrolyte must be very pure and water-free so that charging and discharging can take place without disruption. To prevent a short circuit in the battery, a separator separates the two electrodes from each other. This is a thin membrane that only allows the ions to pass through.

Loading and unloading

When charging, voltage is applied to the battery from the outside, which creates an excess of negatively charged electrons in the anode. Electrons are then removed from the cathode, and the positively charged lithium ions therefore migrate from the cathode to the anode. There they combine again with an excess electron and are deposited - again as a neutral particle - in the layered structure of the graphite. The battery is then charged.

When discharging, for example when driving an electric car or using a smartphone, this process is reversed: the lithium ions then migrate through the electrolyte back to the cathode and the stored energy is released again.

Lithium-ion battery life

This process cannot be repeated endlessly, and that is why batteries age after a while. After many charging cycles, the crystalline structure of the lithium layer changes, which is why fewer and fewer lithium ions can be activated. This is why batteries lose their performance over time. Their lifespan and performance depend on how uniform and pure the chemical composition of the electrodes and electrolyte is.

Depending on treatment, the lithium-ion battery can last between 500 and more than 800 charging cycles. That's more than 25,000km of mileage.

A charging cycle represents a complete charging and discharging of the battery, i.e. the use of the complete 100% of the charge level indicator.

So, for example, if I unplug my e-scooter from the power cable in the morning at 100% and use 50% of the battery during the day, then plug the power cable back in at night to charge it and use 50% of the battery again the next day, that was only a single charging cycle, namely 100% in total. So 100% of the battery must be used up in total before a charging cycle is counted.

When the lifespan of a battery is running out, meaning that up to 800 charging cycles have been used up, the battery does not "die" from one day to the next, but rather it slowly loses capacity. This means that over the weeks it will supply fewer and fewer hours of power after charging, and the usage time after charging will become shorter and shorter. The failure of the battery from one day to the next, so that suddenly nothing works anymore, only occurs in exceptional cases.