Energy booster, energy bar, power bar or power briquette – whatever you call it: the battery is the heart of the pedelec. The engine will not run without its juice. It is also the most expensive component on an electric bike. For this reason alone, it is better to treat it well in order to keep the storage cells fit for a long time.
Chic and e-bike battery? That didn’t go together for a long time. Just a few years ago, the pedelec battery was usually attached to the luggage rack. This is a visually clunky solution that is rarely found today.
It is now common to accommodate batteries in the frame triangle or in the frame itself with a favorable center of gravity. They sit on the frame tube or are either partially or fully integrated in the tube.
If the battery disappears completely in the frame, it is ideally protected against stone chipping, dirt and moisture and also against theft, says Thomas Geisler from the press service bicycle (pd-f). “Some integrated solutions have the disadvantage that charging is usually only possible on the e-bike itself.” The entire bike often has to be transported to the socket because the battery is no longer intended for everyday removal.
In the past, nickel-based batteries were also screwed onto e-bikes. The standard today are lithium-ion batteries with a comparatively high energy density. This means: You can store more energy with a relatively low dead weight.
“Compared to other battery technologies, lithium-ion batteries are characterized by a long service life and low self-discharge,” says Tamara Winograd, press officer at Bosch E-Bike Systems. The group’s division is one of the best-known manufacturers of e-bike components alongside Shimano, Yamaha, Panasonic, Mahle and Brose.
The most important key figure for everyday use is measured in watt hours – abbreviated Wh. The energy content in a fully charged state, often also called capacity, is given in Wh. Batteries with capacities from 400 Wh to 750 Wh are common on the market.
How far can you get with one battery charge? A question to which “no general answer can be given,” says Winograd. This depends on different parameters. The weight of the driver, the luggage or the tire pressure influence the power consumption, but also the selected support mode, frequent starting and the motor and the battery itself.
“Environmental factors such as temperature, wind conditions, subsoil and terrain also play a role,” says Winograd. Rough terrain climbs require more energy than flat sections on paved roads. “So less than 20 to well over 100 kilometers are possible with one battery charge.” If you have a double battery on board, you can also cover more than 200 kilometers.
According to the ADAC, poor maintenance can also reduce the range. For example, when a neglected chain causes unnecessary friction losses. If you search the web under “range calculator” and “e-bike”, you will find the appropriate tools to determine individual values.
There is one decisive difference to e-cars: “If the battery is completely empty while driving, you can still move the pedelec with muscle power,” according to the ADAC.
E-bike batteries are charged at the household socket. How long a full charge takes depends on the capacity of the battery and the charger used. Accordingly, it can take between two and six hours until the charge level is 100 percent.
Incidentally, the previously feared memory effect, in which frequent partial discharges at the expense of capacity, generally no longer occurs with lithium-ion batteries, says Dekra bicycle expert Jochen Hof. So you can plug in the battery as often as you want.
But leaving it on the charger for days is not advisable due to the basic risk of fire and explosion – even if integrated battery management systems are intended to protect the battery from overloading when charging. E-bikers should only use the original charger for charging, otherwise warranty and guarantee claims will be void and the material could be damaged.
Because there are occasional battery fires, experts advise keeping an eye on the charging process. Dekra recommends charging the battery on a surface with stones or tiles. A weather-protected place outside of the house or apartment is ideal.
Protection is also required in midsummer: Despite the high safety standards for e-bike batteries, Dekra expert Hof warns against excessive heat influence – for example, if the bike stands in the blazing sun for hours in front of the swimming pool in the summer heat.
“So it’s better to park in the shade or remove the battery.” But even on days that are not so hot, even in autumn and winter, direct sunlight can heat up batteries – and should therefore be avoided.
Lilly Eckstein from e-bike component manufacturer Brose explains what can happen: Extreme heat can lead to an increase in the internal resistance of the battery. This means: More energy is converted into heat in the battery cells. “The motor lacks this energy and inhibits the performance of the e-bike,” says Eckstein.
In summer you can protect the battery from heat with suitable cases or covers with reflective properties. Because batteries feel most comfortable between five and 25 degrees.
Very cold isn’t good either. According to Dekra, the battery works more efficiently in winter if it is protected from the cold with a neoprene cover, for example. Then it keeps the optimal operating temperature better – important, because minus degrees cost kilometers of range.
The ADAC advises: “If the temperature is below freezing, you should remove the battery while parking and store it in a room at room temperature to avoid damage.” Charging in the cold is also not good for the battery.
Better to wait until it’s room temperature. According to the Central Association of German Electrical and Information Technology Trades (ZVEH), this takes about ten minutes. This also applies to a hot battery in summer.
If a pedelec battery is not used for a longer period of time, it is best stored at room temperature in a dry environment and protected from direct sunlight. Dekra expert Hof recommends a charge level of ideally 30 to 60 percent to protect the memory from wear and tear.
The ADAC indicates a sleep mode that some battery models can be put into. Then it is not a problem to store it for up to six months.
As with all electronic components, the same applies to the battery: high-pressure cleaners and harsh cleaning agents are taboo. Instead, Bosch spokeswoman Winograd recommends wiping the battery with a damp cloth from time to time. The best way to dust off the plug poles on the battery and bike is with a dry cloth. Occasionally they should be lightly greased.
The manufacturers of e-bike batteries promise between 500 and 1000 charging cycles. A charging cycle corresponds to a full charge to the entire capacity and can therefore be split into several partial charges. According to manufacturer estimates, this corresponds to three to five years of use or a total distance of 25,000 to 100,000 kilometers.
“But that doesn’t mean that the battery is defective afterwards,” says Thomas Geisler. It still has an output of around 70 percent compared to new models. However, it degrades faster and needs to be recharged more often.
If the battery is defective – the cause can be a fall or prolonged storage in the blazing sun – the manufacturers strongly advise against opening it yourself for safety reasons. “The ingredients of lithium-ion battery cells are fundamentally flammable under certain conditions,” says a Bosch guide. In addition, any warranty and guarantee claims expire.
If the battery is worn out, replacement is expensive. The specialist dealer can read out the status using a diagnostic device. Depending on the capacity and model, a new part can cost up to 1000 euros.
The specialist dealer is responsible for disposing of the old battery and usually cooperates with the Foundation for the Common Battery Return System (GRS). According to the press service Fahrrad, when an e-bike is sold, a sum goes to GRS for the disposal and recycling of the batteries. Disused batteries are collected from the dealer.
Valuable substances in the electricity storage system should thus be returned to the raw material cycle. Bosch assures us: “Depending on the recycling process, more than 80 percent of the valuable raw materials can be recovered and reused.”
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