Why does electric vehicle battery drain fast in Winter ?

Why does the performance of lithium-ion batteries in e-cars, e-bikes and cell phones drop at low temperatures and what can be done about it?
When charging and discharging batteries, an electrochemical process takes place that is significantly influenced by the ambient temperature. In virtually all battery technologies, this works best at temperatures between 10 and 25 degrees Celsius. At lower temperatures, the electrolyte fluid becomes more viscous, increasing internal resistance. This makes part of the battery (temporarily) unusable. 

This is familiar to anyone who has ever carried their cell phone in an outside pocket while skiing: Despite being fully charged in the morning, the device suddenly reports an empty battery and switches off. The increased internal resistance suggests the battery is already empty. Carefully warming the device, however, quickly brings the capacity back. It is then best to carry the phone closer to the body.

But what about electric cars? In winter temperatures, you have to reckon with longer charging times and weaker recuperation. Since energy consumption due to heating of the interior increases at the same time, the effective range is reduced - usually between 10 and 30 percent. 

A practical measure to maintain the range in winter is to park the vehicle in the (not quite so cold) garage. It also makes sense to preheat the car while it is still connected to the power grid. This is already possible in most cars today via the corresponding app. If this feature is not available, consumption can be reduced by heating the interior in recirculation mode. If a long range is important to you, even in winter, you might consider buying a particularly energy-efficient heat pump.

It's easier with e-bikes or e-scooters where the batteries can be removed. If you can, you should take the battery into the warm room immediately after the ride. Once it has reached room temperature, charging can begin. For some bikes there are also neoprene sleeves that slow down battery cooling during the tour. 

If you store your e-bike in the basement, you should make sure that the battery has a medium charge level: Too high a state of charge accelerates battery aging, too low a state of charge can lead to irreparable deep discharge during longer periods of storage. 

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