E-biking in snow and cold: E-bike battery - what to do in sub-zero temperatures?

The good news first of all: a drive in sub-zero temperatures does not harm the battery per se. But there are a few things you should bear in mind. Firstly, to preserve the service life of the battery. And secondly, to avoid running out on tour. This is because both the performance of the motor and the range can suffer in extreme temperatures. This is because the electrical resistance in the battery increases in cold weather. With the right tips, however, the losses are kept within limits.

The biggest mistake with the battery in winter

Let's start with the absolute no-go: Setting off with an ice-cold battery. This will lead to enormous losses in range and performance on a tour, as the battery has to fight against the increased electrical resistance right from the start and finds it difficult to reach operating temperature. This applies from single-digit plus temperatures at the latest. Things get really drastic when temperatures drop below freezing. However, this problem can be easily avoided. The battery should be warmed up to room temperature before the ride and only inserted into the bike shortly before the tour. In the case of permanently installed batteries, the entire e-bike should not be parked in the cold if at all possible.

The same applies to longer breaks on the road. Regardless of whether the bike is parked outside the office for commuting or at the hut on tour: In winter, take the battery into the warmth if at all possible. Incidentally, many batteries are labelled with a temperature range in which the battery may be operated, charged and stored. Most manufacturers specify temperatures above zero degrees for charging, while values down to -10 or even -20 degrees are usually specified for operation.

This keeps the battery in the e-bike warm

During the journey, the e-bike has a certain amount of self-protection on board. This is because the battery and motor heat up when they have to work. The more power the battery has to deliver, the more heat is generated. It may therefore be better to set a high assistance level in icy temperatures. "Saving power with Eco mode doesn't make sense in winter, as the battery doesn't have to deliver enough power and cools down. The capacity of a cold battery collapses, as the electricity literally freezes in the cells," warns bike developer and E-MTB expert Lutz Scheffer from Rotwild.

Accordingly, cold air is not a problem as long as the motor is working. Long breaks or long distances travelled without motor assistance are critical. Protective thermal covers wrapped around the battery or down tube can help to keep the battery at the right temperature. However, you probably shouldn't expect miracles from these neoprene covers.

The construction of the bike can also make a difference to its resistance to cold. An external battery is more directly exposed to wind and weather. However, if the battery is concealed in the down tube, this has a certain insulating effect.

Where to put the e-bike or battery in winter?

For long-term storage, temperatures between five and 25 degrees are fine. The golden mean is ideal, i.e. 10 to 15 degrees. It only becomes really critical in winter when the temperature at the storage location drops below zero degrees, which should be avoided in the long term. So: remove the battery. The charge level of the battery is also important for longer storage. Batteries should not be stored fully charged and certainly not fully discharged. A charge level of 30 to 60 per cent is ideal. Logical: The battery should be stored in a dry place.

Charging an e-bike battery correctly

If the battery has become cold on or after the tour, it should only be connected to the charger once it has warmed up properly and reached room temperature. The ADAC warns that sudden temperature changes can cause condensation to form, which in turn can lead to damage. The general rule for refuelling is: ideally at room temperature.

Correct planning protects against failures

If you take the above tips to heart, you should not experience any enormous loss of range purely due to the outside temperature. Nevertheless, you should take a conservative approach to planning your winter journey. In practice, the range can certainly drop by half. However, this is usually less due to the temperature than to other factors. In snow, the rolling resistance of the tyres increases dramatically. In addition, the tyres have significantly more slip, so they spin easily when accelerating. "On average, the tyres spin around 30 percent faster than the driving speed would normally require," says expert Scheffer.

Increased slip and rolling resistance cost a lot of energy. The same applies to special winter tyres with a soft rubber compound or even spikes. Tours that are easily possible with one battery charge in summer can easily consume twice the battery capacity in unfavourable conditions in winter. In theory, the cold outside temperature even has an advantage for the e-bike system: the motor itself remains cool, which improves efficiency. De-rating, i.e. the reduction in motor power due to overheating, does not occur.

Further tips for cycling in winter

• Tyre choice: Spikes are indispensable on snowy and icy surfaces. A popular classic is the Schwalbe Ice Spiker Pro, available in the 29er version with around 400 teeth. The following applies to all models: the more spikes there are, the better the grip.
• More light! The days are short in winter. That's why you need a light on your bike. Make sure that the battery is fully charged. If the light is not permanently mounted, stow the battery in your rucksack or on your body, as its performance quickly drops at low temperatures.

• Flat instead of click: The cleat means that clipless pedal shoes always have a cold bridge. Therefore, switch to flats in winter. Hiking shoes have slightly less pedal grip, but are often warmer than bike pedals.
• Chassis check: At low temperatures, the composition of the oil in the fork, damper and dropper post changes. Therefore, readjustment is necessary. You may need to change your compression and rebound settings. For hardcore winter bikers: Have the fork and damper oil changed to an oil with a lower viscosity (winter oil) during the autumn service.

• Warm hands: Mountaineers wear silk gloves under their warm gloves. The luxury version is heat pads that are integrated into the gloves, as is the case with the manufacturer TheHeatCompany.
• Chain and brakes: The chain and disc brakes need special care in winter. High-viscosity lubricants for the chain reduce wear. Caution: At extreme sub-zero temperatures, the mineral oil in Magura and Shimano disc brakes can become more viscous.
• Ski helmet is warmer: Pay attention to sensitive areas of skin in sub-zero temperatures: Cheeks and nose. Buffs, ski helmets and ski goggles are warmer and protect your head and face. Poodle hats are only compatible with classic cycle helmets to a limited extent. But there are stylish helmet caps.
• Tour selection: Take the snow conditions into account when planning your tour. Ten centimetres of powder with a frozen ice or hard snow surface are dream conditions - powder biking. In hard and soft snow, it is best to switch to gravel paths.