If you want to power through winter, you’ll need to prevent your e-bike’s battery becoming cold or wet. Here are some tips.
Batteries work best at moderate temperatures. They release stored power through electrochemical reaction, and this reaction doesn’t work as well when it’s cold. When the temperature is approaching or below zero degrees centigrade, you’ll notice that your e-bike’s performance suffers.
A cold battery suffers a drop in capacity. As a result, your won’t get the same assisted-pedalling range that you’re used to. How much will it drop? That’s one of those ‘how long is a piece of string?’ questions, as it will depend on the temperature, the particular battery being used, and how you’re using it. But a 20-30% drop is likely – and it might be worse. As well as that, there’s a drop in voltage. So your e-bike’s assisted top speed will fall.
Beat the cold
The simplest option to stop the cold degrading the battery’s performance is to park your e-bike indoors. That’s ‘room temperature’ indoors, not a freezing cold garage. Not practical? Take just the battery inside with you; most are easily removable.
Use the opportunity to put the battery on charge. If you’re dubious about having enough range to get to work and back, take your charger with you. Alternatively, invest in a second charger that you can leave at work. If the battery has been out in severe cold, don’t put on charge straight away. Let it warm up a bit. This enables it to charge better. This pre-charge ‘thawing’ could take a few hours.
Riding your e-bike in the cold isn’t nearly as bad as storing it there. That’s because the electrochemical reactions going on when the battery is in use also generate heat, so it will keep itself warmer – or at least less cold. For shorter journeys in typical British cold (around zero), the battery shouldn’t need insulating. For longer journeys and/or colder conditions, consider investing in a neoprene battery cover or, if necessary, making your own.
Beat the wet
A cover will also help keep the battery dry. Moisture can do real damage to a battery, and while most e-bike batteries are reasonably well protected against the elements, every little helps.
Fit full length mudguards for winter if your e-bike doesn’t already have them. This will prevent water being sprayed at the battery by the bike’s wheels. You’ll keep cleaner and drier too!
Locks can freeze solid in the cold, including the lock that secures your battery to the bike. Regularly removing the battery and storing it somewhere warmer should be enough to stop this lock seizing. A little lubrication (WD40, for example) will help keep it turning smoothly. While pouring hot water over a stuck lock can free it, this isn’t a great idea when the lock is adjacent to a battery.
If you haven’t yet chosen your e-bike, one with a battery situated low down near the bottom bracket will be more stable than one with the battery high up under a pannier rack. When conditions are slippery – wet or icy roads, wet leaves, mud – you’ll be able to keep control better if the e-bike drifts or wobbles.