Ebike Battery Care Top Ten Q&A
1. I just got a new E-bike … how do I care for my battery?
Awesome – lithium-ion batteries are amazing and you will want to insure your pack is properly cared for. Your eBike comes with a battery charger, and most of the ebikes are shipped with the battery at approximately an 80% charge level. The level may be higher or lower, and you can power up and check your display for an exact reading. Once you plug in your charger, the LED light on the charger will be red, and when fully charged will turn green, indicating the battery is fully charged and ready for use. Unplug it and enjoy your ride.
We use the term “battery” here, but your ebike battery includes the case (pictured left), individual cells within the case (pictured below), a circuit board inside the case that manages the cells and communicates with the bike’s controller (cpu), an off/on switch, a connection plug for mating with the bike, a lock with key for removing the battery, and typically also a push button that will give an approximate read on the battery charge level (independent of your LCD dashboard, and not as accurate).
2. What is the best practice for charging my E-bike battery after my ride?
You may have heard, “top it off after each ride.” Most do this - they charge it fully after each ride. A high voltage cutoff (HVC) in the battery management system (BMS) will shut off power into the battery cells after the pack reaches a level considered 100% (approximately 42V for a 36V battery system or 54.5V for a 48V battery system). This practice provides roughly 400-500 cycles before there is a substantial degradation in the cell chemistry. Ebike battery packs are relatively economical and years down the road - an easy replacement – they range in price from $300. to $700. depending on your model. For most people, five years of charging twice a week is 500 charge cycles, and your battery is still alive and has a decent charge capacity, but your range may be reduced a bit (similar to year two on a cell phone).
3. What should the temperature be on the pack before charging it?
Observe the battery temperature by touching the pack, and charge your battery when it (battery) is not too cold or too hot. Ideally the room air temperature around your ebike, when idle, should be 50 – 80 degrees (normal room temperatures). Avoid storing your ebike where direct sunlight hits the battery and raises the pack’s resting temperature.
Let's say you just came back from a 50- mile ride and the battery pack is pretty warm (you may not be able to feel it by touching the plastic case, but it does get warm). Leave it for 30 minutes so it is back close to the room temperature.
4. Can I double the life of my battery pack?
Studies show you can double the cycle life of your battery by charging it only to 80%, rather than 100%. Here is an infographic - from Grin Tech, one of the innovators in the Li-ion space:
5. I want to maximize battery life ... how can I do it?
Be mindful of a couple parameters:
A. High temperature = is BAD for Li-ion cells. So, what is high temperature? Anything above 40'C or 105'F (trunk of a car on a hot summer day, or exposing the battery to direct sunlight in hot, sunny climates). Below freezing temperatures - those are not great either, so avoid temperature extremes.
B. Time (days or weeks) spent at high or low voltage = is definitely NOT the BEST for Li-ion cells. You charged it to 100% and you're going away on a a month’s vacation. This may not provide the longest lifespan for the pack. Conversely, avoid time spent at 0% charge level = really BAD. Although your BMS may report 0%, there is technically a little bit of voltage left, but after time passes, you may lose this little bit of charge and then not be able to recharge the cells at all – the lithium chemistry magic ends. In the electric automobile space, Tesla’s Elon Musk responds to this topic from a customer’s question, and he recommends charging to 80%:
In the desert SW area, where temperatures can get extremely hot in the summer, and where snow birds may depart the area and leave their bike stored away for months on end - beware. Avoid storing in a hot environment and leaving your ebike discharged for long periods of time when away at your summer retreat. Here is more on the topic ...
6. How should I store my E-bike battery?