We are often asked how long it takes to charge the battery of an e-bike. Depending on the battery's capacity and charger type, it can take 8-12 hours to charge a battery fully. But, it takes only a few seconds to plug in the charger and forget about it until you use your e-bike again.
Lithium-ion batteries have no memory problem
The idea that a battery can only be charged when it is wholly depleted is still persistently making the lives of e-bikers unnecessarily complicated. Many believe that they need to empty the battery before it can be charged again completely. This assumption is incorrect for Lithium-ion batteries.
Nickel-cadmium and nickel-metal-hydride rechargeable batteries did have memory problems. The memory problem could only be rectified with deep charge/discharge cycles.
However, batteries have evolved. Most, if not all modern e-bikes, have lithium-ion batteries. These batteries have no memory problems, and you can charge them as often as needed. It is like using a car: you can top up the gas tank any time and use them at any time.
Please charge the battery shortly before using it, and don't leave the charger connected to the battery for days when it is 100% charged to avoid a cycle of minor charges and discharges.
Use a timer like the our favorite one below, to cut off power to the charger after 12 hours, or set a reminder in your calendar.
Do also not store an empty battery and avoid temperature extremes.
Charging cycles determine the lifespan of lithium-ion batteries
Bosch, a premium brand in the e-bike world, has produced an excellent guide on battery care. Most revealing is the company's guidance on charging cycles. It does not matter how often you plug in the charger and partially charge the battery. What matters is the number of charge cycles over the life span of the battery.
The number of charge cycles measures a lithium-ion battery's lifespan. A battery that has been charged and depleted 500 times will have the same capacity as a battery that has been charged 1,000 times each time it is half-empty. If you have 50% left in the battery and recharge the battery to 100%, you have used 1/2 of one charge cycle. If you have 80% left in a battery and charge it to 100%, this counts as 20% of one charge cycle.
Most modern lithium-ion batteries can be fully charged for 500 or more cycles before losing 30-40% of their capacity. Bosch estimates that 60 to 70% of the original capacity will still be available after 500 full charges.
Interruptions in the charging process do not harm lithium-ion batteries. In other words, the battery does not have to discharge completely before recharging.
Frequent e-biking is good for your health and the health of the e-bike's battery. Don't let the battery's charge stop you from e-biking frequently on shorter trips. A lithium-ion battery performs best when recharged at room temperature, when 40-60 percent of the battery is left. The same may be true for you.
Gregory discovered e-biking after 20 years of overseas work as project manager for the World Bank and USAID. He writes about e-mobility and e-biking in the DMV area, and loves the outdoors (white water kayaking, hiking and biking). He lives with his wife, Janet and Queenie the cat, in Washington DC. He recently e-biked 4,685+ miles across America and raised $180,000 for a charity.
Favorite e-bike: Riese & Muller Super Charger Class 3 touring e-bike.
Dr. Gregory F. Maassen
FOUNDER E-BIKE LOVERS