Does Fast Charging Damage 18650 Lithium-ion Battery Life

Dec 28, 2022 | XTAR

In terms of charging cylindrical lithium-ion batteries, the maximum charging current of many chargers can reach 3A, 4A or even higher. This can fully charge a battery as soon as possible, greatly reducing the waiting time. However, some people also feedback that they don’t like fast charging. They think that the 18650 charging current above 1A is too high and will affect the battery life. Therefore, when they buy lithium-ion battery chargers, they tend to choose those supporting manually adjust the charging current, and use small charging current. So, will fast charging damage the li-ion battery life?To answer this question, we need to know three pieces of information firstly.

What’s the li-ion battery charging method?

The traditional cylindrical lithium-ion battery chargers mainly use CC-CV charging method. In the constant current(CC) charging phase, fast charging is performed to increase the charging speed. When the battery is almost be fully charged, constant voltage charging is used. The voltage remains unchanged and the charging current decreases, which prevents the battery from overcharging.

Note that the charging current on the charger specification usually refers to the current in the constant-current charging phase. The same as the manually charging current.

What is the optimal charging current for the Li-ion battery?

We usually use C-rate to calculate the battery charging current. The li-ion battery is 0.5C. For example, a 18650 2200mAh takes constant charging current of 1A, and charging speed of 2-3 hours. Shortening the charging time increases the charging current, which increases the battery temperature. This is a key factor in accelerating battery aging. High-speed charging above the charging C-rate can accelerate degradation, which can adversely affect battery performance.

Besides the proper charging C-rate, you need also to consider the battery internal resistance.

Are manufacturers doing anything to protect batteries?

XTAR, as a professional lithium-ion charger manufacturer, firstly adds trickle charging on the basis of CC/CV charging, that is, TC/CC/CV three-stage charging. With this charging method, if the battery voltage is less than 3V, it will start the trickle charging stage, waking up and protecting the battery with a small current. Then it starts fast charging after the voltage enters the normal value with 0.5C rate. When the battery voltage approaches 4.2V, it goes into constant voltage charging. The charging current continues to drop until the battery is fully charged, and the cut-off is accurate to prevent overcharging.

At the same time, the XTAR chargers automatically detect the battery type, intelligently select the best charging solution according to the battery condition. Even if you manually select the charging current, the XTAR charger will intelligently judge whether it is suitable according to the internal resistance of the battery and the battery type.

Besides, all of the XTAR chargers have built-in multiple protections to prevent the battery from overcharging, overcurrent, and short circuit. Some advanced chargers can also regulate the battery to the optimal storage voltage to prolong battery life.

Now, with the above knowledge of charging, let’s answer the question on the title. Fast charging will not damage your 18650 li-ion battery if you use a good smart charger. The premise is, please make sure to buy a top brand high-quality charger instead of no name one. Because those cheap low-quality chargers do not take any protection measures during the battery charging.


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