What is Pulse Charging? Advantages & Disadvantages of Pulse Charging
What is Pulse Charging? What are its pros and cons?
The following is an explanation of pulse charging copied from Baidu Baike to help everyone easily understand the working mode of pulse charging, as well as its advantages and disadvantages:
[According to incomplete statistics, pulse charging is divided into: negative pulse, positive pulse, and positive-negative pulse. Pulse charging can use a pulse current with adjustable amplitude and duty cycle for charging.
During positive pulse charging, it charges for a period, rests for a period, and so on in a cycle. Adding rest periods during the charging process can eliminate ohmic polarization and electrochemical polarization to a certain extent, but has limited effect on eliminating concentration polarization.
Pulse charging mainly includes three stages: pre-charge, constant current charging, and pulse charging. Compared with conventional charging methods, pulse charging can charge with a larger current. During the charging pause, the concentration polarization and ohmic polarization of the battery are eliminated, making the next round of charging proceed more smoothly. It offers fast charging speed, minimal temperature change, and little impact on battery life, which is why it is now widely used. However, its disadvantages are obvious: it requires a power supply with current limiting function, which increases the cost of the pulse charging method.
For lithium-ion batteries operating under high-current pulse mode, the lithium salt LiPF6 in the electrolyte is more likely to decompose into LiF. The presence of LiF causes the battery's ionic diffusion impedance and charge transfer impedance to increase rapidly. This causes the battery's polarization voltage to rise quickly during high-current charging, exceeding the lithium-ion battery's voltage limit and making it impossible to complete the charging process.
Since nickel-cadmium batteries are prone to polarization during conventional charging, both conventional constant voltage or constant current charging will cause the electrolyte to continuously generate hydrogen and oxygen gases. Under high internal pressure, the oxygen penetrates to the negative electrode and reacts with the cadmium plate to form CdO, reducing the effective capacity of the plate. Pulse charging typically adopts a charge-and-discharge method, meaning it charges for 5 seconds and then discharges for 1 second.
In this way, most of the oxygen generated during the charging process is reduced back into electrolyte during the discharge pulse. This not only limits the amount of electrolyte vaporization inside but also, for those severely polarized old batteries, using this charging method for 5-10 charge-discharge cycles will gradually restore or approach their original capacity.]
From Baidu Baike's explanation of pulse charging, it can be summarized that the advantage of pulse charging is very obvious: it is very friendly to batteries and can even repair batteries that have not been severely over-discharged. However, the disadvantages are also clear. Because pulse charging is a continuous cycle of charge, pause, charge, pause, the repeated starting and stopping causes frequent current impacts on the power supply, making it particularly prone to damaging the charger. This places extremely high demands on the charger's circuit design and power supply.
How to solve the disadvantages of pulse charging while fully utilizing its advantages?
As mentioned earlier, although the pulse charging method is friendly to batteries, it has a non-negligible drawback: it can easily damage charger components. Radiolink's independent balance charger, the CB86/CB86-PLUS, uses a standard low-frequency pulse charging method, which is a cyclic charging mode of charging for 5 seconds, pausing for 1 second, then charging for another 5 seconds, pausing for 1 second. This is why we observe that the charging current of the CB86-PLUS continuously changes during the charging process. Although relatively expensive components are used to ensure product quality, prolonged use inevitably leads to component aging, posing potential safety risks.
Therefore, the latest firmware for the CB86-PLUS (V2.5 and above are considered new firmware; as of December 30, 2021, it has been updated to V3.3; the latest CB86-PLUS firmware download link is: https://www.radiolink.com.cn/cb86plus_firmware) upgrades the hard switching technology of the older CB86 to soft switching technology. This softens the current impact caused by repeated startups, extending component lifespan. Most importantly, Radiolink engineers, after testing common power supplies on the market, developed a hardware fault analysis algorithm specifically for the CB86-PLUS. Through software optimization, this algorithm significantly reduces the stress on component parameters, thereby increasing component service life. It uses software data statistics to analyze charging trends, enabling the charger to stop working immediately and report an error when a hardware fault is detected, greatly enhancing charging safety. Additionally, when the maximum output of the power supply cannot meet the charging power demand, the charger automatically reduces the current to adapt to the power supply's maximum output.
Furthermore, smooth power technology effectively solves the problem of some power supplies being unable to instantly activate their rated power. Consequently, the integration of the fault self-check algorithm, pulse charging, and soft switching technology not only fully utilizes the advantages of pulse charging but also resolves the potential issue of charger component damage caused by pulse charging, allowing users to use it with confidence.