The correct charging method for
26650 lithium-ion batteries.
1. High voltage charging: This charging method does not have a dedicated control circuit, and directly charges the battery with a protective board using a 5V power head, relying entirely on the high voltage limit of the protective board. The characteristic is that the current is high at the beginning, then gradually decreases, and float charging is available at any time; Most of the things that will explode are this type, commonly seen in low-end card insertion MP3 players, high-end ones that cannot be afford and do not understand - I dare not say that such an expensive machine should have a charging circuit - there are many things that should be done, but there are more things that should be done but not done;
2. Constant voltage charging: This method is similar to the previous one. Constant voltage is actually "voltage limiting", setting a relatively precise maximum voltage, and then charging to that voltage without stopping until it reaches 4.2V, which is called "stupid charging" by the public. If the cut-off voltage of this charger is made very accurate, it is safe if it is too low. If it is too high, it still needs to rely on a protective board. As for bare batteries, they should seek more blessings on their own. Commonly seen today are universal chargers for mobile phones and direct chargers for flashlights. These chargers cost less than one yuan and are made up of inferior parts. The retail price on Taobao ranges from 2.00 to 15.00 yuan, and it is difficult to say how long they will last;
3. Constant current charging: This method is still derived from the previous and previous circuits, but it limits the maximum charging current. Constant current and constant voltage are actually "current and voltage limiting", which can be considered foolish charging. This type of circuit is quite popular, such as Nanfu, and Xinyu. After overflowing, it is not completely cut off and instead uses trickle float charging - nowadays, it is believed that long-term low current charging is one of the reasons for the swelling of 18650 lithium-ion batteries;
4. Intelligent charging: This is currently considered an ideal charging management method, following the charging algorithm mentioned at the beginning of this section and integrated into a small chip IC. The peripheral circuit is simple, stable, and reliable, such as TP4054/4055/4056/4057, TP4002/5000, MAX1879, and so on. The main feature of this chip is that it monitors both voltage and current simultaneously when determining whether it is overflowing. It stops charging at 4.2V or when the charging current is less than 0.01C (usually around 50mA); Completely cut off after overflowing, without trickle float charging, but monitor the voltage at any time. If the voltage of the 18650 lithium-ion battery drops to a certain value, start charging again.
