Voltage protection: overcharge, overdischarge, this should be changed according to the different materials of the battery, this seems simple, but to see the details, or experience learning.
Overcharge protection, in our previous single battery protection voltage will be 50~150mV higher than the battery charging voltage. But power batteries are different. If you want to extend battery life, your protection voltage should be the full battery voltage, or even lower than this voltage. For example, manganese lithium battery, can choose 4.18V~4.2V. Because it is a number of strings, the life capacity of the entire battery pack is mainly the lowest capacity of the battery to the accuracy, small capacity is always in the high current and high voltage work, so the decay is accelerated. And large capacity each time is light charge light release, natural decay is much slower. In order to make the small capacity battery is also light charge and release, so the overcharge protection voltage point should not be too high. This protection delay can be accomplished for 1S to prevent the impact of pulse and thus protect.
Overdischarge protection is also related to the material of the battery, such as manganese lithium battery is generally selected in 2.8V~3.0V. Try to be slightly higher than the overvoltage of its single battery. Because, in the domestic production of batteries, battery voltage is lower than 3.3V, the discharge characteristics of each battery is completely different, so it is to protect the battery in advance, so the life of the battery is a good protection.
The general point is to try to make every battery work in light charge down work, must be a help to the life of the battery.
Overdischarge protection delay time, it should be changed according to the different load, such as power tools, his starting current is generally above 10C, so in a short time to pull the voltage of the battery to the over-discharge voltage point to protect. The battery will not work at this time. This is something to note.