What is the way to extend battery life?

1. Voltage maintenance: overcharge and overdischarge, this should be changed according to different battery data, this seems simple, but in terms of details, there is still experience and knowledge. Overcharge maintenance, the maintenance voltage of our previous single-cell battery will be 50~150mV higher than the full battery voltage. But the power lithium-ion battery is not the same. If you want to extend the battery life, your maintenance voltage is to choose the battery's full charge voltage, or even lower than this voltage. For example, manganese lithium battery can choose 4.18V~4.2V. Because it has multiple strings, the life capacity of the entire battery pack is mainly based on the battery with the lowest capacity. The small capacity always operates at high current and high voltage, so the attenuation speeds up. The large capacity is lightly charged and discharged every time, and the natural attenuation is much slower. In order to make small-capacity batteries also lightly charge and discharge, do not choose too high an overcharge maintenance voltage point. This maintenance delay can be achieved 1S, prevent the impact of pulse and then maintain. Over-discharge maintenance is also related to battery data, such as manganese-lithium batteries generally choose 2.8V~3.0V. Try to be slightly higher than the over-discharge voltage of a single battery. Since the discharge characteristics of the batteries produced in China are completely different after the battery voltage is lower than 3.3V, the batteries are maintained in advance, which is a good maintenance for the battery life. The general point is to try to make every battery work with light charge and light operation. It must be an assistance to the life of the battery. Over-discharge maintenance delay time, it needs to be changed according to the different load, for example, power tools, his starting current is generally above 10C, so the battery voltage will be pulled to the over-discharge voltage point in a short time. maintain. The battery cannot be operated at the moment. This is something worth paying attention to. 2. Current maintenance: It is mainly reflected in the operating current and overcurrent to disconnect the switch MOS and then maintain the battery pack or load. The damage of the MOS tube is mainly due to the sharp rise in temperature. Its heating is also determined by the size of the current and its own internal resistance. Of course, a small current has no effect on the MOS, but for a large current, this needs to be dealt with. When passing the rated current, the small current is below 10A, we can directly use the voltage to drive the MOS tube. For high current, it must be driven to provide enough drive current for the MOS. In the following, the operating current is mentioned in the MOS tube driver. At the planning time, the power of the MOS tube cannot exceed 0.3W. Calculation method: I2*R/N. R is the internal resistance of MOS, and N is the number of MOS. If the power exceeds, the temperature of the MOS will rise above 25 degrees, and because they are all sealed, even if there is a heat sink, the temperature will still go up during long-term operation, because it has no place to dissipate heat. Of course, there is no problem with the MOS tube. The problem is that the heat generated by it will affect the battery. After all, the maintenance board is placed with the battery. Overcurrent maintenance (maximum current), this item is indispensable for the maintenance board, a very critical maintenance parameter. The size of the maintenance current is closely related to the power of the MOS, so when planning, it is necessary to give the margin of MOS capability as much as possible. At the time of layout, the current detection point must be selected. It can't just be switched on. This requires experience value. It is generally recommended to connect to the middle end of the detection resistor. Also pay attention to the interference problem of the current detection terminal, because its signal is easily interfered. Over-current maintenance delay, it also needs to be adjusted accordingly for different products. Not much to say here. 3. Short-circuit maintenance: Strictly speaking, it is a voltage comparison type maintenance, that is, it is directly shut down or driven by voltage comparison, and does not go through the remaining treatment. The setting of the short-circuit delay is also very important. Because in our products, the input filter capacitor is very large, the capacitor is charged at the first moment of touch, and it is appropriate to charge the capacitor at the moment when the battery is short-circuited. 4. Temperature maintenance: generally used on smart batteries, it is also indispensable. But often its perfection always brings another shortcoming. Our first step is to detect the temperature of the battery to disconnect the main switch to maintain the battery itself or the load. If it is under a constant environmental condition, of course there will be no problems. Since the operating environment of the battery is beyond our control, there are too many and too messy changes, so it is not easy to choose. For example, in the winter in the north, how much is suitable for us? And how much is suitable for the southern region in the summer? Obviously, the scale is too wide and there are too many uncontrollable factors. 5. MOS maintenance: the first is the voltage, current and temperature of the MOS. Of course, it involves the selection of the MOS tube. Of course, the withstand voltage of MOS must exceed the voltage of the battery pack, which is a must. The current refers to the temperature rise on the MOS tube body when the rated current is passed, and the temperature rise generally does not exceed 25 degrees. The personal experience value is for reference only. For the MOS drive, some people may say that I use MOS transistors with low internal resistance and high current, but why is there still a very high temperature? This is because the driving part of the MOS tube is not done well, and the driving MOS must be large enough The current, the driving current in detail, depends on the input capacitance of the power MOS tube. Therefore, the general over-current and short-circuit drive cannot be directly driven by the chip, and must be added. When working with high current (exceeding 50A), multi-level and multi-channel drive must be required to ensure that the MOS is normally opened and closed at the same time with the same current. Since the MOS tube has an input capacitance, the greater the power and current of the MOS tube, the larger the input capacitance. If there is not enough current, it will not be able to make perfect control in a short time. Especially when the current exceeds 50A, the current planning must be more detailed, and multi-level and multi-channel drive control must be done. In this way, the normal overcurrent and short circuit maintenance of MOS can be ensured. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What factors will affect the life of the battery?