There are various types of batteries, such as ternary lithium, lithium manganese, and lithium iron phosphate batteries, which are divided by the raw material system; The volume, rate, and high rate of use of rechargeable batteries in different zones; High temperature resistant lithium electronic and low-temperature resistant lithium batteries planned by the application area; The steel shell, polymer, square, 18650, 26650, etc., which are divided by their appearance, have a complete range of varieties and cannot be illustrated one by one here. Now let's talk about lithium batteries. What are the hazards of pressure difference in lithium batteries?
Nowadays, the key lithium batteries used in electric vehicles include ternary lithium batteries and lithium iron phosphate rechargeable batteries, 18650 cylindrical and polymer hard packs, but the popular one is 18650 cylindrical ternary lithium. The working voltage range of ternary lithium batteries is the nominal voltage. Lithium batteries are composed of several batteries connected in series according to the specified working voltage and volume during application.
For example, if a rechargeable battery with a capacity of 2Ah must be assembled into a 36V/10A lithium battery pack, then five must be combined, and then 10 must be strung together, resulting in a total of 50 18650; Lithium batteries are afraid of overcharging and over discharging, so the lithium battery pack and external power supply circuit should limit the working voltage of the rechargeable battery according to a maintenance power circuit.
The unified regulations for multiple lithium battery packs and lithium battery packs are very high. The volume, internal resistance, and charging and discharging service platform of a 18650 lithium battery pack all need to be the same; But then again, we can't find two identical lithium battery packs in the world all the time. Therefore, it must be impossible to make the same lithium battery pack. There are some differences allowed, but the specifications of each lithium battery pack are different, so the quality is also uneven.
What are the hazards of the pressure difference in lithium batteries? For example, a 36V battery, due to various reasons, one of the rechargeable batteries in the series has already reached the maintenance value during battery charging, and the charging function of the lithium battery protection board may be turned off, even if the working voltage of other rechargeable batteries is still unable to perform volume filling.
When charging and discharging, those with low capacity will first maintain the limit value under the working voltage. Even if the rechargeable battery has a capacity that has not been charged or discharged, the lithium battery protection board will also turn off the charging and discharging function, which is the so-called short board effect! This should be understood by everyone, as pressure differences can cause the overall efficiency of lithium battery packs to be fully utilized, which is reflected in factors such as shorter schedules, power outages during cycling, and insufficient battery charging.