Battery pack application is very wide, including lithium batteries, all batteries can be used battery PACK technology, battery PACK threshold is low, with a certain knowledge of the battery can be operated, but in the actual operation process, may encounter a lot of unknown problems can not be solved, now the lithium battery PACK factory to organize the causes and solutions, to give you some reference.
A, the battery cell inspection
1) Poor voltage consistency, the existence of a certain pressure difference in the core.
① The self-discharge problem of the core will lead to a large change in its voltage, which is more obvious in the nickel electricity placed for too long, and less in lithium batteries. When the cells are found to have pressure difference, if there is no condition to replace the batch of cells, then the battery needs to be screened again for sub-volume.
② When charging, uneven cell charging is caused by contact resistance or inconsistent testing cabinet charging current. Short-term storage (within 12 hours) measurement voltage difference is very small, but long-term storage voltage difference is large, this kind of solution by charging, and no quality problems, production time can be measured again after the state of charge more than 24 hours (resting).
2）Large internal resistance
①Equipment cause
Need to check whether the first time by the equipment, check the value of several readings, if there is a large deviation, focus on checking the equipment
2）Storage time is too long
Battery storage time is too long will lead to internal passivation, can re-volume solution
3. Abnormal heat causes large internal resistance
The internal resistance is increased due to heat during the welding process.
Second, the lithium battery pack process problems and the need for attention
1) Lithium battery expansion
① expansion when charging
When charging, the lithium battery will naturally swell, but generally not more than 0.1mm, but if overcharged, this phenomenon will intensify.
② Expansion during cyclic operation
Lithium battery will expand during the first 50 charging cycles of cyclic use, and will generally increase by 0.3-0.5mm. This is a normal battery reaction.
(2) The battery has a dropout phenomenon after spot welding
① If the voltage after spot welding is lower than 3.7V, it may be due to excessive spot welding current resulting in short circuit due to internal diaphragm breakdown of the cell, causing the voltage to drop too fast.
The correct spot welding position should be at the bottom or marked "A" or "-" side spot welding, no markings on the side and large surface is not spot welding.
After spot welding battery power loss may also be caused by the self-consumption of the battery cell itself.
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