Lithium battery module recovery
01 Lithium battery charging
I. Introduction
This is the lithium battery used to power the on-board computer of the small smart model, and it cannot be charged now with its original charger. One of the batteries is always in the cycle charging display state, and the other one cannot display charging. It is now estimated that both batteries have been discharged, causing the batteries to not charge properly. · Let’s do a preliminary test on it.
2. Battery structure
A battery casing can now be opened. After removing the upper cover, you can see a circuit board on the top for testing. There is a SOP8 packaged chip on the circuit board, a button, and four LED displays. They correspond to the CHECK button on the battery casing and the four display states from E to F. Remove the battery base, and you can see a charge and discharge circuit board under the battery, which contains two power MOS tubes and an SSOP16 packaged chip. Let’s take a look at the models and functions of these chips. It can be used as a reference for future designs.
First, take a look at the models of the two power tubes on the circuit board. They are placed side by side. The model number is 6508. Search the corresponding data sheet on the Internet and you can see that the close signal is AON6508, which is a low internal resistance N-channel. MOS tube. Withstand voltage 30V, maximum current 32A.
The second SSOP16 packaged chip on the charging board is SH367103X. Searching the data sheet of this chip on the Internet, you can see that it is a dedicated lithium battery containing the chip. It can charge and discharge protection for 3s or 4s lithium battery pack.
On the front test board of the battery, the SOP8 packaged chip model cannot be clearly seen. The LR50B SOT23 packaged chip next to it is probably a linear series voltage regulator chip.
Assemble the battery into the casing. Use a multimeter to measure the charging port of the battery. Among the two batteries, one battery charging port shows 0.89V, and the other shows about 0V. This shows that the two battery terminal voltages are in a very abnormal state. Next, use a DC power supply to recharge them directly, rather than through a charger, to see if they can evoke their normal voltage.
3. Battery replenishment
The port voltage of the four lithium batteries should be 16.8V. This charger can charge a single battery, two batteries, or four batteries in series. It is estimated that because of its internal voltage protection function, it is impossible to continue charging the two lithium batteries that are discharged.
Use the alligator clip to connect the battery to the DH1766 DC power supply, and use the adjusted DC power supply voltage to recharge the battery. One of the batteries will not charge no matter how high the voltage is. Another battery that has been opened can be charged with current. During the charging process, the voltage across the battery reaches about 1.2.6V.
After recharging for three minutes, the battery port voltage can be maintained at around 13.5V. Place it on the smart charger and you can see that it can be charged normally. After a while, the charging current continues to rise.
※ Summary ※
This article checks the two lithium batteries at hand. After a long time of discharge, the power of these two batteries will be 0. It can no longer be charged using a charger. After recharging, one of the batteries regained its rechargeable characteristics.
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