For lithium battery manufacturers, can polymer lithium batteries be charged without a protective board?

With the increasing application demand of electronic products, everyone's demand for lithium polymer batteries is getting higher and higher. As a battery with relatively large electric storage, lithium polymer batteries are used in various electronic products. However, there is a product that can effectively prevent lithium polymer batteries from overcharging, overdischarging and short-circuiting of internal circuits. It is a lithium polymer battery protection board.

Lithium polymer battery protection board:

It is the charging and discharging protection for the series lithium polymer battery pack; when fully charged, the voltage difference between the individual cells can be ensured to be less than the set value (generally ±20mV), so as to realize the equal charge of the individual cells of the battery pack, which is effective The charging effect under the series charging mode is improved; at the same time, the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack are detected to protect and extend the battery life; undervoltage protection makes every single cell When discharging the battery, avoid damage to the battery due to over-discharge.

Principle of lithium polymer battery protection board:

The reason why lithium polymer battery (rechargeable type) needs protection is determined by its own characteristics. Because the material of the lithium polymer battery itself determines that it cannot be overcharged, overdischarged, overcurrent, short circuited, and ultra-high temperature charging and discharging, the lithium battery components of the lithium polymer battery will always appear with a delicate protection board and a current fuse. .

The protection function of lithium polymer battery is usually completed by a protection circuit board and current devices such as PTC. The protection board is composed of electronic circuits, which can accurately monitor the voltage and charge and discharge of the cell at all times under an environment of -40°C to +85°C The current of the loop can be switched on and off in time to control the current loop; PTC prevents severe damage to the battery in a high temperature environment.

Ordinary lithium polymer battery protection board usually includes control IC, MOS switch, resistor, capacitor and auxiliary devices FUSE, PTC, NTC, ID, memory, etc. Among them, the control IC controls the MOS switch to turn on under all normal conditions to make the cell and the external circuit conduct, and when the cell voltage or loop current exceeds the specified value, it immediately controls the MOS switch to turn off to protect the cell’s Safety.

The main function of lithium polymer battery protection board:

Generally, it is required that Control (IC) detect the voltage of the control cell and the working current and voltage of the charging and discharging circuit at -25℃～85℃. Under all normal conditions, the C-MOS switch tube is turned on, so that the cell and the protection circuit board are in contact with each other. Normal working state, and when the cell voltage or the working current in the loop exceeds the preset value of the comparison circuit in the control IC, the CMOS is turned off within 15-30ms (different control ICs and C-MOS have different response times) , That is, close the battery discharge or charging circuit to ensure the safety of the user and the battery.

Is it okay to charge the lithium polymer battery without the protection board?

As to why some people have the idea that lithium polymer batteries do not need to protect the board, a big reason lies in the emergence of lithium iron phosphate polymer batteries. Because there is news that lithium iron phosphate lithium polymer batteries are not afraid of overcharging and overdischarging, the argument that lithium polymer batteries can be used without a protective plate has emerged.

However, so far, there has not been a manufacturer that publicly declares not to use lithium polymer battery protection boards. Since everyone has disputes on this issue, let us return to the protection board itself, back to its definition and use, so that we can have our own views on whether lithium polymer batteries can be used without the protection board. The lithium polymer battery protection board, as the name suggests, is used to protect the lithium polymer battery. The role of the lithium polymer battery protection board is to protect the battery from over-discharge, over-charge, and over-current, as well as output short-circuit protection.

Those who think that lithium polymer batteries do not need a protective plate feel that the lithium polymer battery will be damaged if the protective plate is not connected, and the protective plate will discharge the lithium polymer battery that has not been used for a long time. Obviously, I don’t know much about the role of the protection board. The role of the protective plate on the lithium polymer battery is equivalent to an extra protective barrier, and the role of the protective plate is to ensure the safety of the lithium polymer battery and extend the service life. Without the protection board, not only the life span is difficult to guarantee, but also very dangerous.

Therefore, when the lithium polymer battery is completely immune to overcharge, overdischarge, etc., when the lithium polymer battery can completely replace the role of the protective plate in the design of the lithium polymer battery itself, the lithium polymer battery may not need the protective plate, but At this stage, lithium polymer batteries still need a protective plate. The lithium polymer battery protection board is to protect the battery from overcharge, overdischarge, short circuit and other problems. Since the protection board is so important to the safety of the battery, it is best to use the protection board to avoid unnecessary damage to the battery.