The balancing principle of lithium battery protection board and the
activation method of lithium battery protection board. As we all know, lithium
batteries are new energy batteries that are currently used in various fields.
However, lithium batteries require protection from protective plates. Many
people don’t know that protective plates play a vital role in the use of
batteries. Let’s learn about it below. Let’s talk about the activation method of
the protective board and its protection principle.
Lithium battery protection board
The lithium battery protection board is to protect the charge and discharge
of the series-connected lithium battery pack; when fully charged, it can ensure
that the voltage difference between each single cell is less than the set value
(generally ±20mV), achieving even charging of each single cell in the battery
pack. , effectively improves the charging effect in series charging mode;
simultaneously detects the overvoltage, undervoltage, overcurrent, short
circuit, and overtemperature status of each single cell in the battery pack to
protect and extend the service life of the battery; undervoltage protection
enables each When a single battery is discharged, it can prevent the battery
from being damaged due to over-discharge.
The finished lithium battery mainly consists of two parts, the lithium
battery core and the protective plate. The lithium battery core is mainly
composed of positive plate, separator, negative plate, and electrolyte; the
positive plate, separator, and negative plate are wound or laminated, packaged,
and filled with electrolyte , it is made into a battery core after
packaging.
Balancing principle of lithium battery protection board
Lithium battery protection board balancing principle Commonly used
balancing charging technologies include constant shunt resistance balancing
charging, on-off shunt resistor balancing charging, average battery voltage
balancing charging, switched capacitor balancing charging, buck converter
balancing charging, inductor balancing charging, etc.
When charging a group of lithium batteries in series, each battery should
be charged evenly, otherwise the performance and life of the entire battery
group will be affected during use. However, the existing single-cell lithium
battery protection chips do not contain the balanced charge control function.
The balanced charge control function of the multi-cell lithium battery
protection chip requires an external CPU; it is realized through serial
communication with the protection chip (such as I2C bus), which increases the
This increases the complexity and design difficulty of the protection circuit,
reduces the efficiency and reliability of the system, and increases power
consumption.
The charging overvoltage protection control signal of the single-cell
lithium battery protection chip in the control circuit part of the lithium
battery pack protection board system is output in parallel after being isolated
by an optical coupler to provide the gate voltage for the conduction of the
charging switch device in the main circuit; such as a certain cell Or if several
lithium batteries enter the overvoltage protection state first during the
charging process, the overvoltage protection signal controls the discharge of
the shunt discharge branch connected in parallel at the positive and negative
ends of the single lithium battery, and at the same time, the corresponding
shunt discharge branch connected in series in the charging circuit is
discharged. The single lithium battery is disconnected from the charging
circuit.
Lithium battery protection board activation method
The protection function of lithium batteries is usually completed by a
protection circuit board and current devices such as PTC. The protection board
is composed of electronic circuits and can accurately monitor the voltage and
charge return circuit of the battery core at all times in an environment of
-40°C to +85°C. Current, timely control the on and off of the current loop; PTC
prevents severe damage to the battery in high temperature environments.
Now not all lithium battery protection boards need to be activated, but
some protection ICs need to be activated, and this is an old IC solution. The
old IC solution needs to be done so that the protection board does not work to
reduce static electricity. Discharge energy so that lithium batteries can be
stored longer. This is why the design requires charge activation.
If the lithium battery protection board is under current limiting
protection, it may need to be activated by charging or completely disconnecting
the load, which is relatively troublesome, but you can also short-circuit B-
(battery negative) and P- (discharge negative). Once, the protection will be
released. Remember not to carry a large load when short-circuiting and touching
it (for example, turning the bar and twisting it all the time), otherwise there
may be big sparks. The fundamental reason is that after the protection, a large
discharge MOS is formed at both ends. Voltage difference, a short-circuit touch
will directly reset the D-S level of the discharge MOS to 0V, and the protection
will be released at this moment.
How to activate the lithium battery protection board?
If the protection board is protected by current limiting, it may need to be
activated by charging or completely disconnecting the load, which is relatively
troublesome. However, you can also short-circuit B- (battery negative) and P-
(discharge negative). The protection will be released. Remember not to carry a
large load when the short circuit is touched (such as turning the bar and
twisting it all the time), otherwise there may be big sparks. The fundamental
reason for this is that a large voltage difference is formed between the two
ends of the discharge MOS after protection. , a short-circuit touch will
directly reset the D-S level of the discharge MOS to 0V, and the protection will
be released at this moment.
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