Introduction

During the charging and discharging process of the battery, if parameters such as voltage, current or temperature are unstable or exceed the safe range of the battery, it will cause damage to the battery and may even cause a safety accident. In order to protect the safety of the battery and prolong the service life of the battery, a protection board is required to control and monitor the charging and discharging process of the battery. The protection board usually includes the following functions:

Protective function	effect
overcharge protection	Prevent battery overcharging and protect battery safety
Over discharge protection	Prevent excessive battery discharge and protect battery safety
overcurrent protection	Prevent battery charging and discharging current from being too large and protect battery safety
Short circuit protection	Prevent short circuits and protect battery safety
temperature protection	Prevent the battery from overheating and protect the battery safety

Charge

lithium battery

question	reason	solution
Lithium battery overcharge cut-off voltage	The maximum cut-off voltage can be tolerated up to 4.29V, which depends on the design of different protection board manufacturers	Some design 4.2V±0.05V, some design 4.2-4.29V
Lithium battery over-protection board has no charging current	There is a problem with the wiring of the protection board; the voltage of a single battery reaches the overcharge protection voltage	Check the wiring of the protection board; measure the voltage of a single battery
After the battery is fully charged, there is a certain voltage drop between the output battery voltage and the voltage after passing the protection board (within 0.4V)	No-load: The battery is aging, and the charging is prone to false highs, which leads to the overcharge protection being reached in advance and charging is stopped in advance; Loading: the wire is not suitable, the internal resistance is large and the wire is small and long, resulting in a drop in voltage when it is transmitted to the load	No-load: replace the battery; Load: use a suitable wire, not too long or too thin

Lithium iron phosphate battery

question	reason	solution
Overcharge cut-off voltage of lithium iron battery	The maximum cut-off voltage can be tolerated up to 3.75±0.025V, which depends on the design of different protection board manufacturers	Some design 3.7V±0.05V, some design 3.75±0.025V
Iron lithium battery over protection board has no charging current	There is a problem with the wiring of the protection board; the voltage of a single battery reaches the overcharge protection voltage	Check the wiring of the protection board; measure the voltage of a single battery
After the iron-lithium battery is fully charged, there is a certain voltage drop between the output battery voltage and the voltage after passing the protection board (within 0.8V)	Normal iron-lithium batteries will have a little false high after being fully charged, so there will be a little voltage drop within 0.4V. If it exceeds 0.4V, you can analyze the no-load according to the following: the battery is aging, and charging is prone to false highs, which lead to overcharge protection in advance and thus Stop charging in advance; load: the wire is not suitable, the internal resistance is large and the wire is small, and the voltage is reduced when it is transmitted to the load	No-load: replace the battery; Load: use a suitable wire, not too long or too thin

discharge

question	reason	solution
The protection board has no output voltage or the output voltage is lower than the input terminal of the battery.	①The function of the protection board is not started normally. ②Wrong wiring occurs.	① Use the charging voltage to activate and turn on the output ② Check the wiring of the protection board; measure the voltage of a single battery, if the protection is triggered, use the charging voltage to activate again
Output with high power load appears direct protection	①The over-current capability of the protection board is small and directly triggers the over-current protection ②The over-current capacity of the line connecting the battery output terminal to the B+B- of the protection board is small, and the line is too long, resulting in large internal resistance and high power over-current, resulting in a voltage drop Single-cell battery over-discharge protection of the large-scale protection board ③The discharge rate of the battery itself is too low to reach the power of the output load, resulting in a large current and voltage drop. Single-cell battery voltage over-discharge protection at the input terminal	①Confirm the current required by your load and select a protection board with an appropriate current ②Select an appropriate cable to connect to B+B according to the current required by the load-to prevent large voltage drops due to small over-current capabilities, and re-use charging if the protection is triggered Voltage activation ③ Replace the high-rate discharge battery to reduce this situation, if the protection is triggered, re-use the charging voltage to activate

Summarize

Various problems are often encountered during the use of the battery protection board. If you encounter some problems, you can leave a message under the comments. We can test the relevant reasons and find out the relevant solutions. This article is updated from time to time!

Battery Protection Board- Problem Summary