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Lithium Battery Charging&Protection Module
What is lithium Battery Protection Board?
It’s a small circuit board specially used to prevent lithium batteries from overcharging. The core IC is tp4056, it can provide overcharge protection. If the current is too high during charging, it will indirectly reduce the battery life, and too much current can also affect safety. But TP4056 can limit the charging current according to the set maximum current value, avoiding reducing battery life due to excessive charging current. Also, it automatically cuts off the power input when the battery is fully charged. When discharging, if battery voltage is extremely low, it will seriously reduce the battery life and capacity, or even make it completely useless. So generally, lithium batteries have a fixed minimum discharge voltage. When it’s lower than this voltage, you must stop discharging immediately. But tp4056 only has charging protection function.
TP4056 Charging Module
TP4056 is a commonly used single-cell lithium-ion battery charging management chip. The charging voltage of TP4056 is fixed at 4.2V, ensuring charging accuracy. It has few peripheral components, so it suitable for portable products. And it can be used with USB power supplies and so on.
Working Principle
When lithium-ion battery voltage is low (below 2.9V), TP4056 first performs trickle charging, using a small current to pre-charge the battery, avoid damage to the low-power battery from a large current. When the battery voltage rises to a certain level, it switches to constant current charging, using a steady, larger current to charge,helps cut down on charging time.When the battery voltage is close to the full charge voltage (4.2V), it automatically switches to constant voltage charging mode. As the battery is gradually fully charged, the charging current decreases gradually until the battery is completely full, it shuts off the charging process automatically.
Pin Definition
| Pin Name | Pin Function |
|---|---|
| TEMP | Battery temperature detection input |
| PROG | Constant – current charging current setting and charging current monitoring terminal |
| GND | Ground wire |
| VCC | Input voltage positive input terminal |
| BAT | Battery connection terminal |
| STDBY | Battery charging completion indicator terminal |
| CHRG | Charging status indicator terminal |
| CE | Chip enable input terminal |
| Heat Sink Pad | Can be grounded or left floating, not connectable to other potentials |
SDB6284——Boost Converter Module
2A input voltage range 2V-24V boost IC
Feature
- Internal 4A switch current limit
- 2V-24V Input voltage, VFB: 0.6V
- 1.2MHz fixed operating frequency
- Output current 2A
- Internal compensation function
- Output voltage up to 28V
- Under light load conditions, it can perform automatic pulse modulation.
- Efficiency up to 97%
Pin Definition
| PIN | NAME | FUNCTION |
|---|---|---|
| 1 | SW | Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 28V. |
| 2 | GND | Ground Pin |
| 3 | FB | Feedback Input. The FB voltage is 0.6V. Connect a resistor divider to FB. |
| 4 | EN | Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input supply for automatic startup. |
| 5 | IN | Input Supply Pin. Must be locally bypassed. |
| 6 | NC | NC |
Protection Feature
（一）Under-voltage lockout
If input voltage lower than the preset under-voltage lockout threshold, the boost converter will automatically turn off and stop working.
（二） Current limit
The internal 4A switch current limit function can prevent damage to the circuit from overload.
（三）Thermal overload protection
When the chip temperature exceeds the safe range, the thermal overload protection mechanism will be triggered. The converter will automatically reduce the output power, and when the temperature returns to the normal range, the converter will automatically resume normal operation.
How To Choose A Suitable Protection Board
choose the right current based on the battery’s capacity. But most charging protection boards let you adjust the current now—just adjust it based on how big the battery is and how long you’re willing to wait for it to charge. Like, a 500mAh battery works with a 250mAh charging current. Smaller current is better for the battery, but you gotta think about how long you should wait
If the protection board has discharge protection, check if it only does low-voltage protection or both over-current and low-voltage. Usually, they just cut the circuit when the voltage is low. Boards with over-current protection cost more but are safer—they cut the circuit faster if there’s a short. Of course, if you’re just a casual DIYer, you could skip the over-current protection, but I don’t recommend it. Also, if you’re just powering a 3.3V MCU, you might not need a protection board at all—MCUs can’t work when voltage is too low, so they use barely any power. Just charge it after the MCU turns off, and make sure you don’t plug it in backwards.
Pick based on the battery type and how many you have. Different batteries use different voltage ranges, so they need different protection boards. Like, nickel-cadmium batteries are 1.2V, but lithium ones are 3.7V. Picking by number of batteries is easy—you can put one protection board on each battery, or use a multi-series one for all of them.
Some protection boards have other functions, such as boosting. Choose according to actual needs.
The Important Of Battery Display
Regular protection boards only cut off the output when the voltage hits rock bottom—like around 2.5V. But you shouldn’t let lithium batteries discharge below 3.3V if you want them to work well. But who’s gonna pull out a multimeter every time to check the voltage? If you wanna see the battery level quickly, there’s a cheap, handy tool: the lithium battery power display.
This display shows the power between 4.2V and 3.3V. And it doesn’t just go off the battery’s voltage directly—it’s tuned specifically to the way lithium battery voltage and power relate, so the level it shows is accurate. When the voltage drops below 3.3V, the red lights around it turn on to remind you to charge.
FAQs
How do you get a lithium battery out of protection mode?
Generally, if the over-discharge protection function is triggered, you just need to reconnect the power supply to reactivate it. But you should also note that you can’t trigger the protection function frequently.
What is the best protection for lithium batteries?
If you need to extend the battery life, you can choose a smaller charging current and keep the battery current between 20%-80%. If you don’t use it for a long time, you also need to charge and discharge it once in a while.
What is the difference between BMS and protection board?
BMS has more complex functions. In addition to the same charging and discharging protection functions as the board, it also has temperature overheating protection, over-current protection, battery capacity balancing function, etc. Of course, its size and price are also higher.
Do all lithium batteries have overcharge protection?
To be precise, the battery is only responsible for storing and releasing electrical energy. All lithium battery protection functions require an external protection board.
How to tell if a lithium battery is protected?
You can check if has a small circuit board around the battery, or charge the battery and see if the charging is cut off when the voltage exceeds 4.2V.
What to do if a lithium battery catches fire at home
Never use water to put out a lithium battery fire. Instead, use sand to cover it.
Is it okay to leave a lithium-ion battery on the charger overnight?
Theoretically, lithium batteries equipped with a protection board can be connected to the charger all the time, but for safety reasons, it’s not recommended to do so.
