3.7V 5000mAh Lithium Battery Design Scheme for Police Helmet

3.7V 5000mAh Lithium Battery Design Scheme for Police Helmet

The police helmet is a device for civil servants to record accidents and on-site law enforcement activities. It has various functions such as distance measurement, communication, photography, positioning, and audio recording, which greatly improves the work efficiency of sub-officers. The helmet uses a polymer lithium-ion battery with a high safety factor, which can provide continuous, stable, reliable and ultra-long power supply to the device.

1. Design requirements for backup batteries for police helmet equipment

   This solution uses a polymer battery with high energy density ratio and high safety system. The shell is made of ABS+PC UL-94V0 fireproof grade material, and the ultrasonic waterproof assembly process is used. The battery has IPX1 waterproof grade.

 1) Design requirements for lithium battery models:  polymer lithium-ion battery1S1P /3.7V/5AH/ 500Cycle life

 2) Design requirements of the circuit part:

     1、Over charge Protection: 4.300±0.050V

     2、Over discharge protection：2.800±0.075V

     3、Over current protection：4-8A

     4、Interior resistance：VC=4.2V,RDS≤80mΩ

     5、Current consumption：≤6uA

     6、Charge Temperature：0-45℃

     7、Discharge Temperature：-20-60℃

2.Design scheme of backup battery for police helmet equipment

    1）PCM 

            If a protection circuit is designed for a rechargeable high-capacity battery pack, due to the chemical characteristics of the lithium battery itself, it is necessary to provide protection functions such as overcharge, overdischarge, short circuit, overcurrent and overtemperature to avoid dangers such as burning and explosion.

     2)Protection IC 

The dual IC protection function design scheme is selected to monitor the battery cells on-line with functions such as overcharge, overdischarge, overcurrent, and short circuit. Make the cells work in a safe, stable and efficient range.

     3)MOSFET

       Double MOSFETs are selected to play a switching role in the protection circuit, making the circuit safer.

     4)PTC

   Mainly designed for the secondary protection function. The PTC resettable thermal fuse has dual functions of overcurrent protection and automatic recovery. The PTC in the battery product can prevent the high temperature discharge of the battery and the occurrence of unsafe high current.

     5)Cell:Polymer 955565P lithium ion battery

    6)Battery pack packaging: plastic shell sonic packaging.

     7)Design schematic

     8)Product realization map