First, the field water quality monitor battery design requirements:
Field water quality monitor is a portable water quality testing equipment, water resources can be quality inspection, test the degree of contamination of water quality, the main components of the instrument for small electric pumping machine, mixer, heating device, sensing part, display part, etc.. Equipment start instantaneous current requirements, peak current up to 20A, normal working current 4 ~ 5A, the battery continuous working time requirements are high, for this reason we use imported Sanyo battery, the battery has a high energy ratio, light quality, small size, high cycle life, high security, high voltage consistency and other advantages, lithium battery pack design output overcurrent protection value 30A, continuous working current 7A, charge capacity 20Ah, fully meet the power requirements of the instrument. Specific design requirements parameters are as follows:
1) Lithium battery pack type design requirements: 18650-3S8P/20Ah/11.1V.
2) Circuit part design requirements:
1, single-cell overcharge protection voltage: 4.35±0.025V
2, single section overcharge recovery voltage: 4.15±0.050V
3、Single section over discharge protection voltage: 2.40±0.08V
4、Single section over discharge recovery voltage: 3.00±0.10V
5、Combination battery overcurrent protection value (10ms): 30~35A
6, the combination of battery over-temperature protection value (recoverable): 70±5 degrees
7, the finished battery also has a short circuit, reverse charge protection.
(3) battery cycle life design requirements: 300 ~ 500 times (national standard charge and discharge standards)
(4) the battery appearance size design requirements:
Second, the field water quality monitor battery design program:
(1) protection board (PCM): mainly on the rechargeable lithium battery pack is designed to protect the circuit, due to the chemical properties of the lithium battery itself, the need to provide intelligent power calculation, overcharge, over discharge, short circuit, overcurrent and other protection functions. To avoid causing combustion, explosion and other dangers.
(2) Protection IC: The main protection function chip of the design program, which is used to monitor the online time of overcharge, overdischarge, overcurrent, short circuit and other functions of the battery cell, so that the battery cell works in a safe, stable and efficient range.
(3) Temperature switch: mainly designed for the temperature protection function. When the temperature of the battery itself reaches 70±5℃ range due to other abnormal problems, the temperature switch operates for temperature protection
4）18650 Li-ion cell/18650/2500mAh/3.7V Li-ion cell (SANYO)
5) Field effect tube (MOSFET): MOSFET tube, in the protection circuit to play a switching role, always so that the voltage at both ends of the load will not rise nor fall, to ensure voltage stability.