Traditional field exploration tester uses lead-acid batteries as mobile backup power, due to the low energy density of lead-acid batteries themselves, heavy mass, low multiplier discharge efficiency, non-environmental protection and other shortcomings, has been unable to meet the needs of modern portable industrial instruments and equipment required backup power. Due to the unique advantages of high energy ratio, light mass, small size, high cycle life, high safety, high voltage consistency, etc., Li-ion battery pack has become the first choice to replace lead-acid batteries in many industrial instruments and equipment.
First, the ground probe tester backup power requirements:
Probe tester with high working voltage, long time and special ambient temperature requirements, in the lithium battery cells using the domestic first-class brand of BAK long life lithium battery cells, with 6 series and 8 combinations to achieve customer demand for relevant parameters. In terms of lithium battery protection circuit protection, 6 strings of precision hardware protection circuit + 6 strings of charging balance circuit are used to achieve the requirements of maximum overcurrent 25A, continuous discharge current 8A and charging balance current 300mA for the finished lithium battery. In the related working environment, the high-grade white waterproof box shell is used to realize the customer's waterproof environment requirements. The specific parameters of the finished battery after combination are as follows:
1) Li-ion battery pack type design requirements: 18650-6S8P/16Ah/22.2V.
2) Circuit part design requirements:
1, single cell overcharge protection voltage: 4.35±0.25V
2, single section overcharge recovery voltage: 4.15±0.50V
3、Single section over discharge protection voltage: 2.70±0.08V
4、Single section over discharge recovery voltage: 3.00±0.10V
5、Combination battery overcurrent protection value (10ms): 30~35A
6、Charging balance current: 300±50mA
7、Charging balance voltage: 4.20±25mV
8、Battery over-temperature protection value (recoverable): 70±5 degrees
9, the finished battery also has a short circuit, reverse charge protection.
(3) battery cycle life design requirements: 500 ~ 1000 times (national standard charge and discharge standards)
(4) battery size design requirements: reference shell
Second, the ground-probing special tester backup power design program:
(1) protection board (PCM): mainly for rechargeable lithium battery pack design protection 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 monitors the battery cell online in time for overcharge, overdischarge, overcurrent, short circuit and other functions. Make the electric core work in a safe, stable and efficient range.
3) Charge balance module: balance the voltage difference of each cell during charging, enhance the consistency of the voltage of each cell to extend the service life of the combined battery.
4) Temperature switch: mainly designed for temperature protection function. When the temperature of the battery itself reaches 75 degrees due to other abnormal problems, the temperature switch acts to achieve over-temperature protection, and automatically recovers when the temperature drops.
5）18650 Li-ion cell/18650/2000mAh/3.7V BAK cell (long life cell)
(6) field effect tube (MOSFET): MOSFET tube, in the protection circuit to play a switching role, always make the voltage at both ends of the load will not rise nor fall, to ensure voltage stability.