11.1V 20Ah Lithium-ion Battery Design Scheme of Petroleum Exploration Equipment

Foreword: oil crisis becomes the heated topic all over the world. As the rapid development of modern society, people tend to rely on petroleum energy urgently. Seeking for more and more petroleum energy is a global discussion. The imported portable petroleum exploration equipment with high precision is the essential tool for long-term fieldspecial, so it is the important assurance for researcher to dedicate to long-term field work that provides the high precision exploration equipment with efficient, portable, light and abundant back-up source solutions. Due to its unique advantages, 18650 battery has been the first choice of this back-up source solutions of high-tech test instrument.

1) The requirements of lithium ion battery design scheme of petroleum exploration equipment

Petroleum exploration equipment is a portable equipment to explore field petroleum geology and petroleum backup source. Analyzed by advanced magnetic resonance imaging (MRI), utilize hydrogen nucleus of petroleum and water in magnetic field to explore physical properties of rock  so as to discover related petroleum source underground, because hydrogen nucleus has a capability of sympathetic vibration and signal generation. The traditional outdoor power unit tends to increase workload for researchers due to its shortcomings of low energy density, large volume, good quality, etc. the lithium ion battery pack design scheme is composited by imported SANYO cell with large capacity, waterproof housing, waterproofspecial plug and LED digital display screen. Over-discharge cut-off current of the scheme is 20A, the maximum design capacity is 40Ah. Automatic protective device with over temperature performance at 70℃ is applied in the scheme, which can meet the long-term power demand of equipment and is widely used in the field of petroleum exploration equipment.

The design parameters are as follow:

1. Design requirement of the type of lithium ion battery: 18650-3S8P/20Ah/11.1V

2. Design requirement of electric circuit

• Over-charged protection voltage of single battery: 4.35±0.25V

• Over-charged recovery voltage of single battery: 4.15±0.50V

• Over-discharged protection voltage of single battery: 2.40±0.08V

• Over-discharged recovery voltage of single battery: 3.00±0.10V

• Over-discharge cut-off current of battery pack (10ms): 30~35A

• Over temperature protection value of battery pack (restorable): 70±5℃

• The finished product has protective function of short circuit and reverse-charging.

3. Design requirement of cycle life: 300~500 times (national standard of charging and discharging)

4. Design requirement of housing dimension: 200*120*75mm

2) Lithium ion battery design scheme of petroleum exploration equipment

1. Guard plate (PCM): it is protective circuit of rechargeable lithium ion battery pack. Because of the chemical characteristics of lithium ion battery, it needs protective function of intelligent capacity calculation, overcharging, over-discharging, short circuit, overcurrent, etc. so as to avoid combustion, explosion, etc.

2. Protection IC: it is the chip has main protective function in the design scheme. The chip monitors the cell on the functions of overcharging, over-discharging, overcurrent, short circuit, etc. at any time, which helps the battery works under safe, stable and efficient circumstance.
   

3. Temperature switch: it is designed for temperature protection. When the battery is heated up to 70±5℃ due to any issues, the temperature switch begins to protect the battery.

4. 18650 lithium ion battery/18650/2500mAh/3.7V Li-ion cell（SANYO）

5. MOSFET: it works as the switch in protective circuit to make sure that the voltages of two ends won’t be up and down, so that the voltage will be stable.

6. LED voltage display: It displays the voltage of battery module so as to monitor the voltage and capacity of the battery.

7. Waterproof mode: it contains vacuum waterproof input and output plug, waterproof switch and battery waterproof white box, which makes the whole battery under waterproof status.