The light vehicle uses batteries to generate power, environmental protection, pollution-free, and effective use of resources. It has the advantages of personalized control system, flexible steering, comfortable handle, light and smooth, simple driving, electric recycling, long service life and so on. At present, sightseeing buses are widely used in hotels, scenic spots, sales vehicles, factories, airports, railway stations, bus stations, docks, gymnasiums, parks and other places.
1. Design requirements of lithium battery for patrol, sightseeing and golf course
Patrol, sightseeing and golf cart lithium batteries are conventional lithium-ion batteries and lithium iron phosphate batteries. Ternary lithium battery has the characteristics of high energy density, good low temperature performance, high reliability, long life and longer battery life, but the cost is high. However, LiFePO4 battery has the advantages of low cost, convenient for mass production and easy to recycle, higher safety than lithium ternary battery, but worse battery life than lithium ternary battery.
1. Lithium polymer battery pack
(1) Good safety performance: the structure of the lithium polymer battery pack is packed with aluminum plastic film. In case of potential safety hazard, the lithium polymer battery pack will only blow air and crack at most, unlike the steel shell and aluminum shell cell, which will explode.
(2) Light weight: the weight of the flexible battery is 40% lighter than that of the steel shell lithium battery of the same capacity and 20% lighter than that of the aluminum shell lithium battery.
(3) Large capacity: flexible packaging can save more than 20% volume and increase 50% specific capacity.
(4) Small internal resistance: the internal resistance of the lithium polymer battery pack is smaller than that of the lithium battery, which can greatly reduce the self-consumption of the battery.
(5) Flexible design: the shape can be changed to any shape, it can be made thinner, and it can be customized according to the needs of customers to develop new cell models.
(6) The consistency is poor.
(7) The cost is high, which can be solved by large-scale production.
(8) Leakage can be solved by improving the quality of aluminum plastic film.
2. Cylindrical cell
(1) The automatic production process is mature, the product yield is high, and the pack cost is low.
(2) The cylindrical battery pack has strong consistency and high energy density.
(3) Small battery, large heat dissipation area and better heat dissipation performance than square battery.
(4) The production process is mature and the consistency of the battery is high.
(5) People are generally worried that if one of the batteries has a problem, it will affect the power supply of the whole vehicle. The light one will cause electric vehicles to lie on the ground, and the heavy one will cause all kinds of accidents.
3. Square battery
(1) The shell is made of aluminum alloy and stainless steel, and the inner part is wound or laminated.
(2) The protection of the cell is stronger than that of the aluminum plastic film battery, and the cell safety is better than that of the cylindrical battery.
(3) Heavy shell leads to limited energy density, low degree of automation, low yield and poor consistency of battery pack.
Our company adopts IFR square lithium iron phosphate battery, adopts strict separation process, so that the consistency of the battery tends to ternary lithium-ion battery; the specific parameters are as follows.
Nominal voltage: 76.8V
Nominal capacity: 150Ah
Charging voltage: 84V
Discharge current: 50A
Instantaneous discharge current: 150A
Discharge cut-off voltage: 57.5V
Product size: 750 * 230 * 310mm
Charging temperature: 0 ~ 45 ℃
Discharge temperature: - 10 ~ 60 ℃
Battery shell: cold rolled sheet metal
2. Design scheme of lithium battery for patrol, sightseeing and golf course:
1) BMS: it is mainly a protection circuit designed for rechargeable lithium battery pack. Due to the chemical characteristics of lithium battery, it is necessary to provide intelligent power calculation, overcharge, over discharge, short circuit, overcurrent and other protection functions to avoid burning, explosion and other hazards.
2) Protection IC: the main protection function chip of the design scheme, which can monitor the overcharge, over discharge, over current, short circuit and other functions of the cell online and constantly, so that the cell can work in a safe, stable and efficient range.
3) Temperature switch: mainly designed for temperature protection function. When the temperature of the battery itself reaches 70±5℃ due to other abnormal problems, the temperature switch will act for temperature protection
4) Lithium ion cell: lithium ternary / lithium cobalt oxide.
5) Field effect transistor (MOSFET): MOSFET, in the protection circuit to play a switching role, always make the voltage at both ends of the load will not rise or fall, to ensure voltage stability.
6) Battery packaging: cold rolled sheet metal.