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25.6V 80Ah Electric Forklift Lithium Battery Design Scheme

Electric forklifts mostly used lead-acid batteries in the early days, but lead-acid batteries are large in size and low in specific energy, which easily pollutes the environment. The new lithium battery has high specific energy, small size, light weight and long cycle life at the same power/capacity. Today’s logistics forklifts generally start to use lithium batteries to replace lead-acid batteries. Combining industry characteristics and customer needs, our company chooses the lithium iron phosphate battery solution to match the customer’s electric forklift products. The battery can continue to work with high current. The protection board uses imported IC and MOS tubes for control and management. The service life is 3-5 times that of lead-acid batteries. times.

1. Design requirements of lithium battery for electric forklift

The battery is designed to be used in conjunction with logistics forklifts. It requires a small size and relatively long working hours, and can drive two motors: one is to drive the car to run, and the other is to drive the lifting object.

MANLY’s lithium iron phosphate battery electric forklift design has a total power of 800W and an instantaneous power of 1000W.

The appearance is moisture-proof, the cycle life is long, and the high-power and high-current discharge performance are good. The whole product is suitable for indoor environments and has low-temperature rise.

2. Design scheme of lithium battery for electric forklift

1) Battery Management System (BMS): According to the chemical characteristics of the lithium iron phosphate lithium battery itself and the working characteristics of the forklift, the protection circuit is designed in a targeted manner. In addition to functions such as overcharge, over-discharge, overcurrent, and short circuit protection, the protection board The design also fully considers the problem of high-power heat dissipation and the balance of the entire battery pack. The entire protection board uses aluminum alloy as the heat dissipation substrate, and the temperature rise is less than 20 degrees.

2) Protection circuit: Imported IC and MOS tubes are used to conduct online real-time monitoring of overcharge, over-discharge, overcurrent, short circuit, and other functions on the battery cell so that the battery cell can work in a safe, stable, and efficient range.

3) Overcurrent fuse: It is mainly designed for the protection failure of the battery management system of the lithium battery itself. Since the battery pack uses high-power cells with relatively large capacity, although the battery management system has over-current and short-circuit protection, if an abnormality occurs, the protection function will also fail. In the case of an output short circuit, a very large current will be generated, resulting in danger. Therefore, an overcurrent fuse is added to the scheme. When an abnormal short circuit occurs, the fuse disconnects the circuit and cannot be restored, so as to achieve the purpose of abnormal protection.

4) Batteries: MANLY 32700/3.2V/6000mAh lithium iron phosphate batteries are used. The maximum charging rate of this battery can reach 1C, and the maximum discharge rate can reach 2C. The battery itself has multiple safety protection functions. The cell has a built-in thermistor (PTC), and the unit structure is also isolated by PTC when combined to prevent the occurrence of surge currents.

5) The whole set of battery parameters: 25.6V/80Ah (usually nominal: 24V80Ah). The normal working current is 30A, the maximum working current can reach 50A, and the instantaneous starting current can reach 120A.

6) Resistive equalization is adopted inside the battery pack, which can effectively compensate for the capacity reduction caused by the difference of single cells during use, and maximize the service life of the battery. 7) Battery parallel unit: PTC isolation is used to avoid inrush safety problems caused by large capacity.

8) The high-current main circuit of the battery uses copper strips as current collectors to make the discharge current of the single battery as close as possible.

9) The battery pack uses a plastic bracket to isolate and fix the battery cells, which is more conducive to heat dissipation and safe use of the battery.

3. Characteristics of the lithium battery for electric forklift

Long service life (the capacity is not less than 90% after 5000 cycles discharge and charge);

Excellent working temperature (it can operate stably under the temperature condition of -20℃~+75℃ for a long time);

Installing a battery detection unit in the battery pack can accurately detect battery voltage, temperature, capacity, and other conditions in real-time, and transmit it to the main system through the communication system in time, which can fully improve the safety of the product’s work;

The battery pack shell is designed with sheet metal material, which has superior impact resistance and high and low-temperature resistance, effective flame retardant high performance, which can ensure that the battery pack always maintains effective protection ability under external impact. It is equipped with a folding handle. Convenient to carry;

The battery cell has passed various safety tests of the People’s Republic of China’s automotive industry standard “QC/T743-2006 Lithium Battery for Electric Vehicles”, and all meet the standard’s indicators;

Simple installation and combination (the design concept of the unit module makes the product installation flexible and reliable);

IV. Structure Of Electric Forklift Battery

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