1. Basic situation of batteries for electric bicycles
Lead-acid batteries used in two- or three-wheeled mobility tools are collectively referred to as batteries for electric bicycles. At present, the battery for electric bicycles is a fixed valve regulated battery, which is generally composed of 6 single batteries connected in series, with a rated voltage of 12 V and a capacity of 6~32 A·h. Generally, 2 or 3 batteries are used in series. This type of battery is a power battery, that is, it is mostly used in a use environment with a large depth of discharge and a corresponding large amount of charge during use, that is, the so-called deep charge and deep discharge type.
The service life of the early electric bicycle battery is about 6 months. After the unremitting efforts of technicians, the service life can now reach 3 years. In order to solve the problem of lifespan in the early batteries, the front grid had to use highly toxic figurines and lead brocade alloys. Now the country has phased out the alloys before 2013 and gradually transformed them into lead-calcium-tin alloys. The moped battery made of lead-calcium-tin alloy for the front grid can completely replace the battery containing pot alloy, and has achieved a very good service life and can meet the needs.
2. Requirements for battery indicators of electric bicycles
(1) Capacity: an index to measure the amount of power stored in a battery, the unit is A h, and it is generally expressed as a 2 h rate. Such as 6-DZM-10 battery, discharge at 5 A, to reach more than 120 minutes.
(2) Capacity preservation rate: Under specified conditions, the capacity preservation performance of a fully charged battery after open-circuit storage. The battery is placed at 25 °C for 28 days, and a 2-hour rate capacity test is performed. The percentage of the ratio of the released capacity to the 2-hour rate capacity before being placed is the storage rate of the capacity, and the standard stipulates that it should be greater than 85%.
(3) Low temperature capacity: evaluate the discharge performance under low temperature conditions. The battery is discharged to 10.5 V at a 2h rate capacity current at 15°C, which should not be lower than 0.7 times the 2h rate capacity at room temperature.
(4) Sealing reaction efficiency: Under the specified conditions, the gas generated by the decomposition of water in the battery electrolyte is absorbed and reduced to water through the negative electrode.
(5) Cycle life: an indicator for assessing battery life. In the environment of 25 ℃, discharge with a current of 1.0 I2 (A) for 1.6 h, and then charge at a constant voltage of 16 V [current limit 0.4 I2 (A)] for 6.4 h; the above is one cycle. The cycle life specified in the national standard is greater than 350 times. The above discharge depth is 80%, and many factories also carry out 100% deep discharge, that is, discharge to 10.5 V with I2, and then charge for 10 h with a constant voltage of 14.8 V and a current limit of 0.4 I 2 A, which is a cycle. This charging and discharging method is close to the state of electric bicycles, and the lifespan can better reflect the actual situation. Test with 100% depth of discharge, if it reaches 700 cycles, the actual use of the battery can reach more than 3 years.
(6) The electric bicycle battery should also have good over-discharge performance: that is, after being discharged, it can be stored for a long time and can be charged for use. Early batteries often fail because of this poor performance; the consistency of the combination is a performance of the battery pairing and use. The better the consistency, the longer the service life of the battery; there are also safety, explosion-proof, vibration resistance, etc.
3. Model name of electric bicycle battery
Such as 6-DZM-10 battery, In the model number, the first digit represents the number of single cells connected in series, “6” represents 6 cells, indicating that the rated voltage of the battery is 12V; “DZ” represents the battery for moped; “M” represents the sealed valve control type; the last number represents the 2h rate capacity.