[[TitleIndustry]]

Can lithium iron phosphate batteries be used in electric bicycles

Date:Aug 19, 2020

Can lithium iron phosphate batteries be used in electric bicycles

Certainly. Among the lithium batteries used in electric bicycle products, the proportion of lithium iron phosphate is still relatively small, and the most common is ternary lithium battery pack. Although the proportion is relatively small, the high safety and high cycle life of LiFePO4 are favored by the high-end demand of electric bicycle products. Now, let's talk about why the proportion of LiFePO4 is so small, and why can it be sought after by special needs? Why is lithium iron phosphate used in such a small proportion? This is inseparable from its material disadvantage, but also the problem of energy density. For example, for 18650 cylindrical cells, the larger capacity of LiFePO4 is 18650-3.2v-1800mah (5.76wh), while the larger capacity of ternary lithium is 18650-3.6v-3500mah (12.6wh). It can be seen that the energy density of lithium ternary is more than twice that of lithium iron phosphate at the same volume.

For another example, for the 36v18ah battery pack, if the lithium iron phosphate battery cells are used, the combination of 10 series and 10 parallel is required, that is, 100 18650 cells; if the ternary lithium battery cell is used, 10 series and 5 parallel, that is, 50 18650 cells are required. Volume and weight will be reduced by twice, which will make some focus on small weight and small volume of electric bicycle products, have to choose ternary lithium battery pack. In the case of the same volume, the more the number, the stronger the endurance, so ternary lithium is the first choice. This is why lithium iron phosphate accounts for a small proportion. Although it has the advantages of high energy density and high safety of lithium iron phosphate battery, it has high safety. As we all know, the most important thing for lithium battery pack is safety. Compared with lithium ternary, lithium iron phosphate is still inactive. Especially at high temperature, the safety of lithium iron phosphate is higher than that of lithium ternary.

Electric bicycle is an outdoor product. It runs on the ground for a long time. When the lithium battery pack is discharged, it will generate high temperature rise at the same time. Especially when exposed to the sun in summer, the continuous high temperature will make ternary lithium face great risk, ranging from short life to explosion and fire. This is why some high safety E-bike products choose to use lithium iron phosphate battery pack. High cycle life LiFePO4 LiFePO4 life: in terms of cell, the nominal cycle life is 2000 cycles, and the nominal cycle life can reach 1500 cycles after the lithium battery pack is combined with pack. The service life of ternary lithium: in terms of cell, the nominal cycle life is only 500 cycles. After the lithium battery pack is combined with pack, the nominal cycle life is only about 400 times. In terms of cycle life, LiFePO4 battery is about 4 times as long as that of lithium ternary battery.

This is another important reason why LiFePO4 is so popular. How to use the lithium iron phosphate battery pack on the electric bicycle? First of all, volume and weight need to be increased. Secondly, the number of series and parallel needs to be changed. For example, the 36V ternary lithium battery pack is 10 strings, but lithium iron phosphate needs to be 12 strings. It is possible to achieve 13 strings of lithium ternary at 48V, but 15 strings of lithium iron phosphate are needed. The increase of these series numbers is due to the nominal voltage of LiFePO4 monomer is 3.2V, while that of lithium ternary battery is 3.6V. The voltage platform divided by the nominal voltage of the unit is the number of strings. The same is true of the combination. The capacity of the battery pack divided by the capacity of the monomer is equal to the union. For example, for the 36v18ah battery pack, using 18650-3.2v-1800mah of LiFePO4, 12 strings and 10 parallels are required. Speaking of this, we should know that lithium iron phosphate battery can be used in electric bicycle, and know how to use it? Hope to help you, thank you.

Previous: LiFePO4 is expected to dominate the energy storage and electric vehicle markets

Next: E-bike speed is slow, can you add batteries? Chaowei warning: No