A few days ago, some customers used to asked me if the cycle of life electric bike lithium battery can last to 5 years? So I write an article to everybody to answer the doubts.
Nowadays, electric bicycles are becoming more and more advanced and intelligent. Electric bicycle R&D and manufacturing technology is constantly improving, manufacturing technology is also day ripeness. But there is a disease, but has been restricted the development of electric bicycle, that is the core of electric bicycle “Lithium Battery”!
In the field of R & D and application of lithium battery, with various advantages, lithium battery quickly occupied half of the battery category, and became the main force in the power market and energy storage products. The development of lithium battery is inevitable, at present the popularization of lithium battery in the energy storage market has been very extensive. By comparison, lithium-ion batteries are superior both in weight and in volume. Many people are worried about lithium battery life, because the general lead-acid battery life is about 3 years to end, so people is also concern about the cycle life of lithium battery.
Can lithium-ion batteries on electric bicycles last for 5 years?
Correct statement: Lithium battery whether can be used for 5 years is mainly depends on the completion of the charge cycle, and do not have a direct relationship with charge times. A simple understanding, for example, is that a piece of lithium-ion battery uses half of the power on the first day and then recharges it again. If you do it again the next day, charge the battery in half and charge it twice, it counts as one charge cycle, not two. As a result, it can often take several recharges to complete a cycle. Each time a charge cycle is completed, the charge is reduced a little bit. But the reduction is so small that high-quality batteries retain 80% of their original charge after many cycles, which is why many lithium-ion power-supply products are still in use after 3 or 4 years. Of course, old lithium-ion batteries eventually need to be replaced by new customized lithium battery.
It says the theoretical lifetime of a lithium ion battery is about 800 cycles. Assuming Q is the electricity provided by a complete discharge, regardless of the reduction in charge after each charge cycle, a lithium battery can supply or supplement about 800Q over its lifetime. From this we know that if you charge it with 1/2, you can charge it about 1,200 times; if you charge it with 1/3, you can charge it about 2,400 times. By analogy, if the charge is random, the number of times is variable. Anyway, no matter how you charge it, it’s going to add up to about 600Q, which is constant. So, we can also understand: lithium-ion battery life have relationship with the total charge capacity of the battery, and do not have relationship with charge times.
In fact, shallow charge shallow discharge is more beneficial to lithium battery, only in the product’s power module for lithium battery calibration, deep discharge is necessary. Therefore, the use of lithium-powered products do not adhere to the process, all in the first convenience, ready to charge, do not have to worry about the impact of life.
The capacity loss of Ebike lithium battery can be expressed during charging and self-discharging:
1. Every time a lithium ion battery goes through a full cycle, it takes a little less time to charge. The charging platform of lithium-ion battery is 3.7 V ~ 4.2 V, the charging capacity of lithium-ion battery is more than 90% of the total charging capacity.
2. The discharge platform of lithium battery is 4.1 V ~ 2.75 V (the lowest discharge voltage of single lithium battery is 2.75 V) , the discharge capacity of this stage accounts for more than 90% of the total capacity. With the increase of cycle times, the discharge platform of lithium battery decreases, the discharge capacity is also reduced.
3. The ratio of self-discharge to the total charge of li-ion battery increases with the increase of cycle times, but makes the discharge platform accelerate and decrease.
The decline in lithium-ion battery life is characterized by a decline in capacity, which means that lithium batteries have a finite lifespan, just as everything else does, and that capacity decline is a form of qualitative change. From this performance, we can see that the way to prolong the life of lithium battery is from the point of view of scientific charge and discharge and reducing self-discharge.
If want lithium battery life to play the best, then consumers must understand the “Lithium battery”three big taboos!
First, Temperature: Lithium battery afraid of high temperature.
Second, high current: for example, the 18650 battery is 3C discharge, your electric bike is 2000W, the battery used is lower than your electric bicycle discharge current, this will lead to lithium battery temperature is too high, the current is too large and short life, there will be a bulge scrap situation, if your electric bike is very high power, speed is very fast, recommended to choose 10C current 18650 cell, so choose the right cell is obviously very important!
Third, full charge storage: take NCM battery pack for example, full charge is 4.35 V, the current market protection board is 4.2 V on the cut-off charge, so many people buy electric bike lithium battery said not more than the nominal capacity, in fact, this is the reason, generally long-term storage of lithium-ion batteries in electric vehicles, the best way is charge the battery to 50%, such as you buy a new mobile phone, many are 50% of the power. If the battery is kept at full capacity for a long time, it will reduce the capacity of the lithium-ion battery. In addition to lithium iron phosphate and lithium titanate, these two kinds can be stored at full power, but also need to pay attention to the choice of better quality protection board, the biggest taboo of lithium battery is over-charge and over-discharge.
Pay attention to these points, your electric bicycle “Lithium battery”can use 4 ~ 5 years.
SmartPropel Original Writer:Nancy