Can I Mix Different LiFePO4 Batteries in a Pack?

Can I Mix Different LiFePO4 Batteries? Well, to mix different LiFePO4 batteries is not recommended. The reason is very simple, mixing different LiFePO4 batteries will affect the effect of the entire battery pack, including output power, safety, etc. But for some specific details, I hope this Blog can help you learn relevant knowledge.
Mixing different LiFePO4 batteries, we usually say “not recommended”, why is it not recommended? We can keep this question first. Generally speaking, the use of LiFePO4 batteries can be divided into two categories, discharging and charging.

About mixing different LiFePO4 batteries

Discharge is the part that more people pay attention to. Because the performance of a normal battery pack depends on the size, type, voltage, capacity, brand, and newness of each battery. If these parameters are not the same, it will cause confusion in the function of the entire battery pack, causing problems such as degradation of battery pack performance.Some rare cases even leakage and explosion. Of course, LiFePO4 battery will not explode, because it depends on its chemical properties.
Different shapes of LiFePO4 batteries mean some differences. Common LiFePO4 batteries are cylindrical, prismatic, etc. If you mix these batteries, I believe your electrical appliances will soon be damaged, because the different manufacturing methods will bring some characteristics. The slight difference.
Currently popular rechargeable batteries are generally nickel-metal hydride batteries, lead-acid batteries and lithium-ion batteries. However, these batteries are very different, which can be specifically expressed in terms of capacity, voltage, cycle times, life, safety, DOD, and so on. It is definitely not a good idea to mix these batteries. Different types of batteries in the same battery pack will have a great safety hazard. The same type of battery may only affect the battery performance, but if the two are completely different Terrible things will happen to batteries (such as AGM batteries and LiFePO4 batteries). Due to the difference in voltage and DOD, LiFePO4 batteries will undoubtedly be killed, so do not mix AGM batteries with LiFePO4 batteries!
LiFePO4 batteries of different capacities are better understood. A smaller capacity will definitely discharge faster than a larger capacity battery. However, in the case of parallel connection, batteries with similar capacities can be mixed.
In addition, there will also be differences between brands. Frequently, batteries of the same type, voltage and capacity produced by different brands will have subtle differences, because at present, many battery brands produce batteries that are better than the nominal ones. The capacity is 5%~10% higher, which causes the differentiation of batteries between brands. Therefore, do not mix LiFePO4 batteries of different brands.
Finally, how old or new each cell is will also affect the overall performance of the battery pack to a greater or lesser extent. If possible, it is best not to mix old and new batteries. After the old battery is used for many times, the parameters may change to some extent. Likewise, old batteries can affect the performance of new batteries, which in turn affects the performance of the entire battery pack. In principle, it is allowed to mix old and new batteries, but for the overall performance of the battery pack, it will be better to use the same new batteries.
The charging part of LiFePO4 battery is more subtle. Similarly, batteries of different shapes, types, brands, old and new levels cannot be mixed. However, under the condition that all parameters are the same, LiFePO4 batteries of different capacities can be charged in parallel. For a simple example, two water tanks with the same height but different widths are connected together by a connector, and they are filled with water at the same time. Eventually, they will be filled with water at the same time without causing any harm. Similarly, the battery is the same. When only the capacity is different, it is finally fully charged at the same time, which will not cause any damage to the LiFePO4 battery.

Disadvantages of mixing different LiFePO4 batteries

First of all, if you mix different LiFePO4 batteries, one of the most obvious consequences is that the effect of your battery pack will not meet your expectations. In the battery pack, high-performance batteries will always be constrained by weaker batteries. For example, when discharging, the voltage is forced to drop to the same level as the weaker battery, which increases the risk of battery damage. In the process of using such a battery pack, the performance difference of each battery will become larger and larger, such as capacity, discharge rate, etc. These differences will cause the BMS to lose its function and fail to provide you with safety protection. Finally, one or more of the batteries will be over-discharged, causing damage or leakage, causing irreparable losses. And due to a problem with the battery pack, the output power is of course unstable, and your electrical appliances may suffer some damages and cause malfunctions.


Through the above description, I believe you already know why we keep saying “not recommended” to mix different LiFePO4 batteries. Our suggestion is to use LiFePO4 batteries of the same shape, same type, same brand, same capacity, same voltage, same new and old level to build a battery pack, and don’t forget to also choose the appropriate busbars to connect your battery.