What is the recoverable memory effect of NiMH batteries?

What is the recoverable memory effect of nickel-metal hydride batteries? It is different from lithium batteries. When a sealed nickel-metal hydride battery (mh-ni) repeats incomplete charge and discharge cycles, the battery has recoverable voltage drop and capacity reduction. For example, the battery is fully discharged once, and then partially discharged several times, reaching 1.15v and the charging cycle. During the cycle, the voltage and capacity gradually decrease, and then the battery is completely discharged. The voltage is lower than the initial full discharge voltage of the battery. When discharged to the initial termination voltage, the battery cannot release its full capacity. This phenomenon is called voltage drop. Because the battery seems to be able to remember lower capacities, this is sometimes called the memory effect. However, after several charging and discharging, the battery can recover its full capacity, that is to say, mh-ni battery has a slight but recoverable memory effect. In recent years, you may often hear people saying that nickel-cadmium and nickel-metal hydride batteries are difficult to use due to their memory effect or when the battery starts to show memory effect, it’s time to replace it. In some rechargeable batteries, the memory effect of the battery does exist, which is manifested as a phenomenon in which the capacity of the rechargeable battery decreases. This term is increasingly used to describe similar situations, but it is not actually a permanent phenomenon. However, many users don't seem to really understand its meaning. Here are the reasons. Technically speaking, the battery memory effect is a reversible battery failure. The memory effect refers to automatically maintaining a specific tendency for a long period of time after a specific work cycle. Pouch batteries have no memory effect. Sintered batteries have a memory effect. If the battery goes through a long period of shallow discharge, the capacity loss or voltage drop is most obvious during deep discharge. Let us discuss the method of eliminating the memory effect, that is, let the battery be fully charged with the normal charging method, usually the method of overcharging. After the battery is fully charged, use a large current to discharge the termination voltage, and then use a small current to discharge the fully discharged state, and then install a constant current 0.1c5a for more than 20h to ensure that the positive and negative electrodes of the battery meet the complete charging requirements, and then fully discharge the discharged state According to the traditional discharge. The memory effect can be eliminated by multiple charging and discharging. The reason for the voltage drop is that only part of the active material participates in the discharge and charge during shallow charging or partial discharge. The physical properties of the active material not participating in the cycle change, and the battery resistance increases. Through a complete charge and discharge cycle, the active material can be restored to its original state. The degree of voltage drop and capacity loss depends on the depth of discharge. This phenomenon is obvious when the discharge reaches a higher end voltage. When the terminal voltage is 1.15-1.10v, the loss is very small. If the terminal voltage is lower than 1.1v, there will be no significant voltage drop and capacity drop during the subsequent discharge. The memory effect is also related to the discharge rate. Regarding a specific discharge termination voltage, the higher the discharge rate, the smaller the depth of discharge, the less active material involved in the cycle, and the greater the capacity loss. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Research and design of lithium battery automatic test system