How long can Ni-Mh batteries store? What is the cycle life of Ni-Mh battery?

If it is not used, it will discharge at a rate of 0.2%-0.3% every day, and after a period of storage, even if it is not recycled, a small part of its capacity will be permanently lost, and its life will also be attenuated. Therefore, the battery should not be stored for more than 1 year.

First, nickel-hydrogen battery

1. Under normal circumstances, the new NiMH battery contains only a small amount of electricity, and you must charge it before you buy it. However, if the battery is shipped out of the factory for a short period of time, it is recommended to use it first and then recharge it.

2. The newly purchased nickel-metal hydride battery generally has to be charged and used 3-4 times, and the performance can be brought to the best state. Many friends have encountered small problems in the first charge, for example, the number of PP after the first charge is not So many imaginations? After 3-4 times of charging and use, it was solved.

3. Although the memory effect of Ni-MH battery is small, it is recommended that you try to recharge it after each use, and it is a one-time full. Do not charge it for a while and then recharge it. This is an important point of "prolonging life."

4. When charging the battery, pay attention to the heat dissipation around the charger. It is not necessary to use any fan to deliberately blow it. However, be careful not to place too much debris around the charger. In the process of using the battery, the ordinary user often does not have a dedicated storage bag; after replacing the battery, the user will habitually put the battery on, regardless of whether the place is clean and humid. The consequence of this is that the battery is easily soiled, the contacts are easily in contact with metals such as keys, and are susceptible to moisture, which are the enemy of the battery. Recommendation: Users should set a battery-specific placement point and keep the battery clean. To avoid problems such as loss of power, keep the contact points on both ends of the battery and the inside of the battery cover clean. If necessary, wipe with a soft, clean, dry cloth.

5. When not in use for a long time, remember to take the battery out of the battery compartment and put it in a dry environment. It is recommended to put it in the battery compartment to avoid short circuit.

6. Nickel-hydrogen batteries that are not used for a long time will naturally enter a "sleep" state after a few months of storage, and the battery life is greatly reduced. If the NiMH battery has been left for a long time, it is recommended that you charge it with a slow charge first. Here is another key question: For NiMH batteries, should the battery be fully discharged before being stored, or is it stored live? Which two different views should be adopted? Many people think that the former should be used, but the author believes that battery storage is more reasonable. Because: According to the test, the best condition for nickel-metal hydride battery storage is to save about 80% of electricity. This is because the self-discharge of Ni-MH batteries is large (about 10%-15% in one month). If the battery is completely discharged and then stored, it will not be used for a long time. The self-discharge phenomenon of the battery will cause over-discharge of the battery will damage the battery. Do not believe? Then you think about whether the newly purchased Ni-MH rechargeable battery has electricity. This is the reason. Suggestion: Compare more, correct the wrong view, and start to maintain the battery from the right direction, otherwise it will backfire.

7. A lot of friends posted a message asking how to discharge nickel-metal hydride? After asking a lot of battery experts, I came to a consistent conclusion to remind my friends. Try not to discharge the Ni-MH battery. Over-discharge will cause the charging failure. The harm of this is far greater than the memory effect of the Ni-MH battery itself!

8. The multi meter self-test battery is full or not. Generally, the nickel-hydrogen battery has a voltage of 1.2V or less before charging, and the normal voltage is about 1.4V after being fully charged. With this judgment, it is easy to judge the status of the battery.

9. Chargers are mainly divided into fast charge and slow charge. The slow charge current is small, usually around 200mA. For example, our common charging current is around 160mA. Her charging time is long, and it takes about 16 hours to charge a 1800mAh NiMH battery. Although the time is slower, the charging will be sufficient and the battery will not be damaged. The fast charge current is usually above 400mA, the charging time is obviously reduced a lot, it can be done in 3-4 hours, and it has won everyone's favorite. There are many types of fast charge, and the prices are different. Therefore, everyone may doubt, the same is fast charge, why the price is very different? Good chargers, especially good fast chargers, are equipped with anti-overcharge protection. For example, our common Panasonic charger BQ390 is particularly good in this respect. The excellent chip software design ability also charges the battery when charging Fast charge damage to the battery is reduced to a minimum.

10. Contradictions appear: slow charge does not hurt the battery but the charging time is too long; fast charge can save time, but it is harmful to the battery, even the best Panasonic best charger BQ390 in the world can only reduce the damage degree very well. But not completely avoided. The way to resolve the contradiction is to buy a fast charge and a slow charge. Charge with a fast charge for a period of time, for example, after 5 or 10 times, switch to slow charge once or twice. This will restore the battery's performance to its optimum state.

11. When the battery is used, it is usually a battery pack, which is 4 or 6 in series. At this time, it is important to maintain the balance of each battery. Otherwise, the battery problem will affect the operation of the entire battery pack. First of all, to ensure the same battery capacity, it is best to choose the same brand of the same model purchased at the same time. Then, to keep the internal charge of the battery consistent, in short, the battery pack's power is either full or empty. If there are more batteries to make several sets of battery packs, you can try "select". Specifically, battery cells with similar parameters such as capacity and voltage are connected in series to form a battery pack. Due to insufficient conditions, it is generally possible to measure the voltage after the discharge point and the voltage of the good power.

12. Finally talk about charging and discharging.

The high-end NI-MH charger uses -DELTAV to detect the battery voltage to determine if the battery is fully charged. The voltage curve of the battery is similar to that of the discharge. It starts at a relatively fast rise and then slowly rises. When it is charged, the voltage starts to drop rapidly, but the drop is not very large. The previously used nickel-cadmium batteries are similar, except that the speed and amplitude of the drop are larger than those of NI-MH. The most chargers on the market (the cheaper ones) often use constant voltage charging. For example, the old GP charging treasure is 1.4V voltage, that is, when the battery is flushed to 1.4V, there is no voltage difference, and the charging is over. . The result is often that the battery can not be fully charged, especially some older batteries, because the internal resistance increases, the voltage actually added to the battery is lower. Moreover, the current of such a charger tends to be small, and charging often takes more than 10 hours. The charger that is automatically cut off by -DELTAV can accurately control the charging time, so it can be reliably used for charging with a large current. The damage of high-current charging for nickel-metal hydride batteries is not as much as everyone thinks. On the contrary, the current use of DC requires more high-current charging. The first is the issue of time, don't need to talk about it. Then, the nickel-hydrogen battery has a characteristic is that the more current you charge, the more current it can discharge. Now DC is an electric tiger, the current is not small, so the relatively large use is relatively large. Current charging is a wise choice to keep the battery cleaner. Generally, the charging current of No. 5 can't exceed 1.5C, C is the battery capacity, which is 1000MAH battery, not more than 1.5A. I usually use 0.5C for charging (my charger is adjustable current). In terms of discharge, under normal circumstances, DC black screen can be used to charge, NI-MH memory effect is very small. However, after a period of use, as well as to balance the battery and activate the battery, it is necessary to control the termination voltage of the battery discharge. The termination voltage of the NI-MH battery is 0.9V. Be careful not to over discharge when discharging. Put it on each battery. The discharge can be stopped at 9V. NI-MH batteries are not as strong as nickel-cadmium batteries, and are sensitive to overcharge and over discharge and high temperatures, charge and discharge temperature. In general, do not let the battery temperature exceed 45 degrees. When the battery is full, the battery will heat up. When the high current is full, the temperature should be about 42 degrees. Do not exceed 45 degrees. Otherwise, the life will be quickly reduced and the internal resistance of the battery will increase. Also, after charging, the battery temperature is high, and it can be charged after cooling, and the charging money should wait for the battery to cool. Re-use after a long time without using it. It is best to recharge the battery several times. When using it, pay attention to keep the package intact and not damaged, so as to avoid short circuit. Don't hit the impact battery, don't burn it, etc.

Yes, it usually expires after three years, but it can be used after expiration, but the life is short and can be used.

A qualified nickel-metal hydride battery, after being fully charged, will remain in the environment at 20±5°C for 28 days, and the power will remain above 75%. When placed in a 60°C environment for 7 days, the power should be retained above 75%. The higher the temperature, the faster the power loss of the NiMH battery is.

So your Sanyo battery is definitely fake.

Now there are batteries on the market to save better nickel-metal hydride batteries, such as Sanyo's Enloop, Li Kexing's Ekeep. When these batteries are fully charged, they will have more than 80% of their electricity after being placed for 1 year. Of course, the price of this battery is also relatively expensive.

In each unit cell voltage of view, are nickel-metal hydride and nickel cadmium 1.2V, the lithium battery has to 3.6V, lithium voltage battery is 3 times of the other two. And the weight of the same type of battery lithium battery is almost equal to the nickel-cadmium battery, while the nickel-hydrogen battery is relatively heavy. It can be seen that the weight of each battery itself is different, but the lithium battery is reduced by 1/3 of the single battery when outputting the same voltage due to the high voltage of 3.6V, so that the weight and volume of the battery after molding are reduced.

Memory effect

Nickel-metal hydride batteries have the same memory effect as nickel-cadmium batteries. Therefore, regular discharge management is also required. This kind of periodic discharge management is handled in a fuzzy state, and some even discharge under the incorrect knowledge (the discharge is different for each discharge or after several uses). This cumbersome discharge management It is unavoidable when using NiMH batteries. Relative lithium batteries are very convenient and simple to use because they have no memory effect at all. It does not need to pay attention to the residual voltage, it can be directly charged, and the charging time can naturally be shortened.

Self-discharge rate

Nickel-cadmium batteries are 15 to 30% (months). Ni-MH batteries are 25 to 35% (months), and lithium batteries are 2 to 5% (months). The above nickel-hydrogen battery has the highest self-discharge rate, while the lithium battery has a very low discharge rate compared with the other two types of batteries.

charging method

NiMH batteries and lithium batteries cannot withstand overcharging. Therefore, in the PICKCUT control mode in which the nickel-hydrogen battery is charged at a constant current, when the charging voltage reaches the maximum, the charging is stopped as the best charging method. The lithium battery is best charged by constant current and constant voltage. If it is charged by the charger of the nickel-cadmium battery-DV control method, it is for the nickel-hydrogen battery and the lithium battery.

Capacity problem

Different models (especially different volumes) of the battery, the higher its capacity, the longer cycle life is, throwing away the volume and weight factor, of course, the higher the better.

But the same battery model, the nominal capacity (such as 600mAh) is also the same. The actual measured initial capacity is different: for example, one is 660mAh, the other is 605mAh, then 660mAh is better than 605mAh.

The actual situation may be that the capacity is high because the electrode material has more things to increase the initial capacity, and the electrode is used for stability. As a result, after a few dozen cycles, the battery with high capacity is rapidly depleted, and the capacity is low. The battery is still strong. Many domestic battery manufacturers often use this method to obtain high-capacity batteries, but the user's standby time after half a year is a mess.

The civilian AA nickel-metal hydride batteries (that is, the fifth battery), generally 1400mAh, but also have the standard ultra-high capacity (1600mAh), the same is true.

The cost of increasing capacity is to sacrifice cycle life. Manufacturers are not in the context of the modification of battery materials, it is impossible to really "improve" battery capacity.