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A Summary of Frequently Asked Questions About NI-MH Batteries!

does nimh stand

Regarding some common problems of NiMH batteries, I have summarized some, and I hope it will be helpful to everyone.

#1-What Does Nimh Stand For?

does mah rating mean

NiMH means “nickel-metal hydride”. The material is nickel metal hydride (NiMH). The nickel-hydrogen battery uses the same nickel hydroxide positive electrode and KOH electrolyte as the nickel-cadmium battery, but it uses hydrogen instead of cadmium in the negative electrode. It uses a pressure vessel to contain hydrogen. Ni-MH batteries are used in low-orbit satellites. They charge and discharge the batteries every time the earth passes, so it can be a long-life battery.

Another method of storing hydrogen is intermetallic compounds called metal hydrides. Some metals have spaces in their atomic lattice to accommodate hydrogen atoms. Hydrogen can be induced to enter and leave the metal matrix by electrochemical methods. Therefore, metal hydride is a variant of nickel-metal hydride batteries, using a new low-pressure hydrogen storage method.

#2-What Does Mah Rating Mean?

mah 看图王

It refers to the discharge capacity of the battery discharged to the cut-off voltage under certain discharge conditions. According to IEC61951-2:2017 “secondary cells and batteries containing alkaline or other non-acid electrolytes- Portable sealed rechargeable single cells- Part 2: Nickel metal hydride batteries”, Ni-MH batteries are charged at 0.1C at 20±5℃ 16 hours, then discharge to 1.0V under 0.2C condition.

#3-What Is the Best Use of NI-MH Batteries?

use of ni mh batteries

Most of the applications where energy consumption and demand are high are for Ni-MH batteries.

#4-What Does Battery Memory Mean?

does battery memory mean

The previous batteries and batteries with other chemical compositions will have a memory effect. This is a situation where the battery must be completely exhausted or its capacity reduced before charging. This new generation of Ni-MH battery has no memory effect and can be charged during the life cycle at any time. If you are not sure about the battery charge level or condition, please recharge it.

#5-How Many Times Can the NI-MH Battery Be Charged?

ni mh battery be charged

Generally speaking, low-capacity rechargeable AA batteries of 1700 to 2000 mAh can be charged up to 1000 times in the night slow charging mode, and 2100 to 2400 mAh rechargeable batteries can be charged up to 600 to 800 times in the night slow charging mode.

The new high-capacity AA 2500 mAh rechargeable batteries have greater power capacity, but they can only be charged about 500 times in night mode. Capacity improvement or fast charging will always reduce the number of cycles. Every battery above 2100 mAh on the market will have less than 1000 charging cycles.

#6-Why Does NI-MH Battery Not Work in Some Applications, Such as Smoke Alarms?

ni mh battery not work

The Ni-MH battery self-discharges about 1% every day, so if it is used in low energy consumption or standby equipment, the battery only needs to last about 90 days before it can be recharged.

#7-Which Applications Are Not Suitable for Using NI-MH Batteries?

using ni mh batteries

Do not use batteries or low-energy consumption devices within 30 days under any circumstances, such as smoke alarms, emergency flashlights, clocks, TV remote controls, etc.

#8-Can I Use Higher-Rated Mah Batteries (Ie 1800mah and 2000mah) In Electronic Devices?

better battery

Yes, the mAh level allows you to get a longer running time between charges. The mAh with a higher battery rating has no effect on electronic devices and is only allowed for long-term use.

#9-Why Is the Rated Voltage of AA and AAA Batteries 1.2v and the Rated Voltage of Alkaline Batteries 1.5v?


This is caused by the positive and negative materials of the battery itself, and the electromotive force difference between the two ends of the positive and negative materials is different. However, as a disposable battery, the voltage of alkaline batteries drops quickly during the discharge process. The minimum voltage required by general electrical appliances is 0.9V. It can be simply said that the average voltage of alkaline batteries is about 1.2 volts during operation. However, Ni-MH batteries have a very slow voltage drop and are suitable for high-current discharge. About 80% of the discharge time is kept at about 1.2 volts.

#10-Will NI-MH Batteries Lose Capacity Over Time?

ni mh batteries lose

Yes, this is not serious. At a charge level of 400 to 800, about 10% to 15% of the battery mAh capacity will be lost. This situation can vary greatly due to the quality of the battery and charger and how consumers treat the battery.

#11-What if I Don’t Want to Use a Replaceable Battery?

use a replaceable battery

Do not mix batteries from different manufacturers

Do not mix batteries of different capacities

Do not mix batteries with different chemical substances, such as nickel-cadmium, nickel-metal hydride, lithium, etc.

Do not store NiMH in the refrigerator

Do not expose to extreme heat

#12-After Receiving the Battery, Do I Need to Charge It?

need to charge

Yes, you need to fully charge the NiMH battery before using it for the first time. But it should be noted that for new nickel-metal hydride batteries, it usually needs to be cycled at least three to five times to achieve peak performance and capacity. The first few times you use NiMH batteries, you may find that they run out quickly during use. Don’t worry, this is normal until the internal structure of the battery is stable.

#13-Are There Differences in Chargers? Ie Fast, Slow, Microprocessor Controlled, Etc.?

microprocessor controlled

Yes, there are differences between different chargers on the market. If the charger is recently designed and sold, and it is clearly stated that it is charging Ni-MH batteries, it may still be usable. Most new chargers use small computer chips to manage charging and should get at least 500 charges from the battery. If not, buy a new charger. Some non-guaranteed batteries sometimes have a short lifespan. Fast chargers also tend to shorten battery life by at least 500 recharges.

#14-Will Ni-MH batteries leakWill NI-MH Batteries Leak?

ni mh batteries leak

Yes, for example, the electrolyte added during the production process exceeds the standard. The seal was not properly sealed. However, this situation can generally be detected during factory inspection.

During use, if the charger used is not suitable, or the charger does not have protective measures, it will cause overcharging, long time overcharging, multiple overcharging, and overdischarging, which may cause liquid leakage.

#15-How to Dispose of the Old NI-MH Battery?

old ni mh battery

Different countries have different requirements, but they should not be treated as general garbage. It is recommended to recycle those that are conditional.

Carl Zhang

Carl Zhang

I am a senior sales with 15 years in the battery industry and a bachelor's degree in economics.
I will be sharing some of my expertise on batteries and my insights into the battery industry in my blog, which should help you with your purchases in China.

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