Some common questions about NiMH battery

Some common questions about NiMH battery

  1. What is NiMH?

NiMH stands for nickel metal hydride and has many advantages over other battery construction materials.


  1. What does battery memory effects mean?

Previous batteries and batteries of other chemical composition can have memory effects. This is the case when the battery must be completely depleted or its capacity is reduced before charging. The new generation of nickel-metal hydride batteries has no memory effect and can be charged at any time during the use cycle. If you are unsure of the battery charge level or condition, recharge it.


  1. What is mAh?

This is the level of energy storage capacity mAh = “milliamp hours”. Therefore, if the battery is compared to AA with a 2000mAh rating, its capacity will be twice the 1000mAh rating.


  1. What is the best use of Ni-MH batteries?

Most applications where energy consumption and demand are high are the uses of nickel-metal hydride batteries, such as power tool, rc car etc.


  1. How many times can NiMH batteries be charged?

Generally speaking, 1700 to 2000mAh low-capacity rechargeable AA batteries can be charged up to 1,000 times in the night slow charge mode, and 2100 to 2400mAh rechargeable batteries can be charged to 600 to 800 times in the night slow charge mode. New high-capacity AA rechargeable batteries have greater power capacity, but they can only be charged about 500 times in night mode. Capacity improvements or fast charging will always reduce the number of cycles. Every battery above 2100mAh on the market will have less than 1000 charge cycles.


  1. Which applications are not suitable for NiMH batteries?

Low-energy devices that do not use batteries  under any circumstances for 30 days, such as smoke alarms, emergency flashlights, clocks, TV remotes, etc.


  1. Why does Ni-MH battery not work in some applications, such as smoke alarms?

Nickel-metal hydride batteries self-discharge about 1% every day, so if used in low energy consumption or backup equipment, the battery only can last about 90 days before recharge.


  1. Can I use higher rated mAh batteries (ie 1800mAh and 2000mAh) in electronic devices?

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


  1. Why are NiMH AA and AAA batteries at 1.2 volts and alkaline batteries at 1.5 volts?

In fact, the average voltage of alkaline batteries during discharge is about 1.2 volts. The main difference is that alkaline batteries start at 1.5 volts and gradually fall below 1.0 volts, and nickel-metal hydride batteries remain at about 1.2 volts for nearly 80% of their discharge cycle. Once the alkaline battery is discharged to 50% capacity, it will provide a lower voltage than NiMH batteries.


  1. Will NiMH batteries lose capacity over time?

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


  1. Do I need to charge the batteries when I receive them?

Yes, they need to be fully charged before they are used for the first time. Note, however, that for new nickel-metal hydride batteries, they usually need to be cycled at least three to five or more times to reach peak performance and capacity. When using nickel-metal hydride batteries for the first few times, you may find that they deplete (discharge) quickly during use. Don't worry, this is normal.


  1. Is there a difference between the chargers? Ie fast, slow, microprocessor controlled, etc?

Yes, there are differences between different chargers on the market. If the charger was recently designed and marketed and clearly states that it is charging a nickel-metal hydride battery, it may still work. 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 unsecured batteries sometimes have a short life. Fast chargers also tend to reduce battery life by at least 500 charges.


  1. How to dispose of old Ni-MH batteries?

Recycle as much as possible

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