Frequently Asked Questions about Batteries.

Batteries available for public sale usually fall into two categories, primary and rechargeable.
Primary Batteries are same as disposable batteries, which are designed not to be recharged and have to be discarded after fully discharged. Common primary battery types include alkaline, carbon zinc, lithium, silver oxide and zinc air batteries.
Rechargeable batteries can be recharged and reused from 500 to 1000 times depending on usage. Common rechargeable battery types include nickel metal hydride (NiMH), nickel cadmium (NiCd) and lithium ion (Li-ion) batteries.

Battery types

Voltage (V)

Daily applications

Primary Batteries





MP3 players, Toys, Cameras, Remote controls

Carbon Zinc


Clocks, Radios, Smoke alarms

Lithium Ion


Personal computers, PDAs

Photo Lithium

3.0 / 6.0


Silver Oxide



Zinc Air


Hearing aids

Rechargeable Batteries





Digital cameras, MP3 players, Radio-controlled cars



MP3 players, Radio-controlled cars



Laptop computers, PDAs, Mobile phones, Video cameras, Digital cameras,

Batteries are usually marketed with buzzwords such as 'high capacity', 'ultimate power' and 'long-lasting', but these cannot accurately reflect their service time, as different types of batteries carry distinctive characteristics.
Compared with carbon zinc batteries, alkaline batteries are more expensive. But for high drain applications, alkaline batteries can last 5 to 10 times longer than carbon zinc batteries, thus a more cost-effective choice.
Rechargeable batteries are more expensive than alkaline batteries, and a charger has to be bought with additional cost. However, rechargeable batteries can be recharged and reused up to 1,000 times, making it more economical in long run, and more eco-friendly.
NiMH carries similar characteristics with NiCd, but for the same size, fully charged NiMH batteries can last one time longer than NiCd batteries.
Choosing the appropriate type of batteries requires knowledge of the device’s energy demand. In general, higher drain devices have to operate with higher voltage batteries.
NiMH Batteries
Can provide electronic devices with the longest service time and recharged up to 1,000 cycles, offering the lowest average energy cost compared with alkaline and zinc carbon batteries.
Alkaline Batteries
Are most suitable for electronic devices of medium energy demand.
Carbon Zinc Batteries
Are suitable for devices that demand very low energy.

Energy Demand

Electronic Devices

Suitable batteries


Digital Camera

NiMH, NiZn batteries


Portable televisions, MP3 players, PDAs, Handheld game consoles

NiMH batteries

Medium to High

Portable recorders, MP3 players, Torches

Alkaline batteries


Clock radios, Remote controls, Smoke alarms

Zinc carbon batteries

The nominal voltage of every NiMH and NiCd battery is 1.2 V, while others have varying voltages due to different chemical structures. For example, Li ion batteries’ voltage is 3.6 to 3.7 V.
Yes. Under most situations, NiMH batteries can fully replace primary batteries, especially for high drain electronic devices.
Alkaline batteries’ nominal voltage is 1.5 V but once started discharging, the voltage will be on decline. Throughout the whole discharging process, alkaline batteries’ average output is 1.2 V, similar to that of NiMH batteries. The major difference is that alkaline batteries output 1.5 V when start and end below 1.0 V, while NiMH batteries maintain an average of 1.2 V for most of the time.
Traditional rechargeable batteries start losing charges after one week of storage, therefore requiring a recharge before putting in use. The new generation of rechargeable batteries has a much better storage performance and lower self-discharge rate. When delivered out of factory, the batteries are charged and ready for use.
High Performance - for high-powered electronic devices, NiMH batteries last over 3 times longer than alkaline batteries.
Money saving – NiMH batteries can be recharged up to 1,000 times, so the cost is much lower in long terms.
Eco-friendly - with no toxic chemicals like cadmium and mercury, NiMH batteries provide a better environmental performance.
Using improper charging methods is the most common cause for shorting the service life of NiMH batteries. Both overcharging and over-discharging NiMH batteries will lead to poorer performance, and improper charging will shorten its service life (the number of recharge times). Besides, NiMH batteries are not suitable to operate under high temperature.
Short circuit occurs when the polarities of a battery are in contact with electricity-conductive materials, such as keys and clips, and can lead to serious consequences. For example, it will cause a rise of the batteries' temperature and internal pressure, resulting in leakage. To avoid short circuiting, do not place charged and non-packaged batteries together with conductive materials such as coins and keys.
Lithium ion (Li-ion) batteries are of high capacity and light weight, with a nominal voltage of 3.7 volts. Nickel metal hydride (NiMH) provides even higher energy density, (over 2 times higher than NiCd batteries) and can be recharged rapidly, providing a stable performance. With a 1.2 volts nominal voltage, NiMH batteries are especially suitable for high drain applications such as digital cameras and electronic toys.
Rapid chargers can fully charge a NiMH battery as quick as 2 to 0.5 hour, while it takes slow chargers over 12 hours to reach a full charge, though the results depend on charging rate and nominal capacity. Just imagine, a bigger bucket takes longer time to fill up, but you can also increase the water flow to speed up the process.
Continuous (trickle) charging means charging at very low rate to keep batteries full but not overcharged.
Both rapid charger and slow charger have their own merits, depending on your purpose and budget concern. Rapid chargers take a shorter time to reach a full charge and are more sophisticated in design, thus are more expensive than slow chargers. As overcharging can damage NiMH batteries, rapid chargers are usually equipped with multiple safety systems to avoid overcharging, such as voltage and temperature status monitors, which also lead to higher prices. Therefore, if charge time is not a primary concern, slow chargers are a more economical choice both in terms of budget and cycle life. However, if speed in recharging batteries is called for such as radio controlled cars or digital cameras, rapid chargers are worth investing in to ensure stable energy supply.
It depends on two factors: milli-ampere (mA) for charging current and milli-ampere-hour (mAh) for capacity level.
If we assume charging current as the speed of driving and capacity level as the total travelling distance, then the time of a cycle of recharge can be calculated as:
Capacity level/ charging current x 120%
Charging time would normally be increased by 20 to 40% to make up for possible capacity loss while charging
Yes. But it depends on the designs of different chargers. Theoretically, if the charger’s charging rate is as low as 0.1C, NiMH batteries can be charged continuously.
No. It is normal that batteries get slightly warm during charging.
Memory effect occurs when a rechargeable battery is charged before its capacity is exhausted. It happens if the battery could memorize the last discharge level and would only accept that amount of charge in subsequent charges, therefore shortening its service time.
With the latest technology, NiMH batteries suffer from little or no memory effect.
Self-discharge means that NiMH rechargeable batteries gradually lose their charge after taken out from the charger. On average, NiMH batteries lose 15% to 20% of their charge each month under room temperature. But with improved storage technology, newer rechargeable NiMH batteries can retain up to 85% of their capacity after a year of storage and are therefore ready for use over an extended period of time.
Battery cycle life is defined as the number of complete charge - discharge cycles a battery can perform before its nominal capacity falls below a certain level of its initial rated capacity. In general, if the level falls to 60% to 80% of its nominal capacity, the battery’s cycle has ended. However, this also varies under different charge – discharge situations.
Rechargeable batteries are affected by:
1) Charging:
Choose a smart charger that can automatically shut off under different condition (e.g.when batteries are fully or over charged at negative voltage and overheat). In general, charging at a low rate helps extend the service life of batteries than using a rapid charger.
2) Discharging:
- Depth of discharge (DOD) affects the service life of batteries significantly. The higher the DOD, the shorter the service life of the batteries, and vice versa. Therefore, you should avoid over-discharging batteries to extremely low voltage. Depending on the discharge voltage, the acceptable terminal voltage ranges from 0.8V to 1.0V.
- Discharging batteries under high temperature will shorten service life
- If the electronic device does not stop all discharge current (e.g. standby current), leaving batteries inside the device for too long can lead to over-discharging.
- Using a combination of old and new batteries or of different capacities, chemical structures and charge status can result in over-discharging, or even reverse charging.
3) Storage:
- Storing batteries in very warm places for an extended period of time reduces service life
- Avoid inserting batteries in a charger for too long
To help extend the life of the batteries, you should:
- Turn off battery-operated appliances when they're not in use
- Store the batteries in a dry and ventilated place at normal room temperature without direct sunshine; For long-term storage, the room temperature should be below 30 degrees Celsius; Do not use or charge batteries under extreme temperatures
- Charge the batteries using suitable chargers and prevent overcharging; Use charger with a voltage sensing capability; Choose packages that include both the batteries and the charger
- Charge and discharge batteries occasionally to avoid the voltage falling below 0.8V
- Remove batteries from devices that won't be used for an extended period of time
- Avoid overcharging by following the charging time stated by the battery manufacturer
- Not to use a combination of mixed batteries of different chemical structure, capacity and energy level
In general, the higher the temperature, the easier the NiMH battery loses its charges.
Extreme heat or cold reduces battery performance, and battery-powered devices should not be put in very warm places. In addition, batteries should be stored at room temperature in a dry environment. Refrigeration is not necessary or recommended.

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