Batteries are widely used in a variety of electrical devices. Apart from lifespan of batteries, consumers should also pay more attention to the problems of electrolyte leakage and their heavy metals content.
The Consumer Council tested a total of 40 models of AA and AAA size single-use batteries comprising 22 alkaline and 18 zinc carbon models. The test items included service life, electrolyte leakage and heavy metals analysis.
According to limits in the European Union (EU) directive on environmental protection, all alkaline models passed the heavy metals analysis. The content of heavy metals namely mercury and cadmium were found exceeding the EU set limit in some of the zinc carbon models. Mercury was found at 7 times of the set limit in one of the tested models while cadmium in another model was 6 times of the set limit. The EU directive stipulates portable batteries containing more than 0.0005% of mercury by weight and 0.002% of cadmium by weight are prohibited from sale in the EU market.
According to the EU directive, batteries should also be marked with the chemical symbol "Pb" under the sign if they contain more than 0.004% lead content. It came out that all tested zinc carbon batteries were found with lead content exceeding the threshold for additional labeling under the EU directive. Some models did not carry the additional labeling.
In Hong Kong, there is neither regulation on heavy metals content nor recycling system for single-use batteries. Heavy metals in batteries will not in general affect the health of users if properly used. Heavy metals, however, may pollute the environment. Hence, the Council urges manufacturers to remove heavy metals including mercury and cadmium, in battery production to avoid pollution.
Electrolyte leakage of batteries will damage the electrical devices if the used batteries are left idle in the devices for a long period of time. All the tested models were found in compliance with the IEC standard on the electrolyte leakage resistance test. However, in a test designed by the Council simulating the careless usage habit of average consumers, leakage was found in samples of 10 tested models. To avoid accidental leakage, consumers are reminded not to leave batteries in electric devices if they will be idle for a long period of time.
On the service life of batteries, alkaline models performed better than zinc carbon batteries in high, medium and low power consumption tests regardless of the size of the batteries. The average service life of alkaline batteries was 1.5 to 2.5 times longer than zinc carbon batteries. Though zinc carbon batteries are cheaper in price, using alkaline batteries may reduce solid waste. For sustainability, consumers are however advised to switch from single-use to rechargeable batteries for cost effectiveness and environmental protection.
In the October issue of CHOICE, tips are offered for purchase and use of batteries:
- Check the expiry date as battery capacity drops with time, the later the expiry date the better.
- Choose the package size that suits your need though a big pack is usually more economical.
- Remove all batteries from a device if it is not going to be used for a long time.
- Install batteries properly and do not mix up the positive and negative terminals.
- Replace the whole set of batteries at the same time.
- Store batteries in cool and dry places.
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