Disposable Batteries – Service Life of Alkaline 2 Times Longer than Zinc Carbon Over 40% of Batteries were at Risk of Electrolyte Leakage

17 August 2020
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Disposable batteries are common household items, yet their durability and electrolyte leakage problems often caused criticisms from consumers. The Consumer Council tested 30 models of disposable batteries and found the average price per piece of zinc carbon battery models ($1.6) was only around half of the alkaline battery models ($3), however, the service life of zinc carbon batteries used in 3 types of electronic appliances including remote controls/radio, wireless accessories/digital audio and toys were rather inferior. Taking AA batteries used in remote controls/radio as an example, the alkaline battery model with the longest service life was 41.3 hours more durable than the zinc carbon battery model with the shortest service life, marking a difference of 2.7 times. The Council also found that when certain brand of alkaline battery was used in household appliances, the difference in service life between the claimed “enhanced” version and “regular” version was less than 2 hours, or even no difference. Consumers should be mindful when making a purchase.

According to the simulation test designed by the Council, over 40% (13) of the models were at risks of electrolyte leakage which may damage electrical appliances if left unused for a long period of time. 75% (6 models) of zinc carbon battery models were found to contain lead which may pose greater environmental hazard when disposed. Since there is neither recycling system for disposable batteries nor any regulation on heavy metal content in disposable batteries in Hong Kong, the Council recommends the government to make reference to the regulatory regime on disposable batteries of the European Union (EU) and Taiwan etc., so as to establish an environmental regulation and recycling system suitable to our city.

The test included 30 models of disposable batteries comprising equal amount of AA and AAA batteries, among which 22 were alkaline batteries while 8 were zinc carbon batteries. The test items included service life, resistance of electrolyte leakage and heavy metal contents. Regarding their prices, the unit price declined as the packed size increase. The price of zinc carbon batteries ranged from $1.0 to $2.5 per piece, while alkaline batteries were more expensive with prices ranging from $1.7 to $9.5 per piece. To compare the service life per $1, the cheapest AA alkaline model could last 5.1 hours per $1 cost when used in toys while the most expensive AA alkaline model could only last for 0.7 hours per $1 cost, marking a difference of 6.3 times. Test results once again reflected that product price does not necessarily indicate product durability.

The test made reference to the international standard in measuring the service life of battery models when used in remote controls/radio, wireless accessories/digital audio and toys. During discharge, the voltage of zinc carbon batteries dropped faster than alkaline batteries, the service life was thus shorter and scored merely 1 to 1.5 points in this test item, while alkaline batteries scored 3 to 4.5 points as the service life was generally longer.

When used in toys with higher power consumption, the service life between the 2 types of batteries showed the biggest disparity. The average service life of AA and AAA alkaline batteries models were 7.8 and 4.3 hours respectively, while those of zinc carbon models were just 2.1 and 1.4 hours respectively, showing a difference of 2.7 and 2.1 times.

Alkaline batteries also performed better than zinc carbon batteries when used in remote controls/radio and wireless accessories/digital audio with a service life difference of 2.1 and 1.6 times respectively. When used in remote controls/radio, AA and AAA alkaline batteries models could last 50.2 hours and 20.3 hours respectively, versus of AA and AAA zinc carbon models could only last 16.3 hours and 7.9 hours respectively. AA and AAA alkaline batteries models could last 24.4 hours and 22.4 hours respectively while those of zinc carbon models could only last 7.8 and 8.5 hours respectively, when used in wireless accessories/digital audio.

Test results also showed that the claimed “enhanced” version of alkaline batteries was not necessarily more durable than the “regular” version. Comparing the service life between the “enhanced” and “regular” versions of 2 different brands of alkaline batteries, the differences were all under 2 hours when used on all 3 types of electrical appliances. For one brand of AA alkaline battery, both “enhanced” and “regular” versions lasted equally 53.1 hours when used in remote controls/radio. Similar observation was noted on another brand of AAA alkaline battery as both “enhanced” and “regular” versions lasted equally 4.6 hours when used in toys. As such, consumers should consider the value in paying more for the “enhanced” version.

All test models were found in compliance with the IEC standard on the electrolyte leakage resistance test. However, in a test designed by the Council stimulating a real-life situation when the user forgot to switch off the power of toys and the batteries were discharged for 4 days continuously and the batteries were then stored for 45 days at room temperature after all of their power was exhausted, 13 models, including all (8) zinc carbon batteries and 5 alkaline batteries were found to have electrolyte leakage which could corrode and damage electrical appliances.

Heavy metals pollute the environment. Taking reference of the European Union (EU) directive on environmental protection, batteries with over 0.004% lead content are obliged to mark on them a label showing a crossed-out wheeled bin with the chemical symbol of lead below it for reminding users not to discard them anywhere. In the test, 6 zinc carbon battery models were detected with lead content ranging from 0.032% to 0.065%, but 3 of them were not labelled as stipulated in the EU directive.

The Council reminds consumers that disposable batteries may seem convenient, but they will take 50 to 100 years to decompose. They are not environmentally friendly and will aggravate the burden of landfills. If batteries containing lead are not properly handled, it may harm the environment and human body. Therefore, the Council advises consumers to replace disposable batteries with rechargeable ones as far as possible so that it can on the one hand save money and on the other hand reduce disposal through recycling.

Consumers may refer to the following when purchase or use disposable batteries:

  • Read the labels carefully and choose more environmentally friendly products;
  • Battery capacity drop with time, consumers should thus choose the right packed size based on their needs and take note of the expiry date;
  • Install the batteries correctly, pay attention to the position of positive and negative poles;
  • Do not mix new batteries with old ones as there will be differences in their voltages. A mix-used will shift the loading onto the old ones and may cause electrolyte leakage due to over discharge;
  • Remember to take the batteries out from the electrical appliance if they will be left idle for a long period of time to avoid electrolyte leakage and damaging the appliance;
  • Do not store batteries in a high temperature or humid environment but should store them in cool and dry places.

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