Three out of 10 portable power chargers tested by the Consumer Council failed safety requirements.
The Consumer Council said on Thursday it had carried out tests on 30 portable external chargers and nine of them failed to completely pass safety tests in fire resistance, short-circuit protection and temperature rise, according to a release on its website.
One model had stopped working properly after being used just 26 times.
The power banks or chargers that were tested are priced from HK$79 (US$10) to HK$500 and had a rated capacity ranging from 5,000 mAh to 12,000 mAh (milliamp hours), but the performance of different models varied in quality.
Three were found to have a discrepancy of over 40% between the energy measured in the test and the energy rated on the products.
The consumer watchdog called on users to unplug devices once they finish charging and store them in a cool place. It recommended that people should stop using a device if it appears to overheat when charging or if the battery becomes swollen.
On Wednesday, 300 passengers were evacuated from a Mass Transit Railway (MTR) train when a passenger found smoke coming out of his portable mobile-phone charger.