Battery explodes in man's hand
An off-duty police officer was injured when a rechargeable battery he was holding exploded early yesterday.
The 39-year-old officer had heard a strange buzzing sound and detected an odd smell coming from a set of AA batteries recharging in the living room of his Mei Foo Sun Chuen flat at about 4am.
He unplugged the recharger and took it to the kitchen. He noticed the four batteries felt hot, and then one exploded while he was holding them, debris injuring his neck and eye.
The officer's girlfriend called an ambulance and he was taken to Caritas Medical Centre in Sham Shui Po, where he remained in stable condition last night.
Police and Electrical and Mechanical Services Department officers were following up the case.
Police said investigation showed two different capacities of batteries were being recharged on the device when the explosion occurred.
An engineer from the department of mechanical engineering at Polytechnic University, Lo Kok-keung, said a charger operating normally would automatically cut itself off when the batteries were full, but charging might continue if batteries of different capacities were sharing the same device. Overcharging would bring overheating followed by short-circuiting, which could cause an explosion, he said.
The recharging of ageing batteries could also cause the same result.