By Li Hongmei

An iPhone 3GS that was neither being charged nor in the middle of a telephone call suddenly exploded in Beijing's Changping district on Nov. 13.

The smartphone's owner said he does not intend to seek compensation from Apple but would like to know the cause, reports the Beijing Morning Post.

The owner, surnamed Ma, bought the smartphone in late 2009 and used it for two years until Apple released the iPhone 4. He did not use the 3GS again until a month ago when he needed another phone for his job. Ma said that during the past month he left the iPhone 3GS at home and he only used it from time to time when he returned home from work.

The smartphone was on a nightstand besides his bed when it suddenly exploded into pieces on Nov. 13. Unlike other instances where Apple smartphones have exploded, the phone was not being charged. Ma found the phone had split open at one side and the broken pieces were still warm. His SIM card remained intact, slightly blackened.

Ma said he does not intend to seek compensation from Apple since the smartphone's warranty has expired and the phone has been one of his prized collection of Apple products. He would however like to know why the phone exploded while it was on standby.

A staff member at an Apple retailer said the most likely cause was the smartphone's battery, which could be defective or have discharged an abnormal amount of electricity due to unusual surrounding temperature or humidity, or it may not have fitted the battery compartment well.

Apple's customer service said they can only confirm the cause after Ma sends the smartphone, relevant receipts and its components to their technicians. Another Apple store said that if Ma was using an original battery, the most likely cause was the aging battery since he bought the phone four years ago.