Lessons learned: Power banks should be unplugged as soon as they are fully charged

The incident

A crew member on a vessel was inside his cabin bedroom when he heard a popping sound in his dayroom. Upon investigating he noticed the USB battery bank (containing Lithium-polymer batteries) charging on the desk was on fire. He immediately smothered the power bank with nearby clothing to knock down the flames and at the same time disconnected the power bank from the mains. He then sprayed the clothing with water to remove heat and placed the whole lot in metal for removal from the room.

Damage was contained to the desk, adjacent bulkhead and deck where the battery bank rested after being extinguished. There were no injuries. The prompt action of the crew member (who was in the cabin at the time) meant that power was isolated from the USB power bank and the fire was quickly extinguished. The individual was very familiar with the company policy on personal electrical appliances.

Findings

• The power bank was not supplied with an adaptor when purchased, leaving the buyer to match the adaptor plug with the unit for wall charging. In this case the adaptors did match the input and output requirements and the USB cord;
• The USB power bank was plugged into a 220V wall outlet for charging. A 240V-100V adapter (European to North American plug) was plugged into the wall outlet then a standard, North American style, USB charge adapter plugged into the 240V-100V adapter. A type ‘C’ charge cord was used from the North American style USB charge adapter to the power bank;
• The crew member had noted at 19:10 that the power bank was 97% charged and planned to wait for a full charge. At approximately 19:50, the crew member heard the popping sound and saw a flash of light and flames coming from the power bank;
• From the location of the burn pattern away from the outlet, the failure looked to be within the USB power bank itself and not in the receptacle or adaptor;
• There were no reported electrical or power interruptions in the ship supply or in the receptacle in which the unit was charging. Trends were normal and didn’t show any interruptions. Power at the receptacle was reported by the chief engineer to be 237 V.

Lessons learned

whilst these devices are becoming more and more popular and are necessary for crew members who have long travel times to and from the vessel, there is no particular reason for their general or daily use onboard. There is more than enough power and electrical supply onboard for charging personal devices

…says IMCA.

IMCA proposes to control how and when these devices are charged up (as distinct from a possibly unpopular blanket ban on them). Such battery/power banks should:

• Never be left unattended when on charge;
• Be unplugged as soon as they are fully charged.