BEIJING, Jan. 31 (Xinhuanet) -- U.S. regulators on Wednesday said they asked Boeing to hand in a full operating history of lithium-ion batteries used in its grounded 787 Dreamliners.

The request comes after Japan’s All Nippon Airways revealed it had repeatedly replaced the batteries even before the overheating problems surfaced.

All Nippon Airways said on Wednesday it had replaced 10 below-par lithium-ion batteries on its Boeing 787 Dreamliners in the months before one of the passenger jets was forced to make an emergency landing due to an overheated battery.

Investigators from the US and Japan this week shifted their attention from the maker of the batteries to the Japanese manufacturer of a monitoring system. All 50 jets of the Boeing 787 in use around the world have been grounded since the emergency landing in Japan.

(Source: CNTV.cn)