MSDF overpaid ¥81 million for submarine battery charging, sources say

The Maritime Self-Defense Force (MSDF) overpaid some ¥81 million to outsourcing companies tasked with charging submarine batteries, because the batteries were not fully charged as they should have been, people familiar with an investigation by the Board of Audit said Monday.

Twenty MSDF submarines use lead-acid storage batteries for power while they are submerged. The batteries are charged during regular inspections every three years, a task outsourced to submarine makers Kawasaki Heavy Industries and Mitsubishi Heavy Industries.

The board investigated about 22 outsourcing contracts concluded in fiscal 2020-22. Contract documents did not spell out the amount of power needed for a full charge. As a result, there were 15 cases in which batteries were not properly charged, resulting in the overpayment.