SEOUL—South Korean battery firms LG Chem Ltd. and LG Electronics Inc. will be shouldering a combined $1.2 billion for General Motors Co.’s Bolt electric vehicle recall—the lion’s share of the expected costs. GM in August expanded the recall, which will replace LG battery modules due to the risk of fire, to more than 140,000 cars, estimating the cost at $1.8 billion, but that has risen to $2 billion. It previously said battery production resumed on Sept. 20 and replacements would begin in mid-October. As a result of the agreement, GM said its estimated recovery in the third quarter will offset $1.9 billion of the $2 billion in charges associated with the recalls, based on accruals under U.S. accounting standards. GM said LG agreed to cover recall costs and expenses. The final recall costs will depend on the number of battery modules replaced. “LG is a valued and respected supplier to …