Li-ion batteries are categorized as Class 9 Dangerous Goods and therefore require additional shipping requirements over standard packages. OE Electrics is certified to handle and ship Class 9 dangerous goods via FedEx and UPS domestically in the US (ground and air) and via other shipping options internationally (sea and air). The main requirement for shipping Class 9 Dangerous Goods is a UN certified shipping box. In instances where batteries need to be returned to OE, we can provide the box/boxes and schedule the shipment to return them to an OE facility on your behalf. To meet Class 9 dangerous goods shipping requirements, the batteries need to be shipped at 30% state of charge (SOC). It is advised that when the batteries arrive at their destination, the first step is to bring them to full charge before use.