Electrolyzers are IC2 Machines that will convert Water Cells into Electrolyzed Water Cells , and vice versa. An Electrolyzed Water Cell is an efficient way to store EU, as it stores 15,000 EU. Unlike most IC2 Machines, and Electrolyzer must be directly adjacent to one, and only one, EU Storage Device, such as an MFE .
When the adjacent Storage Device has at least 70% of its capacity, the Electrolyzer will convert Water Cells to Electrolyzed Water Cells, taking 15,000 EU from the Storage Device (though not all at one time; therefore a BatBox still can be used.) Though, if the adjacent Storage Device has less than 25% of its EU Capacity, the Electrolzyer will take Electrolyzed Water Cells and convert them into Water Cells, giving the adjacent Storage Device 13,500 EU. Note that there is a 1,500 EU transfer loss.