Battery.lua

local Battery = {
    capacity = 0,
    stored = 0,
}
setmetatable(Battery, Battery)

function Battery:new(battery)
    battery = battery or {}
    setmetatable(battery, Battery)
    Battery.__index = Battery

    return {
        capacity = function()
            return battery.capacity
        end,
        producedLastTick = function()
            return 0
        end,
        stored = function()
            return battery.stored
        end,
    }
end

return Battery