I have "repaired" the previous code, now using the args given by the widget itself.

Commented the tooltip, and using a vicious batwidget instead obvious.battery, showing up acpi information when the cursor gets over it.

baticon = widget({ type = "imagebox" })
--baticon_t = awful.tooltip({ objects = { baticon }, })
--baticon.image = image(beautiful.baticon_bat1)
vicious.register(baticon, vicious.widgets.bat, function (widget, args)
--                                                  baticon_t:set_text(args[1] .." ".. args[2].."% " .. args[3] )
                                                 
                                                  local battery_status = ""
                                                  battery_status = args[1]
                                                  if not battery_status then
                                                     baticon.image = image(beautiful.widget_baticon_ac)
                                                  elseif args[1] == "-" then --battery_status == "discharging" then

                                                     if args[2] > 95 and args[2] <= 100 then
                                                        baticon.image = image(beautiful.widget_baticon_bat1)
                                                     elseif args[2] > 90 and args[2] < 95 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat2)
                                                     elseif args[2] >= 80 and args[2] < 90 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat3)
                                                     elseif args[2] >= 70 and args[2] < 80 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat3)
                                                     elseif args[2] >= 60 and args[2] < 70 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat4)
                                                     elseif args[2] >= 50 and args[2] < 60 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat5)
                                                     elseif args[2] >= 40 and args[2] < 50 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat6)
                                                     elseif args[2] >= 30 and args[2] < 40 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat7)
                                                     elseif args[2] >= 20 and args[2] < 30 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat8)
                                                     elseif args[2] >= 10 and args[2] < 20 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat9)
                                                     elseif args[2] > 5 and args[2] < 10 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat10)

                                                     elseif args[2] <= 5 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_bat11)
                                                     end

                                                  elseif args[1] == "+" then--battery_status == "charging" then
                                                     if args[2] > 95 and args[2] <= 100 then
                                                        baticon.image = image(beautiful.widget_baticon_char1)
                                                     elseif args[2] > 90 and args[2] < 95 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char2)
                                                     elseif args[2] >= 80 and args[2] < 90 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char3)
                                                     elseif args[2] >= 70 and args[2] < 80 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char3)
                                                     elseif args[2] >= 60 and args[2] < 70 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char4)
                                                     elseif args[2] >= 50 and args[2] < 60 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char5)
                                                     elseif args[2] >= 40 and args[2] < 50 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char6)
                                                     elseif args[2] >= 30 and args[2] < 40 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char7)
                                                     elseif args[2] >= 20 and args[2] < 30 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char8)
                                                     elseif args[2] >= 10 and args[2] < 20 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char9)
                                                     elseif args[2] > 5 and args[2] < 10 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char10)

                                                     elseif args[2] <= 5 then
                                                    
                                                        baticon.image = image(beautiful.widget_baticon_char10)
                                                     end
                                                  elseif args[1] == "↯" then
                                                       baticon.image = image(beautiful.widget_baticon_ac)

                                                  end

                                                  if args[1] == "⌁" then --battery_present == '0' then
                                                       baticon.image = image(beautiful.widget_baticon_ac)
                                                    end
                                                   
                                                   

                                                 end,
                 1, "BAT0")

batwidget = widget({ type = "textbox" })
vicious.register(batwidget, vicious.widgets.bat, "$2% $3", 61, "BAT0")
batwidget:add_signal('mouse::enter', function()
                                        local fd = nil
                                        fd = io.popen("acpi -btai")
                                        local d = fd:read("*all"):gsub("\n+$", "")
                                        fd:close()
                                        batinfo = {
                                           naughty.notify({
                                                          text         = d
                                                          , timeout    = 0
                                                          , position   = "bottom_right"
                                                       })
                                        }
                                     end)

batwidget:add_signal('mouse::leave', function () naughty.destroy(batinfo[1]) end)

Hope this help.

Happy Hacking!