Sometimes laptop users remove their battery while on AC power.  For example, they might do this to avoid wearing out the battery.  Or to eliminate the risk of a plugged-in-battery fire while the laptop's unattended.

Steps to reproduce:
-  xfce4-battery-plugin starts up
-  there's no battery present
-  and the "Display Percentage" option is on

Symptom:
-  the battery monitor shows the strange text "50%%" in the percentage area.

This could make some people think their battery is plugged in when it actually isn't.  If they then disconnect their AC power, they might lose unsaved work.

Suggested fix:
-  Instead of "50%%", please show the number "0" (without a percentage sign) to show there's no battery.  This will never fool anyone into thinking they have battery power available.  Or, if you insist, you can use the word "none" instead of "0".