How please can you show me how you did it?
Ok
, go to settings and there to activator or just use the activator app.
There go to "Everywhere", on the top right corner you have to tap on "more"
There you have to chose the second option echo is called "Battery Charges"
There you have a slider where you have to set a percentage level when you want to assign an action, in you case to 99%.
Now if your battery level is over 99%, so 100% (fully charged) then something should happen
Now go to "Everywhere", there you have a section "Battery Level" and your new option "Battery charges past 99%".
Tap on that and then assign a Ringtone, either one of the preinstalled or some which you sync to your device via iTunes
If you have questions, then don't hesitate to ask