Although battery operated candles are safe and all, but I would rather choose candles that spill wax anyday. It's not just because of the safety of it or the convenience of just flicking a switch never striking matches ever again. I just would like to use a real candle as it gives a representation to your unconsciousness. The flame stands for activity and the color of the candle stands for something else (depends on the color.) I am not saying the flame less candle is obsolete, just that I would prefer real candles, there are no limitations to magick, but what you don't feel comfortable with limits your progress.
The thing is for me, if you consecrate a candle for a purpose or spell then it is suppose to burn out until the wax is all or mostly gone. This is a form of transformation or messaging from the physical plane to the astral plane, as the rule of all magick states: "It must be in the astral plane for it to manifest in the physical plane." As for annointing of oils, I do not think it is safe as most oils are highly flammable and the candle might spark (Yes, this does happen in some cases.) The flame less candle can still be useful but I urge you still not to use it and purchase the original candle. But you know, be creative see what works best :)