Homemade Candles Won't Stay Lit

I need help. I made some homemade candles from a little left-over-store-bought-candle-wax, food-grade-coconut-oil and food-grade-olive-oil. It was an emergency mash up. I used wooden wicks anchored to the bottom with a wick holder and poured the wax mix up to a quarter inch of wick left. The wicks light fine, nice full flame and the wax starts melting immediately. But once the wax forms a pool, the flame dies down and after 15 minutes, snuffs out. The candles are for outside use, temperature at about 44°F. Is there something I can do to stop the flame from dying out?