The average expected battery life is approximately 200 to 1400 bursts. The actual number will depend greatly upon a large number of variables (i. e . the batteries used, the scene being photographed, etc.)
The batteries are installed in the wrong orientation Install the batteries in the correct orientation The Speedlite's batteries are exhausted If the flash recycling time takes 30 sec. or longer, replace the batteries. Install the Speedlite's batteries even when you use an external power source