Looks to be an old thread but I'll share my experiences nevertheless. I found battery lights not suitable for my needs. I need to remember to charge them. So I decided to invest in high quality dynamo setup. Went with SON all around, dynamo wheel, from Edelux II and SON rear light. Install and forget. No servicing is required, while setup is water proof.
While rear light is very bright it doesn't have blinking mode. Beside being annoying to anyone riding behind you, in total darkness it's almost impossible for a car driver behind you to calculate a distance based on blinking light. Hence blinking lights are prohibited in Germany for example.