Battery is new (Yuasa) and charging system is in perfect condition, there is no problem.
Not sure I was clear in description, it flashes OK, but when I move swith to left or right, fist it pasuses and just then there is first flash (so it does Pause-Flash-Pause-Flash...). Means there is delay from the moment I want to flash till it really flash.
Normally it should be first immidiate flash Flash-Pause-Flash-Pause... like on any today's cars and motorbikes, it is much safer