Looking at the universal and having used it for awhile now I've figured out the indiactors for the two that I have at least.
When it starts out charging a fully depleted battery the indicator will be fully red.
As the charge progresses it will alternate between red & blue, with the blue flashes becoming more frequent as charging gets closer to being complete.
Once charging has completed it will be showing blue all the time, with no flashes of red.
I hope this helps someone