I have been using a Rayovac 1-hour battery charger for several years, and I’ve noticed that the LEDs flash while some batteries are charging. normally the light remains steady until the battery is finished charging, then it turns off. I figured that flashing lights mean something needs attention, but the batteries charge anyway, so I just continued to use and recharge them and not really think anything about it. now all of the batteries cause the lights to flash, so I’m thinking about it again. I figure that the batteries are old and should be replaced. but they still recharge, so I’m reluctant to toss and replace them. does anybody have any ideas on what the flashing green lights are communicating?
“Robots of the world, unite!” 
If they still work, hang on to them.
FWIW, most of my chargers flash to indicate ‘charging’ and are steady when charged.
“You now have one minute to get to minimum safe distance”
That’s what my Energizer does.
When mine does that, it can’t charge the battery. I usually then drain the battery completely and try again.
thanks for the ideas and interpretations!
Exterminate!
It’s the batteries that are bad – replace em.
We have 2 of those chargers at work we use for headsets… the batteries that are bad get the quick blinky light.