[6 Battery Charger]

I've got a number of Ryobi 18v tools and invested in the 6 battery charger.  I've had it for 3 years and have kept my batteries in it without issue.  Today I went to use my 18v chainsaw and it wouldn't stay running.  I tried a different battery with the same issue.  When I plugged the batteries back into the charger I noticed than none of the charge lights for the other batteries were on. There should be a solid green light indicating they are charged and in maintenance mode.  And when these were plugged in the low level light on them flashed indicating they were almost dead. I had just pulled them from the charger.  I pulled each battery and replaced it and the red light came on, indicating they were waiting to charge (it charges one at a time). The first one I plugged in was flashing green, indicating it was charging.

 

Since, one battery reached full charge and the saw now runs fine.  I placed the others on the single chargers I have so I can get them all recharged and I can do my cutting tomorrow.

 

So, evidently somethng happened and all the batteries were discharged while on the charger that was plugged in.

 

Anyone know what may have happened?