The Yellow and Green light both come on and stay on when I put in a battery to charge !!! This is a Ryobi 18v battery charger model #1423701.....

If yellow and green light come on and stay on then your battery is bad if not get a new charger

If i have this striaght two chargers and the green and yellow lights are on and the batterys will not charge and there 14.4v batterys correct . Then the batterys must be no good unless bolth chargers are bad and have the same problem witch is exterimly unlikely. most likely the batterys and are NG.They don't do well if left in cold condutions or hot for that matter but cold is worse . 14.4 V is is an unasul size and if its not a lithuim ion battery its going to be obisilete and unavaible soon if not already . Ihad the same problem with my RYOBI 7.2 volt can't get the batterys for under a 100 dollars thats one and a speical order i paid 39 dollars for the gun and 2 batterys . They make the money off resale on batterys . And you can do far better then RYOBI for a screw gun now a days

In some model the FUSE got burn.But if this is not your case one or both,batts and charger are burn.Try first to change the batt, then if this not work, change the charger.

i always thoiught that when you light is green it is fully charges yellow is weak and red is dead
maybe you have it reversed check it again also make sure that (altho hard to do) the battery is in right

see if your charger is under warranty and have it replaced..yours is bad..

I have found when I put a battery on to charge and the green and yellow light turn on the battery is low voltage and the charger will not charge the battery ( bad battery)

Use
AC / DC Power Adapter Replaces Ryobi One+ Batteryhttp://lcdpayless.com/ryobi_one_power_adapter.php

Solution is two fold. Will try the freeze and re charge approach today and do this a few times. The long term soluiton is to purchase two Lithium batteries and a duel chemical charger. Expensive solution but seems it will work.

Just was on a website for Ryobi drills and it states that if the yellow and green light stay on for more than 15 minutes the battery is fried. Couldn't find the link but if you do a search for Ryobi Drill 18 volt you should find the same info. It was as product review from Australia I think.

I also have a problem with the charging of Ryobi batterys. They seem to charge AOK with the green light coming on but the charge does not last at all. Not sure if the problem is with the batteries on the charger.