Delta CL 180 model charger turns on when you plug in and the yellow light comes on but when you put the battery in to charge the lights go out?

SOURCE: Ryobi Model 1412001, 16vdc, 2A

I've open the charger and found that Q4 is open. But they have removed the part number from the component so you can't get a replacement.

SOURCE: Some Ryobi 18v batteries charge, others don't.

Had the same problem with some makita batteries, Was going to throw them away so decided to take apart and see what was happening. The are made up of 1.5 volt cells soldered together, found that many had .9 volts or less and others had 1.5 or more. This means that some of the cells had gone bad (probably due to lack of chemical reaction). Found that if I collected all of the 1.5 volt together could charge just fine. Problem is it is very hard to get them all soldered back together and even harder to enclose them. If a mfg. could come up with some way to change cells individually they could make a lot of money and save us a lot. So the answer to your question is buy you at least one more battery and recycle your old one.

SOURCE: light on ryobi 18v charger

More than likely a defective battery sinse the other ones charge fine..
Bring it back for exchange of another one..

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SOURCE: not charging

try wiggling the battery around and see if a light flashes

also look and see if a light flashes when you plug it in

i'm about 98% sure it's the charger

SOURCE: Batteries not charging

sounds like my charger, not making good contact

wiggle the battery around while pushing down and you can probably get it to make contact

sounds like you just need a new charger