Battery won't hold charge

For the past week the battery in my 02 F4i won't hold a charge, or take a full charge for that matter. I have been putting it on the battery tender and leaving it for hours. When I come back it will either tell me it is fully charged or is 80% charged. But, when I go to start it it will only turn over like three times and then nothing. WTF!!!! The battery is only four months old, would you expect this after only four months? I am confused?! Anyone else have a problem like this or have any advise? Thanks.

how many volts does the battery say when you hook it all up?

sounds like the battery is tossed. my still be able to return it under warranty.

My battery charger does not give me the actual volts , I am going to try to get a voltage meter from a friend. I don't know if I still have a receipt. I bought it in CA and now in NY. May just have to buy another one. Thanks mang!