05 arctic cat 400 atv

i posted this in the atv forums as well. its having starting issues.
When i try to start it, i get the dead battery clicking sound. lights and winch work with the key on, so there's juice in the battery, or so it seems. so i put some jumper cables on it, it starts and idles good. once i take off the cables, it dies right away. has anyone else ever had this problem on their atv? i'm just wondering where to start looking on it.

thanks

05 arctic cat 400 atv