battery not charging on vostro 3500

Hello,

I have been using these days the Dell Power Manager to fix my battery at 80% max it charges up to that point all good but for eg if I have to stop and set my laptop to sleep/hibernate and come back to it to use it while plugged in the battery stays at the same level saying it is plugged in the way I fix it is set the battery setting to "adaptive" then "customizes" again for it to work .

so can someone pls help.