Samsung Galaxy S — Phone Stops Charging while connected to charger

just got a new battery- a couple months ago as well as a new 3.5 (usb) charging cable about a month a go ..everything was fine until a couple days ago..when i plugged up my phone to charge it it would begin to charge but shortly after stop in the middle and the notification would come up about the phone being low on charge,, i would adjust (the way it was positioned or where it was sitting and... this would just repeat.. any ideas on what could be the problem?

now the phone is doing something even weirder...the battery symbol in the top right corner is presumably showing that it is charging..but the please connect to charger notification is popping up literally EVERY Two or three seconds