Battery Tester

anyone used one of these i thought it would be handy for my bikes and car. so i tried it out and its saying the triumph is ok it should be its only a year old then i tried it on the R1 and my car and its saying that they are both over charging in the red bit but they both run fine no issues. the car was only serviced two weeks ago and a health check was done. so have i bought another fairly expensive gadget (£35) destined for the wheelie bin