Hi...
When you go to control panel on the 720 and then tap Power, you get a screen that tells you the status of your backup battery. On mine all three "Good Low Very Low" were greyed out when I checked. I closed the window and went back in and now it says Good. Just a glitch or did I not wait long enough?
Did you just turn your J720 on and then go to the control panel to check the battery indicator?
I know that after a reset or when the machine is just turned on-it doesn't register as Good right away. I had 2 J720's that gave me messages that the backup battery was either low or missing. I was able to fix that problem by tightening the set screw on the backup battery clip. As I have had this problem with the battery not registering-I regularly check the backup battery charge in control panel and have notices that on resets and when just turned on-it doesn't register instantly for some reason. I don't think there is anything wrong unless you get a message that it is low or not present.
wildbill