A web search revealed that this now read only link is the answer that Dell wants everyone to turn to in order to change your keyboard back light timeout.
I think that the advice given there is wrong--at least for Precision laptops running Windows 10.
This Dell link says that you must change the keyboard back light timeout in BIOS. I have done that on my new 7530, and it works.
Before I stumbled across that link to modify my BIOS, I tried the advice in that first link. Namely, I installed the Dell Feature Enhancement Pack from here. I then opened the Keyboard Control Panel, clicked on the Backlight tab, and tried to select the 5 minute option. That failed to work. So, I uninstalled the Dell Feature Enhancement Pack. I am not surprised that it failed to work, since it is really old software that is not listed as working with either my laptop or my operating system (Windows 10).
Problem is older Dell laptops may not have a setting for keyboard backlight timeout in the BIOS menu.
For a Dell laptop with no other options, I posted a tutorial on how to change the keyboard backlight timeout with currently available software elsewhere on Dell's Forums here. This was for a Dell XPS 15 9550, but will probably work with any Dell laptop. This should work, for example, with a Dell Precision 5510 - which is pretty much the same machine as a XPS 15 9550. (Dell Command and Configure might also work with the Precision series, but I was unable to get --KbdBacklightTimeoutAc or --KbdBacklightTimeoutBatt BIOS options to work with the XPS 15 9550.)