Workaround! "AC adapter Wattage and Type cannot be determined" Latitude E6530
Posting this as I've not seen my workaround mentioned in my google searches, just lots of discussion of bad jack connections, shorting the AC adapter, etc. I wish I had a more permanent solution, but this works for me.
I'm running a (bought used) latitude E6530 with Nvidia discreet GPU, OEM 19.5V 6.7A adapter, OEM battery that holds a decent charge (I've also tried a different battery).
I have the common problem after I switch to battery and back to AC that the Nvidia GPU is no longer used, battery won't charge, and when I reboot I get the error "Alert! AC Adapter wattage and type cannot be determined" etc. Mine won't even boot from there, forcing a shutdown.
While shutdown, to workaround I:
1. Unplug AC.
2. Disconnect battery
3. Reconnect battery.
4. Start system.
5. Wait until the Windows startup splash screen (or later) and reconnect AC.
6. Voila! System runs perfect until I switch back to battery. I've been doing it this way for over a year now.
From the many posts I've read about this problem it remains unclear to me if there is a straightforward permanent fix, I wish there was. From what I've read it surprises me that this approach works and makes me think it is a software or bios problem, where most people seem certain it is some sort of hardware problem.
I have let the startup continue all the way till I'm at my desktop to plug in, and it still then works: discreet GPU engages, battery begins charging. Thus it seems like the problem is actually in switching from AC to battery while windows is running that then causes it to fail to switch back. But if I boot up on battery, it has no problem switching to AC on the fly.
Seems to me this is a software/firmware issue that could be resolved. Maybe my problem is different than other people's. Hope this helps someone. Good luck.