Would you mind checking that any BIOS options for dimming the screen when on battery power are disabled?
I have seen laptops (mine, for instance) that dim the screen when on battery, but in hardware--as far as the OS is concerned it's still at 100% even though the screen is very dim. Of course, plugging the laptop back in should cause it to go back to 100%--but maybe your machine didn't notice since you restored AC power during hibernation... -- Sam Morris https://robots.org.uk/ PGP key id 1024D/5EA01078 3412 EA18 1277 354B 991B C869 B219 7FDB 5EA0 1078
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