Cool article. Thanks. Opera low power mode is a boon on laptops and iOS devices as well.
Still rocking a MacBook 2008- on El Capitan. The battery is now down to less than a hour- but at least the thing will boot when I finally remove it (on mains of course) cannot say that on all devices / MacBooks.
By the way Amazon no longer ships laptop, UPS and portable battery chargers to Hawaii - making these tips even better when everything else is working.
(I believe they were fined in the U.K. For shipping batteries via air less protected than they should have been)