I would like to have a describtion for every category. Sure most of them are easy to understand, but i don't get "Battery endurance in cycles". And i would like to see when a certain rating get what specific rating. There is a phone with Battery endurance per cycle of 118h 45min and one with 48h 30min, but both have A rating over all. So how good is the 48h 30min as rating? Is the other just overperforming or does the 48h 30 min phone suck in that category?
That page had some description, but not enough for my liking. You can poke around the page and find links to the related documents, though (may have to click "see text"
If I'm understanding your question, you're asking about the energy efficiency index rating (EEI) (the letter) vs the battery endurance per cycle (the time), which aren't the same, but are mathmatically related using the devices voltage x battery capacity.
(2) ‘battery endurance per cycle’ means the time a smartphone or slate tablet can operate running a defined test scenario with an initially fully charged battery, before the device shuts off automatically due to a drained battery, expressed in hours (h);
(10) ‘energy efficiency index’ means the ratio between the battery endurance per cycle (ENDdevice) and the nominal voltage of the battery multiplied by the rated capacity of the battery;
The rating of the "Energy efficiency index" appears to be threshold based, and the best class (A class) makes no distinction for devices just meeting its criteria vs far exceeding, so it's also possible that very similar devices might have dissimilar runtimes if their energy efficiency diffs substantially within the same class. I'd recommend that if a device is substantially better than the best class, that they would add some form of multiplier to the displayed class. Or even better, just include the EEI I'm Smalltext somewhere.
My takeaway is:
customers who only care about runtime need only focus on the rated runtime
customers who care about runtime AND energy conservation should try to pick the device with the best runtime amongst the A class of EEI.
** if you plan to carry a battery pack, (1) is not wholly correct. The amount of time your battery pack will add will be heavily dependent on the EEI of the device.
Hoo boy, I better not drop my tablet.