Ah yes, the law of unintended consequences! How can such an indication ever be anywhere near accurate? It's just not "apples for apples", is it? A "guide" at best. Perhaps the manual makes this clear? I don't know. But who ever reads the manual?
It's yet another example of flawed (but, no doubt, well intentioned) design - and there are many others in the medical equipment "arena" (nice BS word). All that's required are a couple of charts in the users' handbook showing "typical" time remaining at such-and-such residual capacity at a couple of settings. Oh well, back to the drawing board.
Being "helpful" to the user in this way is also known as "making a rod for your own back"!
