DELL officially stated that capacity of batteries it provides differs from the capacity marked on the cover. If you decide to by a battery and it is marked as 97 Wh, you have not to be surprised if you receive item with lower capacity.
Manufacture (designed) capacity of a battery is not visible at first sight. Windows did not show it and you have to check it manually.
There is some specialized software, which connects to battery controller and reads the real capacity from it. You could use for example, a free software named BatteryInfoView to do this. Just run the program and it will output you the real designed capacity of the battery. No more marketing tricks.
I tested this on my brand new genuine DELL battery. The software showed designed capacity lower than the marked on the battery cover. I contacted DELL support, because I supposed that the ebay seller provided me a fake battery... replica. But the support stated that
"That's normal if you see your battery software shows different value for manufacture capacity" (DELL operator with nick name "TIP_John Ha", 20:29:24 2015.02.03 UTC +2).
I own the highest business class notebook from DELL and I started to consider whether is this true. If DELL cheats for battery capacity, it is possible to cheat for every other part in my premium class laptop. This seems logical according the facts.
And something more. If they lie for the most expensive class, what about its low-end class? May be hundreds of lies? Time will tell us.
But I will consider whether my next notebook to be DELL or some of the other brands - HP or Lenovo. They both have bigger market share, so may be they will provide better quality for the money in any class?