In the initial web page splash for the Marvel, a 24-hour battery life was announced for the Marvel and 4 hours of streaming reduced the battery life to 16 hours. All that original PR is gone now but it’s reflected in many early forum threads such as my post here:
If you look now, the datasheets currently available for the Marvel and the Paradise just say each has an expected operating time of 18 hours. So, apparently Phonak has decided it’s better not to claim a 24-hour runtime for folks who never make any phone calls or never stream anything and just come up with an average operating time, which is the same as for the Lumity, 18 hours, as I noted above.
Marvel Rechargeable: https://www.phonakpro.com/content/dam/phonakpro/gc_hq/en/products_solutions/hearing_aid/audeo_marvel/documents/datasheet_audeo_marvel_r.pdf
Paradise Rechargeable: https://www.phonakpro.com/content/dam/phonakpro/gc_hq/en/products_solutions/hearing_aid/audeo_paradise/documents/datasheet_audeo_paradise_r.pdf
Edit_Update: Actually, in the Phonak article that Abram Bailey started the thread that I referenced at the beginning of this post, Phonak explains how they arrive at their runtime for the Marvels. Here is Fig. 5 from that article and I will provide a direct link to the Hearing Tracker article after the figure. 24 hours with only environmental listening, 16 hours with 4 hours of Bluetooth streaming and 4 hours of TV streaming, 11 hours with 100% of BT streaming via A2DP and HFP (best audio, handsfree protocol).
Link to Hearing Tracker Article written by a Phonak rep: How Phonak Achieved Universal Bluetooth Hearing Aid Connectivity (hearingtracker.com)