Do you find battery supplies inferior to well designed power supplies?

I have to ask, because every single battery powered unit or battery supply I have ever tried sounded great for the first few tracks, then focus gets blurry and things sound lost. This has happened with every single battery powered audio device I have tried. All of these devices are regulated as well, and really kind of have to be, but I just never got the consistency that I get with Linear Supplies and or well designed switch mode supplies, for example.

Fresh charge, sounds great, play awhile, things get lost. This is battery powered DAC’s, Hubs, Battery Power Supplies with SuperCaps, etc. I only have experience with digital products using batteries, which is why I posted this in Digital forum.

Look forward to your experiences and thoughts!
No problems with my Chord Hugo.  It sounds best on batteries only.  There are colors from blue to green to amber and then to red to indicate battery level.  I don't notice any change until the level goes to amber which diminishes dynamics.  I usually get around 7 hours before a recharge.
My Jeff Rowland Criterion Preamp sounds absolutely INCREDIBLE on battery power.  
Maybe Tesla should be looking at the high end audio market for their Powerwall ;-)