23 hours 5 minutes

Not an objective test though.
I used the radio in a dimly lit
setting and the backlight for the
display and keypad comes
on automatically if the room light is
too dim and you press any button.
It came on quite a few times,
and not always because it had to.
I think the backlight looks cool so I made it
happen on purpose a few times.
All of that had to use some
extra juice. So maybe normal usage,
in a well lit room would give 24 hours?
All listening was through the speaker,
no earbuds/headphones.

Also, this Chinese version uses
220v. It came with a 110 to 220 converter.
I was told charging the included
1100 mAh NiMH batteries for 5
hours with the 220v input would
give me a full charge.
(1100 / 220 = 5)

I'm not sure if I could have set the
radio for a 6, 7, 8 hour charge safely,
so I didn't. (You can charge anywhere
from 1 to 9 hours)

I'm assuming higher capacity batteries
would give longer playing time. I have
some new 1800s here, so I might change
over.

The batteries charge in the radio, so
23 hours isn't so bad in my case. I'm going
to use it on the bedstand and can recharge
anytime when going to sleep or work.