User Manual Sony ICD-P620 Digital Voice Recorder

Please see attached from the instruction manual. It seems you can play back as much as you want.
Th3 Start playback.
(!) Press ...P.L.AY/ENTER.
® Adjust the volume with the VOL
control.
4 Stop playback.
Press * (stop).
After playing back one message,the unit stops at the beginning of the next message. When the
continuous play function is set to

Since it take two ordinary AAA batteries, they cannot be recharged. I have found that I get excellent battery life out of the alkaline batteries. Buy rechargeable batteries and charge them externally.