Like all devices that utilize lithium batteries, the Delphin will lose its charge very slowly while it is off. The Delphin will run for 6 hours of continuous music playback at full volume at a full charge. The screen, WiFi, and Bluetooth take a lot out of the battery. Airplane mode will dramatically increase your battery life.
Recently, we have learned that charging your Delphin while there is water in the headphone jack will kill the device. Make sure to avoid that :). The good news is that Delphin charges in about an hour. The Delphin will also turn itself off after 30 minutes of inactivity, which is a lifesaver. You can turn off smart shutdown if you want in settings.
I don’t know how to help the lithium ion battery keep it’s charge better, but there are probably some great resources online that have good advice.