My Kindle Fire seems to steadily lose battery life even while it's in sleep mode - troubleshooting advice?

Sounds pretty normal to me.

Never seen anything like a 25% loss after a day in sleep in any other relatively-new device

here is some information on how to conserve battery life in your Fire.

If I were to hazard a guess, it’s because you’re putting it to sleep while it’s still connected to WiFi, and you have background apps (like email) running.

The Fire hd6 is only rated for 8 hours of mixed-use battery life. It’s not a huge battery.

That said, 25% power loss in a full day is not surprising for a tablet computer. If you want a way to read books without charging daily, get a regular eReader. Those can last for weeks.

I was going to ask if you are comparing to an e-ink LCD device like Kindle Paperwhite.

I miss the LCD phones that needed a charge once per week instead of once per day.

Fire is a tablet and they have wimpy batteries. This is typical.

Thanks all – I’m comparing it to all my previous experience which is with Apple tablets & phones (that have almost no loss while in sleep with all radios off). I see these are different beasts – still to be appreciated for low price.