We have a plug in but DD is good about first thing in the morning taking it out and handing it to me to put out of reach.
We also have the Cloud B Twilight Ladybug. They now offer a Twilight Turtle. E might enjoy it if he makes it though the night which I believe he does. We also set ours up next to the crib so that DD can reach it through the slats and turn it back on when she wakes up. She has done this in the past when we were working on getting her to sleep through the night. LOL.
Twilight Turtle