Actually, I think you are right!
It was a rubbish question.
I think the ego is a 510 device.
My brain was broken, was thinking of Riva, which I believe is the same battery, but in 510 or 901.
Ignore my twaddle.
Would still rather a more experienced forum member back me up, but battery sounds wrong to remain lit to me.
I would unplug it until someone more experienced confirms.