I doubt VERY much that is a parasitic drain problem. OR at least the NORMAL parasitic drain for this light.
Your issue is Not the norm for this light.
I have Two of them. One stays on my key chain. Sometimes I do not use it for weeks and the Efest 10440 maintains its voltage very well.That is when the lock out is applied and even when it is not.
I think something is wrong with your light.[I am a genius]! What it is, I do not know. Appears to me some kind of defect in the lights operating system!