Welcome to the forums. Juice Defender is not longer in the Play Store and hasn't been updated since 2012. This kind of apps made a bit of sense in the past but they are not longer necessary, or even recommended, with the recent versions of Android.
I would recommend you to create an account so you can reply on this thread.
You dont see it in the play store might have to look for its apk file as your operating system is very old and not going be compatible with lot of apps.