When you install JuiceDefender you’ll notice that it requires several Android permissions to do its work.
Most of them are system permissions necessary to control the various components in your device; however, some may (and should) raise an eyebrow at first glance as they don’t seem relevant to JuiceDefender’s functioning. This article explains what they’re used for. JuiceDefender does not collect any kind of personal or sensitive information.

Modify/delete SD card contents

This is used by the Backup/Restore feature. JuiceDefender saves one single file to your SD card (/sdcard/Download/JuiceDefender.backup) containing all your settings and locations, so that you can effortlessly restore your configuration after uninstall/reinstall or on a new phone.

Read sensitive log data

This is used to show you JuiceDefender’s log in the main UI, by requesting to the system log only the entries that were logged by JuiceDefender itself. If you’re using JuiceDefender beta and have enabled verbose log, JuiceDefender will keep its own logfile instead of using the global system log (at the cost of a slight performance hit).

Read phone state and identity

This is used to detect whether you’re currently in a phone call when JuiceDefender has to perform certain operations (such as mobile data autofix) that would disrupt your conversation.

Receive MMS, receive SMS, receive WAP

WAP and MMS are used to detect when you’re sending an MMS or about to receive one, so that JuiceDefender can enable mobile data if it’s currently disabled to allow the MMS to go through. More info in this thread.
SMS is used for the disable via SMS function (About/Troubleshooting) for better compatibility with device tracking apps – more info in this thread.