I have a simple soarer I want to fly and I dont have a BEC and I don't want to use my other ESCs. Could I plug in a 5V battery or less directly into my receiver? Or will that still hurt it?
yes. you can find a cheap LED flashlight from HF, take the 3 battery pack holder out and solder servo leads to it (only need power and ground). 3 AAA batteries will give you the voltage you need, then just plug into empty spot on your Rx. i have done this on DLG's before and it works fine.
those will work but 4 batteries is a little over kill for voltage and weight. i really like the cheap LED flashlight that you can get for $1. they have the same thing but with 3 batteries instead of 4.
If you want to save some weight and can solder, there are 3.7v batteries available for cameras and such. They are smaller and lighter than AAA or AAs and you only need two.