Kayle W on allies

I've been noticing this every time i play Kayle. Using kayle's w to heal allies only provides half the amount to the target than the ability tells you. I tested this myself by using w on myself to see how much i gained and got the full amount. When i use it on allies i looked at what health they currently are at to know how much it should bring it to and found out it was only giving half the value every time and the ability gives no description of having half the effect on ally targets.