So much play with Battery that i had to investigate how it really works.
Something i found that seems really useful is... When you want to heal your army say in a fight, you have 6 goons that you are microing in your main.
You then want to heal and you decide to rightclick with all goons on the battery. This seems to be the wrong way of doing it.
What you do instead is to have battery hotkeyed to 2-3 (close to R) and in a quick succession click the hotkey followed by R on the GROUND kind of close to the goons you want to heal. What will happen is that the goons that are attacking will NOT move towards battery, only the ones that actually need healing. This means they can keep shooting and not get interrupted moving to battery as they have full shield. Could potentially mean one more volley of shots.
The radius of battery healing on ground seems to be quite enormous so this could be used on bigger armies too.
If you click healing on a unit, it only affects that unit.
Have a good day!