Someone posted this "Power cube" summary on the Ingress community. She tested it out so others would not make the same mistakes as she did to waste these "precious/mysterious" cubes.
What does it do?
It's essentially like a mana/health potion from
any other game. It recharges your XM bar up to the value of the cube
itself. So a level 4 cube will inject you with 4k XM.
Does it increase your XM bar above cap?
No. It only refills the
bar you already have (up to its own value).
What happens if it's worth more than the XM you need?
the overspill fizzles. The cube is consumed utterly on use, and will
only give you up to the full amount, as much as you have room for. For
example, I had 1348 XM short of 100%, used a 4000XM cube, so I gained
1348 to bring me to 100% and the other 2652XM just dissipated into the
What does it look/sound like?
It's pretty nifty! Swirley gold XM
droplets spiral around you while a "chargin' mah laz0rs!" sound effect
revs up. There is no residue once the cube's power has been used.
EDIT: Courtesy of +Fevenis Silverwind : Power Cube animation (RAW)
Can you use cubes of a higher level than yourself?
Nope! The 'Use'
button is greyed out, and trying to click it gets an "insufficient
Can you use a cube while already at 100% XM?
Yes, and it'll be
totally wasted. So don't. (Thanks +Alexandre Luna Barros for the
I'm not getting any cubes from hacking, whassup with that?!?
are dropping for people, but it still seems to be rather hit and miss.
My theory is that the portals need their 'loot tables' to be refreshed
post-update, either by flipping them, or waiting on the daily decay.
Hopefully over the course of the next day any stubborn portals will
get updated, and in the meantime try not to get too frustrated. Also,
bad luck is bad, but not permanent, so try not to despair if you're
burning out and still not seeing any just yet!
Link to G+: https://plus.google.com/113226483052150160303/posts/2dSSuN43Xt2