Hi Gio,
First what is OT? Over time?

No problem for me!
I always get in trouble on the forum for my suggestions on battery packs (sometimes I put my foot in my mouth too!).
I will try to get it right the first time now! An Innova PleoRB can use all of the batteries made (that is why it has two holes in its battery bay). The Ugobe (1st plain Pleo) was made BEFORE there was a RB battery and only has the ONE hole in its battery bay. This hole will align with the UGOBE NiMh battery and the EGG Li-Poly battery.
The RB battery will not fit all the way into the Ugobe battery bay (AS IT IS) as the polarity key DOES NOT ALIGN WITH THE HOLE in the battery bay. There is NO technical or electrical reason why it could not be used, IF YOU CUT OFF the polarity key on the RB battery.
THERE ARE REASONS NOT TO DO SO:
1. Possible reverse polarity inserting the battery. Without the polarity key, YOU, the user are responsible for inserting the battery in the correct polarity, i.e., positive terminal toward the front and negative toward the rear. There are reports from users of homemade batteries that negative polarity has damaged their Pleo. It may cause the 3 amp fuse to blow on the bottom of the power input card (requires disassemble to replace/repair).
2. Cutting off the tab will make the RB charger red light flash (battery not charging). The little hole in the bottom of the charger has a contact that must be closed for the red light to remain steady (charging). I have used paper wadded up into the shape of the hole (very tightly packed), or even the cut off key from the battery (if you do a good job!).
Remember, charge RB batteries in RB chargers, as they are different chemistry than Ugobe batteries and have different charging algorithms!
Hope this helps!
Peter