Materials with bump shader not being batched [Mobile]

Hey everyone! I'm currently developing a mobile game, and I'm looking forward to use materials with bump maps. The meshes that receive these materials are pretty low poly, they don't go over 200 polys.

Eventually, when I changed the shader to a simple diffuse one, the draw calls started to be batched, but when I got back to the shader which uses bump maps, this batch isn't being made.

Is there anything that I'm not aware of? How can I work this out?

I really wish to use bump maps, but I need them to be batched, also.

Algo, I forgot to mention that the objects that receive these materials are dynamic ones.

Thanks in advance!