Is the follow sentences right? For the devices are often powered by batteries with limited weight and lifetime, power control become a main concerned issue for reserving the energy. Because the devices are often powered by batteries with limited weight and lifetime, power control become a main concerned issue for reserving the energy.

Are the following sentences right/correct?

The conjuction "for" is not used (not that I have seen anyway) at the beginning of a sentence. So you could rewrite your first sentence as....

Power control became a major issue for conserving energy, for the devices are often powered by batteries with limited weight and lifetime.

notes:
1) become should be became
2) reserving is probably better written as conserving
3) main concerned issue sounds awkward...major issue or major concern or serious issue or serious concern

Your second sentence is better, though it needs some work.

Because the devices are often powered by batteries with limited weight and lifetime, power control became a major concern for conserving the energy.

See the previous notes.

Hope this helps.

MountainHiker