Me and my team are making a Rov but we really could use some ideas on how to power it , till now i was thinking of using batteries but i am really concerned about the weight problem , i would be glad if you can help
Batteries are definitely the easiest and safest option. I would recommend looking a lithium polymer batteries, which have a very high power density.
If you are concerned about weight, you can add buoyancy foam to your design to offset the weight. Most professional-level ROVs have quite a bit of flotation for this reason. We’ve got buoyancy foam available here and there are other options out there, especially if you aren’t going very deep.
Hope that helps!