I'm working on a a project that requires around 35 volts--can someone tell me if it is safe to wire a series of these batteries? I apologize if this question doesn't belong here, I'll take redirection Their actual voltage is around 7.2v a battery. So, I was going to use 5.

 

Looks ok to me...

 

Those batteries look like nominal 9V to me (but I don't read Chinese). In any case, each battery is made from several cells in series, so you are just adding more cells in series.

It should be fine, but just keep in mind that batteries can supply a huge amount of current into a short, and you have a fairly large voltage there. It borders on the edge of "dangerous."

 

Put a fuse in series.

 

I appreciate the help. I will add a fuse and try not to blow myself up. I literally know just enough to be dangerous.