the Rcond warning can be very common when using specialized power systesm. Essentially, the tool generates matrices behind the scenes, and they can be near singular depending on circuit topologies and parameter values. It can be non-trivial to determine what is causing these. Some things to try is adding snubbers, changing your time step value, removing extremely small or extremely larger circuit parameters. Eliminating parts of the model and and replacing them with controlled current/voltage sources to isolate what is causing the issue is another possibility. There is a chance your model will work just fine though. It is good to compare fixed step to variable step (ode23Tb) to make sure the results line up.
However, the error in your case is that something with the connection of the battery has the wrong signal dimensions. Can you provide a screen shot of both how you have connected the battery to the microgrid and the battery parameter settings?