We just finished a movie called Apollo 13 because in the book we just read called Cosmic they get back to earth using the way Apollo 13’s crew got back to earth. I did some research and this is what I found out, that caused the problem on Apollo 13.
First off Mission Control had requested that the crew stir the oxygen tanks, a task required to prevent the oxygen ‘slush’ from stratifying. The Teflon-insulated wires that provided electricity to the stirrer motor were damaged, causing a large fire when electricity was passed through them. The fire heated the surrounding oxygen, increasing the pressure inside the tank above its nominal 1,000 PSI (7 MPa) limit, and causing the tank to explode. The cause of the explosion was unknown at the time, however, and the crew and Houston conjectured that a meteoroid had struck the SM or even the Lunar Module (LM).
This explosion caused damage to other parts of the Service Module, including, critically, the number one oxygen tank. Because the Command/Service Module(CSM) relied on the oxygen tanks to generate electricity, damage to number one tank meant that very little power was available for the spacecraft. The Command Module (CM) contained batteries for use during re-entry, after the SM was jettisoned, but these would only last about ten hours. Because this power needed to be saved for re-entry, the crew survived by using the LM, still attached to the CSM, as a “lifeboat”. The LM “lifeboat” procedure had actually been created during a training simulation (in the simulator) not long before the flight of Apollo 13.