Mainstream Star Wars material never truly answered this question for us. Since energy can neither be created or destroyed, it’s been a mystery for more casual fans.
While you’ve heard of the terms “kyber crystal” or “diatium power cell” you probably have no clue what they mean. You’d have to dive into deep Star Wars lore to even figure out what makes a lightsaber light up.
Luckily, we did that for you.
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What Powers a Lightsaber?
Lightsabers are energized mostly by use of a kyber crystal. They help focus the output of energy, and make the trademarked illustrious glow.
The kyber crystal doesn’t do all the work, though. To turn on the lightsaber, you must have a diatium power cell underneath the crystal. It acts as a battery of sorts, storing and recycling energy for the lightsaber to run on.
Do Lightsabers Have Infinite Energy?
No, but almost.
The First Law of Thermodynamics tells us that energy cannot be created or destroyed. This is the case for both our universe and a long time ago in a galaxy far, far away. Basically, infinite energy is impossible in reality and in fiction.
Diatium power cells follow that law as well. The convenient factor of the power cells is that they run out of energy very slowly, as seen in the book I, Jedi. It’s like leaving your car running without driving it.
A lightsaber won’t expend any energy until it comes into contact with a solid object. When it does hit something, it exchanges an almost equal amount of energy with the source of impact. This recharges the diatium power cell naturally.
Do Lightsabers Need to be Charged, and How Long Can They Stay On?
Though the lightsaber can charge itself, it does lose tiny traces of power with each exchange. They can eventually run out of power and need recharging.
This happens in the Legends novel Shatterpoint, when Mace Windu’s lightsaber powers down in the middle of battle. At first, he believes it was caused by sabotage, but later realizes it was because of extensive usage.
Due to the nature of diatium power cells, Jedi don’t have to consistently recharge them. If built right, a power cell can last indefinitely.
However, lightsabers are difficult to construct, and not everyone gets it perfect. The battery life of a normal lightsaber can range anywhere from 50-100 years. This is dependent upon the user and if it was assembled correctly.
How Much Energy is in a Lightsaber?
In Star Wars: The Phantom Menace, Qui-Gon Jinn tries to melt a hole in the blast doors of Nute Gunray’s ship. He was almost successful, until a group of droidekas stopped his progress.
According to calculations by a group from Rakuten, his lightsaber contains 1.69 gigajoules of thermal energy. That’s equal to 120,380 AA batteries, or 0.05 seconds of Earth’s entire power supply.
Qui-Gon’s lightsaber isn’t even the most powerful, with Kylo Ren’s measuring at 2.5 gigajoules of thermal energy.
So, Do Lightsabers Run Out of Energy?
Yes, and no.
It pretty much depends on how the lightsaber is initially built. Even if yours can’t, it has the potential of lasting you a hundred years before needing a recharge.
Even with their varying battery life, lightsabers are the most iconic Star Wars weapon out there. They can definitely outlive even the most powerful Jedi Master.