Crystal power cells are power sources created by the Ancients (presumably similar to batteries) which not only power much of their portable technology, but Asuran technology as well, including their pistols. They are capable of powering energy weapons that can kill a human with one shot, suggesting their power output is vastly superior to even the most advanced Earth equivalent. It is unknown if these devices are rechargeable or if they generate their own power in some way, but it is likely the former.
The Ancients also have another type of crystal cell built after their return to Earth. It is capable of powering Arthur's Mantle for very large amounts of time. The Ori use similar crystals to power the staff weapons of the Ori soldiers. A crystal from an Ori staff was proven to be able to power Arthur's Mantle but the crystals are larger than the one in Arthur's Mantle. (SG1: "Line in the Sand", "The Road Not Taken")