The original battery for the C14 Mag taillight with 4.4 Wh, 22h max. runtime and a charging time of 3h.Once the factory-fitted battery has reached the end of its service life, you can replace it yourself using the TX5 tool provided. To do this, open the screws and remove the panelling. If this is difficult to remove, use the magnetic holder as a lever. Then release the battery contact and replace it with the new one.