EE was attempting to jump 380-7 Komatsu with the 320 Komatsu. EE was told by other senior employee, to wait for other EE to finish loading a truck, for other EE's assistance. EE proceeded to connect cables, unassisted, and incorrectly attached cables to battery of 380-7 causing the battery to explode. EE was wearing PPE but was exposed to acid in EE's face and eyes.