a battery tester device for measuring remaining battery life in a battery is provided . the battery tester device comprises a length of wire having a first end , a second end , and a middle portion . a light bulb holding mechanism is formed in the second end of the wire . a light bulb is releasably securable within the light bulb holding mechanism with the light bulb electrically connected to the light bulb holding mechanism . upon insertion of the battery between the first end and the second end of the wire , the light bulb illuminates to indicate the remaining battery life .