The Fluke 885AB DC Differential Voltmeter achieved an absolute accuracy of ±25 parts per million of input +1 ppm of range +5 microvolts from 0 to 1100 VDC. The unit operates from either line or battery power. Batteries are compact, rechargeable nickel-cadmium units which operate the voltmeter more than 24 hours on full charge. In addition to true portability, battery power offers complete line isolation for elimination of ground loop errors.