An electrochromic device is provided. The device includes a first transparent substrate, a second transparent substrate, a first conductive layer having a first resistance gradient disposed on an inner surface of the first transparent substrate, and a second conductive layer having a second resistance gradient disposed on an inner surface of the second transparent substrate. The device further includes a first
bus bar in contact with the first conductive layer, a second
bus bar in contact with the second conductive layer, and a first detection
voltage pad disposed on an inner surface of the first transparent substrate, the detection
voltage pad configured to measure a local battery potential at a detection
voltage measurement location within the electrochromic device, the first resistance gradient and the second resistance gradient are configured to form a region containing a maximum local battery potential that substantially coincides with the detected voltage measurement location.