Accumulator battery system, comprising: - first and second electrochemical accumulator stages (41, 42) connected in series; - a first control device powered via the potentials across the terminals of at least one accumulator of the first stage, configured to measure the potential difference between the terminals of an accumulator of the first stage, comprising a first output interface, and comprising a first analog/digital converter configured to encode the potential difference measured between the terminals of said accumulator of the first stage, said first output interface being configured to deliver a first digital sequence corresponding to the encoded potential difference, with logic levels defined by at least two potentials across the accumulator terminals of the first stage; - a second control device powered via the potentials across the terminals of at least one accumulator of the second stage, configured to measure the potential difference between the terminals of an accumulator of the second stage, comprising an input interface, comprising a second output interface, comprising a decoder configured to decode the potential difference measured by the first control device from the first digital sequence received on the input interface, and comprising a second analog/digital converter; - a potential level converter configured to convert two potentials of the first digital sequence applied by the first output interface into two potentials between the supply potentials of the second control device, and configured to apply the first digital sequence converted to the input interface of the second control device, characterized in that the second analog/digital converter is configured to selectively encode: - the potential difference measured between the terminals of said accumulator of the second stage; or - two potentials of the digital sequence received on the input interface; the second control device comprising a processing device configured to extrapolate the potential difference across the terminals of said accumulator of the first stage based on two potentials of the digital sequence received; and the second output interface being configured to deliver a second digital sequence selectively corresponding to the encoded potential difference, to the decoded potential difference, or to information representative of the potential difference extrapolated by the processing device. - first and second electrochemical accumulator stages (41, 42) connected in series; - a first control device powered via the potentials across the terminals of at least one accumulator of the first stage, configured to measure the potential difference between the terminals of an accumulator of the first stage, comprising a first output interface, and comprising a first analog/digital converter configured to encode the potential difference measured between the terminals of said accumulator of the first stage, said first output interface being configured to deliver a first digital sequence corresponding to the encoded potential difference, with logic levels defined by at least two potentials across the accumulator terminals of the first stage; - a second control device powered via the potentials across the terminals of at least one accumulator of the second stage, configured to measure the potential difference between the terminals of an accumulator of the second stage, comprising an input interface, comprising a second output interface, comprising a decoder configured to decode the potential difference measured by the first control device from the first digital sequence received on the input interface, and comprising a second analog/digital converter; - a potential level converter configured to convert two potentials of the first digital sequence applied by the first output interface into two potentials between the supply potentials of the second control device, and configured to apply the first digital sequence converted to the input interface of the second control device, characterized in that the second analog/digital converter is configured to selectively encode: - the potential difference measured between the terminals of said accumulator of the second stage; or - two potentials of the digital sequence received on the input interface; - the potential difference measured between the terminals of said accumulator of the second stage; or - two potentials of the digital sequence received on the input interface;