An electrochemical cell, comprising: a sealed vessel comprising a relief valve, said sealed vessel being partially filled with a liquid electrolyte; a cathode at least partially submerged in the liquid electrolyte; an anode at least partially submerged in the liquid electrolyte and not in direct contact with the cathode; a third electrode at least partially submerged in the liquid electrolyte and not in direct contact with either the cathode or the anode; a cathode circuit between the third electrode and the cathode wherein the cathode circuit contains a cathode switch; an anode circuit between the third electrode and the anode wherein the anode circuit contains an anode switch; a first gas pressure sensor within the sealed vessel, the first gas pressure sensor not in contact with the liquid electrolyte; a second gas pressure sensor within the sealed vessel, the second gas pressure sensor not in contact with the liquid electrolyte; and a microcontroller in communication with the anode switch, the cathode switch, the first gas pressure sensor and the second gas pressure sensor, wherein, in use, the microcontroller reads the pressure sensors (170, 180), and is configured for recording the measured pressures, calculates oxygen and hydrogen partial pressures, and calculates the state of charge difference between the anode and the cathode, and wherein the microcontroller is configured to close the anode switch when the difference in state of charge between the anode and the cathode is greater than a first threshold value, and to close the cathode switch when the difference in state of charge between the anode and the cathode is less than a second threshold value. a sealed vessel comprising a relief valve, said sealed vessel being partially filled with a liquid electrolyte; a cathode at least partially submerged in the liquid electrolyte; an anode at least partially submerged in the liquid electrolyte and not in direct contact with the cathode; a third electrode at least partially submerged in the liquid electrolyte and not in direct contact with either the cathode or the anode; a cathode circuit between the third electrode and the cathode wherein the cathode circuit contains a cathode switch; an anode circuit between the third electrode and the anode wherein the anode circuit contains an anode switch; a first gas pressure sensor within the sealed vessel, the first gas pressure sensor not in contact with the liquid electrolyte; a second gas pressure sensor within the sealed vessel, the second gas pressure sensor not in contact with the liquid electrolyte; and a microcontroller in communication with the anode switch, the cathode switch, the first gas pressure sensor and the second gas pressure sensor, wherein, in use, the microcontroller reads the pressure sensors (170, 180), and is configured for recording the measured pressures, calculates oxygen and hydrogen partial pressures, and calculates the state of charge difference between the anode and the cathode, and wherein the microcontroller is configured to close the anode switch when the difference in state of charge between the anode and the cathode is greater than a first threshold value, and to close the cathode switch when the difference in state of charge between the anode and the cathode is less than a second threshold value.