Accelerated failure testing of valve regulated lead-acid batteries using gas studies

Laboratory failure testing of VRLA batteries is usually accelerated by increasing the temperature and/or charge voltage. Based on the electrochemistry of VRLA batteries on overcharge, the rates of water loss and positive grid corrosion can be determined directly by measuring the hydrogen and oxygen gas venting rates from the battery. The integrated gassing rates over the life of the battery can then be used to estimate battery float life. The accuracy of the prediction depends on the accuracy of the gas measurements. At low gassing rates, gassing measurements are difficult to perform. Potential hydrogen gas and water vapor losses through leaks and diffusion can introduce significant errors. In order to make accurate extrapolations from the accelerating to the standard operating conditions, a good understanding of the validity of the assumed temperature and voltage dependence to the failure mechanism is necessary.