Estimation of VRLS battery capacity using the analysis of the coup de fouet region

Abstract

This paper presents a novel approach for estimating the capacity of VRLA batteries. Emphasis is placed on operating conditions and exclude the effects of ageing. The approach is based on the analysis of the start of discharge region known as the coup defouet. Experimental results reveal that parameters extracted from this region are strongly correlated to battery capacity. This has been verified for a good range of operating conditions including discharge rate and ambient temperature. The main advantages of the approach compared to existing methods are; a) Simple and can be implemented on-line within low level controllers in a real-time mode., b) Requires a very short duration discharge (in the order of 2 minutes is sufficient)., and c) An accuracy of estimating relative battery c‘apacity of better than &5% may be obtained.