Lead-acid Battery State-of-Health Evaluation with Short Discharge Method

Electricity access to rural areas in third world countries is still a big problem. Second-life components can present a good solution for these areas as solar PV (Photo-Voltaic) panels can still be used after twenty five years of use. PSUs (power supply units) from computers can be used as solar charge controllers after just a little change while batteries can also be used in their second-life when they are eliminated from their first use. This second life use of electrical components is done with the frugal innovation principles. But using batteries in second-life requires SoH accurate measurement which is still difficult with already existing methods especially when history of battery is unknown. In this paper, a new method is introduced based on short discharge of the battery. This method is cheap, fast, reliable and accurate enough for second-life batteries. A second-life battery means that when a battery is done for its life but still it can be used for small load than before. The method can be applied in two different ways and maximum error for both variations is around 10% which is very much acceptable for second-life batteries. The well-known two-pulse method is also performed to compare results for same conditions and error can be as high as 55% in some cases. The method is equally good for flooded (car) and AGM (solar) lead-acid batteries. The method introduced in the paper highly relies on SoC accurate measurement. Here, two-pulse method is used as SoC measurement method with short discharge method.