PD IEC TS 61044-2021 Opportunity charging of lead-acid traction batteries

PD IEC TS 61044-2021 Opportunity charging of lead-acid traction batteries. 4 Planning the implementation of opportunity charging The following list items a) to c) shall be considered when planning to introduce opportunity charging. • Indications that opportunity charging may be beneficial are: a) when the maximum permissible physical size of the battery for the vehicle does not have enough capacity to complete the daily workload before a next complete recharge becomes necessary. This allows an undesirable physical change-out of the battery to be avoided. b) when the operational requirements of the vehicle are such that it is impossible to predict when the battery will next be released for a complete recharge. This can occur for example in locations such as airports where 24 h per day working is a rule. c) when a battery is close to the end of its operational life and the use of opportunity charging can be shown to maintain an acceptable performance of the vehicle. An implementation of opportunity charging will result in an additional energy turnover in the battery beyond the 60 % or 80 % limit per cycle specified by the manufacturer. This change in operational mode is therefore to be cleared beforehand with the battery manufacturer as it is possible that this will have an impact on warranty terms and conditions. NOTE 1 If the periods available for charging are of short duration and infrequent, then opportunity charging will be of little benefit. NOTE 2 When opportunity charging enables the user to discharge substantially more than the recommended percentage of the rated capacity each day, the battery-life measured in years will be reduced as the battery-life measured in terms of cumulative ampere-hours discharged is approximately constant. NOTE 3 Opportunity charging at a SoC > 70 % is less effective and can result in a significant increase of battery temperature, gassing, water loss or sudden failure of VRLA designs. NOTE 4 Opportunity charging results in higher electrolyte working temperatures that accelerate battery ageing. 5 Operational procedures 5.1 General The following information in 5.2 to 5.5 shall be considered when operational procedures are being established. 5.2 Charging conditions Self-compensating chargers are preferred when opportunity charging is carried out. A correctly sized battery and charger combination is essential for all batteries. For opportunity charging of valve regulated lead-acid batteries it is essential that onlychargers with a current-voltage-time characteristic in accordance with the battery manufacturer’s recommendation...