SAE J3012:2020 pdf free

SAE J3012:2020 pdf free.Storage Batteries for Start-Stop Operations
Capacity is the amount of usable (voltage-limited) charge (ampere-hours) that can be extracted from a battery. Batteries have capacity ratings using standard discharge current and temperature conditions, but usable capacity varies with battery temperature and discharge rates seen in the various vehicle operating conditions. Manufacturers are to provide capacity rating values that their new, fully charged batteries should meet or exceed. Capacity ratings provided by battery manufacturers are to be statistically compliant when tested according to the relevant test standard. Capacity will ultimately decline with age and use. Like conventional vehicle batteries, batteries in start-stop operation should never need to deliver full discharge capacity except under failed charging system conditions.
The capacity (in ampere-hours) obtained from a battery discharged at a constant current to an end-of-discharge condition (i.e., discharge cutoff voltage of 10.5 V) in 20 hours at 25 °C (refer to SAE J1715/2). The constant current l20 (also listed as In) is the nominally rated C20 capacity divided by 20 hours. Discharge rates may be set as multiples of l20 such as 5l20 and will result in different capacity values. C20 (also listed as Cn) capacity represents the maximum practical capacity for a battery by slow discharge under ideal conditions. Discharge rates in start-stop operation needed to supply the vehicle electrical system are normally much higher than l20.
The amount of time (minutes) a fully charged battery can discharge at a constant current of 25 A to an end-of-discharge condition (i.e., discharge cutoff voltage of 10.5 V) at 27。C (refer to SAE J537). The reserve capacity test was developed to better represent enhanced load discharge conditions (lights, fans, etc.) in a vehicle electrical system without an operating alternator; it is also more typical in start-stop operation. Wherever possible, discharges used in this start-stop testing document use the RC rating and discharge rate.
Capacity measured using one of the above testing methods to determine the remaining charge in batteries that have been subjected to cycling, stand testing, or other service-related conditions listed in the testing specifications. Residual capacity shall be run at one of the rated currents established for new batteries.SAE J3012 pdf free download.