I have an application that calls for a "12V battery 120AH/1000A (EN)". I want to be sure I'm reading it correctly in that the 120AH is the battery capacity and the 1000A is probably CCA? And the EN is some European standard. Does anyone know what the actual EN standard is?
If a typical car battery is 55Ah with 750 CCA then that sounds right. I also read that 12V 180 Ah = 1100 A comes from Varta.
I'll let someone else dig up the EN standard.... assuming it exists.
I forget exact details on CCA temperature 0'C? vs CA for 25'C
But I recall CA is defined at room temp as the max current sustained for 30 seconds at 7.5V from a fully charged 12.5 V battery.
.. Battery U cites " SAE J537 specifies that a battery with a CCA reading of 500A can deliver 500A at –18'C (0'F) for 30 seconds without dropping below 7.2 volts."
So I conclude ESR= (12.5-7.5)/CCA at cold temp. or replace 7.5 with 7.2 ??
ESR lowers as Ah capacity rises but is not necessarily in a perfectly inverse relationship because Capacity is mainly condition of dielectric and its specific gravity while ESR includes Anode and Cathode materials and condition.
Therefore ESR is a great indicator of electrodes but a poor indicator of dielectric or the Ah Capacity
Electrode degradation from sulphation or deep discharge of the dielectric causes ESR to rise so it not a great predictor for normal operation of Ah capacity but generally must be lowered at some material cost for increased high density batteries with rapid charge rates. (<1h)