Battery Rating

By Industries and government organizations following standards have been adopted to get a fair result of battery quantity:

Ampere-Hour capacity:

It is a function of the total plate area i.e. size of the individualplate multipied by the number of plate( A x N).

How to Measure

For measuring this capacity the battery is discharged continuously for 20 hrs and its current output supplied to a standard load measured. suppose that the battery delivers 30A current for 20 hrs that mean its rating is 30x20= 600 Ah. which is stamped on the battery case.

Reserve Capacity:

It is one of the newly developed rating standards and it is more realistic because its provide a double check on the ampere-hour rating.

How to Measure

The capacity is given by the number of minutes a battery will tolerate a 25 A drain without below 10.5 v. higher this rating battery is better.

Zero Cranking Power:

It was first cold weather rating and it is applicable in the relation to crafts which ply in freezing weather. This zero degree performance test gives a valuable insight into battery quality.

How to Measure

large batteries are tested at a 300 A drain with battery chilled to 18 degree C. And smaller sizes batteries are tested at half this value.
This test consist of two part:-

1. The battery is first chilled to 18 degree C and the load applied for 5 sec. The Voltage output is recorded.
2. The test is continued further till voltage drops ton 5V. The number of minutes it takes to reduce the voltage to 5V forms the second half of the rating. Higher both the digit battery is better quality.

Cold Cranking Power: 

This simple rating is applied to all 12 V batteries regardless of their size.

How to Measure

The battery is loaded at 18 degree C till the total voltage drops to 7.2 V. The output current in amperes is measured for 30 Seconds. Higher the Output, battery is better.