Battery AH Rating

Hook up a load and measure the volts and amps over a period of time. The amps times the hours until the battery goes low (according to the definition of "low" being used) = the amp-hours that the battery actually produces.

Usually this is not calculated; instead the battery already has a factory rating. But if it can no longer be found, such a test may be needed.

The amp-hour rating is strongly a function of the load current drawn. There is no single AH value; it will depend on the load, so you want to load the battery the way you will actually use it, in order to get a useful number.

emc_c

Good point. I should have suggested using a test load similar to the expected use. That said, batteries come factory rated in AH; is there some standard load to which this refers? (I don't remember such conditions being specified in ratings, but maybe just didn't look closely enough.)

The manufacturer decides at what load to specify the AH rating. That load should bear some resemblance to the battery's intended use. But for example you won't get the manufacturer's AH rating on a 12 Vdc lead-acid battery used in an automobile if you load it to draw maximum cold-cranking amps!

emc_c

Dear Sir,

It is only for battery bank for AC and DC UPS.

Before conducting the test we have to collect the battery specification including data and test procedure. Conduct the test by using dummy load bank, record ampere (do not loading the battery over its rating), test duration, voltage each cell and room temperature.

The test is stopped when:

1). Test duration that have been decided before testing already exceeded or

2). The time duration multiplied by ampere is exceed battery AH, or

3). If there is one cell battery already reach 1.8 Volts (check in the battery specification & data), even AH value have not reached yet. It means AH battery do not meet the requirement.

Best Regards,

can u tell what kind of battery u want to test, primary battery or rechargeble battery? As there would be different concept for testing these two type of battery as per IEC standard.

Please let me know, I would sincerely to help.