Batteries must be subjected to regular testing to ensure their starting capacity is maintained at an optimum performance level. A battery must also be scrutinised for any physical condition which may reduce battery life and impede starting performance such as broken or damaged posts and leaks to the battery case or lid
The first step in evaluating starting capacity involves testing a battery’s state of charge using a hydrometer or voltmeter. All non-sealed batteries should be checked using a hydrometer. As a cheap and reliable method of determining state of charge, the hydrometer also reveals differences between cells and allows visual inspection of the electrolyte colour. Where the hydrometer reading shows no significant difference between cells and produces a reading of 1230 or above (at 20-25C) the battery has sufficient charge for a load test.
Sealed batteries must produce a voltage of 12.5 or greater before a load test may be performed. Since the loss/fail criteria varies depending on the make of load tester used, be sure to consult the instruction manual provided with the tester to ensure success.
This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia