The battery shown below was in a 3.2L(A) diesel engine Mitsubishi Triton belonged to a friend of mine. Those whitish, ashy deposits were the result of corrosion. When I opened the plastic cover on the right, I found more corrosion on the positive terminal than the negative one on the left.
After I cleaned it, the difference was like day and night as shown below.
Opening the caps of the 6 cells revealed that the 3rd and 5th cells (from the negative terminal) needed to be topped up.
Next I checked the voltage of the battery using a multimeter like this one here:
The battery registered a voltage reading of 13V across the terminals which shows that it was still fully charged. You won't be able to start a car engine if the voltage falls below 12.6V.
The table below shows you the voltage vs. charge percentage of a car battery.
|Taken from: .topbuzz.co.uk|
A new battery normally carries a one-year warranty from the manufacturer subject to terms and conditions. If you take care of your battery, it can last you for at least 2 years.
The longest life span of a car battery I owned exceeded 3 years since I took good care of it. If you don't bother to inspect your battery periodically, be prepared to buy a new one just slightly more than a year of usage.