Q:
I have a 2005 Dodge Caravan with about 60,000 miles on it. Over the past couple of years, it's gone through three batteries. The first of those lasted about two years. Each of the others went bad in less than two months. When they went bad, it was as though there was no battery in the car. Tests of these batteries indicated internal shorts. A test of the car showed it to be in good order electrically. Is there anything in the electrical system of this car that could cause this type of damage in a battery? I was told by an automotive technician that today's batteries are universally lacking in quality. I now wonder how many people are having this problem. Because the batteries are under warranty, it has cost me nothing for replacements. However, the inconvenience of being stranded and then sorting out things has been costly.
-R. Blair
A: The early death of an automotive battery is usually the result of one, or a combination, of the following: excessive vibration (an alarming number of replacement batteries are not remounted properly), excessive cycling (running the battery down to a low charge many times), undercharging or overcharging, high accessory usage under short driving cycles (not enough charging time to properly refill the charge), and excessive heat (can't be helped in some climates). It's tempting to say today's batteries aren't built as well those of the past, but I don't have the data to support that claim.
As for your issue, you can determine if a battery's internal cells are shorting with a conductance tester, which is the modern way of testing batteries, as opposed to the older, 1/2 CCA load test. Shorted cells can result from vibration-induced mechanical stress, poor manufacturing methods or a buildup of plate material in the bottom of a battery.
I'm wondering if another look might be taken to ensure your Caravan isn't behind some of this.
Car issues that can shorten battery life include small-but-persistent parasitic loads, such as a glove box light that never turns off or a network module that fails to go to sleep. In vehicles that are driven daily this might not pose a noticeable problem, but for folks who only occasionally drive their vehicle, especially for only short distances, this can lead to failed starts and dramatically shortened battery life. Testing for a parasitic drain has become a bit more complicated on newer vehicles as they have so many modules doing smart things.
Another way a battery can be quickly damaged is by an overcharging alternator boiling away electrolytes and overheating cells. Symptoms include battery sweating, excessive terminal corrosion and a battery that's unusually warm to the touch after driving. A bad alternator is easily tested for. High accessory use, coupled with short run times (less than 80 percent charge recovery), can lead to acid stratification, a growing problem with newer accessory-laden vehicles. This condition promotes internal corrosion, shortening life.
Two final things you can do are: a starter current draw test (rules out the possibility of a problematic starter overstressing the battery) and an alternator output test to ensure the charging system can function to its listed specification.