Hi guys, it’s Mark Phillips. In spite of all the advances in automotive technology in recent years, one item that hasn’t changed much over the years is the 12-volt wet cell lead-acid storage battery. It’s pretty much the same basic design that’s been around for more than a century. The only major differences are that today’s car batteries are 12-volts (versus 6-volts back in the 1950s), and they are maintenance free and require no make-up water. Even so, the average lifespan of a car battery today is still only about four or five years — and only about three years in many hot climates!
One weakness is that wet cell car batteries have to be kept at or near full charge to maximize their output and lifespan. If a battery is run down and chronically undercharged, it will drastically reduce its service life. Sulfate builds up quickly on the cell plates when the battery is discharged or undercharged. This forms a barrier that prevents the plates from accepting and holding a normal charge. Over time, this causes a loss of storage capacity and the battery gets weaker and weaker. If the battery can’t pass a load test, it needs to be replaced.
Most late-model vehicles place high electrical loads on the battery, so if the vehicle is not driven often enough or far enough to keep the battery fully charged (a process that typically takes at least 15 to 20 minutes), the battery will gradually run down.
Batteries can also fail suddenly as a result of shaking and vibration. The diecast metal connectors that tie the cells together tend to be brittle, and can crack or break if a battery is bouncing around on its tray and is not secured with a hold-down clamp or strap. And heat… Heat is a real killer of batteries too. High underhood temperatures combined with a hot climate can shorten battery life by increasing the evaporation of water from the battery cells.
The bottom line is that when a battery becomes weak or suddenly dies, it needs to be replaced with a similar battery that has the same configuration —Group Size — and equal or greater CCA capacity. Finally, the charging system should also be tested to make sure it can keep the battery charged, and power needs to be maintained to the vehicle’s electrical system with a backup power supply while the battery is being replaced to prevent the loss of learned memory settings in onboard modules. I’m Mark Phillips. And thanks for watching.