Why Your Battery Only Lasted Two Years

People arriving from a northern state are consistently surprised by how short battery life is here, because the received wisdom is that cold kills batteries. Cold reveals a weak battery. Heat is what weakens it.

What heat does

Heat accelerates the chemical processes inside a lead-acid battery, including the destructive ones — grid corrosion and water loss from the electrolyte. A battery living in a South Florida engine bay operates well above the temperature its rated service life assumes.

The result is a battery losing capacity steadily without giving any sign, because in warm weather even reduced capacity starts the engine easily.

Short trips make it worse

A battery is recharged by driving. A short trip does not put back what starting consumed, and a vehicle used for short trips in traffic is running at a chronic deficit. Combine that with heat and the life shortens further.

The warnings

• Slower cranking, particularly first thing
• Headlights dimming noticeably during cranking
• Needing a jump even once — a fully discharged battery has permanently lost capacity
• Corrosion at the terminals
• A swollen case, which means heat damage and immediate replacement
• Age past about three years in this climate

Battery or alternator?

A useful distinction: if it starts after a jump and dies again later, suspect the charging system. If it starts after a jump and runs for days, the battery was the problem. A battery warning light on the dash generally indicates a charging fault rather than a battery fault.

Getting more life

1. 1Keep terminals clean and protected.
2. 2Drive far enough to actually recharge, or use a maintainer on a vehicle that sits.
3. 3Make sure the hold-down is tight — vibration damages plates.
4. 4Have it load-tested annually once it passes two years.
5. 5Replace on your schedule rather than on the roadside.