When to Replace Your Car Battery

A dead battery is the number one winter breakdown in Ontario. At -25°C, a battery has roughly 50 percent of its warm-weather power, while your engine needs 30 percent more cranking power to start. A battery that starts fine in September can leave you stranded on the first seriously cold morning.

Lifespan in Ontario

Most batteries last 3 to 5 years in our climate. Heat in summer accelerates internal degradation, and cold in winter exposes the weakness. A battery that was marginal through its third summer will likely fail that winter. Do not push a battery past 5 years in Ontario regardless of how well it seems to be performing.

Warning Signs

• Slow cranking — the engine turns over sluggishly, especially on cold mornings
• Dim headlights at idle that brighten when you rev the engine
• The battery warning light appears intermittently
• You needed a jump start within the past year
• The battery is visibly swollen or has white corrosion on the terminals

Testing

Free battery testing is available at Canadian Tire, NAPA, PartSource, and most auto parts stores. The test measures voltage, cold-cranking amps (CCA), and overall health. Get tested every fall as part of your fall maintenance. If it tests marginal, replace it before winter.

Cost

A replacement battery in Ontario costs $150 to $250 installed for most vehicles. Premium AGM (Absorbent Glass Mat) batteries for vehicles with start-stop systems or heavy electrical loads run $200 to $350. Costco and Canadian Tire regularly have competitive prices.

When choosing a replacement, match or exceed the original CCA rating. A higher CCA rating provides more cold-start power. For Ontario, 600+ CCA is a reasonable minimum for most vehicles.

Keep terminals clean with a wire brush and apply terminal protectant spray to prevent corrosion. A portable jump starter ($80 to $120) in your emergency kit is good insurance. For more on cold-weather engine effects, see our cold weather guide.