A 12-volt starter battery lasts about three to five years, and age matters far more than mileage. The reliable way to know where yours stands is a load test, which most parts shops and garages do in minutes, often for free.
Why winter? A cold engine needs more current to turn over, and a cold battery can deliver less of it. A battery that started fine all summer can fail on the first frosty morning, which is why the check belongs in the autumn, before the first cold snap rather than after it. This applies to every vehicle with a starter battery: cars, SUVs, pickups, vans, RVs, motorcycles and snowmobiles, plus the house batteries in an RV or boat. Hybrids and electric vehicles still carry a small 12-volt battery for the electronics, and it ages the same way.
The warning signs: a slow, laboured crank; headlights that dim at idle and brighten when you rev; a battery or charging warning on the dashboard; electronics that reset their clock or settings; a rotten-egg smell or a swollen case, which means stop and replace it now. Any of these on a battery older than three years is a strong hint.
Short trips are the quiet killer. Starting the engine takes a large gulp of charge and the alternator needs a good twenty to thirty minutes of driving to put it back. A vehicle that only does five-minute errands slowly drains its own battery, and the same happens to a motorcycle ridden once every two weeks or an RV parked between trips. Stored vehicles fare worst of all: the alarm, the clock and the computers keep drawing a little current every day.
Check it yourself:
- Ask for a load test. A garage or parts shop connects a tester that measures how the battery holds up under a starter-sized load. It gives you a health percentage, and it is the only test that predicts a cold-morning failure.
- Read the resting voltage. With a cheap multimeter, after the vehicle has sat for a few hours: about 12.6 volts or higher means full, around 12.4 means three-quarters, and 12.2 or below means it needs charging and possibly a closer look. A battery that keeps reading low after a proper charge is on its way out.
- Look at the terminals. White or blue-green crust is corrosion, and it adds resistance exactly where you need it least. Disconnect the negative first, scrub with a wire brush and a paste of baking soda and water, rinse, dry, reconnect positive first, and coat the terminals with a little grease or terminal spray.
- Find the date. Many batteries carry a sticker with the month and year of installation or manufacture. If yours has none, the invoice from your last battery change is the answer, which is where a logbook earns its keep.
- Storing a vehicle? For a motorcycle, snowmobile, boat, jet ski or RV going into storage, either connect a maintenance charger, sometimes called a tender, or disconnect the negative terminal. A battery left flat through a winter is usually ruined by spring.
Log the battery you have now: the install date, the size and type, and the load-test result each autumn. From then on the age question answers itself, and a battery that tests weaker each year tells you to replace it on your schedule instead of the weather's.
Sep 15, 2026