Cold does not kill batteries so much as expose the weak ones. A battery that was marginal in October will not start the car on the first -25°C morning.
In the fall
- Test the battery before the first hard frost, especially if it is over three years old
- Clean the terminals; corrosion that barely mattered in summer is the difference in winter
- Check the block heater cord for damage
Use the block heater
Below about -15°C, plug the block heater in two to four hours before you leave. It warms the oil so the engine turns over easily, which takes the load off the battery. A timer saves power overnight.
On cold mornings
- Switch off the heater fan, lights and heated seats before starting
- Crank in bursts of no more than 10 seconds, with 30 seconds between tries
- If the engine barely turns, stop: every attempt takes more from the battery
A frozen battery
If the case is bulging or cracked, the battery has frozen. Do not boost it: a frozen battery can rupture. We replace it on the spot.
