Why Your Car Won't Start at -30: Batteries, Block Heaters and Cold Starts

It's -30, you turn the key and get a slow crank, a click or nothing at all. Cold-weather no-starts are one of the most common winter calls in Edmonton, and most of them come down to three things: the battery, the block heater and the oil.

Why cold is hard on a battery

A battery produces power through a chemical reaction, and that reaction slows down in the cold. At the same time, cold oil makes the engine harder to turn over. So the battery has less to give right when the engine needs more. A battery that seemed fine in September can fail on the first deep-freeze morning.

Signs your battery won't make it through winter

• The engine cranks slowly, especially in the morning.

• Dash lights dim or flicker while starting.

• The battery is several years old or the terminals show white or green corrosion.

• You've needed a boost more than once.

A load test takes a few minutes and tells you whether the battery can deliver what it's rated for. It's worth doing every fall.

Use your block heater

A block heater warms the engine and its oil so it turns over more easily and warms up faster. In Edmonton winters it's worth plugging in whenever the temperature drops well below freezing. A timer can save power by running it for a few hours before you leave rather than all night.

If you plug in and it still won't start, the heater, cord or outlet may have failed. Check that the cord isn't damaged and that the outlet has power.

Oil matters more than you think

Oil thickens in the cold. Using the grade your owner's manual recommends for winter helps the engine turn over and get oil where it needs to be quickly. If your oil change is close, do it before winter.

What to do if it won't start

• Turn off lights, heater and accessories before trying again.

• Wait a minute between attempts instead of cranking continuously.

• Boost carefully, following your owner's manual, or call for help.

• Once it's running, have the battery and charging system tested. A boost gets you going, but it doesn't fix the cause.

Get ready before the cold hits

Big Toy Shop in south Edmonton tests batteries, charging systems and block heaters on cars, trucks and motorcycles. Book a winter check on our auto service page or call 780-298-2797.