Winter Car Battery Tips: Why Batteries Die in Cold Weather (and What to Do)
Every winter in London, Ontario, we get the same calls: "My car won't start." It's -15°C, there's frost on everything, and your battery has decided today is the day it gives up.
Here's why it happens, how to prevent it, and what to do when it does.
Why Cold Weather Kills Batteries
Car batteries are chemical devices. The chemical reactions that produce electricity slow down dramatically in cold temperatures.
The numbers:
- At 0°C, a battery loses about 35% of its cranking power
- At -18°C (a normal London February night), it loses about 60%
- Meanwhile, your engine needs 2–3x more power to start in cold weather (thicker oil, cold fuel)
So your battery is weaker AND your engine is harder to start. That's why cold mornings are battery death.
Signs Your Battery Is About to Die
Don't wait for the no-start morning. Watch for these warning signs:
- Slow cranking — The engine turns over sluggishly when you turn the key
- Dim headlights — Noticeably dimmer, especially at idle
- Dashboard warning light — Battery or charging system light comes on
- Age — Most batteries last 3–5 years. If yours is 4+ years old, it's on borrowed time
- Clicking sound — You turn the key and hear rapid clicking but no engine turnover
- Electrical issues — Radio resets, clock loses time, power windows are slow
How to Prevent Winter Battery Failure
1. Get Your Battery Tested Before Winter
Most auto shops will test your battery for free. Do this in October/November. If it's weak, replace it before the first cold snap.
2. Park in a Garage
Even an unheated garage is 5–10°C warmer than outside. That's enough to make a difference.
3. Use a Battery Maintainer
If you don't drive daily, a trickle charger or battery maintainer keeps the battery topped up. Especially important for weekend vehicles or seasonal cars.
4. Limit Short Trips
Short drives don't give your alternator enough time to fully recharge the battery. In winter, try to drive for at least 15–20 minutes to let the battery recover.
5. Turn Off Accessories Before Shutting Down
Heated seats, defogger, radio, lights — turn them all off before you turn off the engine. This means less demand on the battery next time you start.
6. Keep Terminals Clean
Corrosion on battery terminals reduces electrical flow. Clean them with a wire brush and apply dielectric grease to prevent buildup.
What to Do When Your Battery Dies
Option 1: Jump Start It
If you have jumper cables and a willing neighbour:
- Connect red (+) to dead battery positive
- Connect other red (+) to good battery positive
- Connect black (-) to good battery negative
- Connect other black (-) to unpainted metal on dead car (NOT the battery)
- Start the good car, wait 2–3 minutes, then try the dead car
- Drive for at least 20 minutes to recharge
Option 2: Call for a Battery Boost
No cables? No neighbour? No problem.
** EMS Towing: (226) 476-4176** — We carry professional-grade jump packs that work on everything from compact cars to diesel trucks. We come to you — parking lots, driveways, underground garages, wherever you're stuck.
Option 3: Replace the Battery
If your battery is old and this keeps happening, it's time for a new one. We can boost you and tow you to a shop if needed.
When a Boost Won't Work
Sometimes the battery is too far gone:
- If it's frozen solid (yes, dead batteries can freeze)
- If it's swollen or leaking
- If it won't hold a charge after boosting (dies again within minutes)
In these cases, you need a new battery — and possibly a tow to a shop.
London Winter Battery Survival Kit
Keep in your car:
- Portable jump pack (lithium ones are small and powerful — $60–$100)
- Warm blanket
- Phone charger
- Flashlight
- EMS Towing number: (226) 476-4176
EMS Towing provides 24/7 battery boost service across London, St. Thomas, Woodstock, and surrounding areas. Our industrial-grade jump packs work on all vehicle types — even in underground parking where tow trucks can't fit.