Car batteries in a Calgary winter: testing, boosting, replacing

Why cold weather is hard on a car battery

A battery makes its current through chemistry, and cold slows that chemistry down, CAA-Quebec explains. The Alberta Motor Association (AMA) puts numbers on the loss, and its articles do not agree: one says about half of a battery’s output is gone at −18 °C, another that a battery can lose up to 60 percent of its power once it is zero degrees out, just as the engine wants twice its usual current to start. Cold oil is thick and slow to circulate, Natural Resources Canada (NRCan) explained in an article it has since retired, so a cold engine takes more effort to turn. Transport Canada’s winter checklist starts from the same place: in the cold, an engine will only start on a battery with a full charge.

Summer does some of the damage. AMA notes that intense heat actually wears a battery harder than cold does, and Ryan Lemont, who manages AMA Driver Education, warns that a battery which limped through the summer may not have the strength to crank a cold engine come winter.

Cold cranking amps and reserve capacity

Two ratings on the label tell you what a battery can do. Cold cranking amps (CCA), as Battery Council International defines them, is the current in amperes that a new, fully charged 12-volt battery can keep up for 30 seconds at −18 °C (0 °F) without its voltage falling below 7.2 volts. It is the rating that speaks to a cold start: the higher the number, the more current the battery can give the starter on a frigid morning.

Reserve capacity counts the minutes a new, fully charged battery, starting at 26.7 °C, can supply a steady 25 amperes before it drops to 1.75 volts per cell. CAA-Quebec points to the owner’s manual for the battery size and type a car takes; when you compare replacements, hold their CCA and reserve capacity up against what the manual, or the original battery, calls for.

Sources: [2] CAA-Quebec: battery life; [3] AMA: prepare for winter; [4] AMA: winter batteries; [5] NRCan, archived; [6] Transport Canada: winter preparation; [7] AMA: block heaters and batteries; [8] Battery Council International

What a Calgary winter asks of a battery

In Environment and Climate Change Canada’s 1991–2020 climate normals for Calgary (Airport), January is the coldest month, with an average daily low of −13.5 °C; December’s is −12.1 °C and February’s −11.8 °C. In a typical year the overnight low falls below −20 °C on about 22 days and below −30 °C on about 3. The coldest reading in those thirty years was −39.7 °C, in January 1997.

Cold snaps show up in the roadside calls. Between January 9 and 16, 2024, AMA logged more than 45,600 requests for help, online requests not included, and by January 17 Calgary’s requests for boosts and light service were running at 21 times the usual level. In a cold spell, AMA says, failing batteries are the biggest single surge in its roadside calls, and its battery calls almost double over the winter.

Sources: [9] ECCC climate normals; [1] AMA, January 2024; [4] AMA: winter batteries; [7] AMA: block heaters and batteries

Signs a battery is failing

AMA lists these warning signs:

• The engine cranks slowly, or is slow to turn over.
• The headlights look dim or yellowish instead of white, or the lights dim and the heater fan slows at a stop.
• A warning light shows on the dashboard.
• Electrical accessories stop working, the interior lights look dim, or the horn sounds odd.
• The case is swollen or cracked, or you smell sulphur or rotten eggs.
• You have had to boost it several times recently, or the car will not start at all.

CAA adds corrosion, wetness or bulging on the casing to the things to check. Age counts too: CAA says a battery of three to five years could fail, and AMA suggests you keep track of how old yours is.

Not every weak battery warns you first: AMA says one can fail without symptoms, and only a test tells you for sure.

Sources: [4] AMA: winter batteries; [10] AMA: 5 signs; [11] CAA: winter car care; [12] AMA: battery service

How long a car battery lasts in Alberta

AMA puts the typical life of a car battery in Alberta at three to five years, and says that keeping devices charging in the car pulls it toward the low end. CAA North & East Ontario gives the same range and adds that how much the car is used, the climate and the way it is driven can move it a long way.

Driving habits count. CAA-Quebec’s advice is to drive the car regularly and skip short trips, since a battery that sits idle drains faster, and to put a car that will be parked for weeks on a trickle charger.

Sources: [10] AMA: 5 signs; [4] AMA: winter batteries; [13] CAA North & East Ontario: boost or replace; [2] CAA-Quebec: battery life

Have it tested before the cold

From a battery’s third year, CAA North & East Ontario advises a test every year. Autumn is the time for it: Transport Canada’s list for a winter inspection includes cleaning the terminals, checking the belts and the charging system, and replacing a weak battery before it fails. Ask the shop to look at the charging system at the same visit.

AMA tests members’ batteries free through its mobile battery service; other roadside plans vary, so ask.

Sources: [13] CAA North & East Ontario: boost or replace; [6] Transport Canada: winter preparation; [12] AMA: battery service

Boost it or replace it?

A boost gets a car with a flat battery moving, but it is meant to be occasional: AMA says that once you find yourself boosting the car again and again, the battery is due for replacement. CAA North & East Ontario’s view is that a battery needing several boosts within a short time is probably on its way out, and is better replaced than boosted again.

Until it has been tested or replaced, a doubtful battery is a gamble in deep cold. AMA suggests finding another way to get around until the test is done or the new battery is in, rather than risk being stuck outside.

Sources: [10] AMA: 5 signs; [13] CAA North & East Ontario: boost or replace; [14] AMA, December 2021

What affects the price of a new battery

GarageMap does not publish battery prices: they depend on the car, and no source publishes Calgary figures we can stand behind. What the sources do say is what moves the bill:

• The battery the car needs. Cars with stop-start often need an AGM (absorbent glass mat) or EFB (enhanced flooded) battery, and CAA-Quebec cautions that putting an ordinary lead-acid battery in their place could harm the car.
• Where the battery sits. AMA notes that some sit in a wheel well, in the firewall or under parts that must come off first, and those jobs need special tools.
• Programming. On some vehicles a new battery has to be registered with a scan tool so the car charges it properly, and the windows, the sunroof or the infotainment system may need resetting afterwards.

An old battery is hazardous waste. In Calgary a lead-acid vehicle battery can be left free of charge at a household hazardous waste drop-off (a designated fire hall) or at a City Eco Centre, though the Eco Centre charges if you bring other garbage with it; it must never go in a blue, black or green cart. Ask the shop that fits the new one whether it takes the old one away.

Sources: [2] CAA-Quebec: battery life; [15] AMA: hard-to-install batteries; [16] City of Calgary: battery disposal

How to boost a car safely

Before you connect anything, CAA-Quebec’s checklist is:

• The two cars are not touching each other.
• The flat battery is not frozen, swollen or bulging. If it is, leave it alone.
• Nothing nearby can spark, flame or smoke: a battery gives off hydrogen, which can explode.
• You have gloves and safety glasses on, and have taken off any jewellery.

Then, in this order:

1. Clamp one red cable end to the positive (+) terminal of the flat battery.
2. Clamp the other red end to the positive (+) terminal of the good battery.
3. Clamp one black end to the negative (−) terminal of the good battery.
4. Clamp the last black end to the engine block of the car that will not start, or to another metal part of its engine such as the alternator bracket, at least 30 cm from the battery: never to the flat battery’s negative terminal, and never to a body panel.
5. Start the engine of the car giving the boost.
6. Start the other car the way its owner’s manual says, running the starter for 15 seconds at most each time.
7. Once it runs, leave the cables on for 5 minutes, then take them off in the reverse order.

CAA North & East Ontario also stresses eye protection, gloves and reading a jump starter’s instructions.

Sources: [17] CAA-Quebec: boosting; [18] CAA North & East Ontario: jump-starting

Electric cars and hybrids: the 12-volt battery

An electric car draws its driving power from a large high-voltage battery, but it also carries a small 12-volt battery for accessories such as the lights, windows and wipers, AMA explains. CAA North & East Ontario notes that most hybrids carry an ordinary 12-volt battery too, beside the high-voltage one.

Only that 12-volt battery may be boosted. CAA North & East Ontario warns never to jump the high-voltage battery, which usually has orange wiring, and says that using an EV or a hybrid to boost another car can damage one car or both. The 12-volt battery can also be hard to find, so check the manual. For either kind of car, the club suggests leaving the battery to a professional technician.

For an electric car in the cold, CAA suggests heating the cabin while the car is still on the charger, and timing that preconditioning to your departure where the car can do it. In CAA’s winter road test the electric cars covered 14 to 39 percent less distance than their official range.

Sources: [19] AMA Insider: batteries; [13] CAA North & East Ontario: boost or replace; [18] CAA North & East Ontario: jump-starting; [20] CAA: EVs in winter

When to call roadside assistance

Call for help instead of boosting the car yourself when the battery is frozen, swollen or bulging, which CAA-Quebec says should not be boosted at all; when it is misshapen, cracked or leaking acid, or smells acrid or burnt, which CAA North & East Ontario says needs a professional; and when the car is an EV or a hybrid.

If the car dies away from home in severe cold, AMA’s advice is to get yourself somewhere warm first and call once you are safe. Expect to wait during a cold snap: AMA took just over 9,000 calls in the 24 hours of January 12, 2024.

Sources: [17] CAA-Quebec: boosting; [13] CAA North & East Ontario: boost or replace; [18] CAA North & East Ontario: jump-starting; [14] AMA, December 2021; [1] AMA, January 2024