Before you call anyone
We sell boosts, so read this the way you would read any vendor’s guide. Most of what follows is the part you can do yourself in the next five minutes, for nothing. If it works, you do not need us, and we would rather you knew that than paid us for a call-out you did not need.
Written for Edmonton conditions. Last reviewed September 2026.
The short version
At minus thirty a healthy battery has lost roughly half its usable power, and the engine it has to turn over has become far harder to turn. Those two things happen at the same moment, which is why a battery that was perfectly fine in October is a dead lump in January. Nothing has failed. The margin has simply run out.
A boost puts current back across the terminals so the starter can do its job once. That is all it does. Whether you actually needed a boost, a battery, an alternator or a tow is a different question, and the answer is usually visible within two minutes of the engine running.
Why the cold does this
A lead-acid battery makes electricity through a chemical reaction, and that reaction slows down as it gets colder. The rough numbers are worse than most people expect.
| Temperature | Roughly how much of the battery you can still use | Roughly how much power the engine now demands |
|---|---|---|
| +25°C | 100% | 100% |
| 0°C | about 80% | about 150% |
| −18°C | about 60% | about 200% |
| −30°C | about 50% | more than 200% |
The second column is chemistry. The third column is engine oil. Cold oil is thick, thick oil resists being pushed around, and the starter motor has to fight that resistance before the engine will fire. So the battery has half its strength on the exact morning the engine wants double. That is the whole story.
This is also why the Cold Cranking Amps figure printed on your battery is measured at −18°C. It is not a marketing number, it is a rating at a specific temperature — and in this city we spend a good part of the winter below the temperature that rating was taken at.
One practical consequence: batteries do not last as long here. Five to seven years is a normal service life in a mild climate. In Edmonton, three to five is more realistic. If yours is past four winters and it struggled once, it will struggle again.
Diesel and dual-battery vehicles are a different job
If you drive a diesel truck, a work van, or anything with two batteries under the hood, none of the above scales the way you would assume.
Diesel engines have much higher compression, so there is far more resistance to overcome before they will start. Before the starter even turns, the glow plugs draw a heavy load warming the cylinders — on a cold morning that can be a significant drain on its own. And two batteries means two things that can be wrong, in a system where one weak battery drags the good one down.
In practice this means a diesel boost takes longer and needs more current than a car. A small consumer booster pack that starts a Corolla will often not start a 6.7 diesel at −30. This is not a difficult job, but it is a different job, and it is worth saying “it’s a diesel” when you call anyone — it changes what goes on the truck. Our current rates for both are here.
The sixty-second check before you call
Listen to what the car does when you turn the key. It tells you most of what you need to know.
| What you hear | What it usually means | Will a boost fix it |
|---|---|---|
| Nothing at all, no dash lights | Flat battery, or a loose or corroded terminal | Usually yes — check the terminals first |
| Rapid clicking | Not enough current to hold the starter engaged | Usually yes |
| One loud clunk, then nothing | Often the starter itself, sometimes the battery | Sometimes |
| Slow, laboured cranking that will not catch | Weak battery, cold oil, or both | Usually yes |
| Cranks strongly but never fires | Fuel, spark or immobiliser — not the battery | No |
| Dash lights normal, key does nothing | Immobiliser, key fob battery, or gear selector switch | No |
Two free things to try before anything else. Turn off the heater, the rear defrost, the seat heaters and the headlights, wait a full minute, then try again — you are giving every available amp to the starter instead of splitting it. And open the hood and look at the terminals: white or blue-green crust, or a clamp you can wiggle by hand, will stop a perfectly good battery from starting a car. Tightening a clamp has ended a lot of call-outs before they started.
Booster pack, jumper cables, or a service call
A modern lithium booster pack is the single most useful thing you can keep in an Edmonton vehicle. Two cautions, both of which catch people every winter. Keep it inside, not in the car — it loses much of its own capacity in the cold, so the day you need it is the day it is weakest. And check its charge in October, because a pack that has sat in a glovebox since last March is usually flat.
Jumper cables from another vehicle work, but thin cables do not carry enough current to start a cold engine, and reversed clamps can damage electronics in both vehicles. Connect last to a bare metal point on the engine block of the dead car rather than to the negative terminal, and let the donor car run for a few minutes before you try.
Call someone when it is dark and genuinely cold and you are not confident, when it is a diesel or a dual-battery vehicle, when the terminals are corroded enough that you do not want to touch them, or when you have already been boosted once today. That last one matters more than people think — see below.
What a boost does not fix
This is the part worth understanding, because it decides whether you spend money once or twice.
A failing alternator. The alternator is what recharges the battery while you drive. If it has failed, a boost will start the car and the car will run until it has consumed whatever charge is left, then stop — often somewhere less convenient than your driveway. The test takes fifteen seconds: with the engine running, the charging voltage should be somewhere around 13.7 to 14.7 volts. If it is sitting at battery voltage, around 12, the alternator is not charging and you need a tow, not a boost. Ask whoever boosts you to check this. We check it as a matter of course.
A battery that is finished. A battery that dies again within a day or two is not undercharged, it is worn out. Cells fail internally and no amount of boosting brings them back. If a battery has needed a boost twice in one winter, replacing it is cheaper than the third call-out.
A starter, fuel or immobiliser problem. If it cranks strongly and never fires, the battery is doing its job and the fault is elsewhere. Boosting it again will not change the outcome.
After the boost — the part everyone gets wrong
The engine starts, and it feels finished. It is not. The battery is still nearly empty, and the alternator now has to put back everything the start consumed plus everything the car is currently using.
Drive it. Twenty to thirty minutes of actual driving, and more if you can. Idling in the driveway is close to useless — at idle the alternator produces relatively little, and the heater fan, rear defrost and headlights are consuming most of it. People boost a car, let it idle for ten minutes, shut it off, and are genuinely surprised the next morning.
Then check it the following day. If it starts normally, the battery took the charge and you are fine. If it is slow again, the battery is on its way out and you now know that in your driveway rather than in a parking lot at closing time.
Block heaters and what actually helps
A block heater warms the coolant and therefore the engine oil. It does not charge your battery, but it removes most of the third column in that first table — warm oil is thin oil, and thin oil means the starter has far less to fight. On a marginal battery that difference is often the whole difference.
Plug in below roughly −15°C. About four hours is enough; leaving it plugged in all night mostly heats the neighbourhood and your power bill. A timer set to come on four hours before you leave is the efficient version.
The rest of it is unglamorous and it works: have the battery tested in October rather than discovering its condition in January, keep the terminals clean, use a winter-appropriate oil, and if the car sits for days at a time during a cold snap, a trickle charger solves a problem that boosting only postpones.
When it is a tow rather than a boost
Charging voltage that never comes up, an engine that cranks strongly and refuses to fire, one clunk and silence from the starter, or a battery that has already been boosted today — those are tows. So is any situation where the vehicle would start but should not be driven.
There is no benefit to us in boosting a car twice, and no benefit to you in paying for it. If we get there and it is clearly not a battery, we will tell you that before anything else happens, and you get the price for the tow in writing before we hook up. What we carry and what each service covers is here, and what any Alberta operator owes you in writing is here.
Frequently asked questions
Why won’t my car start in the cold in Edmonton?
Because a lead-acid battery loses roughly half its usable power by −30°C while thickened engine oil makes the engine more than twice as hard to turn over. Both happen at once. A battery that was adequate in autumn simply runs out of margin, which is why cars that seemed fine die on the first hard cold snap.
How long does a battery boost take?
For a car, usually a few minutes once the operator is with the vehicle — the connection and start take longer than the boost itself. Diesel and dual-battery vehicles take longer because the glow plugs and higher compression need more current and more charging time before cranking. The unpredictable part is travel time, not the work.
Will a boost fix a dead alternator?
No. A boost will start the engine, but with a failed alternator the car runs on the remaining charge and stops again, usually somewhere worse. With the engine running the charging voltage should be roughly 13.7 to 14.7 volts. If it reads around 12, you need a tow rather than a boost. Ask for that reading before you pay.
Do I need to drive after a boost, or is idling enough?
Drive it, twenty to thirty minutes at minimum. At idle the alternator produces relatively little and the heater fan, defrost and lights consume most of it, so the battery gains almost nothing. Most repeat call-outs the next morning come from a car that was boosted and then left idling in a driveway.
How long should I leave a block heater plugged in?
About four hours below roughly −15°C. Longer does not warm the engine further and simply costs electricity. A timer set four hours before you normally leave gets the full benefit. The block heater will not charge your battery, but by thinning the oil it removes most of the load the starter has to overcome.
How often should a battery be replaced in Edmonton?
Every three to five years here, against five to seven in a milder climate. Cold shortens service life. If a battery is past its fourth winter, or has needed a boost twice in one season, replacing it costs less than the call-outs it is going to generate.
Is a boost cheaper than a tow?
Considerably, and a good share of what people assume is a tow turns out to be a boost. The exception is a failing alternator, where a boost buys a few kilometres and a second call-out. Current rates for both are on our pricing page, and you get the number in writing before any work starts.