- In the cold your battery delivers less starting current while your engine actually needs more, so in winter you need more CCA.
- CCA stands for Cold Cranking Amps, the starting current at minus 18 degrees. Exactly the cold situation where things go wrong.
- Choose a jump starter whose CCA is equal to or higher than the EN value on your battery, with an extra step of margin for frost.
- For most cars, 960 CCA gives you plenty of margin, for example with the Boost Pro 8250.
It's the first real frosty night and you turn the key. The engine groans, cranks slowly and doesn't start. Sounds familiar. In winter your starting power drops right when you need it most. In this guide you'll read why cold makes such a difference, what CCA has to do with it, and how much starting power you really need in winter.
CCA stands for Cold Cranking Amps, the starting current a battery or jump starter delivers at minus 18 degrees. It's the most honest measure of starting power, because the value is standardized and measured specifically in the cold. The higher the CCA, the more power to crank a cold engine. You can read the full explanation in what CCA actually is.
Why does a battery deliver less in the cold?
A car battery generates power through a chemical reaction. In the cold that reaction slows down, so the battery can deliver less current. At minus 18 degrees the available starting current of a healthy battery already drops to roughly half its value at room temperature. At the same time, your engine oil becomes thicker and more viscous, so the starter motor has to work harder to turn the engine over. Your battery delivers less, exactly when your engine needs more. Together, these two effects explain why cars mainly fail to start in winter.
Why is CCA specifically the winter measure?
CCA is measured at minus 18 degrees, exactly under the harsh conditions that matter in winter. That makes it the honest measure of starting power. The peak current that many manufacturers print big on the box is the highest current the device delivers for a brief instant, often just a fraction of a second and without a fixed measuring method. That number looks impressive but says nothing about a cold start. That's why we deliberately choose honest CCA values instead of inflated peak current figures. You can read more about this difference in peak current or CCA, what does that big number really say.
How much CCA do you need in winter?
The basic rule remains that the CCA of your jump starter should be equal to or higher than the EN value on your battery. That EN value is printed on your battery's label and is the starting current the battery is designed for. For winter, add some margin on top of that. If you drive short trips, park outside, or your battery is older than 5 years, feel free to choose a model one step higher. A diesel needs more than a petrol engine of the same size, because the compression is higher. The table below shows a sensible winter choice per car type.
| Car type | Indication EN on battery | Winter recommendation | CCA model | Price |
|---|---|---|---|---|
| Small petrol car, city car | 480 to 620 CCA | Boost Mini 3750 | 620 | €109,95 |
| Average car, petrol or small dieselmost chosen | 620 to 960 CCA | Boost Pro 8250 | 960 | €189,95 |
| Diesel or large SUV | 960 CCA or more | Boost Max 10200 | 1,440 | €249,95 |
If your battery's EN value falls right on the border between two models, choose the stronger model for winter. You won't use that extra CCA in full with a healthy battery, but that margin is exactly what keeps you going in frost with a slightly older battery. For most petrol and diesel cars, the Boost Pro 8250 with 960 CCA is therefore a safe winter bet.
- 960 CCA, plenty of margin for a cold start
- Honest CCA value, no inflated peak current
- Ordered before 5:00 PM, shipped the same working day
"Don't store your jump starter in the car during winter, keep it inside, and give it a full charge once in autumn. That way you're guaranteed enough power the moment the first frost hits."
Frequently asked questions
Why does my car start harder in winter?
In the cold your battery delivers less current, while thicker engine oil makes the starter motor work harder. So your battery gives less exactly when your engine needs more. That's why cars mainly fail to start in frost.
Do I need more CCA in winter?
Not strictly more than the EN value on your battery, but extra margin is wise. A model one step above what your battery requires gives you leeway in frost, on short trips, or with an older battery.
Why is CCA a better measure than peak current for winter?
CCA is measured at minus 18 degrees, so under cold conditions. Peak current has no fixed measuring method and is often inflated. For a cold start, the CCA value is what counts.
Does a jump starter itself also perform worse in the cold?
Yes, the lithium cells in a jump starter also temporarily deliver less in severe frost. So keep the device indoors and warm it briefly in your coat before use. That way you have full power available.
Which jump starter should I choose for winter?
For most petrol and diesel cars, the Boost Pro 8250 with 960 CCA is a safe choice. If you drive a heavy diesel or large SUV, choose a model with more margin, such as the Boost Max 10200 with 1,440 CCA.
