You’re standing at the side of the road. Your car won’t start. And you’re staring at two jump starters on Amazon that look almost identical, except one costs $80 more.
Which one do you actually need?
Most people either overspend on power they’ll never use, or underspend. And find out their jump starter can’t handle their engine when they need it most.
This Article cuts through the confusion.
Here’s exactly how to choose a jump starter for your car.
Start Here – The Only Question That Actually Matters
Before anything else, answer this:
What size engine does your car have?
Check the sticker inside your driver’s door frame, your owner’s manual, or the V5C logbook. It will say something like “1.6L” or “2.0L” or “3.5L”.
Your engine size determines the peak amps you need. Everything else price, size, features comes after that.
| Your Engine | Minimum Peak Amps | Our Recommendation |
|---|---|---|
| Small petrol car — up to 1.6L | 400A | NOCO GB40 ✅ |
| Mid-size petrol car — 1.6L to 3.0L | 600A | NOCO GB40 ✅ |
| Large petrol car or SUV — up to 6.0L | 1000A | NOCO GB40 ✅ |
| Small diesel car — up to 3.0L | 1000A | NOCO GB40 ✅ |
| Large diesel SUV, pickup, van | 2000A | NOCO GB70 ✅ |
| V8 petrol, heavy truck, commercial vehicle | 2000A+ | NOCO GB70 ✅ |
Peak Amps vs Cranking Amps – What’s the Difference?
Jump starter packaging loves to throw numbers at you. Here’s what they actually mean:
Peak Amps
The maximum current the battery can deliver for a very short burst, typically less than a second. This is the headline number on most jump starters. Higher is better for starting large engines.
Cranking Amps
The sustained current the battery can deliver over 30 seconds at 32°F (0°C). A more realistic measure of real-world performance, especially in cold weather. Look for this number too if you drive in winter.
How to choose a jump starter – For most car owners, peak amps is the number to focus on. Use the engine size table above to find what you need, then match it to a jump starter’s peak amp rating.
How to Choose a Jump Starter – 5 Features Worth Paying For
Spark-Proof Clamps
The single most important safety feature. Spark-proof clamps prevent accidental sparks when you connect to the battery, which can cause fires near battery gases. Never buy a jump starter without this. NOCO’s spark-proof technology is the best available.
Reverse Polarity Protection
Alerts you or refuses to charge if you connect the clamps the wrong way: red to negative, black to positive. This prevents damage to your car’s electronics. Essential for anyone who might be flustered in a roadside emergency.
USB Power Bank
Most quality jump starters double as a USB power bank. Genuinely useful: charge your phone while waiting for recovery, or top up devices on a road trip. Check how many charges you get per full battery.
LED Torch
A built-in LED torch sounds minor but is genuinely useful at the side of a dark road at night. Look for SOS and strobe modes for emergency signalling. Most quality units include this.
Cold Weather Performance
Cold batteries need more amps to start. If you live in a cold climate, check the cranking amps rating at 0°C, not just the peak amps figure. Lithium-ion jump starters also need warming before use in freezing temperatures.
What to Avoid When Buying a Jump Starter
❌ No-name brands with inflated specs
A cheap no-name unit claiming 2000A peak for $25 is almost certainly lying. Real peak amp ratings require quality lithium cells. Stick to brands with verifiable reputations: NOCO, Tacklife, Beatit.
❌ No spark protection
Old-style jump starters without spark protection require you to connect in a specific sequence to avoid sparks. Under stress at the roadside, this is easy to get wrong. Always choose spark-proof clamps.
❌ Lead-acid jump starters
Old lead-acid jump starter packs are large, heavy, and require regular maintenance and charging. Modern lithium-ion jump starters are far smaller, lighter, and hold their charge for months. Avoid lead-acid entirely.
❌ Wrong size for your engine
Buying a 400A jump starter for a 3.0L diesel is the most common mistake. Always check your engine size first. An undersized unit won’t start your car, and you’ll find out at the worst possible moment.
How to choose a jump starter – Step by Step
Check the charge level
Before anything else, check that your jump starter has sufficient charge. Most have LED indicators. A dead jump starter at the roadside helps no one. Recharge it every 3 months.
Connect red clamp first
Red clamp to the positive (+) terminal on your flat battery. With spark-proof clamps, the order is less critical, but it’s good practice. Keep the unit away from moving engine parts.
Connect the black clamp
Connect the black clamp to the negative (-) terminal. Or to an unpainted metal surface on the engine block away from the battery. This is safer than direct terminal connection.
Start the engine
Wait 30 seconds for the jump starter to initialise, then start your engine. If it doesn’t start in 3 attempts, wait 30 seconds between attempts. Don’t crank continuously; this drains both batteries.
Disconnect in reverse order
Once running, remove the black clamp first, then the red. Drive for at least 15-20 minutes to let the alternator recharge your battery before switching the engine off again.
Our Recommended – How to choose a jump starter?
Based on everything above, these are the two jump starters we recommend for most car owners:
Most Car Owners
1000A peak amps. Covers petrol engines up to 6L and diesel up to 3L. Glove box size. Spark-proof. USB charging. Holds charge for 12 months.
~$100
Large Engines + Diesels
2000A peak amps. Covers any road vehicle including large diesels, V8 petrol, trucks and vans. Same spark-proof reliability as the GB40.
~$160
For a detailed comparison of both, see our full NOCO GB40 vs GB70 guide. For all five top-rated jump starters compared, see our best portable jump starter guide.
Related Guides
Best Portable Jump Starters
Full roundup of the 5 best jump starters all tested and compared.
NOCO GB40 vs GB70
Can’t decide between the two most popular NOCO models? This comparison settles it.
Best Car Gadgets for Road Trips
A jump starter is one of the 10 essential gadgets for any long drive.
Frequently Asked Questions
Final Verdict – How to choose a jump starter?
Choosing a jump starter is simpler than it looks once you know your engine size.
Standard petrol or small diesel car? The NOCO GB40 at $100 covers everything you need: 1000A, spark-proof, glove box size, USB charging. It’s the right choice for the vast majority of car owners.
Large diesel, V8, truck, or van? The NOCO GB70 at $160 is the one. Don’t risk an undersized unit on a big engine.
Whatever you choose, charge it when you get it, top it up every 3 months, and keep it in your boot. The one time you need it, you’ll be very glad it’s there.