Best Portable Jump Starters
Portable lithium jump starters, also called jump boxes, compared on the engine size each maker says it can start, clamp protection and capacity, not the peak-amp headline.
The high-amp budget option: 4000A peak rated for all gas engines and diesels up to 10.0L, with SuperSafe clamp protection and a big enough cell to work as a dual-USB power bank. Note this is the GP model — GOOLOO's pricier GT4000S is the one with 100W two-way USB-C, which this does not have.
The all-rounder for people who want the pack to double as a laptop or phone bank: Hulkman rates the Alpha85's 2000A for gas engines up to 8.5L and diesels up to 6.0L, and its 65W USB-C PD charges in and out. The 3.3-inch screen reports exact charge and fault state rather than making you guess at LED bars.
The headroom option for big trucks and diesels: AVAPOW rates the A68 at 6000A peak and up to a 12L diesel, with an eight-layer clamp protection system and indicator lights that make a wrong connection hard to complete. It also works as a dual-USB power bank with a 3-mode LED light. Overkill for a commuter car, right-sized if you regularly start large diesel powerplants.
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Best Overall is an editorial pick, chosen for the job most buyers in this category are actually doing. DriveScore is a published supporting signal, not the tiebreaker — a cheaper, narrower product can out-score the pick and still be the wrong buy. How we rank.
- Jump starter sizing tool →
Pick your engine size and climate to get a peak-amp target.
What matters most to you?
Best overall is our editorial pick; the rest are derived from the published sub-scores.
Our editorial pick — the best fit for what most buyers in this category need. The all-rounder for people who want the pack to double as a laptop or phone bank: Hulkman rates the Alpha85's 2000A for gas engines up to 8.5L and diesels up to 6.0L, and its 65W USB-C PD charges in and out. The 3.3-inch screen reports exact charge and fault state rather than making you guess at LED bars.
All 3, ranked — deltas vs. the winner
EDITORIAL RANK · DRIVESCORE SHOWNHow to actually pick one
The number on the box is peak amps: the most current a pack can deliver for an instant. Brands measure and report it inconsistently, and few print the sustained cranking current that actually turns an engine over. The more useful figure is the one makers publish alongside it: the largest gas and diesel engine, in litres, the pack is rated to start. Size to your largest vehicle and everything smaller is covered.
| Pack | Peak amps | Engine support the maker states |
|---|---|---|
| Hulkman Alpha85 | 2000A | Up to 8.5L gas and 6.0L diesel |
| GOOLOO GP4000 | 4000A | Gas and diesel up to 10.0L |
| AVAPOW A68 | 6000A | All gas engines, diesel up to 12.0L |
Read that table the right way round. A 6000A rating does not make the AVAPOW three times the pack the Hulkman is; it means AVAPOW claims a bigger diesel ceiling. For a typical gas car or crossover all three clear the bar, and the diesel column is where they separate.
What else to check before you buy:
- Clamp protection. Spark-proof and reverse-polarity protection stop the common mistakes. Read the manual for the exceptions: NOCO's GB40 guide says its pack cannot detect a battery below 2 volts, and that its manual-override mode for those batteries disables both protections.
- A completely dead battery. Hulkman says the Alpha85 can revive completely dead batteries within its rated engine sizes. For any pack, check what the manual says to do when the battery is too flat to detect.
- Storage charge. Lithium packs slowly self-discharge, so a pack left in a drawer for months may not crank a cold engine. Recharge it on the schedule its manual gives and top it up before winter.
- Extras. Capacity (Wh or mAh) and USB-C output decide how many phone charges you get, not whether the car starts.
The jump starter sizing tool turns engine size and climate into a peak-amp target, and how to jump start a car covers clamp order for packs and cables.
More guides for this category
What r/MechanicAdvice say
▶Research Sources (3)
- NOCO Boost GB40 User Guide (rev. 03.07.2025) — clamp connection sequence, storage temperature range, and the instruction that an unused pack discharges and must be recharged before use
- Hulkman — Alpha85 product page: 2000A peak, and the maker's statement that it revives completely dead batteries in vehicles up to 8.5L gas and 6.0L diesel
- GOOLOO — GP4000 product page: 4000A peak, rated for 12V gas and diesel engines up to 10.0L
Frequently asked questions
How many amps do I need to start my car?
Size by the engine, not the peak-amp headline, which brands report inconsistently. Makers now state the largest engine each pack can start: Hulkman rates the Alpha85 for up to 8.5L gas and 6.0L diesel, GOOLOO rates the GP4000 for gas and diesel up to 10.0L, and AVAPOW rates the A68 for all gas engines and diesel up to 12.0L. Match the pack to your largest vehicle, and check the diesel figure if you drive one.
Jump starter sizing tool →What is the difference between a jump box, a jump starter and jumper cables?
A jump box and a portable jump starter are the same thing: a battery pack with clamps that starts a car on its own. Jumper cables only carry current from a second, running car, so they need a donor vehicle and a set connection order. Most lithium packs also hold their output until they sense a correctly connected battery; NOCO's GB40 manual, for example, describes a boost light that appears only once the clamps are connected correctly.
How to jump start a car, step by step →Will a jump starter start a completely dead battery?
Sometimes, and the manual decides how. Hulkman says the Alpha85 can revive completely dead batteries within its rated engine sizes. NOCO's GB40 manual shows the other common design: below 2 volts the pack cannot detect the battery, so it offers a manual override that disables both spark-proof and reverse-polarity protection. Never jump a damaged or frozen battery.
Why won't my jump starter work when I need it?
Usually self-discharge. Lithium packs slowly lose charge in storage, so a pack that sat untouched for months may not have enough left to crank an engine, especially a cold one. Recharge it on the schedule its manual gives, top it up before winter, and check the charge indicator before a long trip.