Leaving your headlights on used to mean a knock on a neighbor’s door—or a long and maybe costly wait for a tow truck. But battery technology changes everything, whether for cars or portable blenders or power packs. Portable jump starters now don’t cost much more than the price of a single tow and can jolt your car awake even with a bone-dead battery. Most can also charge your phone or laptop in a pinch.
My conversion moment happened in a remote stretch of northern Delaware, where I’d left my headlights on after a foggy morning drive. I chased phone signal for most of an hour, until a passing parks employee happened to have one of the new breed of lithium-ion jump starters tucked behind his seat. I drove straight to the auto parts store and procured a basic 1,000-amp NOCO jump starter ($100) that saved my hide multiple times thereafter.
NOCO is still a brand I recommend. The same goes for a reliable, low-cost Gooloo A3 jump starter ($70) that I bought after moving cross-country. But after testing eight of the most highly regarded lithium-ion jump starters on the market over dozens of starts, it’s the Wolfbox 4,000-amp jump starter ($170) that came out on top for its mix of reliability, price, capacity, and sheer cranking power. The Wolfbox charges fast, starts the engine smoothly, and stays above half capacity after 15 jump starts from dead on a six-cylinder engine.
A newer 1250A NOCO Boost X ($125) is the most compact option for six-cylinder engines or lower. A bulkier and more expensive 2,000-amp model from Battery Tender ($170) offers the most comprehensive solution for battery maintenance, as long as your battery’s not stone dead. For this round, I focused on lithium-ion power packs, which may not be suitable for the most extreme weather conditions (see below). In future updates, I’ll also look at the newest generation of battery-free supercapacitor jump starters.
For more power-related coverage, check out WIRED’s guide to the Best Power Banks, the Best MagSafe/Qi2 Power Banks for more magnetic wireless chargers, and Best Portable Power Stations. Also see WIRED’s guide to Essential Emergency Gear.
Featured in this article
Best Jump Starter for Safety and Versatility
Battery Tender 2000A Power Station and Jump starter
Best Portable Jump Starter Overall: Wolfbox 4000A Jump Starter
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Photograph: Matthew Korfhage
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Photograph: Matthew Korfhage
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Photograph: Matthew Korfhage
Wolfbox
4000A Jump Starter
WIRED
- More than 15 jump starts possible before needing recharge
- Charges from dead, with good safety protocols
- Digital display, LED lamp
TIRED
- Power port on side of device is awkward placement
This jump starter from Dallas-based Wolfbox does not have much in the way of bells or whistles. It’ll fast-charge a laptop or phone at 65 watts off a USB-C outlet if you need it to. It has an LED lamp, if it’s dark. But mainly it does two things: It maintains a charge, and it releases a charge. It does so safely, without risk of sparking or reversed polarity if you get your wires crossed. And if you press the Boost button, overriding the low-voltage safety cutoff, this Wolfbox can juice a starter battery that’s as near to dead as a healthy battery can get.
Tested on an old six-cylinder 1994 Land Cruiser with a (dead) six-month-old battery and on a ’97 Mitsubishi Montero, the Wolfbox managed to turn over my engine faster and better than it would normally start after sitting for a couple of days. The 89-watt-hour capacity is among the largest of jump starters I tested. On a single charge, I was able to jump-start the Land Cruiser 15 times before the battery got down to 50-percent capacity. (Beyond this, jump-starting is still quite possible, but the manufacturer notes it begins to lose efficacy.)
That’s a heck of a lot of runway on starts that also give reason for confidence. The LED lamp is placed appropriately, the clamps are larger and offer more spacing than most jump starters, and the device remains relatively compact. While it’s listed above $150, I usually see it much closer to $100, making for a welcome mix of economy and power.
It’s not a sophisticated battery maintainer, and I probably wouldn’t use it that way unsupervised. And if you try and fail to jump a car with this thing five times in 10 minutes, you’ll nonnegotiably need to wait another 10 minutes to try again. This is an intentional safety feature against reckless overheating, but it’s worth noting. The Boost function also can’t be used when the battery core temperature drops below freezing, so don’t store this or most other lithium-ion jump starters in sub-zero temps. I’ll be testing some jump starters in the future that have a self-warming function.
Best Compact Jump Starter: Noco Boost X GBX45
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Photograph: Matthew Korfhage
WIRED
- Most compact jump starter WIRED recommends
- Reliable for two to five jump starts
- Separate lamp controls, USB-C and -A charging
TIRED
- Less power capacity than top jump starters
I don’t know what else you keep in your purse. But this is the only effective jump starter that could fit in there. Ohio-based NOCO is an automotive accessories company of long repute, and even its lowest-amp jump starters have served me admirably with both four- and six-cylinder vehicles.
I haven’t tested the highest-capacity devices from NOCO, but this little 1250A Boost X jump starter packs a reliable wallop despite its diminutive status, able to be tucked into most nooks or crannies and carried around easily in most bags. It’s a lower-capacity battery, which means it’s good for only a couple of cold starts before it reaches half-battery capacity—though it was still able to crank four more times after this before efficacy started to be affected.
The headlamp is controlled by a separate button and is placed appropriately to shine where you’ll be connecting the battery—an odd oversight on some other jump starters. But the small clamp size and cord length may cause trouble on some car models.
Best Jump Starter for Safety and Versatility: Battery Tender 2000A Portable Power Station
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Photograph: Matthew Korfhage
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Photograph: Matthew Korfhage
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Photograph: Matthew Korfhage
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Photograph: Matthew Korfhage
Battery Tender
2000A Power Station and Jump starter
WIRED
- Both maintains and jumpstarts 12V car batteries
- Large power capacity
- Unmatched safety and power maintenance
TIRED
- Bulky
- No LED lamp
- Can’t charge from dead
This device from Battery Tender, owned by legacy auto and marine company Deltran, is the most sophisticated device I tested. It was the most reliably spark-free and the best shielded from any minute current discharge. It is also able to operate as a battery maintainer, topping up batteries so they don’t need jump starting in the first place—and reliably shutting off before overcharging them. In addition to being an effective jump starter, it’s also an excellent all-in-one battery management device for a car you keep in the garage and only drive sometimes.
It charges slowly from a wall outlet but can also top up through a cigarette lighter outlet in your car, which makes it a welcome power bank while on the road. It offers 100-watt AC power with a standard three-prong outlet, as well as USB-C, USB-A, and DC charging. It’s a nice all-in-one power station and jump starter with admirable safety.
But this said, if your car battery drops below 2 volts, it’s not going to jump your car. Battery Tender does not offer a safety-override button. In practice, you’ll have to leave your headlights on for a very long time to get your battery much lower than 2 volts if it’s otherwise healthy: I left my headlights on for multiple days and still got a jump from this Tender. But it’s a consideration. I also could wish for an LED lamp, rather than have to fumble for a separate flashlight or use my phone at night.
But all in all, it’s a powerful system. And while it’s quite bulky and slow to charge, I’d prefer the versatility of this device over the more svelte, dedicated jump starter options I also tested from Battery Tender.
Other Jump Starters I Like
Gooloo 6000-Amp Jump Starter for $170: This flagship device from Chinese brand Gooloo is a quite good jump starter, one that performed almost as well in testing as the 4,000-amp starter from Wolfbox. The price is also comparable, and I’d have no trouble recommending it. But my starts weren’t quite as frictionless with this Gooloo as with the Wolfbox. The device’s LED lamp is also placed nonsensically so that it faces away from where you’d connect the battery. This said, capacity is slightly bigger than the flagship Wolfbox, and fast-charging is slightly faster at 1.4 hours to full charge—but only if you buy a separate fast-charging port.
Battery Tender 1,500-Amp Jump Starter for $150: This 1,500-amp Battery Tender jump starter has lower battery capacity than some at 44 Wh but still managed to eke out 10 jump starts on a six-cylinder Land Cruiser before reaching half-capacity—a sure sign of Battery Tender’s excellent power management. I’d still generally go for the versatility of the Battery Tender’s more expensive power station, or jump starters that offer an override function for dead batteries.
Battery Tender 1,200-Amp Charge-N-Start for $150: This low-capacity jump starter has its place, offering a toggle switch to optimally charge either lithium or standard lead-acid car batteries. The performance or raw oomph doesn’t match the top picks on this list, however, and for whatever reason I could never get this jump starter to agree that it was fully charged.
Also Tested
Gooloo A3 3,000-Amp Charger and Air Compressor for $110: This device from Gooloo often goes on sale well below $100, making it a discount option that has served me well in the past. Indeed, the A3 without the air compressor was a device I used happily for more than a year. But this charger is good for only about three charge attempts on a V-6 engine. Despite Gooloo’s claims that the A3 holds charge better and longer than other batteries, that’s not a lot of runway in case of a failed jump start. I’d opt for Gooloo’s higher-capacity, flagship jump starters instead.
Frequently Asked Questions
What’s a Portable Jump Starter?
The current world of portable jump starters is a bit more than a decade old and coincides with the rise of the lithium-ion battery as a more compact energy source.
Previously, charging a car battery often happened in one of two ways: slowly, with a car battery charger that plugged into your wall outlet, often over as long as 24 hours; or by hooking up your car battery to the battery of another running car, using jumper cables attached to the terminals of each car’s battery.
Photograph: Matthew Korfhage
Lead-acid jump starters, using a prior generation of battery technology, have also existed for decades. They are effective, long-lasting, and reliable in a wide range of temperatures. But they are often also bulky, heavy, and expensive. This limited their adoption somewhat.
Newer portable jump starters, which rely on somewhat recent improvements in battery technology, are now often compact enough to fit under your car seat. Each is a powerful battery that can be attached to jumper cables to start your car—often more reliably than trying to jump using your neighbor’s car, whose battery might not be in good health or able to deliver enough current.
What Are the Drawbacks of Lithium-Ion Jump Starters?
Lithium-ion batteries spurred a revolution in portable products since their first introduction in the early ’90s, arguably paving the way for the modern mobile phone. As the technology improved and became more accessible, it also changed the math on other portable devices, from beard trimmers to power tools.
But there are some main limitations, and the biggest one is temperature. Lithium-ion batteries function best at around room temperature. They’re safe in the range from -4 to 140 degrees Fahrenheit. Depending where you live, this may make them less than ideal to store in your car during certain months. If you allow the battery to freeze , it’ll be dramatically less effective—losing as much as 90 percent of is capacity to charge. (As a rule of thumb, storing a jump starter under your seat will offer milder temperatures than in your trunk or glove box.)
The other concern is safety. Batteries have become much safer since a host of Li-ion–powered devices turned into firebombs a decade back, often due to overheating and other faulty device issues. But you still want to take care not to keep a lithium-ion device in a car during baking-hot weather. (This goes for your phone, too, by the way.)
How Many Amps Should My Jump Starter Be?
OK, so here’s the thing. Amp ratings on jump starters are a bit like SPF for sunblock. Grain of salt, here.
After all, your average gasoline car draws just 300 amps to start. A big diesel engine might draw 400 to 600 amps. Cold temperatures will cause greater power needs, as will faulty batteries.
So what to make of a jump starter advertising 6,000 amps, enough to power some manufacturing facilities? Nothing, really. The amp ratings on your jump starters are probably mostly fictional. Or at least, they probably don’t bear direct relation to the current that will actually be delivered, and they are hard to compare across devices.
In practice, your car will only draw as much current as it needs. And it really doesn’t need that much.
From the same brand, or the same maker, higher-amp devices will almost certainly offer more cranking power than lower-amp devices. But across makers, it’s difficult to make any particular claims. I tested each device apples to apples, under the assumption that the “amp” ratings were inscrutable at best.
What is directly comparable among batteries, however, is capacity. Specifically, look for the number of watt-hours (Wh). The biggest-capacity jump starters I tested have close to 100 Wh. The smaller ones are closer to 40. This will have a direct effect on the number of jump starts before the device’s power is drained. Higher-capacity batteries will also be more likely to function in adverse conditions, or after they’ve been left sitting for longer.
There are two main qualities I want in a jump starter. I want it to be able to start my car even when I’ve left my headlights on for most of a week and drained the poor battery down to near-submission. And I want it to be available for repeat jump starts: in case a jump fails, in case my car battery is having a hard time retaining charge, or in case I just forget to recharge or periodically top up my jump starter.
So I tested both things with a six-cylinder ’94 Toyota Land Cruiser and with a similarly six-cylinder ’97 Mitsubishi Montero. I used older models with few electronics to speak of in order to avoid the outside possibility that repeated jump starts caused any problems or variables.
Photograph: Matthew Korfhage
First, I let cars drain their battery down over multiple days with headlights on, until the battery voltage was below 2 volts, and tested whether each jump starter could bring the car back from the near-dead. If this took multiple attempts, I documented this.
Then I tested all of the devices on the same battery, on the same day, in a round-robin elimination tournament—draining down until each jump starter’s battery reached half-capacity. I continually let the 12-volt car battery drain down to 4 volts, then started the car but didn’t let the battery charge. I instead let the battery drain back down to 4 volts and moved on to the next and then the next charger.
This did not merely test battery capacity but also power management. Some jump starters, like the Gooloo A3, released a lot of charge in order to start a car. Some, like the Battery Tender and Wolfbox, were quite economical with power outlays.
I also tested the safety of each device, attempting to reverse polarity or to create sparks by touching the clamps to each other or to a battery terminal. I tested to see whether I caught any small jolts from insufficient jumper cable insulation or current shutoff measures. I likewise tested for signs (or smells) of overheating on repeat jump starts.
Beyond this, I looked at simple usability. Is there an LED lamp for use at night, and is it properly placed? Is the device unreasonably bulky? Are the clamps easy to affix to a battery? Are the clamps too small or the cables too short? All of this matters, especially on car models where battery terminals might be difficult to access.
Can I Store a Jump Starter in My Car?
A lithium-ion battery is happiest near room temperature.
So if you’re using a lithium-ion jump starter, some caution is needed when it comes to keeping the jump starter permanently in your car. The new generation of chargers uses lithium-ion phosphate technology that’s a lot more stable than previous lithium-ion batteries. This is generally safe to store in temperatures between -4 and 140 degrees Fahrenheit.
But charging is still far less efficient at lower temperatures—and you should not charge a jump starter or use a boost/override function, when the battery’s core is frozen. This will permanently damage the battery. The battery also degrades more quickly at temperatures significantly higher than room temp.
This is why most jump starter manufactures don’t recommend you keep the device in your car, even though you probably would rather do that. I live in temperate climes, so I tend to do so anyway. Specifically, I keep one under my seat, where temperature swings won’t be as dramatic as in the glove box or trunk.
If you live in a place with extreme winters or summers, you may want to consider keeping the jump starter in your garage or home—but bring it along on long trips. Especially in the winter, you may be better off not storing the jump starter outside in a car overnight. When the weather gets colder again, I’ll also test jump starters that claim to have a self-warming function to keep the battery from losing efficacy.
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