Sooner or later you’ll have a dead car battery and if you have a portable jump starter you’ll be on your way within minutes, whereas if you have jumper cables you’ll need to find someone to give you a jump start.

The AstroAI S8 is a reasonably priced portable jump starter that offers features you’ll find in more expensive models. It has a 1,500 peak amperes (amps) capacity—the maximum immediate current a device can deliver—which is more than adequate to start almost all passenger vehicles.

In fact, the AstroAI S8’s peak-amp capacity is almost equal to or greater than some of the other portable jump starters I tested—like the Battery Tender Charge N Start 4120 and Noco Boost Plus—that cost much more. The AstroAI’s 8,000 milliamp-hours (mAh) capacity determines how many jump starts it can provide before needing to be recharged. Keep in mind that any portable jump starter with at least a 5,000-mAh rating can hold a charge for months.

The interface of the Astro AI S8 is the most basic of all the units I tested. It comes with a nylon storage bag, a USB-A-to-USB-C charging cable, and an LED flashlight with three modes, and has a boost button.

Because I own three older vehicles I deal with a lot of dead batteries. I tested the AstroAI S8 over several months both in Mexico where I live in winter and during the summer in Oregon. With an average of a dozen uses, I noted how quickly the AstroAI started vehicles (typically within seconds) and how many jump starts it provided before needing a recharge. I also used it to power portable devices such as my smartphone, which took three hours to bring to a full charge after it had died.

I tested the AstroAI S8 by jump starting my Honda Element after I left the lights on for a few hours and the engine wouldn’t start. I also used it with my Thor Majestic RV after it sat for several months and the battery was too low to fully crank the engine. Since the RV has a 6.8L V10 engine, the AstroAI S8 punched way above its weight when I needed to start the engine and get going.

I also tested it over five months at the RV park after at least six guests drained their batteries, and the Astro AI cranked each engine every time. I only needed to use the boost button once when a park patron had a severely drained battery. The internal battery also never got below 50 percent over the 12 months or so that I used it.

The AstroAI S8’s recent redesign is even more compact than its predecessor. It’s now just larger than my iPhone 16, but twice as thick and heavy. It’s also smaller than any of the other portable jump starters I tested by at least half, small enough to fit in a car’s glovebox, even including its 12-inch detachable cables with clamps that attach to a battery.

The front side of the Astro has a power button and blue power-indicator LEDs that show the internal lithium battery’s charge in 25-percent increments. It’s the only portable jump starter that I have seen with this type of informational style and it’s less informative than one with a digital display that shows the exact state of charge by percentage.

The sides of the jump starter have raised ribs that make it easy to grip when holding it in your hand. On one long side is the port for the jumper cables and on one short side are the auxiliary power port, the flashlight lens, and the recharging port. The 12-inch jumper cables have a boost button that, as mentioned above, provides roughly an additional 10 amps to start a severely depleted battery, and two indicator LEDs that confirm if the jump cables are correctly connected.

At 8,000 mAh, the battery is on the low side of storage capacity compared to the others I’ve tested like the Gooloo GT6000 or the Etenwolf Helios J1. For reference, higher-priced models like the Gooloo GT6000 offer up to 27,000 mAh, but don’t let that deter you from choosing the AstroAI. With a 1,500-amp peak current, it can jump start 6.0 L gas/3.0 L diesel engines and other 12-volt vehicles like motorcycles and ATVs. It's on par with even larger and more expensive competitors although in a smaller package and at a lower price.

In addition, the AstroAI S8 has 18 months of standby time and I found it barely lost power over the 12 months where I’ve used it probably about 20 times. Even though it has an automatic shutoff after 30 seconds, I intentionally drained its battery by charging my iPhone 16. It took about 4 hours to recharge the portable jump starter’s battery from 25 to 100 percent, although AstroAI recommends that users keep it at least a 75 percent charge.

The AstroAI S8 only has one output port—a 5-volt/2.1-amp USB-A output port—for charging portable electronics, while most of the portable jump starters I tested have at least two. I used the port to charge my iPhone 16 from 1 to 100 percent, which took about three hours.

Unlike the Gooloo GT9000’s 100-volt USB-C charging port, for example, Astro’s is an input-only to charge the device’s internal battery and doesn’t do dual duty as an output to charge other devices. Another downside: the supplied USB-A-to-USB-C charge cord charges slower than a double-sided USB-C charge cord. As previously mentioned, it took about 4 hours to recharge from 25 to 100 percent, whereas the Gooloo GT9000’s powerful 100-volt charging port fully recharges that device in just under 1.5 hours.

The AstroAI S8 has 10 safety features to safeguard against almost anything that can go wrong. These include reverse polarity if you hook up the jumper cables in reverse, reverse connection that prevents current from flowing back into the jump starter from the vehicle's battery, and short circuit protection to prevent current surges and sparks if the positive and negative clamps accidentally touch each other.

The built-in LED has flashlight, strobe, and SOS modes that are accessed by pressing and holding the power button. While not the brightest flashlight compared to larger and more expensive units like the Gooloo GT 6000 or Etenwolf Helios J1, it provides sufficient illumination.

The AstroAI S8 is as simple to operate as any portable jump starter I’ve tested. It’s the portable jump starter I’d recommend to anyone who needs a device that’s inexpensive, easy to use, and manageable to store but doesn’t include an LED display like the Gooloo GT6000 and more expensive devices

This portable jump starter may not suit owners of large vehicles who need more power or for those who prefer more output ports. But if you find yourself with a dead car battery—or even a dead phone battery—you’ll be glad you have the AstroAI S8 on hand, and that you don’t have to deal with jumper cables and finding someone to give you a jump start.

Shop the AstroAI S8