Editors' note: Portions of this review were copied from CNET's review of the Bolt Power D28 portable jump starter. The X-5 Mini underwent similar testing.
Portable jump starters used to be a basic car battery in a plastic casing, weighing up to 20 pounds. Now, improvements in lithium ion batteries enable a new breed of jump starter, one that can fit in your glove compartment and weighs about 10 ounces. Such is the Bolt Power X-5 Mini, a compact device with a convenient screen that's also capable of charging your smartphone.
At 5.5 inches long, 3 inches wide and well under a pound in weight, the X-5 Mini can easily be carried around in one hand. It's a little big to fit in a pocket but would fit in a car's glovebox or trunk easily enough. The X-5 Mini comes in a zippered nylon case, holding its adapter and charging cables, which add considerable size to the whole package. You might want to leave the case at home and just pack what's necessary in the car.
Contoured yellow plastic covers the top of the X-5 Mini, with cutouts for a small LCD and a power button for the integrated flashlight. The front end houses two USB ports, a port to charge the X-5 Mini's battery and the flashlight lens. One of the long sides holds the main power switch, while the other has a port for the battery clamps.
Cables included with the X-5 Mini are the battery clamp adapter and a white multijack adapter with older and newer iOS plugs and plugs for Mini- and Micro-USB. In addition, Bolt Power includes AC and 12-volt adapter cables for charging the X-5 Mini.
To charge up my iPhone 5S, I had to plug in the white multiadapter cable, or I could have used my own iPhone cable, then turned on the power switch. To further test the capabilities of the X-5 Mini, I plugged another device in to the Mini-USB plug at the same time my iPhone was connected, and the two charged simultaneously.
As the X-5 Mini's battery is rated at 8,000-mAh capacity, it could charge up my 1,900-mAh iPhone 5S battery four times over. That amount of power is enough to charge a Nexus 7 tablet a couple of times, but it falls short of the latest iPad's 11,560-mAh battery, so could provide only a partial charge. The USB port outputs power at 2.1 amps, the maximum for USB 2.0 charging.
One of the X-5 Mini's key features is its ability to jump-start a car. Unlike a typical portable battery backup just for charging devices, the X-5 Mini comes with battery clamps that plug into a special port in its side. It can also output a peak 400 amps, enough to jump-start a typical passenger car or truck engine up to a V-8.
To test the X-5 Mini's jump-starting capabilities, I borrowed a Ford Country Squire station wagon with a 5-liter V-8. The car did not have a dead battery, so I took the positive battery cable off the battery. I attached the X-5 Mini's black battery clamp to the car's negative terminal, and the red clamp to the positive battery cable. When I turned the Country Squire's ignition key, the engine fired right up, as if it had a fully charged battery.
Finally, as a convenience feature, the X-5 Mini includes a white LED flashlight integrated into one end. To use it, I had to turn on the main power switch, then push and hold a second button on top of the device until the light came on. Touching the second button again started the light flashing, with two different selectable frequencies. The X-5 Mini's battery pack will run that light for a very long time, making it suitable to use in place of a flare if you are stuck on the side of the road at night.
The list price for the Bolt Power X-5 Mini is a hefty $129. However, online prices seem considerably lower, well under $100. ($129 converts to about £80 or $145, but the only place we've found it sold so far is on the US version of Amazon. Some Amazon sellers ship internationally.) Getting just one successful jump start out of it would justify the price, compared with the time and cost for getting roadside assistance.
I like that the X-5 Mini has a dedicated power switch, so you know when its ports are powered up. In addition, the LCD, with its numerical charge readout, tells exactly how much juice is available. The two USB ports are very convenient for charging multiple devices at the same time, as is the white multiadapter cable.
The flashlight is a nice accessory feature, especially as you might be fumbling around looking for your battery terminals on a dark and stormy night. One thing that larger portable jump starters sometimes include, which the X-5 Mini lacks, is an air compressor. However, its small size makes it easy to stow in any car, so you are more likely to have it handy when your battery quits.