Start the vehicle within 60 seconds after pressing the power button on Boost. After the 60-second timeout is complete, the unit must be powered off, then back on, to initiate a new jump-start sequence.

We took our UltraSafe technology and made it better— UltraSafe 2.0. It’s still our simple, mistake-free design featuring spark-proof technology and reverse polarity protection, but with enhanced thermal efficiency and power management to provide better performance and longer battery life.

With two built-in 2.1A USB ports, you can power multiple devices at the same time, such as smartphones, tablets, action cameras, wireless headphones, wearables and more. With over 137 watt-hours of lithium power, the GB251+ can provide endless hours of operation and recharge your devices multiple times before needing a recharge.

From 0-100% 4X Faster. Charge directly from the vehicle’s 12-volt auxiliary port or the XGC4 4-Amp Power Adapter to recharge it’s 137 watt-hours lithium-ion battery in 8.5 hours.

More than a jump starter, Boost MAX is a useful tool for daily use and emergency situations alike. The GB251+ is equipped with a 600-Lumen LED flashlight with various brightness modes, SOS, and emergency strobe— handy to have as a roadside or road trip tool.

Integrated Voltmeter / 60 Second Countdown Timer. The Boost MAX GB250+ is equipped with an integrated voltmeter to help pinpoint battery issues. The voltmeter doubles as a 60-second countdown timer, which shuts off GB251+ after 60 seconds to help preserve internal battery charge.

Technical Specifications

What’s in The Box

  • GB251+ Lithium Battery Jump Starter
  • 56-Watt XGC Power Adapter
  • 12-Volt 2-Foot XGC Cable
  • Protective Carrying Case
  • User Guide & Warranty Information

Starting Current

3000 Amps (Peak)


24 Volt

Battery Types

24 Volt Lead-Acid Battery Systems

Internal Battery

137 Watt-Hour Lithium-Ion

Operating Temperature

-4°F to 122°F (-20°C to +50°C)

Charging Temperature

32°F to 104°F (0°C to +40°C)

USB (Output)

Dual 5 Volts, 2.1 Amps


Natural Convection

12V XGC (Input)

12 Volts, 4 Amp

12V XGC (Output)

12 Volts, 15 Amp

Gas Engine Rating

Up to 32.0 Liters

Diesel Engine Rating

Up to 32.0 Liters

LED Worklight


Product Size

Height: 8.62 Inches (218.9 mm)
Width: 12.43 Inches (315.7 mm)
Depth 3.68 Inches (93.5 mm)
Weight: 14.7 lbs (6.67 kg)

IP Rating

IP65 (w/ Ports Closed)

Limited Warranty

1-Year Hassle-Free Warranty