Charge your NOCO Boost Plus GB40 using the included USB-C cable and a standard wall outlet, car charger, or solar panel — the process takes about 4 to 5 hours from empty to full on household power.

The NOCO Boost Plus GB40 ships with a USB-C charging cable that connects to any USB-C power adapter. You can use the wall charger that came in the box, borrow one from a phone or laptop, or plug into a car's USB port. The jump starter has an internal battery management system that stops charging automatically when full, so you cannot overcharge it.

Charging time depends on which power source you use. A standard 5-watt wall adapter takes roughly 4 to 5 hours. A higher-wattage adapter (10 watts or more) cuts that to 2 to 3 hours. A car's USB port typically takes 6 to 8 hours because most car ports deliver only 1 to 2 watts. A solar panel charger, if you have one, will charge much more slowly depending on sunlight and panel size.

Key Takeaways

  • The NOCO Boost Plus GB40 charges via USB-C cable with any standard power adapter, taking 4 to 5 hours on a typical wall charger.
  • You can charge from a wall outlet, car USB port, or optional solar panel — the device automatically stops when the battery is full.
  • A higher-wattage adapter (10W or more) cuts charging time roughly in half compared to a standard 5W charger.
  • The LED indicator on the device shows charging progress: a blinking light means charging is underway, and a solid light means the battery is full.

Charging from a Wall Outlet

Plug the USB-C cable into the charging port on the bottom of the NOCO Boost Plus GB40. Connect the other end to a USB-C power adapter, then plug the adapter into a standard wall outlet. The device will begin charging when ready — you will see a blinking LED light on the front panel.

The LED indicator cycles through the charge level as the battery fills. A single blinking light means the device is charging. Once the battery reaches full capacity, the LED will stop blinking and remain solid, or the light may turn off entirely depending on your model year. At that point, you can unplug the cable.

If you do not have a USB-C power adapter at home, any phone or laptop charger with a USB-C port will work. Higher-wattage adapters (marked 10W, 18W, 20W, or higher on the plug) will charge the GB40 faster than a standard 5-watt phone charger, though the device will not be damaged by using either one.

Charging from a Car USB Port

You can charge the NOCO Boost Plus GB40 while driving or parked, using your car's USB-C port if it has one. Plug the USB-C cable into the jump starter, then connect it to the car's USB port. The device will charge, but much more slowly than from a wall outlet — expect 6 to 8 hours to reach full capacity.

Most car USB ports deliver only 1 to 2 watts of power, which is why charging takes longer. If your car has a USB-C port specifically labeled for fast charging or high-power output, charging will be noticeably faster. Check your car's manual or look for any labels near the USB port to see if it supports higher wattages.

Keep the NOCO Boost Plus GB40 in a cool location inside your vehicle while charging. Do not leave it in direct sunlight on the dashboard for extended periods, as heat can slow the charging process and stress the battery.

Using a Solar Panel Charger

NOCO sells an optional solar panel charger that connects to the GB40 via USB-C cable. If you own one, place the solar panel in direct sunlight and connect it to your jump starter. Charging speed depends on the panel's wattage, the angle of the sun, cloud cover, and time of day — a full charge can take anywhere from 8 hours in bright conditions to a full day or more in cloudy weather.

Solar charging is useful for keeping the device topped up during outdoor activities or camping trips, but it is not practical for a quick charge before you need to jump a car. Use solar as a maintenance tool rather than your primary charging method.

Understanding the LED Charging Indicator

The NOCO Boost Plus GB40 has an LED light on the front that tells you the charging status. When you first plug in the cable, the light will blink — this means the device is actively charging. The blinking continues until the battery reaches full capacity.

Once fully charged, the LED will either stop blinking and remain solid, or turn off completely — the exact behavior depends on your specific model year. If the light stops blinking but the device is still plugged in, it is safe to leave it connected; the internal charging circuit will not overcharge the battery.

If the LED does not light up at all when you plug in the cable, check that the cable is fully inserted into the charging port and that the power adapter is plugged into a working outlet. Try a different outlet or a different power adapter to rule out a faulty wall socket or charger.

Charging Safety and Best Practices

The NOCO Boost Plus GB40 is designed to charge safely in most conditions. The device has built-in protection against overcharging, short circuits, and overheating. You can leave it plugged in after it reaches full capacity without risk of damage.

Charge the jump starter in a cool, dry location. Avoid charging in extreme heat (above 104°F or 40°C) or extreme cold (below 32°F or 0°C), as temperature extremes can reduce charging efficiency and stress the battery. If the device feels hot to the touch while charging, unplug it and let it cool for 30 minutes before trying again.

Store the NOCO Boost Plus GB40 with a partial charge — around 50 percent — if you plan to leave it unused for more than a month. Recharge it every 3 to 6 months even if you are not using it, to keep the internal battery in good condition. Check the LED indicator periodically to confirm the device has not drained completely during storage.

Troubleshooting Charging Problems

If the NOCO Boost Plus GB40 will not charge, first confirm the USB-C cable is fully inserted into the charging port on the bottom of the device. The port can be tight — push the cable in firmly until you feel it seat. Then check that the power adapter is plugged into a working wall outlet by testing the outlet with another device, such as a lamp.

If the cable and outlet are both fine but the device still will not charge, try a different USB-C power adapter. Some adapters have compatibility issues with certain devices, though this is rare with the GB40. If you have access to another USB-C charger — from a phone, tablet, or laptop — test with that one.

If the device charges very slowly or the LED blinks for hours without reaching full capacity, the power adapter may not be delivering enough wattage. A 5-watt adapter is the minimum; if you are using one, switch to a 10-watt or higher adapter for faster charging. If you have tried multiple adapters and cables without success, contact NOCO customer support, as the device may have an internal charging circuit fault.

Frequently Asked Questions

Can I use any USB-C charger to charge the NOCO Boost Plus GB40?

Yes. Any USB-C power adapter will work, including chargers from phones, tablets, and laptops. Higher-wattage adapters (10W or more) charge faster than standard 5W chargers, but any wattage is safe to use. The device's internal circuit prevents overcharging.

How long does it take to fully charge the GB40?

On a standard 5-watt wall charger, expect 4 to 5 hours. A 10-watt or higher adapter cuts that to 2 to 3 hours. Car USB ports take 6 to 8 hours. Solar panels vary widely depending on sunlight and panel wattage.

Is it safe to leave the GB40 plugged in overnight?

Yes. Once the battery is full, the internal charging circuit stops accepting power. Leaving it plugged in will not overcharge or damage the device. You can safely charge it overnight and unplug it in the morning.

What does it mean if the LED keeps blinking after several hours of charging?

A blinking LED means the device is still charging. If it has been plugged in for more than 5 to 6 hours and the LED is still blinking, the power adapter may not be delivering enough wattage, or there may be an internal issue. Try a different adapter with at least 10 watts of output.

Can I charge the GB40 while using it to jump a car?

No. The device is designed to charge or jump-start, but not both at the same time. Charge the jump starter fully before you need to use it, or wait until after you have finished jump-starting to plug it in and recharge.