NOCO Boost X GBX45 1250A Lithium Jump Starter and USB Power Bank

Every boater has been there. You turn the key and get a single click, or worse, dead silence. The NOCO Boost X GBX45 exists for exactly that moment. It's a lithium jump starter about the size of a paperback that holds enough punch to bring a stone-dead battery back to life. 1250 peak amps is plenty for gas engines up to 6.5 liters, and it'll turn over a diesel up to 4 liters. That covers the vast majority of what's bolted into recreational boats, from outboards to small inboard diesels.

We keep one in the console on our own boat, and it's earned its spot more than once. The workflow is simple. Clip the included jumper cables onto the battery, red to positive and black to negative, and the Boost X handles the rest. There's no guessing about polarity because the unit won't send current until it sees a proper connection. So you can hand it to a first-time owner without worrying they'll cross the leads and throw sparks. The clamps are HD precision terminals that grip marine battery posts properly, not the flimsy stamped clips you find on cheap boosters. When you're done, wind the cables up and drop it back in the microfiber bag it ships with.

But this isn't only a jump starter. The GBX45 is a genuine power bank too. It carries a 31 watt-hour lithium-ion pack and three ways to get power back out: a 12-volt DC output, a USB-A port that pushes 5 to 12 volts, and a USB-C port that ranges from 5 all the way to 20 volts. That USB-C port is the one that matters. It's quick enough to top off a phone, a handheld VHF, a tablet running your charts, or even a small laptop on a long day offshore. The same port recharges the unit itself in about 48 minutes when you feed it enough wattage, so a quick stop at the dock before you leave gets you topped up. Built into the front is an LED flashlight with the usual emergency modes, which is exactly what you want when you're crawling into an engine bay after dark.

A few honest notes from living with these around salt water. Lithium packs don't love heat or humidity, so don't leave it baking in a closed compartment all season. Store it somewhere dry, ideally in a sealed bag or a locker with some air flow, and top it off every couple of months so it's ready when you actually need it. Keep the USB ports covered when they're not in use. A little salt spray on exposed contacts is the enemy of any electronics on board. On a planing hull that pounds through chop, tuck it in with a bit of foam padding so it isn't rattling around loose. Treat it like the safety gear it is and it'll be there on the morning your battery isn't.

One thing we'll be straight about: cold diesels are the toughest test for any jump starter this size. The GBX45's 1250 amps will spin a warm 4-liter diesel without drama, but a genuinely cold diesel that wants a full glow-plug cycle is asking a lot of any compact pack. If you run a diesel auxiliary, give the glow plugs their time before you crank, and don't be surprised if a stubborn engine needs a second go. For gas engines up to 6.5 liters, that's rarely a concern.

So who's this for? Center console owners, RIB and dinghy operators, sailors with a small diesel auxiliary, anyone running a single battery who wants a backup that doesn't eat half a locker. The X in Boost X means faster recharging and more starts per charge than the standard Boost line. This is the version without an air compressor, so if you also want to air up fenders or a dinghy on the fly, look at a model that includes one. For pure starting muscle and USB charging in a package you can hold in one hand, the GBX45 is tough to beat. And at this price, it's cheap insurance against a ruined day.