There’s a particular kind of stress that comes with a dead car battery in an underground car park. No signal, no easy access for another car, and calling a breakdown service feels like a massive faff for something that should be simple. That was my situation a couple of years back, and it’s exactly why I eventually bought the NOCO Boost Plus GB40 portable jump starter.
I’ll be honest: I bought it about two days after I actually needed it. The day the battery died, I was fitting a new stereo during a cold snap and left too much running for too long. Lesson learned. The jump starter pack went straight into the boot after that, and it’s been sitting there ever since, doing its job of just existing and giving me peace of mind.
Using It
When the moment finally came, it was genuinely straightforward. Clip on, wait for the green light, start the car. The GB40 has built-in protection that tells you if the clips are on backwards, which takes the guesswork out of it if you’re not used to using a jump starter. It made short work of my 2015 Kia Ceed, which is a diesel. I had a vague memory of hearing that you couldn’t jump-start diesel engines with a portable jump starter, but that’s outdated thinking. Modern units like this handle diesel without issue, though you do want to make sure the pack is rated for the engine size.
Beyond jump-starting, there’s a built-in safety light and a couple of USB ports for charging your phone in a pinch. Useful extras rather than gimmicks.
Charging the Pack Itself
The GB40 charges via USB-C, which is genuinely convenient. I used an old MacBook charger and it worked fine. That said, there’s no charging brick in the box, and if you plug this car jump pack into something underpowered, it charges very slowly. For a unit this size, you really want a proper fast charger, ideally 45W or above. NOCO sells a 65W charger separately, but it’d be better value if something decent was included at the €100 price point. It’s a minor gripe, but worth knowing before you buy.
Once charged, it holds its charge well over time. I’ve set a calendar reminder to top it up every six months. I also picked up a high-wattage in-car USB-C charger, so on longer drives I can just plug the pack in and make sure it’s ready to go.
A Note on the Battery Itself
After the flat battery incident, I used the episode as a reason to learn how to use a multimeter properly – mainly with AI helping me out on readings so I know what good or bad was. Being able to test the battery voltage myself meant I could confirm the battery was still healthy and didn’t need replacing. The stereo fitting in the cold had done the damage, not the battery itself. That kind of confidence is worth something. A jump starter gets you going again, but knowing whether your battery actually needs replacing saves you from an unnecessary garage bill.
Worth It?
At around €100, the GB40 is a solid buy. It’s compact enough to live in the boot without taking up noticeable space, simple enough that you don’t need to read a manual every time, and powerful enough for a diesel engine up to 6 litres. The lack of a decent charger in the box is a bit tight at this price, but if you already have a USB-C fast charger knocking around (and most people do), it’s a non-issue.
If you park somewhere awkward, drive a car that’s seen better days, or just want a reliable car jump pack tucked in the boot as a safety net, this is one of the more practical things you can buy for your car. Paying the little bit extra means it’ll likely have held a charge better for when you need it too.
