Nebo Rambler 20k Review

Every traveller should have a torch, (preferably one that isn’t their phone) and a power bank. You never know when an emergency is going to happen and you will be left without light, power, or both. So, in my search for the latest travel gear I attended the National Outdoor Show 2025 in Birmingham and came across the Nebo Rambler 20k, which solves both issues in one almighty package. 

Nebo gifted me the Rambler 20k along with their Luxtreme Nano. Nebo do not see my reviews in advance, nor have any input. So all reviews and opinions in the review are my own.

This powerbank is a real brick, but I’m not surprised given the capacity. At 20,000mAh, this is a real powerhouse, and I’m looking forward to seeing how it performs. Realistically, I wouldn’t necessarily use this size as a day-to-day charger. But for festivals, multi-day hikes, areas where power can be unreliable or even emergencies, this will be fantastic. 

A 20k power bank may be a tad overkill for most uses. If you want a powerbank to sling in your bag, just in case you forget to top up in the office or want to go out after work and you’re worried your phone may die, then you may want something lighter. But if you are a power-hungry user or want to charge bigger devices, this is going to be great. I could comfortably top up my phone, tablet, cameras and laptops without battery anxiety taking hold.

20000mAh battery works out to be an average of 4.5 phone charges. Obviously, this is an average. I have been using the S24 Ultra, and if I charge nothing else, it works out to be just over three complete charges. Which I like, for the size and weight of this power bank. I’ve had bigger and heavier ones that charge less than that.

Nebo has followed the popular design for power banks, making it a slimmer, rectangular shape. This always makes the most sense, as it’s able to slip into any size bag; however, if the bags are small enough, you might not have a lot of room left. Having such a high capacity, it does naturally come out a bit thicker, which helps accommodate the torch into the side too.

With an output charge of 18w, this is classed as fast charging, but it’s more designed for power and not speed. My usual go-to, the Anker Nano Power Bank, is capable of 30w, almost double the Rambler 20k. But it does hold half the battery capacity. Power banks with ultrafast speeds are more of a luxury than a necessity. You aren’t tied to an outlet, and if you do have to move before your device is charged, you just carry it with you.

The Rambler 20k comes with one USB-A outlet and one USB-C. This allows you to charge multiple devices simultaneously. Input charging is only available through the USB-C. I have tested and checked, the Rambler 20k is capable of pass-through charging. So if you have both a USB A and USB C cable you can charge the power bank and a device together.

It takes an average of 5.5 hours for the Nebo Rambler 20k to fully recharge. This is a fairly significant time, but considering how often you can go between charges is understandable. You definitely want to make sure you put it on charge overnight though so you aren’t waiting around all day. You could realistically go a day or two between having to charge it up, and even longer if you top it up on your hotel room visits.

The Rambler 20k has been pretty impressive at how it handles heat. All battery packs will warm up when being used, but you want to keep this to a minimum, where possible. If it gets hot in the UK when charging at home, then I wouldn’t consider taking this with me on my travels.

Luckily, the Rambler 20k is great at keeping itself cool. I’ve been using it pretty intensely over the last week when testing. I charge devices at home using my phone and the bank itself. With it needing a full 5.5 hours to recharge, I have checked it at various times throughout the charge, and it only slightly heats up. I could confidently take this with me to a place like Africa and charge devices in my bag without having to worry about overheating.  

The Torch is a floodlight and is perfect for lighting up a whole room. I have mostly been testing it at home, and the light disperses enough that I can see everything, and it isn’t too directional. I can simply put it in a corner and go about what I need to do. My bedside table doesn’t have a lamp, so it’s been handy lighting up the room as I make my way to bed. The kickstands are really helpful, letting it stand vertically.

It makes sense how durable the Rambler 20k feels. The plastic is thick and capable of sustaining a few knocks. The front and back are also textured, which provides a bit of extra grip, which you’ll need if you’re using it as a torch, as there isn’t a handle. If you’re using it outside in a drizzle, too, it’ll prevent it from slipping.

The hinges on the kickstand are solid. They move easily enough when you need to adjust, but are sturdy enough to support the power bank’s weight without moving. One thing I would like to see improved is perhaps some rubberised corners instead of the full plastic design. I think this would help add a bit more drop protection to the power bank.

Not everyone will need a power bank this big, and even then, not all the time. But there are still plenty of opportunities when this power bank will come in handy. Festival revellers will love how many charges they can get, and the torch will come in handy for those late nights when you are searching for items in your tent. For hikers, having a source of power will be great on those multi-day hikes, giving power to your phone and a lifeline in an emergency. 

And when you don’t need something this big, it’s perfect for the car. I have mine in the glove compartment for emergencies. I have a source of power in case I have a breakdown, and a source of light if that happens to be at night. A torch should be in everyone’s car; combining that with a source of power makes it a road trip essential.

There is a small LED digital display built into the torch’s bulb, allowing you to easily check on the Ramblers’ capacity. I have made the mistake of holding it upside down once or twice as only glimpsing the capacity. Confusing 68% with 89%, so I had less battery than I thought. But I’ve since learned to be a bit more careful, and when the capacity is this large, 68% of 20,000mAh is still a lot of battery to burn through.

Currently, the Rambler 20k retails for £59.99. It may be on the more expensive end for power banks, but you are getting something that’s a lot more durable and rugged compared to others. This is a power bank designed for adventures and the outdoors. It will last a lot longer than cheaper ones, especially if you spend a lot of time adventuring.

The Rambler 20k is a tank when it comes to power banks; it might not be the lightest, but it certainly has the power to keep going. I have some big adventures planned over the next few years, and the Rambler 20k will be with me every step of the way.