TechnologyTell Review: Justin 5400mAh Power Bank

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External battery packs are totally useful, that is, until you happen to forget the cable. There’s nothing worse than having a need unfulfilled because of just one missing element. Fortunately, some manufacturers, such as Innovative Technology, has taken this into consideration. You’re not going to lose a cable that’s built-into the battery itself!


The size of the Justin 5400mAh Power Bank is not bad for the capacity. It’s a touch larger than others, mostly due to the built-in wall prong and cables. But that there is the charm and convenience. This external battery pack is self-sufficient so long as you have access to a free wall socket. Forgot your charging cables? Who cares! It has one each for Lightning and Micro USB compatible devices. There is also a standard USB port at the bottom works with any cable type you have lying around.

Justin 5400mAh power bank top

Moderately sized with standard 4-LED indicators.

If you hate the look of your fingerprints, prepare to be irked. This battery is all gloss, all prints, all the time. One useful solution to keep on hand would be a pocket toddy. Great for your other gadgets, too.

Although the Justin power bank has more bulk than it does weight, it’s still quite portable. The construction of this battery pack is good, basic. There isn’t anything exceptional about it, except maybe the pair of cables, which are thick and sufficiently flexible. They lie flush alongside the battery and tuck in at the top. You get a small little bump on the end of the plug to push in order to extract them.

The Lightning and Micro USB cables may not extend far, but they’re long enough to get the job done. At first, tucking the tips back into the locked position takes a bit of effort. But once the cables have had a bit of stretch and movement, they slide in smoothly and stay in place.

While this battery can plug easily into power strips, I find it to be better suited for wall socket – the bottom of the pair so the top stays open. Mostly. A standard 3-prong plug can nestle right above the Justin 5400mAh power bank on the wall, but bigger plugs than that likely won’t.

Justin 5400mAh power bank side

Thicker than preferred, but not that bad at all.

The width of this power bank takes up three outlets on a standard power strip, two if you place it on the end. Since it also sticks out, you have to make sure it doesn’t tip itself over far enough to break contact while charging up. So, yes, it is convenient, but with a few slight limitations.

Like most external battery packs available, the Justin 5400mAh power bank features four LEDs to show the approximate battery power left. Each blue bulb indicates a 25 percent threshold with pretty reasonable accuracy. Some batteries can be way off (unless it’s full or empty), but this one is not too bad. The LEDs blink while the Justin power bank is charging up, turning off once completely full and ready to go. When charging out, the power bank does get slightly warm to the touch, right around the area with the LEDs. But the bottom and sides stay cool.

One feature I’m happy to not see included is a “flashlight.” There are a lot of other external battery packs that employ a single, dinky LED that can toggle on as a light. When I need a real light, I’ll reach for my ThruNite T10S flashlight. Or a smartphone with a flashlight app does quite well in a pinch. Thankfully, this Justin battery doesn’t waste space with a gimmick.

Battery Performance

This Justin 5400mAh power bank does not auto-detect devices when they are plugged in. Pressing the power button is mandatory. When charging out, this battery is the kind that doesn’t give any indicator of working either. All the LEDs remain dark. So if you want to check the progress of charging, you’ll have to peek at the device plugged into this battery.

Justin 5400mAh power bank prong

Built-in wall prong is very convenient.

I happen to find it convenient when LEDs are lit while charging, since a single glance from afar appraises me of the status. It’s too bad this one do it like the Justin Slim Power Bank does. One great aspect about this power bank is that it completely shuts off when charging has completed. Some external batteries continue to trickle charge out, which ends up as a waste as hours pass.

Unfortunately, the Justin 5400mAh power bank does not feature passthrough charging. Bummer. Normally, paying attention to device and battery levels during the day negates most needs for passthrough charging. However, this power bank’s built-in prongs would have made it an ideal travel gadget to charge itself and devices either in a room or on the go. So you’ll still have to bring that extra wall adapter for mobile devices on trips or vacations away from home.

The extendable cables, as well as the USB port at the bottom, effectively output 5V/1.5A to my Samsung Galaxy Note 4. It’s what I’d expect from a battery pack with max 2.1A out, so thumbs up on that. Keep in mind that plugging in two or more devices splits that output – I’d probably only stick with two, max, so each can draw 1A equally.

Justin 5400mAh power bank cable

Flat cable tips lie flush with the exterior body.

Note: Most external battery packs I’ve ever purchased and used came only partially charged, so I’ve always made it a habit to fully charge them before use. I tend to fully charge and discharge a new battery a few times, just so I can level out the charge states of the individual cells. It helps to maximize the battery’s manufacturer-listed potential.

The standard efficiency rating of external battery packs currently on the market is 70 percent. This means that 30 percent of the battery’s listed capacity is consumed while charging up devices. So, for example, a basic 1000mAh battery would effectively deliver 700mAh of energy.

Right out of the box, the Justin 5400mAh power bank was able to deliver a total of 102 percent charge, or 3284mAh of usable energy, to my Samsung Galaxy Note 4 battery (3220mAh). That’s equivalent to 60.8 percent efficiency. Notably below average. However, additional charge cycles brought up the values to a peak of 66.7 percent efficiency, where it pretty much remained consistent. That average is equivalent to 3606mAh of usable energy. Maybe it’s not the best, but it’s also far from the worst.

So what can you do with 3606mAh of battery energy? That’s good for 1.12 full charges to a Samsung Galaxy Note 4 (3220mAh), or 1.99 full charges to an Apple iPhone 6 (1810mAh), or 0.80 full charges to a 7″ Kindle Fire HDX (4500mAh).


If you own both iOS and Android mobile devices, the Justin 5400mAh Power Bank is a convenient no-brainer. Lighten your carry load by leaving the pair of cables at home. Easy. The battery’s built-in wall prongs means you can also forget the wall adapter. Mostly.

The lack of passthrough charging is a small letdown; this power bank has such potential for being a must-have travel gadget. Although this Justin 5400mAh power bank is a 3-in-1 battery with cables and wall prongs, you’ll still need an additional wall adapter to charge mobile devices at the same time. It may not be a big deal to some, but I’ve had those days out of the house where everything was empty before nightfall. Either way, this is still a great battery for travel and daily use.

The only drawback with this Justin power bank is the sub-average efficiency. I wouldn’t say it’s a lot less than others, but it’s enough if you’re going to cost-compare. However, when you take into consideration your gear as a whole, the additional features of this external battery really help balance it out.



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