When away from 240 volt power sockets, having a 5 volt portable charger bank is a neat way to charge phones and other bits of kit when no power is available. Power banks alleviate the worry or batteries running out and are particularly useful on boating holidays, camping festivals and hiking trips where you won't have access to electrical sockets.
The AINOPE Explorer X2 portable charger isn't too heavy and it's very compact so it fits well into a backpack or bumbag, meaning you can easily take it in and out to charge gadgets such as vape pens and e-cigarettes. The body construction of the AINOPE Explorer X2 is made of matte thermoplastic material. Total weight is 335 grams, measuring 14cm long, 6cm wide and 2.3 cm thick.
There is really no better way for handy charging on the go than taking a power bank with you. A power bank serves you well when you need it the most like in a concert or motorway traffic jam. When buying a power bank, you want to look for some key features, including mAh capacity, current draw and safety features. The AINOPE Explorer X2 has a 20,000 mAh (77Wh) capacity, which means if your phone has a battery capacity of 2,000 mAh you can recharge it ten times over.
With that said, the real capacity of power banks is always much lower; hence why you want to look for the power bank's "rated capacity" which isn't always listed. AINOPE does list the rated capacity of the Explorer X2 power bank at 12,500 mAh, which also takes into account the conversion loss of the power bank converting 3.7V to 5V.
If you want to find out the "real" capacity of any power bank, you need to use the formula (3.7 x mAh capacity/5) so in the case of the AINOPE, it is 3.7 x 20,000/5 which equals 14,800 mAh. Since the rated capacity is 12,500 mAh that means, the AINOPE Explorer X2 loses 2300 mAh during the process of converting 3.7V to 5V.
More important than mAh capacity though, it's "current draw" and that is because devices (i.e. phones, tablets, etc) require anywhere from 1 amp to 2 amp to charge their batteries. Many new devices today (i.e. tablets, phones, etc) feature "quick charge" technology which requires 2 amps or more.
The AINOPE Explorer X2 can output both fast charge (5V/2 amps), as well as slow charge (5V/1 amp) via a second USB port. When you have two devices plugged-in, the built-in "smart circuitry" kicks in, allowing the AINOPE Explorer X2 power bank to deliver as much charge as it's needed via both USB ports up to a maximum of 2.1 amps from both USB ports.
Any power bank delivering more than 2 amps is classed as high speed charging, which means less time charging your devices as long as they support fast charging like the iPhone XS Max and Samsung Galaxy Note 9 whose built-in batteries take approximately 1.5 hours to recharge.
Safety is also very important in a power bank so, most new power banks these days will feature at least over-charge protection so the power bank will automatically switch off after full charge is complete. While the AINOPE Explorer X2 does feature over-charge protection, it doesn't appear to have built-in over-voltage protection (OVP) and over-temperature protection (OTP).
A couple other features the AINOPE Explorer X2 power bank has going for is a digital power indicator and pass-through charge so you can charge the powerbank and anything connected to it at the same time from the same charger adapter.
Most power banks typically feature led indicators to show you how much charge is left but a digital LCD display is way more convenient because you can tell exactly how much battery charge is available so you don't have to guess.
As far as charging the power bank itself, the AINOPE Explorer X2 power bank is not as quick to charge as a power bank with quick charge input. It can take up to 24 hours to fully charge the Explorer X2, which is a very long time but the power bank does hold its charge well and that is the main thing. If you're looking to buy this power bank, you can get 50% off using discount code: OJ6OEMKL (the code expires on 27th September 2019)

The idea behind a power bank is that when you are out-and-about, you can recharge your gadgets without needing a wall socket! The overwhelming majority of power banks are limited to USB devices like a smartphone, although there are some power banks like the Maxoak K2, which can also output 30W (12V/2.5A) and 60W (20V/5A) to charge a laptop!
The Maxoak K2 is a behemoth of a powerhouse, way larger (20.7cm long, 13.5cm wide and 3.2cm thick) than your average power bank but, then again, it would be since the Maxoak K2 can store over 30 hours of power. The K2 weighs 1.2 kg too, which is even heavier than some laptops.
The aluminium body of the Maxoak K2 wraps around the front, back and sides of the power bank, while the bottom and top end panels are capped with hard plastic that is rounded off at the corners. Across the sides of the Maxoak K2 powerbank there are glossy bronze plastic strips with printed information.
The top panel contains the functionality, including battery led indicators, DC input, power button, a 20V/5A DC output and a 12V/2.5A DC output. The power button also activates the battery led indicator. The K2 power bank has been programmed to power off automatically after 30 seconds of current load not being detected.
There is also four USB output ports, two of which can output 2.1A, while the other two USB ports can output 1A, which is ideal for charging 5V USB powered devices like a smartphone or, even smaller power banks. The K2 power bank is able to recharge 16 times over, a 4000mAh smartphone and 2 times over, a 60W laptop.
The K2 power bank has a 1000 cycle life, which means you will be able to completely charge it and discharge it 1000 times without losing charge capacity. After 1000 complete charges/discharges though, the K2 power bank will start experiencing issues holding charge, which is an issue all power banks/rechargeable batteries eventually experience.
With 1000 complete charges/discharges, you are probably looking at 3 years, although you can easily extend this number by simply not letting the battery go flat. If you only let the Maxoak K2 battery discharge to 50% and then charge it back up to 100%, it only counts as a 1/2 cycle.
The Maxoak K2 power bank supports simultaneous charging/discharging, which means you can charge devices and recharge the K2 power bank, all at the same without having to wait for the power bank to fully recharge.
In order to recharge the Maxoak K2 50000mAh battery, it requires a 1.5A input within 100V and 240V voltage range. The United Kingdom (UK) operates on a 230V supply voltage, while other places like North America and Hong Kong operate on a 110V and 220V supply voltage respectively.
You won't be able to use an AC 100-240V to DC 12V/1.5A power adapter to recharge the K2 power bank. The included power brink though, it's effectively a 42-watt fast charger, which can recharge the K2 in 7 hours. With this much power going into, the K2 power bank has not problems outputting its total 120-watt power capacity from the DC outputs and USB outputs at the same time.
The power supply that is included with the Maxoak K2  is a branded power brick AC/DC adapter made by KAYO Maxtar (Model Number: XVE-1680250). KAYO Maxtar seem to be a subsidiary company of Maxoak.
The KAYO Maxtar AC power adapter has the same footprint as a regular laptop power adapter and it's also limited to 1.5A, although you won't be able to directly connect the KAYO Maxtar power adapter to a laptop without the K2 power bank. The reason being, the KAYO Maxtar power adapter output has been customized to 16.8V at 2.5A, which is lower output than most laptop charger bricks.
Speaking of laptops, the Maxoak K2 power bank comes with 14 male jack connectors to fit a range of laptop charging ports (Apple laptops not supported). All the jack connectors are dual-sided and have a 5.5 x 2.1mm DC female jack on the rear to plug in the included DC male to male 20 AWG cable, which is rated for a maximum working voltage up to 125V.
The dimensions of the jack connectors are as follows: 6.0 x 1.4mm (Fujitsu), 6.5 x 4.4mm (Sony), 5.5 x 2.5mm (Acer, Asus, IBM, Dell, HP/Compaq, Fujitsu, Toshiba and NEC), 5.5  x 1.7mm (Acer), 4.8 x 1.7mm (HP), 5.0 x 1.0mm (Samsung), 7.4 x 0.6mm (Dell), 7.4 x 5.0mm (HP), 7.4 x 0.6mm (Dell), 7.4 x 5.0mm (Dell), 7.9 x 0.9mm (IBM), 7.9/5.5mm (Lenovo), 3.0 x 1.1mm (Samsung), 4.5 x 3.0mm (HP), 4.5 x 3.0mm (Dell), 4.0 x 1.35mm (Asus), ASUS and 4.0 x 1.7mm (Lenovo). The 4.5 x 3.0mm connector does not work with the Dell XPS 12.
There is also a Lenovo square connector for the ThinkPad Yoga S1, ThinkPad Helix and ThinkPad T431s laptops. This Lenovo square tip connector will not fit any other Lenovo laptop, including the Yoga 3 14, Yoga 900 (20V 3.21A), Yoga 700S, Yoga 3 11, Yoga 13 and One Mix 4 Yoga.
If the included connectors don't fit your laptop, you will need to buy a jack connector in order to be able to use the Maxoak K2 power bank. The included jack connectors will not fit a Surface Pro 3 or Surface Pro 4 since these two laptops require a 5.5mm x 2.1mm DC male connector.
While talking about the Surface Pro 3 and 4 laptops, it's worth pointing out that the Surface Pro 3 and Pro 4 have a stock voltage input of 12V and 15V respectively. That said,  the Surface Pro 3 will accept any voltage supply between 11V and 16V, while the Surface Pro 4 can still operate from a 12V power supply, although charging will be naturally slower. The 20V outlet is good for laptops with voltage ranging from 18.5 volts to 20.5 volts. This includes the HP Envy 360 Convertible laptops, which have a 19.5 volt rating.
The KAYO Maxtar power adapter internal circuit has a class 2 rating, just like most laptop chargers; hence the KAYO Maxtar power adapter integrates double insulation that prevents electric shock and fire. The KAYO Maxtar power adapter features at one side a figure 8 female port to plug in the included detachable power cord, as well as a non-detachable cable with a DC barrel plug connector (4.0mm x 1.35mm) at the other end.
As far as safety, The Maxoak K2 power bank comes with a safety warning to remind users to use the correct voltage for the device they intend to power/recharge because you may well damage the device if it doesn't have over-voltage protection. Most devices these days though, have intelligent circuitry that detects voltage automatically to prevent any damage.
Being a 185 watt hours (Wh) power bank, the K2 powerbank is well above the 100Wh passenger airline threshold, meaning you won't be able to take the Maxoak K2 on a plane, not even in checked baggage.
Other accessories included with the K2 power bank are a USB-A to micro USB cable and a neoprene pouch to carry or safely store the Maxoak K2 power bank. Being neoprene (rubber), the pouch provides moderate shock-absorbing protection against bumps.
The neoprene pouch has two pocket compartments. One for the powerbank, which has dual zippers, while the second (front pocket) has a single zipper. The zippers have stocky hard plastic pull tabs and a reverse coil design, which provides some water resistance, although not waterproof like neoprene. You can buy the Maxoak K2 laptop power bank on Amazon.

If you  like the idea of being able to recharge any electronics, including 100~230V devices, anywhere you may want, check out the AL390 Power Bank by XTORM!
The XTORM AL390 Laptop Power Bank is a super powerful power bank with an internal 18000 mAh lithium battery and external AC socket that allows you to plug any 100~230V devices directly into it.
You can charge your laptop, macbook, smartphone, tablet, a lamp, a shaver or fan, all simultaneously without mains electricity. The AL390 Power Bank is essentially mains electric power on the go. If you're plugging in a device that is compatible with multiple voltages, then an adapter is all you need
When the 18,000 mAh internal battery of the AL390 Power Bank is fully charged, you can recharge your smartphone 10 times before having to charge the power bank again. To charge the AL390 Laptop Power Bank, you simply plug it into mains via the supplied AC adapter.
The XTORM AL390 Laptop Power Bank also comes standard with 2 USB charging ports that allows you to charge two USB devices simultaneously.
The AL390 18,000 mAh Power Bank consists of two USB ports, a power/check switch and an AC power switch that switches the AC output ON or OFF. The USB ports have an output of 5V/2.4A each.

With a 20-minute recharge time, the ElecJet Apollo graphene-based power bank takes the meaning of "fast charging" to a new different level!
The ElecJet Apollo power bank stores 6000mAh of electric power very fast via a USB C port that integrates both Quick Charge 3.0 and USB PD 3.0 technology that lets the Apollo powerbank be able to handle up to 60W input current from a 60W USB C adapter; hence how the ElecJet Apollo 6000mAh powerbank can be fully recharged in just 20 minutes.
USB Power Delivery 3.0 is backwards compatible with USB PD 2.0 and works pretty much the same way, meaning the Apollo powerbank is able to handle different voltage ranges from 5V, 9V and 15V. This means, you can virtually use any USB C power adapter such as the Nintendo Switch 45W adapter or any Apple MacBook adapters (29W, 61W and 87W) interchangeably to recharge the Apollo powerbank.
The other main benefit that really sells the Apollo powerbank aside from the fast and furious charging is battery safety. The Apollo power bank is made with graphene cells which are thinner than li-on battery packs, making the Apollo power bank very streamline at just 16 cm long, 7.5 cm wide and 1.3 cm thick.
The battery composition of the Apollo power bank is definitely its highlight as it's a graphene-based battery as opposed to being a graphene-enhanced Li-Ion battery. Being a graphene-based battery makes the Apollo lighter in weight compared to a power bank of similar mAh capacity. Weight is a little over 200 grams which is pretty lightweight for a 6000mAh power bank.
As far as safety concerns, graphene batteries are not supposed to swell and burst when overheated like lithium-ion batteries do, which makes the Apollo power bank even more appealing. The surface of the Apollo power bank is surprisingly cool to the touch too so the Apollo power bank doesn't get hot.
Heat generation in batteries is wasted energy so the less heat generated the better performing the battery is. At least that is the theory. One thing for sure is that the Apollo graphene battery generates very little heat even at high input current so the Apollo power bank should last longer than a li-on power bank.
The ElecJet Apollo power bank has two USB A outputs, one of which supports Quick Charge 3.0 so the ElecJet Apollo can deliver various voltages and currents, including 3A/5V, 2A/9V and 1.5A/15V which provides a maximum wattage of 18W. The other USB A output delivers a maximum of 2.4A at 5V, which is perfect for quickly recharging 40W gadgets such as the iPhone X or iPhone 8 in under an hour, which is pretty amazing considering the standard recharge time for the latest iphones is three hours.
The Apollo powerbank includes a USB C charging cable but if you have laying around a MagSafe adapter with a T-style MagSafe connector or the newer L-style MagSafe connector, you can use the Anywatt USB C to MagSafe adapter to charge Apollo too.