MAXOAK Laptop Power Bank 185Wh/50000mAh(Max.130W) Portable Laptop Charger External Battery Pack for Laptop iPad Phone Notebook

You need to look no further for a reliable 5 STARS power bank.I own a 17” ASUS G750-JM with an intel i7 quad core and Geforce 860m GTX. In terms of electricity consumption, my laptop is definitely power hungry. I have all 4 ram slots full and 2 hard drives installed.Before purchasing the K2 power bank I had purchased another power bank but had to return it because it could not power my laptop, not even when off.With the K2 I was able to get almost 9 hours of power on standby only. Screen saver was off to prevent the screen from turning off. Yes, the power bank kept my huge laptop on for almost 9 hours on standby (not using the computer). This test was performed to figure out how long the laptop could be powered by the K2.I got 6 hours of power under normal laptop usage, I was even able to watch a dvd movie for about 2 hours and still had more than half the power left to do some work and mess around. I should mention that I had an external mouse and keyboard plugged in the USB slots during both tests, and even though the power consumption from these peripherals is minimal, it is something to keep in mind regarding the tests I ran, since in a real life scenario on an airplane for instance, the keyboard and the mouse will not be plugged in, therefore increasing the overall power left from the K2.Keep in mind that both tests were performed using the “high performance” power profile in windows 7. If I wanted to be more conservative, I could have lowered the screen brightness all the way down, turn off the laptop’s keyboard backlight, and put the power profile on “power saver” which overall could have given me a few more hours of juice in both tests, but since I almost never use the power saver windows profile, I thought I would use it under more realistic circumstances that apply to me on a daily basis. The K2 performed fantastic!Things you need to know and consider: The battery will not change my laptop when I am using it. That is because my laptop is a power hungry one (this will probably not apply to your laptop). I have no problem with that because honestly all I want is to be able to use it on the go. So if you own a power hungry laptop like mine, make sure your laptop’s battery is charged all the way before using it, so that the K2 will hold the charge at 100% for 6 or more hours until the K2 discharges completely, then when that happens you can continue to use your laptop’s battery for as long that one will last. If your laptop is a power hungry one and you wanted your laptop’s battery to be charged by the K2, you can do so if you turn off the laptop. In that case the K2 will be able to recharge the battery of your laptop. So, charging the laptop’s battery is an issue only if the laptop is on, but if you do not have a power hungry laptop like mine, you will sure be able to use your laptop while simultaneously charging its battery if it was discharged.This honestly does not bother me because like I said, what matters to me is being able to use my power hungry laptop on the go, which so far other power banks simply have not been able to do.I’ve read the reviews for power banks of other brands out there and they all scared me honestly. I read the reviews for the K2 and I was convinced I could try it with confidence, and boy… I am glad I trusted them!This is exactly what I was looking for. I am really looking forward to trying the K2 during my next international flight and probably being the only one in the plane with the laptop on during the entire flight.All USB ports worked fine. The unit looks really high quality. It’s a bit on the heavier side but listen: we are talking about quality here not something made out of cheap plastic, the unit looks and feels very durable. It can be fully charged over 1000 times. That’s a lot of times… to give you an idea, there are 365 days in a year. Are you going to be using the K2 every day? Very likely not! And if you would, you could do it for about 3 years. That’s a lot of time. Batteries degrade over time whether you use them or not, so more realistically this unit will last me 5 years maybe more, which is plenty of time for me. The original battery from an iphone 3GS lasted me 6 years (it recently died), and that was because I gave it good maintenance. If you plan on having the battery of your devices or power banks last as long as they possibly can, I recommend you to inform yourself about the type of battery your electronic device is using and learn the best practices to maintain the quality and extend the life of your battery. All the batteries of the laptops I have used have lasted me very long because I always gave them great maintenance.I found on youtube what seems to be an official video of the K2, check it out: [...]The customer support for the K2 is among the best I’ve ever ran into. The unit came with a free gift which was another smaller power bank for smartphones and tablet. I thought that was nice. It turned out the small power bank was defective and so I corresponded through amazon with the K2’s customer support. Minutes later I received an email telling me that I was going to get a new small power bank (replacing the free gift) at no cost to me. The person I corresponded to was incredibly friendly and kind. Help was offered to me in case I had difficulties using the K2.Customer support so efficient is what unfortunately you almost NEVER run into on amazon. I can’t even mention the amount of times that sneaky amazon resellers have tried to scam the crap out of me, and have made almost impossible returns of cheap $2 purchases. Shame on them for being such beggars.This is not an issue you will run into with this company. You can buy with confidence.This product is a great purchase at this price. It’s a 50000mah power bank and you are not gonna find another one at this price. Read the reviews! Not only for the K2, but for the other power banks as well. Look for 1 star feedback on amazon and really ask yourself if you want to go through what other people have gone through with other brands. I don’t know about you, but I don’t like to waste my time and do trial and error or hope that I am the lucky one. I like to go with what works. If you are paying less, you are gonna get less. Before purchasing the K2 I thought I could save money buying another power bank, I did it and I wasted my time. After that I went back to the K2. I should have purchased it the first time, but oh well, another lesson learned…Thank you to the people at the MAXOAK for the very fast support given to me and for their kindness. It honestly took me longer to write my review than it took them to answer my inquiry, but I hope this review can help other customers not go through the hassle I experienced before buying the K2.

I've tested several battery banks in recent years, rated from 10,000 mAh to 2,400,000 mAh (the Maxoak Bluetti EB240), but most of them have had severely exaggerated capacity ratings, whehter stated in mAh (milliamp-hours) or Wh (Watt-hours).First, a quick primer: mAh (milliamp-hour) ratings are normally tied to the average voltage of indivdual cells within the battery. For LiPo batteries, this is 3.7V. So, when a manufacturer says that their battery has a capacity of 10,000 mAh, for example, they are claiming that if you attach a device that operates at 3.7V and constantly pulls 1000 mA (milliamps) of current, for example, from a full charge the battery is supposed to last how many hours? Here's the arithmetic:10,000 mAh / 1000 mA = 1 hourBut remember, that's only if your device operates at 3.7V and the battery pack provides a 3.7V output port. Instead, these battery packs have ports designed to support devices that operate at voltages no lower than 5V (USB ports). So how does that affect the arithmetic? If it's a 5V device that again pulls 1000 mA of current, then...(10,000 mAh / 1000 mA) * ( 3.7 V / 5.0 V ) = 1 * 0.74 hour = 44.4 minutesSo, the higher the voltage of your device, the fewer hours of operation you will enjoy, even when comparing devices that pull the same amount of current (at those different voltages).Therein lies the confusion with these mAh capacity ratings. So here's an equation you can use for translating the alleged capacity of a battery bank, obfuscatingly stated in mAh for 3.7V, into hours of operation for any given device for which you know its operating voltage and how much current it pulls:Hours = (rated capacity in mAh / mA pulled by your device) * (3.7 / voltage required by your device)For example, if you have a device that pulls 2 Amps (which is 2000 mA) at 5V, a battery rated at 20,000 mAh would theoretically last...(20,000 / 2000) * (3.7 / 5) = 7.4 hoursIt's made a little more complicated by the fact that these capacity ratings given by manufactuers do not communicate the fact that their battery management systems (BMS) are designed to prevent you from draining out the the last 10% of capacity, which can permanently damage the cells. And this percentage isn't carved in stone, so some manufacturers might set a bottom at 15% remaining while others at 8%. Who knows? They don't tell us. But it's safe to assume that you will never be allowed to drain a well-designed battery all the way down to 0%. Even if it has some sort of indicator that uses % readouts, 0% is not 0%. It's something around 10%. So, we must modify our equation, as follows:Hours = (rated capacity in mAh / mA pulled by your device) * (3.7 / voltage required by your device) * 0.9Even so, we have a bunch of fly-by-night manufacturers out there who grossly exaggerate the capacity of their batteries. I've seen YT videos where reviewers have disassembled allegedly 100,000 mAh battery packs and found only a tiny 3,500 mAh battery inside the much larger case. And I have personally bought, tested and returned battery packs with capacities exaggerated 2 to 3 times their actual capacity.Enter the Maxoak K2, that I'm here to review. It's a breath of fresh air.First, Maxoak provided capacity soecifications in both mAh (50,000) and in Wh (185).Uh oh! You thought class was dismissed?Come back! There's more to learn.Your giant brain can handle it, I promise!Unlike a mAh rating, a Watt-hours (Wh) rating expresses the capacity with no dependence on the voltage or the curent demand of any given device. Wh is, therefore, in my opinion, a far more useful and less confusing unit of measure of the total energy a battery can deliver.Wh = Ah * VNotice that this equation is using Ah, not mAh (amp-hours, not milliamp-hours).This Maxoak K2 has a rated capacity of 185 Wh = 50Ah * 3.7V = 50,000 mAh * 3.7VSo, the arithmetic checks out perfectly for the Maxoak K2's two capacity soecifications. I've seen specs from other manufacturers who might actually provide a Wh rating, but when you do the math, it doesn't jive with the mAh ratting at 3.7V. Doh!If you can find a battery pack that has both ratings, as does the Maxoak K2, here's an equation you can use for translating the alleged capacity stated in Wh, into hours of operation for any given device for which you know its operating voltage and how much current it pulls:Hours = (rated capacity in Wh / Amps pulled by your device / voltage required by your device) * 0.9Notice that this equation is using Amps, not milliamps.OK, class dismissed. But wait - you came to get a review of the Maxoak K2, right?In three sencences, here's my review:The Maxoak K2 is not only one of the very few power banks I've tested that actually delivers 90% of its rated capacity - 168 Wh (the most one should expect) - and that capacity is enormous considering the price (not to mention the superb build quality), driving a 2 Amp load at 12V for a whopping 7 hours, for example, from a full charge, or a 1 Amp load at 5V for an insane 33.6 hours.I measured those results, but they calculate perfectly as 2A * 12V * 7 hours = 168 Wh and 1A * 5V * 33.6 hours = 168 Wh.Get one, you'll love it, but don't be surprised by its weight and size.