I need to charge, I found $ 1 on Ebay, in a review they write what works, can I take it?
Make a good charge for the money is impossible. Usually there are a dozen parts inside, two of which are jumpers, and sticking a structure into an outlet risks creating a fire in the apartment or getting an electric shock, not to mention damage to the smartphone. The minimum price of USB charging satisfactory quality ~ $ 3.

Written 5V, well, but the current is 2A, a bit too much. Will not the smartphone burn?
More current than the smartphone maker intended, it will not go into it. What kind of current to charge, decides a special chip inside, and not charging, which only provides this chip with room for action. The current indicated on the label is maximum, and the more, the more powerful the charge. Pro voltage see below. If we talk about 5V, it is desirable that the voltage be kept within the boundaries of 4.75-5.50V (see USB standard).

And connect to the QuickCharge charging the old phone? There 20 volts say it happens
Theoretically, smart charging serves to increase the voltage on the device only after “communicating” with it via USB and an old phone cannot “agree” about anything above 5V. Practically, to avoid possible problems (happening, one more), use the device's native charging, or a universal replacement recommended in this topic. P.S. The 20V charging for the microUSB connector was never released, a maximum of 12V, it is easy to see at the value of the filter capacitors, and the label on the case, of course.

Is it true that fast charging kills a battery?
All pleasant bad) But seriously, the greatest harm to the Li-ion battery bring two things: fever and complete cycles of charge-discharge. Fast Charge Technology harmfulindirectly(Eng.) - if the smartphone of it overheats. Try to charge as much as possible without allowing deep discharge (below 10%), a smartphone and avoid overheating. For example, it is not necessary in the summer heat to play heavy 3D games, especially while recharging the smart large current from the ground or middle. Everything else can be, including the officially recommended by the manufacturer charging function QuickCharge, provided that the smart is not overheated. For maximum reduction of battery wear or use QuickCharge, not discharge below 20%, no charge is above 80% (in practice difficult to implement) follow temperature (optimum 30-35 В° C). Together these measures can extend the battery life in half, and individually - by 20-40%link(Eng.) Do not forget also about the advantage of a smartphone with a removable battery - pulled out, replaced, forgot.

What is the difference between Anker, Aukey, BlitzWolf, CRDC, Orico, Tronsmart and UGreen?
It seems that they are produced on the same equipment and one design each. The schematic is unified, only the stickers and the shape of the body / cable sheath are changed. Products with stickers Orico, Ugreen, Choetech, etc., stand out a little apart, but they are not fundamentally different, the quality is the same.

Never heard of these stamps. Can you trust them?
Brands relatively young, but proven, providing the best quality / price ratio for several scroll years. However, the main advantage - they are not fake. Try to buy the original Apple or Samsung battery charger on the Internet or in the city. Do not copy or a good copy, but it is original. Therefore, when choosing between the original charge and thousands of counterfeit stuff for pennies, it makes sense to pay attention to the topic discussed in the brands as a middle ground. Chinese does not mean bad. Technically, these devices are often superior to the original through the use of cutting-edge components and cost-effective solutions schematic.

What is the difference between cables?
Flexibility at different temperatures, the thickness of conductors, a metal resistance part connector, contact reliability, resistance to frequent bending, high-frequency properties. Inside, the most common type in the 2014-2017 years, USB 2.0 micro-B, in four, not including screening, conductor: minus, D +, D-, positive. Found nonstandard type USB-cable data bridged contacts (D + D-), which, in theory, should speed up the charging process, under certain conditions, with a net data transmission impossibility of such a cable. usually sellerswritewhen the tire is closed. For details, see the article describing standards.

Can I leave the charge in the outlet?
The usual recommendation is to take out if you leave home for a long time. With everyday use, you can leave the outlet, like any other appliance with a standby mode: TV, computer. Moreover, the latest models (we are not talking about $ 1 products) smart phone charges have extremely low background power consumption - up to 10 MW