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37 votes

What is the ideal way to handle data pins D+ and D- on a USB power adapter to be compatible with fast charging on devices?

I found this page answers your question clearly. I quote the relevant parts below. The BC1.2 outlines three distinct types of USB port and two key monikers. A "charging" port is one that ...
37 votes

What is the ideal way to handle data pins D+ and D- on a USB power adapter to be compatible with fast charging on devices?

What is the ideal way to handle data pins D+ and D- on a USB power adapter to be compatible with fast charging on devices? ... I am hoping to figure out which method provides the best compatibility ...
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32 votes
Accepted

How come charging bricks don't work backwards?

It just doesn't work that way. It's a different operation so different hardware is required. Like how running an signal backwards through an adder won't make it subtract. The circuit itself has a ...
  • 49.6k
28 votes
Accepted

Why some phones need a 5V charger although the battery needs 3.7V only?

If you look at the charge profile of a lithium battery you'll see that at certain points it changes from constant current to constant voltage charging: - This means that some form of "in series" ...
  • 396k
24 votes

How come charging bricks don't work backwards?

The 120V AC to 5V AC transformer inside your brick works both ways. But that is possible only for AC to AC. The "problem" is the 5V AC -> 5V DC conversion ("rectification") that ...
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21 votes
Accepted

Why doesn't my computer USB port break when I plug in a 2A device?

To be compatible with the original standard, USB devices should not draw more than 100mA (which is plenty to power the logic interface), until they have negotiated with the host, to find out what it ...
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19 votes
Accepted

For how long should I charge my dead car battery without damaging it?

A typical Pb-Acid car battery is charged with around 13.8V. So 13V will be fine. A battery trickle charger is a voltage source, meaning that as the battery voltage rises, the charger puts less ...
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16 votes

Why doesn't my computer USB port break when I plug in a 2A device?

Historically: really old mainboards connect USB power pins to the 5V power rail, with no protection power on by keypress was added, which added a jumper or a BIOS setting that decided whether USB ...
15 votes
Accepted

How can I use two TP4056 with two li-ion batteries, but single load?

Don't. Just use one TP4056 and connect both cells in parallel after balancing them first. Don't connect batteries with more than 0.2V difference in parallel as this can risk fire and explosions (...
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13 votes
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TP4056 Lithium Charger Module issue

I'm not going to try to answer all parts of your description, since part of the problem is that the charger is being used incorrectly. Only after that is resolved, might it be worth investigating the ...
  • 16.8k
13 votes
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What is the function of "Picture tube charger"?

I was thinking "just use google", but then I saw a comment suggesting that many people wouldn't even know what to look for... A common kind of vacuum tube failure is when the gain just gradually goes ...
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12 votes

Why some phones need a 5V charger although the battery needs 3.7V only?

Another reason is standarisation - a few years ago the EU pushed for standarisation of the charging connector in phones which ended being micro USB. USB implies 5V. And as a personal note I worry ...
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12 votes
Accepted

How do cheap phone chargers charge li-ion batteries?

The device (phone, etc.) has the special charging circuit built-in. And the battery pack typically has a special circuit inside to prevent excessive discharge (or charging). Li-ion battery cells are ...
11 votes
Accepted

Is there a reason GaN chargers stop at 65W?

If the input power of the adapter is less than 75W, you don't need a power factor correction stage (by EU and other regulations). So they are easier to design, and they hit the largest segment of ...
  • 20.6k
11 votes

For how long should I charge my dead car battery without damaging it?

If you took it all the way down to 3V, it's probably already significantly compromised. I know they're expensive, but you really should consider replacing it. The sulfer in the acid precipitates ...
  • 4,236
11 votes

For how long should I charge my dead car battery without damaging it?

I would say toss that battery and get a new one unless you don't have strong preferences whether it drops you or not. Typically when they get discharged down that far they don't come back much, if at ...
10 votes

What is the ideal way to handle data pins D+ and D- on a USB power adapter to be compatible with fast charging on devices?

2017 update: There is no ideal way to handle USB data pins to provide compatibility and "fast charge". There could be many different chargers, and there are many USB devices/phones/tablets that need ...
  • 37.7k
10 votes
Accepted

Buck Converter for 59V to 58V?

simulate this circuit – Schematic created using CircuitLab Figure 1. \$ V_{OUT} = V_{IN} - 0.7 \$. A silicon diode will drop about 0.7 V when more than a few milliamps is running through it.
  • 163k
10 votes

How come charging bricks don't work backwards?

Most power supplies have a passive filter. The filter reduces (or output rectifier) the frequency from 60Hz (or 50Hz to DC and smooths it out with a loss in energy.) This smoothing for filters happens ...
  • 65.3k
9 votes

How can I extend this circuit to use it in our real life?

The circuit you have shown WILL NOT WORK: - It shows a transmitter and receiver of power (top and bottom). The transmitter of power has some kind of rectifier THAT WON'T WORK - both diodes are facing ...
  • 396k
9 votes

Could smartphones benefit from the same charging mechanism as in electronic watches?

Feasible: yes Useful: no, because the power needed by a smartphone is orders of magnitude larger than what such a (kinetic) generator generates. A (non smart) wristwatch needs only very little power,...
  • 79.1k
9 votes
Accepted

Charging a 3.7 V with a 5V usb charger

Ok, so you aren't actually asking the right question. I'm going to assume you mean you have a 5V power source (usb, battery pack, etc.) and want to charge a single cell lithium ion battery with ...
  • 291
8 votes

How does a USB 2.0 Wall Charger negotiate current output?

there is no detection on the charging port side, and the charger should always output IDCPIDCP {0.5 - 5.0A max} on the VBUS line - is this correct? I don't understand this completely, because the BC ...
  • 28k
8 votes
Accepted

Will the lower frequency of 50Hz AC affect overall charging time?

No it won't have any effect. The 220v or 110v AC at 50 or 60Hz is stepped down to a lower voltage and rectified to DC before it is used to charge anything. So since the actual charging uses the ...
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8 votes

Battery balancing circuit

Charging one battery from the other will result in overall drop in efficiency and run time. Consider that energy will be lost in the charging circuit and in heat losses of both the battery powering ...
  • 163k
8 votes

Is it possible to convert 19.5V 3.33A to 12V 5.5A?

The answer to your header question is NO! Input 19.5x3.33 = 64.935 Watts. Output 12x5.5 = 66 Watts. So your new output power is higher then your input power which is against the law of conservation ...
  • 14.1k
8 votes

Charging phone battery with a lower voltage, coming from a bike charger?

First of all, the USB is not being fed directly to the phone’s battery. It’s actually being fed to the battery charger circuitry inside the phone. You cannot safely directly connect a normal regulated ...
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8 votes
Accepted

Why can't I replace conventional batteries with rechargeable batteries everywhere?

An alkaline cell has a nominal voltage of 1.5 V when new. A NiMH cell has a nominal voltage of 1.2 V when charged. Your equipment might be expecting a higher voltage than the NiMH can supply.
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8 votes
Accepted

Can a LiPo battery be charged directly from a 5V wall charger?

No, a 5V source is not suitable for this. Battery management systems will refuse to charge cells that are under-voltage because it generally isn't safe to do that. You can, however, manually jump-...
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