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Dear XDA, i really need your help,
I am planning to make this (see thubnail)
i want to make a custom case for my htc one s. (I know it will be a little bigger but that's ok)
I want to charge my phone using a usb cable or a micro usb cable, and at the same time doing OTG. I don't know what resistor i will use yet (tips?)
Also add an extra battery. It is an old phone battery. So if i want to charge from the battery i need to stop the solar cell and guide the electricity through the 5v regulator to charge. What ya think?
I am new to modding so please comment cause i need a lot of help to make this one succeed!
Greetings, pro-one1000
sent from htc one s ville
Don't mean to be negative but I see a couple issues right of the bat. First, where are you going to get a 5 volt charger? I would guess most dc chargers are going to be 12, 24, or 36 volts. I don't think they'll run on significantly less. The solar panel is only going to output about one half of one watt. Assuming no friction loss or inefficiencies that would hardly slow your phone's discharge.
If you want to power the phone and hub I would suggest a small sealed lead acid battery. They're available in 12 volts in many sizes. Easily enough power to keep phone totally charged. Will work with cigarette lighter car chargers so you won't need to customize that part. Depending on the size it'll last a week to a month non-stop. Unfortunately, it probably won't fit in your pocket but if you carry a book bag or briefcase you could hide it there... I use a battery like this at work when I'm using a lot of phone battery and moving around too much to plug in.
Good luck with which ever route you choose!
Sent from my HTC One S using xda app-developers app
thanks
lampel said:
Don't mean to be negative but I see a couple issues right of the bat. First, where are you going to get a 5 volt charger? I would guess most dc chargers are going to be 12, 24, or 36 volts. I don't think they'll run on significantly less. The solar panel is only going to output about one half of one watt. Assuming no friction loss or inefficiencies that would hardly slow your phone's discharge.
If you want to power the phone and hub I would suggest a small sealed lead acid battery. They're available in 12 volts in many sizes. Easily enough power to keep phone totally charged. Will work with cigarette lighter car chargers so you won't need to customize that part. Depending on the size it'll last a week to a month non-stop. Unfortunately, it probably won't fit in your pocket but if you carry a book bag or briefcase you could hide it there... I use a battery like this at work when I'm using a lot of phone battery and moving around too much to plug in.
Good luck with which ever route you choose!
Sent from my HTC One S using xda app-developers app
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Click to collapse
Thanks for your reply!
First about the charger, i will use my 5v 1amp charger (micro usb) or an usb male to male usb cable from my pc to charge. So i'll be able to get a charger.
You're i think right about the solar panel, i need to find a better one indeed, trying to get one cheap on ebay! If i try to search for a "smal sealed lead acid battery" i get 40 dollar + big cases of batteries, could you please give a example in the form of an ebay-link?
Anyway thanks a lot and when i have ordered the parts i will try to upload the stuff!
Greetings
I'm assuming the 5v charger you're talking about it a car charger; which means it would have an input voltage of 12 - 14 and won't run on 3.7 (and even if it could run on the lower voltage the amperage would go up dramatically draining the usable power in the battery in minutes. And I wouldn't connect anything to a USB port for two reasons: first, if you connect two batteries in parallel (red to red and black to black) and they're not identical one will usually drain the other as they try and equalize (unless you isolate them from each other). Second, I don't think most USB ports (USB 3.0 i believe has provisions to receive power) are designed to receive power on a computer and your schematic doesn't include anything to prevent back feeding power to the computer.
There are many solar chargers I've seen that would give you the output you need - I've seen them designed to trickle charge RVs, boats, cars, and motorcycles - but I think they would be way to larger for what your looking for.
And I guess I should clarify what I meant by small... Was a bad choice of words for a cell phone forum, I guess. I meant small relative to other lead acid batteries; i.e. car or boat batteries. This is similiar to what I use:
http://www.ebay.com/itm/12VOLT-5AMP...US_Rechargeable_Batteries&hash=item589ef11aed
Attached is a pic of my batteries and the adapter that gives me a cigarette lighter type receptacle. And I use a spare motorcycle float charger to keep them charged. And because they're 12 volt batteries they'll power and accessory that is designed to run in a car.
I guess I should probably have asked what is your ultimate goal? And do you carry anything where you could stash the battery?
giesse1996 said:
Thanks for your reply!
First about the charger, i will use my 5v 1amp charger (micro usb) or an usb male to male usb cable from my pc to charge. So i'll be able to get a charger.
You're i think right about the solar panel, i need to find a better one indeed, trying to get one cheap on ebay! If i try to search for a "smal sealed lead acid battery" i get 40 dollar + big cases of batteries, could you please give a example in the form of an ebay-link?
Anyway thanks a lot and when i have ordered the parts i will try to upload the stuff!
Greetings
Click to expand...
Click to collapse
Thanks for your reply,
After thinking I want to use a second1-5 volt boost regulator attached a small high capicity battery of 3.7 volt. (like a galaxy sIII battery or something. So if i put the switch to on the extra battery should charge with 5v my phone battery. Or i could charge my phone directly from a high efficient solar cell with 5v.
I indeed have no idea how to prevent backfleeding. Do I need diodes / light emmitting diodes for this? And indeed the batteries you mentioned are way to big. I am planning to use an old battery from an other phone with the 5v boost regulator mentioned above. Further i don't understand where you see a computer in my scheme?
Your mod ( i think i it deserves that wonderfull name) with the 12v battery is a good idea. Very handy when going out without a charge point. I usually go to school and am probably able to put the large battery in there, but as i mentioned i want to keep it a "phone case".
My ultimate goal is to make the tiniest possible case for the htc one s ville with,
- a very small usb hub 4 port for 3 female ports and inside a micro sdhc memory for more storage.
- Add the charge ability, so i don't need to take the phone out of the case to charge
- be in otg mode and charging mode at the same time (i guess the hardest challenge)
optionary:
- Add a battery so when i get the actual phone out of the case the solar cell can keep providing power to the battery
- Add a solar cell
- make it actual work with multiple switches
Really appreciate your help!
Greetings,
I misunderstood "First about the charger, i will use my 5v 1amp charger (micro usb) or an usb male to male usb cable from my pc to charge" to mean you might have a computer available to charge. I guess you just meant the cable itself. Understood.
I'm not an electronics expert by any means but yes I believe diodes will prevent the current from flowing in an undesirable direction but they won't prevent one battery from draining another. Two batteries connected in parallel can drain each other and the diode will slow that but I don't think it will eliminate it. Might be able to mitigate the affect by opening one of your switches when the auxiliary battery is not in use. When two batteries are wired in parallel they are frequently connected to an isolator that has three terminals (for a two battery setup). Terminals one and two go to batteries one and two and terminal three goes to the system it's connected to. Batteries one and two never 'see' each other and therefore cannot affect or drain each other.
Not sure I have anything else that can really help... GOOD LUCK! And post pics and details if you build a working prototype.
Thanks again!
I'll try to order a couple extra diodes with low consuption, that plus the switches will hopefully do the job. I ordered yesterday the parts out of China, so it'll take a month to get it in my hands. Now I have more time to consider how it can be assembled all together, but if i get anything i will post it directly!! If it works i may try to make a tutorial for other people so they could also enjoy more ports on their phone!
Greetings
Does anyone know if there is any way to use the Surface RT with an external battery pack?
I know there are surface RT compatible powerbanks on sale right now but those are really expensive!
Afaik, the surface charges with 12V whereas USB ports output at 5V.
The only difference that I can tell is that the power output is different. This should just result increased charging times but should not have any safety issues at all.
If you aren't aware what a difference between 12v and 5v means in electronics, you probably shouldn't be giving advice like "should not have any safety issues at all". I mean, you're probably right in this case (though only "probably") but if you think that voltage = power output, it's only by sheer luck.
To answer your actual question, I am not. However, I strongly advise against simply... experimenting with this sort of thing on your own. You could easily start an electrical fire, damage your tablet, or do one of many other unpleasant things.
The surface uses a 7.4V battery pack. Attempting to connect a 5v supply to charge without a stepup converter will not charge the surface at all and instead lead to damaging your 5v supply as the surface attempts to supply 7.4v to it, which may also damage the surface too.
In electronics nothing is more important than the correct voltage. Take a raspberry pi, many people (including myself) use them for electronics projects. Both me and a friend added ultrasonic rangefinders to our pi's except I observed the fact that the module in question uses 5v signalling and my friend did not. We both connected the +5v and ground lines to the corresponding points on our pi's. I connected 1 GPIO pin of the pi to the trigger pin of the HC-SR04 (module in question) as did friend. The pi uses 3.3V on its GPIO pins, the HC-SR04 is safe with a 2.7v-5v trigger voltage, thats fine. The echo pin however is +5v. I ran my echo pin through a voltage divider to give myself a 3.0v output instead, this is safe for the pi (it is fine with 2.7-3.3). My friend did not, he connected the echo pin direct to the pi, tried to use the sensor for the first time ever and found he didnt get any results, do a few test lighting an LED and he found he could no longer use that pin, he damaged it.
I would be more concerned about the surface damaging the supply than the other way around in this case.
However you are correct in believing the device charges at 12V (2A or 4A depending on whether its an RT or pro charger). The surface would have the correct voltage regulation to charge the battery and supply 5v to USB internally. There are 4 wires within the charger. Red: +12V, Black: Ground, Blue: charger detection, Yellow: signal for the charger LED. I don't think its known *exactly* how the yellow and blue wires function, the surface does charge without them. Blue is rumored to be something to do with the RT charger identifying itself as a 2A device and telling the pro to not draw more than 2A (it draws 4) hence damaging the charger but exactly how it does that is unknown. If the 12V supply can supply more than 4A your golden. A supply capable of higher currents than the device needs is actually perfectly safe, current is drawn by the device from the supply, the supply does not force the current at the device. If a device requires 2A and the supply is capable of 10, the supply will still only give out 2 as that is all the device is drawing. A device drawing more than the supply can cope with on the other hand IS DANGEROUS. Lets say you were to use a 5v>12v converter from a computer USB port to charge a surface, a computers USB only supplies half an amp under normal conditions (and by shorting D+ and D- it can do 1.2), the pro trying to draw 4 combined with the inefficiency of 5v-12v stepup converters will cause a current draw so large on the USB port that I would be surprised if damaging the USB port is the only thing to happen, you could fry the entire USB controller easily, damaged USB controllers can then cause their own issues, primarily with this amount of current the possibility of fire.
If you want to charge your surface. Find a voltage source *above* 12V (but not too high above) and use a voltage regulator to make a clean 12V. Then make sure both the regulator and battery can cope with the current. The regulator will determine how far above 12V you are safe to go, some might safely regulate 100V to 12 (most likely a switch mode regulator which although highly efficient won't output a clean 12V, it will have alot of voltage drops and spikes) whereas some might only do 20 to 12 (linear, much less efficient but a very clean 12v, stick a heatsink on it as they get warm). A car battery btw is not 12V, its 12.6 nominal and when fresh off the charger as much as 14.
Yeah, I know the basics of electrical physics. Not a complete speculating noob.
P=IV
Power of a 5V 2.1A is 10.5w
The original power adapter supplies 12V at 2A = 24w
My physics may be rusty but, I was under the impression that it would still charge at lower power output albeit half as fast. I've read that the RT when using the 48W charger would still charge at the same rate as the 24w. This means that the current that is drawn by the surface rt is capped at 2A. Hence, I believe that there would be any significant issues with drawing 2A from a charger that is designed to output 2A anyway though at a lower voltage.
If I'm still wrong here, would love some clarification.
lambstone said:
Yeah, I know the basics of electrical physics. Not a complete speculating noob.
P=IV
Power of a 5V 2.1A is 10.5w
The original power adapter supplies 12V at 2A = 24w
My physics may be rusty but, I was under the impression that it would still charge at lower power output albeit half as fast. I've read that the RT when using the 48W charger would still charge at the same rate as the 24w. This means that the current that is drawn by the surface rt is capped at 2A. Hence, I believe that there would be any significant issues with drawing 2A from a charger that is designed to output 2A anyway though at a lower voltage.
If I'm still wrong here, would love some clarification.
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Click to collapse
The wattage is not of concern. The voltage and current must be treated independently. Also, consider that you are trying to charge a 7.4v battery from a 5v supply, the current will not flow from the 5v to the 7.4v (assume old electrical flow not real electron flow), it will end up doing the opposite, 7.4v flowing towards the 5v.
So lets say you step up the 5v to 12v, there is inefficiency in doing that. To get 12V @2A you would not be drawing 5v @2A, you would more likely be drawing 5V @4 or 5A.
As 6677 says, the Voltage and current (and not the power) are what matters. Power (Wattage) is a derived value (and you correctly gave the derivation); it's handy for making comparisons when certain core assumptions are valid but meaningless on its own. In this case, the core assumptions are *not* valid: not all chargers are producing the same Voltage.
To take another example of where assuming all Watts are created equal would get you in trouble, consider an incandescent light bulb. Light bulbs are rated in Watts because incandescent bulbs operate by turning electrical power (Watts) into heat (also measurable in Watts) via resistive filaments that can only dissipate a limited amount of heat. Thus, a 60W bulb has a filament designed to dissipate 60W of heat. However, since power is a derived value, let's look at what it actually means: In the USA (mains run at about 120V) we can use Ohm's Law: P=I*V; V=I*R, so I=V/R, so P=V*V/R=V^2/R, so R=V^2/P. Therefore, the resistance of a 60W bulb in the USA is (120^2)/60=2*120=240 Ohms. Cool. Now, let's take that 60W bulb from the USA and connect it to European mains. It should still consume 60W of energy and produce the same amount of light, right? After all, it says "60W" right on the box! Hmm... but European mains run at 240V. The resistance doesn't change; it's a physical property of the filament. So, using P=V^2/R, we get P=240*240/240=240W That's four times as much as the bulb is meant to handle; it will flash very brightly (much brighter than normal) and burn out instantly! The bulb isn't defective, it just wasn't made to handle 240V. The "60W" on the box is based on an assumption of 120V; the bulb itself does nothing to ensure that it only consumes 60W.
While the basics of Ohm's Law will equip you to understand things like I describe above, it is *not* enough (by itself) to make assumptions about complex electronics. Even a 101-level electrical engineering course will make that abundantly clear; there are many more forces at play in the world of electronics than the familiar and relatively-easily-understood Voltage, current, resistance, and power.
Thanks guys for clearing the air. Man, I thought it would have been possible to jerry rig a Surface Charging USB cable to be used with battery packs.
So from what I understand, to avoid unnecessary complications, it would be best to find a way to supply 2A @ 12V. Obviously finding a power supply that natively does so is most ideal. But there is an alternative of stepping up the voltage from 5V to 12V with will lead to losses due to conversion inefficiency which basically rules this out.
12V Power Bank
I found a 12V 2.5A external battery pack listed above. This seems to work doesn't it? It has a 12V output with a max draw of 2.5A. The Surface RT draws a maximum of 2A from your power source. I can simply splice the provided cables with the Surface Charging Cable and it sounds to me it'll work.
Since the Surface RT is reported to have a 31.5Wh battery, this battery pack seems to have a 78Wh battery making it rather ideal.
If it is indeed 12V @2A or more then yes, it should charge an RT
Use a power gorilla I use one for my macbook pro and other usb items
Just saw flyer for Surface pro/RT powerbank
Got an email with flyer for Surface + laptop Powerbank. I haven't put an order yet but you can check it out at -> qi-infinity website
It seems they already include Surface adapter and its on sale. I have Lenovo X1 carbon laptop and they have proprietary connector for that one included as well. So I might go with them
I've got a plan to install the sony DK48 magnetic dock into my car.
I intend to fix the dock to the top of the dashboard using velcro (so that it can be removed if necessary). I'll bend some thin black acetal plastic rods and glue these onto the dock to stabilise the phone in the dock. I'm going to solder the charging cable onto the cigarette lighter socket, run the cable behind all the fascia panels, the radio and up to the top of the dash.
Anyone got any advice on soldering a usb charging cable onto the cigarette socket. At the moment I'm planning to use the electrics out of a dismantled USB-cigarette socket, but wonder whether it might be better/neater to solder the cable straight to the socket with correct resistors in place, but I'm not sure exactly what I would need.
Anyone got any other advice?
Hoping to get this done sometime next week and will post photos if it all works.
Whoa whoa wait a minute... Sorry if I am reading what you are saying incorrectly but are you saying you want to consider just solder the usb cable directly on to the cigarette lighter and use some resistors to split the voltage so that you will get 5V at the charger??? If that is the case do not do that! A cigarette lighter is 12V so if you can get the resisters to be 7V that means the charger is 5V right? No! It's not that straight forward. Thing is that yes a cigarette lighter is 12V... but it's not a constant 12V. The voltage is just happens to be whatever it is at the time. It ranges from like 10V-15V depending on if your car battery is low or the car is running. When charging the car battery the voltage has to be higher than 12V. I know in my car it's about 14V when running. So when your car is running the cigarette lighter would be 14 and you would be shoving too much voltage into the Z3. Defiantly don't want to fry that expensive Z3!
So yes you defiantly want to keep the circuitry for the car charger. What the circuit does makes it so that it outputs a clean constant 5V with up to 2.1A of current (depending on the model). It cleans up any spikes that may come from the alternator and has safeties on top of that to make sure neither too much voltage or current will end up in your usb port.
Back to your original question. If you can get to the wires right behind the cigarette lighter (behind/under the dash) you could splice into the wires there. There is usually a lot of space you can shove stuff in there. Get something like this:
http://www.ebay.com/itm/12V-Female-...ocket-Plug-Connector-Plug-Cable-/271275968209
And just splice it into the wires. Just two wires, cut, strip, solder, tape and done. No disassembling of charger is needed. Plug in your charge to the socket and run it up your dash. Just keep all of that hidden behind all of the panels and no one can tell you even tapped into the cigarette lighter.
Side note: Please please please do not buy a dirt cheap car charger. Like some random $1 eBay charger from China. There is a reason why it's $1. Short answer: the electricity coming out is probably questionable. Also there probably no safety standards. This rule usually applies more to the AC wall adapters (those $1 AC adapters you should avoid like the plague!) but I prefer to live by the same rule. If the electricity coming out of it is dirty then you will be slowly killing your battery quicker than normal. You will start wondering why your battery life is so poor probably like after a year...
Good point about the variable voltage coming out of the car socket. I'll do it the safe way then and use the hardware from a usb/car adapter. The rest *should* be easy.
Just in case anyone is interested I installed the Sony Magnetic Charging dock onto the dashboard of my car. The magnets hold the phone very well, its stable, and hasn't fallen out in 6 months use. I wired a usb cable from the 12 V socket via a 12V - USB adapter as suggested above.
I'm very pleased with the end result and have a neat method of using my phone as a satnav without all the mess of sticking a holder on the window and cables running everywhere. Its also much quicker to place the phone into or out of the magnetic dock than it is to clamp it in a normal holder.
I need a lesson on how USB charging works and what Watts, Volts, and Amps are and how they are different.
Also, does the USB cable play a role in the charging process? As in, are all USB cables capable of transferring the same amount of power?
I have a LG G3 and want to buy a portable charger, but want to make sure I will buy one that is fast enough and will be supported.
Any help is appreciated.
Volts, amps, watts? Check out the Wiki, they're doing great.
Of course, the cable plays a role in the process, e-very-thing plays a role!
The original USB specification was not originally developed with high power delivery in mind, thence it all started with a measly 5V, something which can pose a real problem when delivering high currents because, as voltage drop is proportional to conductor resistance, nasty cheapass cables can cripple current flow badly (so little volts we can't allow to drop them much).
Wanna see an example of a “that sh1te rocks” cable? Check this out: No frills USB to MicroUSB Heavy-duty Cat-5e 5ft/1'5m cable (No one trashes Jersey city! Uuuh, but me. :laugh
Brief summary: for a cable gauge/section is your ally, lenght your enemy. Aiming at keeping the same voltage drop between the supply (charger) and the load (device), the wire section will have to be proportional to its lenght (equal conductor resistance).
Tips: a reduction of 3 points in the AWG scale is about equivalent to doubling the section; -6 points means around double diameter. For example, AWG22 wire has about 4 times the section of AWG28 (4 times the current delivery, lenght being equal of course). And that (AWG22) is about the minimum gauge required to guarantee 2'1A of current flow through 2 meters of cable while still having just some chances of meeting the USB2.0 specifications (±5% in voltage).
Regarding the PSU (yes, Power Supply Unit), buy some decent brand name one. These things charge nothing, they're just power supplies (I've only seen one “charger” with active load voltage compensation; an LG unit which I converted to microUSB and have somewhere lying around).
It's the power management circuitry of your device the master who owns your battery, not the c̶h̶a̶r̶g̶e̶r̶ supply. The battery receives the remaining energy available from that circuitry (up to the maximum charging current for which it is programmed to deliver) after feeding the guts of your device (and minus innefficiencies). That's the reason your phone barely charges if you're USB connected (500mA) while operating it, because only around 2'5W of power are being delivered (5V×500mA) and, after substracting SoC + screen consumption figures plus power conversion innefficiencies, you may still be lucky if your battery “gets some”.
Charger reviews: http://lygte-info.dk/
Don't know about your device but, if it supports Qualcomm QC protocols you may as well benefit from a QC2.0 compliant charger.
Hope this helps. :silly:
Cheers
My Samsung charger died recently so I tried to replace it with this one from ebay. As soon as it arrived I could tell it was fake but thought I'd share what I found so that others can see what to look out for.
The main giveaways were:
Lettering is poor quality - an official charger has a very high resolution print screen and parts of the letters are not missing.
Poor build quality - the earth on does not move up and down properly.
Use of Philips screws - the official charger uses torx screws.
Quick Fast Charging - Samsung have never used this branding.
I then decided to take both chargers apart to see how different they were. I've attached the pictures, the genuine charger is on the left and the fake is on the right. It's amazing how much difference there was between the build quality. I managed to pop the back off of the fake charger with not too much force but I really had to pry open the genuine one before it eventually gave in. Once the back was off, the PCB in the fake charger slid out really quickly but I had to prise the genuine PCB out, which is why there is a bit of damage to the USB port.
IMO the easiest way to check charger without disassembly it is:
- Checking the letter for typo/the ink are too bold/ you can feel the letter with your finger then it's a fake one
- Check for the USB contacts, official charger usually gold plated
- Check for weight, fake charger use fewer component => fewer weight
- Official charger did have a circuitry built in to make it work with Fast Charging capability device, meanwhile the fake charger are not, obviously it will not able to do the Fast Charging
For the electrical safety:
- On the fake charger, the secondary (USB) are not having enough clearance to the mains side (240v), this could leads to your phone get fried if there is a high voltage spike in the mains causing it to arcs over and you could risk the life of yourself if you're touching the metal parts on the phone, you can clearly see the 8th image of the official charger having a plastic separation between the secondary side and primary side to prevent such arcing occurs.
- Transformer of official charger use 2 layer insulation (magnet wire with a rubber sleeve, you can see the secondary winding of official charger coming out in 9th picture with red and white wire) for the secondary side meanwhile on the fake charger just a bare magnet wire so you're risking yourself if the secondary winding somehow touched the primary winding because of the insulation is so thin, it will broke off because of heat during use.
- Official charger use proper, big class Y capacitor (the cyan color thingy) meanwhile the fake charger use a smaller one, if this thing get fault and shorted then your phone will get direct contact with the mains side.
sandpox said:
IMO the easiest way to check charger without disassembly it is:
- Checking the letter for typo/the ink are too bold/ you can feel the letter with your finger then it's a fake one
- Check for the USB contacts, official charger usually gold plated
- Check for weight, fake charger use fewer component => fewer weight
- Official charger did have a circuitry built in to make it work with Fast Charging capability device, meanwhile the fake charger are not, obviously it will not able to do the Fast Charging
For the electrical safety:
- On the fake charger, the secondary (USB) are not having enough clearance to the mains side (240v), this could leads to your phone get fried if there is a high voltage spike in the mains causing it to arcs over and you could risk the life of yourself if you're touching the metal parts on the phone, you can clearly see the 8th image of the official charger having a plastic separation between the secondary side and primary side to prevent such arcing occurs.
- Transformer of official charger use 2 layer insulation (magnet wire with a rubber sleeve, you can see the secondary winding of official charger coming out in 9th picture with red and white wire) for the secondary side meanwhile on the fake charger just a bare magnet wire so you're risking yourself if the secondary winding somehow touched the primary winding because of the insulation is so thin, it will broke off because of heat during use.
- Official charger use proper, big class Y capacitor (the cyan color thingy) meanwhile the fake charger use a smaller one, if this thing get fault and shorted then your phone will get direct contact with the mains side.
Click to expand...
Click to collapse
Actually there are fake chargers that do adaptative charging. I got one, but the differences i found is that it gets really hot muy hotter than the original, and it makes a little buzz sound while chraging.