Develop Bugs

Will it be safe to use a 2A charger for the Galaxy Nexus?

I just picked up a Nexus 7 and was wondering if I can just use that 2A charger.

No.
You can go under but not over. You risk damaging the phone's charging circuit.

GldRush98 said:
No.
You can go under but not over. You risk damaging the phone's charging circuit.
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Ummm. To the first response....your thinking of voltage not charging amperage. I might be wrong but I believe how much current your phone draws when charging is determined by the phone itself, not the charger. What you really want to watch for is a mismatch between the charger output voltage and phone input voltage, that's when the damage occurs

butikofer08 said:
Ummm. To the first response....your thinking of voltage not charging amperage. I might be wrong but I believe how much current your phone draws when charging is determined by the phone itself, not the charger. What you really want to watch for is a mismatch between the charger output voltage and phone input voltage, that's when the damage occurs
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Your correct. The most it will draw at 5 volts is 1 amp. The best charger is the one that the phone comes with. If you want to learn more research ohms law and resistance balancing. Something like thevenin an mct.

tracerit said:
I just picked up a Nexus 7 and was wondering if I can just use that 2A charger.
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Yes.
The Nexus7 charger will be just fine charging the Galaxy Nexus. It will not damage it at all. I use a Kindle Fire charger to charge my GNexus. It can provide up to 1.8 amps at a nice steady 5Volts, but it doesn't have to provide that many amps to charge the Nexus - so it doesn't.
Its the voltage, not the maximum amp capacity, that is critical, cannot be too high.
It is usually OK to use a too low amp capacity charger as well, the charging just takes longer. Usually...some chargers are designed poorly. When asked for more amps at 5V than they are designed to provide they could fail by just providing less amps than asked for at 5V, which would be fine but slow. What else could happen is that the voltage provided could start to vary. It could start to take on the characteristics of the AC current it is supposed to be converting to 5V DC. This can hurt your phone.

Moral of the story....the chargers that advertise half the charge time because they offer double the amperage are a scam/false. Just because they can provide up to that amperage doesn't matter, the device determines the actual current being pulled (I.e.--charging time)

Charger

I have a car charger that outputs 5.3V and 2A. Will I damage my phone if I use this?

No because the phone will limit it plus it depends on the charges and cable whether it will take an AC charge or USB

Hi
milomak said:
I have a car charger that outputs 5.3V and 2A. Will I damage my phone if I use this?
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The amps aren't a problem as a device will only draw what it needs. The voltage requirements however for USB is 5 Volt +- 5%, which gives a valid range of a maximum 5.25V and minimum 4.75V. If that voltage of 5.3V is the measured voltage and is accurate, it is probably going to be fine, however if that voltage is what it states on the label, then that figure has some leeway also, so if the charger is leaning towards being over rather than under, it is going to be going quite a bit over the USB spec.
Regards
Phil

Bought this external charger...friend says will hurt GN..please advise

i.Sound Portable Charger
Has 16,000 mah
Input: 12V 1A
Output: '5V 2.1A on each connector 2.5 A together'
I charge a number of things on here...
A friend has me a bit confused saying this could damage the charging mechanisms of the phone.
Any input please?
Thanks

rockky said:
i.Sound Portable Charger
Has 16,000 mah
Input: 12V 1A
Output: '5V 2.1A on each connector 2.5 A together'
I charge a number of things on here...
A friend has me a bit confused saying this could damage the charging mechanisms of the phone.
Any input please?
Thanks
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Do u mean, you are giving the Galaxy Note an input of 5V, 2.1A (ie, output of Portable Charger)? if so, it is going to effect the battery life in long run..it may charge your phone faster, but definitely going to hurt the life of the battery..there are a lot of factors which should be considered like how much extra current you can give, temperature etc etc..

I don't think so: charging current is controlled by the device being charged, not the charger.
The Note will draw only ~700mA on an "AC" charger, even if that charger can supply up to 1A, 2A, etc.
On USB, it will draw ~500mA.
A mains/AC charger shorts the 2 data pins, which tells the phone that it's a dumb charger, not a USB host, and it is safe for the device to draw up to its own maximum (700mA for the Note).
---------- Post added at 12:23 AM ---------- Previous post was at 12:16 AM ----------
The corollary to that is that you shouldn't be able to shorten battery life by over-current charging: even with a 2A Nexus charger the Note draws only up to its maximum 700mA.
[I did just that test a moment ago to check: 725mA, on the 2A Nexus 7 charger]
Of course, 700mA is more than the 500mA it will draw from a USB host, so if you were really concerned, you could use that.
But the device ships with a mains/AC charger from which it will draw 700mA, so you're never going to exceed the "official" charger, whatever charging source you use.

cdmackay said:
I don't think so: charging current is controlled by the device being charged, not the charger.
The Note will draw only ~700mA on an "AC" charger, even if that charger can supply up to 1A, 2A, etc.
On USB, it will draw ~500mA.
A mains/AC charger shorts the 2 data pins, which tells the phone that it's a dumb charger, not a USB host, and it is safe for the device to draw up to its own maximum (700mA for the Note).
---------- Post added at 12:23 AM ---------- Previous post was at 12:16 AM ----------
The corollary to that is that you shouldn't be able to shorten battery life by over-current charging: even with a 2A Nexus charger the Note draws only up to its maximum 700mA.
[I did just that test a moment ago to check: 725mA, on the 2A Nexus 7 charger]
Of course, 700mA is more than the 500mA it will draw from a USB host, so if you were really concerned, you could use that.
But the device ships with a mains/AC charger from which it will draw 700mA, so you're never going to exceed the "official" charger, whatever charging source you use.
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yes, though AFAIK the Note will draw more than 700mA from the OEM charger
and I have noticed charging speed differences by using different aftermarket chargers... never put a multimeter to them though

while charging the battery in the note is safe, I don't recommend plugging in your portable charger into a external battery charger. They may not protect the battery from overcurrent. Pay attention to all the specifications of all charging devices you use. Especially if you also have an aftermarket battery.
Cheers
Sent from my GT-N7000

guitarplayerone said:
yes, though AFAIK the Note will draw more than 700mA from the OEM charger
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Are you sure? I didn't think that was the case; I could be wrong of course.
do you have any more details on that, please?
I have used many, many USB chargers: mains/AC, 12V, solar, portable battery, and never seen greater than ~700mA being drawn by the Note.
I'd like to know otherwise, for the odd occasion when i might want a really quick charge!

My friends point was that the i-sound charger would hurt not so much the battery but might damage the charging circuitry in the phone...course I learn this after buying this charger! ( I know its fine for nexus 7 and 10.1 tab).
Again its
Input: 12V 1A
Output: '5V 2.1A on each connector 2.5 A together'

rockky said:
My friends point was that the i-sound charger would hurt not so much the battery but might charging circuitry in the phone...course Ilearn this after buying this charger! ( I know its fine for nexus 7 and 10.1 tab).
Again its
Input: 12V 1A
Output: '5V 2.1A on each connector 2.5 A together'
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Click to collapse
Yup, and I believe the answer is no: you cannot damage the Note's charging circuit by using a charger that has a higher *maximum* current, since the Note will only draw a current of (approx) 700mA regardless of the charger's maximum.
As an example of that, my test showing that the Note still only draws 725mA when connect to the Nexus 7 charger, which has a maximum charging current of 2A.

Thanks

cdmackay said:
Yup, and I believe the answer is no: you cannot damage the Note's charging circuit by using a charger that has a higher *maximum* current, since the Note will only draw a current of (approx) 700mA regardless of the charger's maximum.
As an example of that, my test showing that the Note still only draws 725mA when connect to the Nexus 7 charger, which has a maximum charging current of 2A.
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There was a mid on this site a really long time ago showing how shorting a specific connection in the usb cable will enable ac mode and this is supposedly what the oem charger does

guitarplayerone said:
There was a mid on this site a really long time ago showing how shorting a specific connection in the usb cable will enable ac mode and this is supposedly what the oem charger does
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yup, that's right: shorting the two data pins --- which most "dumb-charger spec" capable chargers do --- tells the Note that it's OK to pull its maximum ~700mA. But it won't pull any more than that even if it's a 2A charger.
Without that short, the Note will only pull the regular ~500mA (again, regardless of charger max current): it thinks it is connected to a standard USB host, which might not be able to supply > 500mA, e.g. a laptop motherboard.
If you have a >500mA charger that *doesn't* follow the dumb-charger spec, i.e. it doesn't short the data pins, e.g. possibly a Mac USB charger, then you can get a charge-only no-data USB cable, that has the data pins shorted internally (in the cable itself), which will achieve the same effect. This is the mod you describe above.
You probably should not use that cable with a regular USB host (although the host will probably just limit its current anyway).
[Macs use some proprietary "signalling" method, whereby differing value resistors are placed across the data pins, telling the device differing levels of current to pull, etc. This is why you'll see external battery packs like Anker Astro 3 having a "Samsung port" and also a "iPad port"; madness]
Finally, some Android kernels have a hack that will allow AC mode (e.g. 700mA on the Note) regardless of the data pins. But this isn't always wise, and so many devs won't touch it. It prob wouldn't bother the Note, but it might not be good for the host/charger.
Apologies for rambling on, but people seem to ask this sort of thing a lot...

yep people wantblong battery life and fast charge.
About time a proper fuel cell is introduced
Sent from my GT-N7000 using Tapatalk 2

Most of this is over my head
So bottom line: charging my note with the i-Sound charger described in the OP will NOT damage my new Note , correct?
Tnx

rockky said:
Most of this is over my head
So bottom line: charging my note with the i-Sound charger described in the OP will NOT damage my new Note , correct?
Tnx
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Click to collapse
I believe that's correct; I would not hesitate to use it.
As someone else stated, however: whilst charging in the phone should be safe, since the phone controls the current, taking the battery out and charging it in a standalone battery charger may not be safe.

rockky said:
Most of this is over my head
So bottom line: charging my note with the i-Sound charger described in the OP will NOT damage my new Note , correct?
Tnx
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Click to collapse
Yes, that's correct. Generally, just make sure the voltage is not too high (or too low). The range of 4.7V to 5V should be OK, since there is some allowance for variations. The current ( ie, the Amperes) only indicates the current the charger is capable of supplying. It doesn't mean the charger will force all that current down the battery's throat. The device/battery will draw as much as it needs, and this will not damage the device or battery whether it's 0.5A or 2A.

6 Volt Charger

Recently bought a camping lantern that runs on a built in 6v 4.5 AH lead acid battery. It also has a USB connector which is for charging cell phones. I initially thought that the USB would be giving off a safe 5v but on testing it turns out that it is 6 volts straight from the battery.
Is this safe to use occasionally while camping? Will that extra 1 volt kill the battery or is there some mechanism inside the phone to regulate that voltage to a safe level?

Good question....hope someone has the answer for you.
Sent from my SCH-I535 using xda app-developers app

executionist said:
Recently bought a camping lantern that runs on a built in 6v 4.5 AH lead acid battery. It also has a USB connector which is for charging cell phones. I initially thought that the USB would be giving off a safe 5v but on testing it turns out that it is 6 volts straight from the battery.
Is this safe to use occasionally while camping? Will that extra 1 volt kill the battery or is there some mechanism inside the phone to regulate that voltage to a safe level?
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Of course there should be.You get more than 6v in a power socket around the house.

Gkikas said:
Of course there should be.You get more than 6v in a power socket around the house.
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No one plugs their phone directly to the wall socket :/ Thats what the charger is for, it only gives 5v to the phone. Just need to know if it can regulate that 6v to a safe level.
*edit. I think no one here would know about the hardware aspects of a phone. Can someone point me to a forum or anywhere where they may know the answer to a question like this?

May I asked how you measured this?
I'd love to check what output my 12v chargers are outputting

TieNN89 said:
May I asked how you measured this?
I'd love to check what output my 12v chargers are outputting
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A multimeter and a stripped usb cable

executionist said:
A multimeter and a stripped usb cable
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ah yeah
My brain has already flicked off for the day LOL

if you use IRC, try the freenode server in the ##electronics channel. they should help you out there. pretty nice ppl in general there.
Sent from my GT-I9300 using xda app-developers app

?
I'm interested as well. Will 6 volts @ 500mAh fry the phone?

Ok, I am an electronic engineer so a few comments.
I have no idea what kind of charging circuit is in our phones, could probably look it up but ..... in my opinion only 10% above 5V is to be considered safe.
Now you are talking about a 6V battery. That battery is not always 6V. A nice example is the 12V battery in your car which is 12.8V when fully charged. Another example are the cells inside our phones which have a nominal Voltage of 3.7V but are charged to 4.2V.
The Voltage they put on those things is the nominal Voltage.
I would check if there is no electronic circuit in that lamp since I would not connect anything directly to a battery at all.
If you go camping I would check this thing coolook pb-2000. Insert 4 x 18650 batts and you can do a couple of recharges. Very good box for the price and you can salvage 18650 from broken laptop batt packs ... but google and youtube a bit before you do that to make sure you do it the right way.

I'm also interested, any news?

You can see the specs of this type of batteries here. The 6V is nominal, as already mentioned above. The maximum noted is 6.9V and TBH, i would be rather reluctant to test is my SGS3 charging circuit likes the idea of being fed with 40% higher voltage than usual.
Are you sure there is nothing in the lantern that would limit the voltage under load? Could be something as simple as 2 diodes in series, in this case measuring the voltage on the open circuit, totally unloaded, with a DMM that barely draws microamps from it, would show the battery voltage. Try drawing some current from it (use a resistor, a USB LED lamp, etc) while measuring. I seriously doubt a self-respecting vendor would setup a USB port on that thing that would potentially output 40% more than specs, really.
PS: if the port is, indeed, fed straight from that battery, i would rather avoid hooking my SGS3 to it. Even though, it would probably survive.
---------- Post added at 07:08 PM ---------- Previous post was at 06:59 PM ----------
lukesan said:
I have no idea what kind of charging circuit is in our phones...
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MAX77686. Good luck finding the datasheet. And good luck trying to guess if there is anything else potentially fed straight from the USB connector. The bottom line is - i wouldn't dare

Solder this to red wire https://en.wikipedia.org/wiki/Zener_diode
OFC you need 5V model

GR0S said:
Solder this to red wire https://en.wikipedia.org/wiki/Zener_diode
OFC you need 5V model
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Not if it doesn't have a resistor in series. And wait. if the battery is at 6.8 Volt and you have a 5.1 Volt zener and it is charging at 1 Amp so you will need a power resistor. You will have a lot of loss of energy because it will go away in heat.
You could use a dc-dc convertor but believe me forget about it and get one of those charging banks where you can put in your own cells.

lukesan said:
Not if it doesn't have a resistor in series. And wait. if the battery is at 6.8 Volt and you have a 5.1 Volt zener and it is charging at 1 Amp so you will need a power resistor. You will have a lot of loss of energy because it will go away in heat.
You could use a dc-dc convertor but believe me forget about it and get one of those charging banks where you can put in your own cells.
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I'm not sure about how practical it would be to be cutting usb cables and wiring zener diodes just to use this lamp....
I think I had a charger that supplied too much voltage (I'm not positive I didn't measure the voltage output or anything), but I can say that the phone did not like it. It would eventually charge somewhat, but the touch screen wouldn't work and would go bezerk if touched lol.
Again I'm not sure how much V it supplied, but I would assume it was more than 6V. It didn't really damage the phones either, I would try it.

Here's your answer, definitively:
6v at the source (the lantern in this case) will probably be 5v or less at the phone because of the resistance in the USB cable itself. The longer the cable is the higher the resistance will be and thus the more voltage you lose to it. Also, the cheaper the cable (the thinner the wires) the more voltage you will lose per foot.
Here's some specs you can plug into THIS VOLTAGE CALCULATOR:
The USB definition specifies up to 5.3v.
Most USB cables will use 30awg wire or maybe 28awg for the better ones.
Depending on which of the sources I've read, some USB cables/chargers use one pair of wires for charging, and some will use two pairs. You can see that using two pairs of conductors drastically improves the voltage transmission but even still, at 28awg over a 6foot cable you're still losing .75v which puts you at 5.25v and well within the USB spec.
So the lantern is fine to use with your phone with your average 6-foot USB cord.
If you're like me and prefer 10-15 foot USB cords in some places you would actually benefit from a 6v or even 7v power supply at the wall. I've found that even on the OEM Samsung wall charger, when I use a 10-foot cable I don't get enough juice to actually charge my S4. With the screen on the battery charge level still drops. The Galaxy Charge Rate app shows something like 500ma charge rate and that's because there's not enough voltage / too much voltage-drop across the long cable. (Radio Shack sells a modular, adjustable voltage wall-wart power supply as well as USB and micro-USB adapters for it. I'm starting to experiment with it and the long cables.)

USB voltage vs charging current
This is an old thread, but I can confirm that my moto G charges at 6v. Apparently the original Motorola charger outputs 5.75v. I hooked up a variable power supply to my phone. The data lines are shorted together to indicate a high current power source is present. The moto G will test load the power supply before settling on a stable charging current. One that does not cause the voltage to sag excessively. When I applied 5v the charging current was approximately 600 mA. At 6v the charging current was approx 1200 mA. The charging current was measured directly on the phone using an app called ampere.
So I conclude that Motorola use this tactic to ensure their phones charge fastest with their chargers. On the up side, its fun watching my phone go from 40% to 100% in 45 minutes

Charger question.

My phone came with a 500ma 5v charger, I seemed to have misplaced it, I have a spare 500ma 5.2v charger at home, Is it safe to use it? Will the extra 0.2V have any adverse effects?
Thanks

Probably OK,
I would say it is OK for most part. Usually, AC/DC adapters are not that precision. You can check voltage output with ohm meter under load for actual voltage output.
Simple way to fix is connect 5v zener diode for quick voltage control between + and -, if your device battery is Lithium battery that is sensitive to input voltage. Check device specification for battery type. You can get zener diode from Radio Shack or electronics part store.

@rhanxdad: good reply but I'm afraid I'm only one of few people in this forum section who understood what you meant Not everybody has EE or electronic hobby background
Here is my take on this. Your battery is 3.7-3.8V, and once you plugin that 5.2V charger into micro-usb (5V standard) interface of your phone conector it depends on tolerance of its input of the internal converter chip (5V -> 3.7V for charging). This can't be guaranteed and will vary between phones, just my guess. Considering your have 500mA charger, I can also guess you don't have the latest brand name smartphone where most of them use 1A-2A chargers. Another thing, everybody makes 5V micro-usb wall chargers, and the fact that you have one rated at 5.2V sounds like some cheap ebay part? So taking all this into consideration, I would probably stay away from that charger. Look up on Amazon, you can find a nice one under $10, like from Anker or Ravpower.

Final Answer
@vectron, yes your answer is better, haha. Sorry about the ambiguous answer.
@aqswde123, How is this, if it is only 5v, then connect to Laptop/PC USB through your Sync cable. You probably already own this and then it will be free.
Good luck.

Thanks guys, will order a new charger and will use my comp to charge it in the meanwhile. After starting this thread I have been googling and I've read that the usual USB tolerance is between 4.75 - 5.25 V and hence anything inbetween is safe, but i wont take the chance anyway.