Charging amps for phones, tablets etc

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Benito

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So I have a phone whose original USB charger states it's output is 1.2A.

I used a charger that says it's output is 2A and the phone says it is Slow Charging.

Then I use a charger with 750mA, and it doesn't say anything.

Does the Slow Charging on the 2A charger mean it knows there is 2A coming in and it is reducing it's charging rate down to the design?

Or does it mean the 2A charger is faulty in some way?
 
Originally Posted By: michaelluscher
Is this a Qualcomm quick charge device?


Nope. LG smartphone.
 
Some of the new lg phones are quick charge 2.0 items but never mind that I think it's probably just a cable. Both the cable and power supply must be capable of the full 2 amp to work properly. I have experienced many cheap eBay cables even ones claiming to be oem that are unable to provide more than 0.5 amps!

Also apple and Android have different coding so sometimes it can be compatibility issues there.

If you really want to get to the bottom of it you'll need some testing equipment otherwise use the oem charging cable and power supply that came with the phone. There's so many fakes on Amazon and eBay but if you want a new charger and cable I can recommend you some products.

The Cadillac of usb meters is this portapow.

PortaPow Premium USB + DC Power Monitor / Multimeter / DC Ammeter

http://www.amazon.com/gp/aw/d/B00LZ07BG0...=A3M1K9LXDRB6PN

The cheaper version is more economical and plenty for your needs.

PortaPow USB Power Monitor Version 2 (Multimeter / DC Ammeter for Solar Panels, Mains Chargers, etc) https://www.amazon.com/dp/B00NTU18KY/ref=cm_sw_r_awd_DC3KvbWM44Q3A


Check out this guy for reviews on usb power supplies and other cheaper usb meters. Lots of inferior products to avoid!.

http://www.lygte-info.dk/info/indexUSB UK.html

If you want good aftermarket stuff Anker and iVoler are pretty good, I just got an iVoler car charger that is Qualcomm quick charge 2.0 compatible for $12 and it works awesome on my note 4.
 
Thanks but:

OEM power supply is 1.2A and works fine with any cable.

2A non OEM power supply using same cables results in "Slow Charging" message.

Surely the cables have proven they can handle 1.2A?
 
It's the phone being a punk because it knows something in the chain isn't OE. It's marketing, trying to get you to upgrade to OE cables and stuff. It's like a printer "cleaning its heads" after every page when it detects aftermarket toner.

I suspect the phone uses the USB data bus on the cable to talk to the wall-wart "cube" and handshake and decide that they're pals and go together. If there's no such handshake the phone knows how to take the 5 volt line and "slow charge" to protect itself, and nag you. At least most phones have the same connector so you can borrow a friends charger, even if it's "slow".
 
Originally Posted By: eljefino
I suspect the phone uses the USB data bus on the cable to talk to the wall-wart "cube" and handshake and decide that they're pals and go together. If there's no such handshake the phone knows how to take the 5 volt line and "slow charge" to protect itself, and nag you. At least most phones have the same connector so you can borrow a friends charger, even if it's "slow".

Pretty much this.
 
Originally Posted By: d00df00d
Originally Posted By: eljefino
I suspect the phone uses the USB data bus on the cable to talk to the wall-wart "cube" and handshake and decide that they're pals and go together. If there's no such handshake the phone knows how to take the 5 volt line and "slow charge" to protect itself, and nag you. At least most phones have the same connector so you can borrow a friends charger, even if it's "slow".

Pretty much this.


These are particularly fussy about charging amperage. I personally had a LG G2 that was the same way ( not what sure your model is ) but it depended on the output of the supply AND the cabling... had same issue with EXPENSIVE and CHEAP cables for this phone. I was told it does a voltage drop/resistance test on the system and can "tell" sort of the caliber of the cabling and system attached to it. I personally have some chargers that say "slow charging" - but in practice are heavy enough wire wise and 2.1 a charger wise that they charge really well DESPITE the slow charging message... so YMMV...

FYI... often times - other than OE - better quality chargers/cables designed for Amazon Kindle seem to be of the best wire size and charging adaptors to support charging at full power / speed on these devices. Works the same way on my new LG G3 ( G2 was fussier tho... )



BurrWinder
 
Originally Posted By: Alfred_B
Apple is famous for things like this. I thought LG would be a more open system.

I'm guessing the quick charge solutions that are now becoming available are more picky about the quality of the power supplies being used. Rather than having to risk device damage by using some cheap no-name PS, the phone manufacturer chose to play it safe and restrict the quick charging unless OEM/approved charger is used.
 
I believe this is due to the "handshake" that due to the voltage on the data lines, the phone knows how much power to draw from the charger. The voltage on the data lines isn't completely standard, this is the same reason there are some chargers that specifically say that they're good with Apple products - the voltages on the data lines tell the phone that it is connected to a charger capable of X current output.

If you take your good charger and measure the voltage between ground and the data lines, you'll see that it's different than the other chargers. The 2A charger probably doesn't have the right voltage on the data lines for your phone to know that it can pull more than the standard 500mA.

There's likely nothing wrong with the charger, it's just not made for your phone.
 
Originally Posted By: EdwardC
I believe this is due to the "handshake" that due to the voltage on the data lines, the phone knows how much power to draw from the charger. The voltage on the data lines isn't completely standard, this is the same reason there are some chargers that specifically say that they're good with Apple products - the voltages on the data lines tell the phone that it is connected to a charger capable of X current output.

If you take your good charger and measure the voltage between ground and the data lines, you'll see that it's different than the other chargers. The 2A charger probably doesn't have the right voltage on the data lines for your phone to know that it can pull more than the standard 500mA.

There's likely nothing wrong with the charger, it's just not made for your phone.


+1
 
EdwardC, thanks for that explanation. It makes sense. The phone also does the slow charging notification when connected to the laptop's USB which makes sense since it's maximum output is 500mA.
 
I have an LG G2 and don't get the slow charging warning when it's connected to a computer, unless it's a cable issue.

E.g., on my desktop:

OE cable + any port = fine
Any good cable + rear ports = fine
6 ft cable + front USB ports = slow charging

This is most likely because the front ports are attached to the motherboard by a long cable run inside the case, whereas the rear ports are right on the motherboard. So, if I don't use the right cable on the front ports, I get slow charging, but most other combos work fine.
 
I've never seen a slow charging message on my G3 and I've never used the adapter and cable that came with it. They're still in the box.
 
There is so much third tier junk and variety of charging my guess if not in operating parms it resorts to slow charge.

Buy a certified charger and cables and charging goes well. Buy china junk from ebay or drug store then wild west. The smartphone makers protect you from your own cheapness.

I spend $10-$20 on chargers and also $10+ on cables that last and work fine on iPhone and Android.
 
Might be a voltage problem.

My LG G2 would go slow charging when plug into my PC.
When I measure with usb meter, it's only putting out 4.5v and resulted in slow charging.
 
I downloaded an app called "Ampere" from the Play store.

Boy are the results interesting!

Seems the Apple & Nexus charger I have are the best for almost any cable and any device. Better than the LG charger on the LG smartphone.

The charger that was coming up as "Slow Charging" on an LG smartphone was actually delivering more charge to the smartphone than other charger / cable combos which were not giving that message.

It seems it is able to deliver a higher charge than the Apple or Nexus charger for the device that it was designed for but delivers less charge than those chargers for other devices.

So I can highly recommend the "Ampere" app. I also used it to figure out which charger / extension cable / usb cable were the best combo for a particular need.
 
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