USB 5V lots of amps wall chargers - Page 1
Forum section: electronics / general

author: akis
author_rank: Frequent Contributor
timestamp: August 23, 2014, 09:22:23 am
content: Does anyone know of a wall plug USB charger that will actually charge thirstier phones and tablets? I have bought 2-3 which purport 1A and 2A outlets but they are awful, you have to keep the phone/tablet in "sleep" mode, screen off, else the charging takes ages. I suspect those wall chargers push out really dirty power getting dirtier as the demand rises and so the average DC is well below what it should be what with all the AC switching noise and that is why it takes so long to charge.Off to try the with the bench PSU.PS:Results from PSU show that at 5V DC there is a draw of 470mA with battery at 19%. There is no difference to the current draw with screen on, browsing the internet or screen off (phone locked). That means that the 470mA must be a limit of the phone and a limit of USB sockets found on PCs and on laptops so that the phone has been designed to never attempt to draw more? Just guessing here.I know tablets require more power however. As this is a 6.5" phone I presume that it could "break the rules" and demand more power ?

author: sleemanj
author_rank: Super Contributor
timestamp: August 23, 2014, 10:29:19 am
content: QuoteStandard USB is limited to 500mA.Higher current charging over USB cables is enabled by the "supply" by way of various fiddles of the data pins, only when the device being charged sees the ability to supply high current will it try to draw high current.http://www.anandtech.com/show/6330/the-iphone-5-review/14

author: PeterG
author_rank: Frequent Contributor
timestamp: August 23, 2014, 11:38:35 am
content: My Nexus 7 charger has a voltage of 5.2v. When connected to 5.2v it draws around 2amps. Charging from USB it draws 450mA. Hope this helps.

author: richms
author_rank: Contributor
timestamp: August 23, 2014, 01:39:34 pm
content: Also watch the USB cable used. My note 3 will just revert to 450mA charge on any cheap nasty cable even on the samsung charger. I bought some nice flat ones to use and they are useless at charging.

author: akis
author_rank: Frequent Contributor
timestamp: August 23, 2014, 03:19:57 pm
content: With the addition of the 220R resistor between the D+ and D- my phone now draws 600mA instead of 470mA without the resistor.Voltage is almost irrelevant I tried up to 5.3V and there is little change - current goes down as voltage increases as you'd expect.I have not tried the Apple wiring as my phone is not an Apple.Applying 3.9V directly to the battery drew 750mA with the battery being at about 3.7V on its own and with the current limit set for 1A and not reached.Maybe the battery has its own protective circuit onboard that limits the charging current.

author: zapta
author_rank: Super Contributor
timestamp: August 23, 2014, 03:53:51 pm
content: These charge monitors are very useful to debug charging issues. The most I could get with Nexus 5 is 1A which is ~0.45C (charger has D+/D- pin shorten and using a good USB cable).

author: Rick Law
author_rank: Super Contributor
timestamp: August 23, 2014, 05:57:39 pm
content: Quote from: sleemanj on August 23, 2014, 10:29:19 amWorst yet, there is no standard on what is on the D+/D-. Some mini USB (Motorola phone) even uses the X pin so you cannot make a converter on the standard 4pin USB outlet. With the Moto, unless X pin and D+/D- is properly set up, it wont even go into charge mode at all.

author: nctnico
author_rank: Super Contributor
timestamp: August 23, 2014, 06:03:06 pm
content: There actually is a standard for USB chargers. The problem is manufacturers adhering to it.

author: Rick Law
author_rank: Super Contributor
timestamp: August 24, 2014, 03:00:28 am
content: Quote from: nctnico on August 23, 2014, 06:03:06 pmWell, I suppose $20 for a charger cable is a revenue stream they are reluctant to give up.

author: akis
author_rank: Frequent Contributor
timestamp: August 24, 2014, 07:49:52 am
content: My phone/phablet will not charge, with any charger, unless the screen is off, completely off. When I close the case there is a window on the cover of the case, through which it displays some vital information, date/time,missed calls, missed messages, it is like a tiny part of the screen. Even with that little thing on, it will not charge, the screen must be black.I am not sure about other large phones/tablets charging off of the USB port and how successfully, because waiting for 10 hours to charge your phone is a joke.I am thinking of the extreme solution to charge the battery outside the phone so it could be charged in one hour. Inconvenient having to open the case and flip batteries but maybe the solution.USB charging really sucks. I am sure iphone 5 does it better.

author: classical
author_rank: Regular Contributor
timestamp: August 24, 2014, 11:47:07 am
content: Fine connection of teardowns and reviews:http://www.lygte-info.dk/info/usbPowerSupplyTest%20UK.htmlFor me the Goobay 42665 is a winner.And it has a screw so that you can open it and adapt the circuit around the data lines. It seems to come with iphone-compatible resistors. My last phone needed a short between the data lines and my current one prefers open data lines.At this site you also find a review of an USB voltag/current detector.http://lygte-info.dk/review/Review%20Xtar%20USB%20current-voltage%20detector%20UK.html

author: radioFlash
author_rank: Regular Contributor
timestamp: August 27, 2014, 11:37:41 am
content: I got the Photive charger below. It's rated for 10A total. It's nice in that all the ports are interchangeable. Many chargers have specific ports designated for different manufacturers. This charger worked with Apple devices, the Nexus 7, Kindle Fire, and an old samsung flip phone that was picky about chargers.Photive 50 Watt 6 Port USB Desktop Rapid Charger. Intelligent USB Charger with Auto Detect Technologyhttps://www.amazon.com/dp/B00LMIA9L4/ref=cm_sw_r_awd_6cC.tb1RF4GK3Sent from my iPad using Tapatalk