How to Modify 1 Amp Car Chargers to show AC Mode

So I was getting a bit frustrated with buying single and dual USB car chargers that were rated at 1Amp/Port and still having the EVO showing USB charging. I have five chargers now and they all show USB Charging while in spare parts. So being frustrated, I wanted to figure out and solve the problem. After a lot of surfing and digging, I came across the answer. If you check out this wikipedia link:

http://en.wikipedia.org/wiki/Universal_Serial_Bus#Power

You'll find the answer in the Battery Charging Specification of the link:
"In Battery Charging Specification,[31] new powering modes are added to the USB specification. A host or hub Charging Downstream Port can supply a maximum of 1.5 A when communicating at low-bandwidth or full-bandwidth, a maximum of 900 mA when communicating at high-bandwidth, and as much current as the connector will safely handle when no communication is taking place; USB 2.0 standard-A connectors are rated at 1500 mA by default. A Dedicated Charging Port can supply a maximum of 1.8 A of current at 5.25 V. A portable device can draw up to 1.8 A from a Dedicated Charging Port. The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200Ω. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured. The increased current (faster, 9 W charging) will occur once both the host/hub and devices support the new charging specification."

The key here is shorting the D+ and D- pins. Looking up the USB pinout can be found here:
http://pinouts.ru/Slots/USB_pinout.shtml

So, taking my cheapest charger that I bought from Walmart for $5.99 that had dual ports that said it was rated at 1A/Port, I opened it up and soldered pins 2 and 3 together for each port and put it back together.

So now with my modified cheapo USB car charger I went to the car and plugged it in and plugged in the EVO. Low and behold, it now says it's "AC Charging" and now it will pull the full 1 Amp.

So with the result to my satisfaction, I opened up my other chargers, ranging from three different Scosche chargers and one single port Belkin 1 Amp charger, soldered pins 2 and 3 together, and now all of my chargers are showing "AC Charging" using the "Spare Parts" app.

Once you take the charger apart, it's fairly obvious which pins are 2 and 3. I guess I should have taken pictures of each one as I had it apart so you could see it.

I hope this helps others with getting the full charging capacity out of their 1 Amp car chargers. Because running Google Navigation or apps such as Pandora/Subsonic will really suck down the juice.

RavenII said:

What gives you the impression that it's not drawing 1A when on an actual USB port...or vice versa, what guarantees you the 1A after this trick? ...(yes, I'm just trying to see your logic)...

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According to everything that I've read on how the EVO and other phones charge, unless it can detect that the charger is a dedicated charger and not connected to a computer, the phone will only draw a max of 500 milliamps at 5 volts. Most of the time, it will only draw 400 milliamps at 5 volts.

There are a lot of threads here on trying to get chargers rated at 1 amp to actually have the EVO charge at 1 amp. The secret is that the 2 and 3 pins must be shorted before the EVO will even attempt to draw more amperage then a normal USB port.

Though you should only do this mod if the charger is truly rated at 1 amp at 5 volts.

scl23enn4m3 said:

So, if I bridge pins 2 and 3, and ground pin 4...I should be able to get it to pull 1 amp and launch into car mode right?

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Just bridge pins 2 and 3. Leave pin 4 alone. You could also mod a cable to do this, but make sure you never plug it into a computer!

The EVO will now see the charger as a dedicated charger and attempt to draw 1 amp. Though, based on what I have been reading, it wil more than likely draw 800 milliamps instead of 1000 milliamps. Same goes for USB charging at 400 milliamps instead of 500.

ntron1 said:

How did you get the belkin apart??

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I had to use my pocket knife to slip it in between the spring loaded metal ground part and the plastic case. Make sure you identify which side will lift off. The top part is attached to one of the halves and you don't want to pry against that side. Just put a bit of pressure on each side until you can crack it apart. When putting it back together, I had to use some super glue on each side of the case after I had pressed it together. Just a couple of drops on each side and it looks none the worse for wear. Except it now charges at a a full amp (probably 800 milliamps)

Just to verify, this is the Belkin charger in question:
http://www.amazon.com/Belkin-Micro-...3?ie=UTF8&s=electronics&qid=1283093014&sr=8-3

Andy S said:

Can someone describe to me specifically what it looks like on 1A AC vs a 500mA?

I've tried plugging mine into a couple of 1A wall chargers that I have (including the HTC included charger) as well as my car and house 5mA chargers, and don't see the difference on screen.

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Download spare parts from the market. Under battery information it will tell you which mode it's charging in. Either USB or AC.

Andy S said:

Ten minutes of looking for a lost soldering iron, and the Rio Carbon's charger now shows AC. Cool.

Back to this one about grounding pin 4. I know that in another thread someone mentioned hacking a cable on the mini USB end to bridge pins 4 and 5 (the "X" on the diagrams on the second page linked in the first post) to automatically put the car in "car dock" mode. Any ideas how we could accomplish this at the regular USB plug end, since there are only 4 contacts on that side?

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Glad to see that the modified charger is showing AC. Afraid I don't know about the car dock mode. Haven't researched that yet.