If you pick up that PowerDuo, let me know how it works. I may pick one up as well, if it works better than a 1A charger.
Charger specs
- Thread starter Novarider
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They aren't entirely shorted - they probably just have a couple of voltage divider resistors to supply an intermediate voltage to the data lines. iPhone chargers are the same deal, because technically under the USB spec, ports are supposed to only deliver 125 mA by default. "High current" (500 mA) can be entered by supplying the right voltage to the data lines (for the iPhone, about 2.25V works, but it's not too picky).
By the way, if I use NC's charger to charge normal phones (mine is Nexus One), will there be any problem?
Shouldn't be a problem - the charger won't push more current than the device will accept, unless there's a short.
Came in here to say the same thing. I wouldn't try to pull 1.9a from a standard charger. Recipe for disaster.The reason why the the charging indicator pops up when you use certain chargers with the Nook microUSB cable is because they are BOTH wired for fast charge - A "fast charger" has its Data+ and Data- pins in the USB port shorted together, and certain extra pins in the Nook's USB cable are likely tied together as well. This tells the Nook that it's connected to a "fast" charger, and it will pull 1.9A in this configuration.
This can be dangerous when you use the Nook cable together with a fast charger that does not supply 1.9A (eg HTC HD2, Motorola Droid USB adapters that only supply 950mA - 1A).
The charger will most definitely run a lot hotter, and that can either damage the charger/Nook/start a fire in the long run.
The iPad wallwart on the other hand, for example, is safe to use with the nook cable since it supplies 2.1A. Excess amperage will not harm your device or adapter. Inadequate amperage will!
In a nutshell :
Standard charger + regular microUSB cable = fine (will charge at 500mA)
Fast charger below 1.9A + regular microUSB cable = fine (will charge at 500mA)
Fast charger below 1.9A + nook cable = not recommended (nook will try to pull 1.9A, but the charger only supplies whatever it can output, thus stressing it out)
Nook Fast charger + nook cable = fine, of course
Hope that wasn't too confusing. I had to rewrite it a few times for it to be coherent.
Nook charging cable is NOT standard micro USB. If you use standard cable, it will charge with 500mA max and no charging indicator on the screen. The only way to have it fast charge is to use Nook cable.
The charger controller inside Nook looks for Dp and Dm pin at~2V. The resistance between these pins is less than 200Ohm. My DIY charger is made from a powered USB hub with 5V 2A supply. I short Dp and Dm together and tied to 2V with voltage divider resistors. (By the way, Try this at your own risk!!!)
The charger controller inside Nook looks for Dp and Dm pin at~2V. The resistance between these pins is less than 200Ohm. My DIY charger is made from a powered USB hub with 5V 2A supply. I short Dp and Dm together and tied to 2V with voltage divider resistors. (By the way, Try this at your own risk!!!)
Ok so if I use THIS backup battery with a regular micro usb cable it will only charge at 500mah even tho the battery is rated at 1750mah? Also your saying that using the stock nook cable with that battery would destroy it?
Has anyone tested to see what the nc actually pulls with the stock charger/cable?
Has anyone tested to see what the nc actually pulls with the stock charger/cable?
You are confusing mA with mAh. They are not the same thing. MA is how much electricity is flowing at once, while mAh is how much electricity is being stored.
Will your DIY charger provide fast charging using a standard micro-USB cable?
So replace mah with ma and its the same question. The energizer charges at 1500MA(not1750 like I said earlier). If I use a regular usb cable will it only charge at 500MA or will it get the full 1500? If I use the stock cable will it damage the battery?
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I can not make NC fast charge with my diy charger even the NC cable. It charges with current about 450mA. It is also the same with standard cable. I modified USB hub to charge iPhone. Without the mod, iphone won't charge. For NC, it can charge with Dp. And Dm float.
Sent from my LogicPD Zoom2 using XDA App
Sent from my LogicPD Zoom2 using XDA App
Anyone? I'm looking for a backup battery and don't want to buy one that's not going to work properly
I get really upset when device manufacturers use their own proprietary signaling protocol to power devices via USB. 1.9 Amps is WAAAYYY out of spec for anything that should be touching USB. The data +- lines are configured in static voltages that drop or rise in specific patterns and increments to tell a device what kind of host it's connected to. I haven't had a chance to breakout the pins from the Nook charger yet, but I might get to that soon and see what kinds of data pins we are dealing with.
Also, I wouldn't be too concerned with noise transferring from the AC lines.. LM78xx chips are great filters by themselves on the DC side of things, and gladly sacrifice themselves before anything goes up on the device side of things.
You see, there's two types of USB chargers, those that supply data line voltages, and those that don't. This is why many people with Apple products can't use other chargers, since those chargers were built with the original USB spec in mind (no mA data units). You can charge devices without giving reference voltages on the data lines, but the device isn't going to know how much to draw, and should default to 500mA.
There's a few established data line values I've found in my research by testing certain chargers, but I haven't found any official specifications about the analog side of USB charging... most documents seem to involve a USB host circuit instead of using charge mechanics themselves.
Anyway, I'll see if I can do some research on the nook charger unit and let you guys know!
(P.S., the NC wall wart is great for a quick charge to cellphones, provided the phones don't overheat. 7% to 75% battery life on my Droid Eris in about an hour
)
Also, I wouldn't be too concerned with noise transferring from the AC lines.. LM78xx chips are great filters by themselves on the DC side of things, and gladly sacrifice themselves before anything goes up on the device side of things.
You see, there's two types of USB chargers, those that supply data line voltages, and those that don't. This is why many people with Apple products can't use other chargers, since those chargers were built with the original USB spec in mind (no mA data units). You can charge devices without giving reference voltages on the data lines, but the device isn't going to know how much to draw, and should default to 500mA.
There's a few established data line values I've found in my research by testing certain chargers, but I haven't found any official specifications about the analog side of USB charging... most documents seem to involve a USB host circuit instead of using charge mechanics themselves.
Anyway, I'll see if I can do some research on the nook charger unit and let you guys know!
(P.S., the NC wall wart is great for a quick charge to cellphones, provided the phones don't overheat. 7% to 75% battery life on my Droid Eris in about an hour
)Nook color uses charger controller from TI. The charging current depends on the USB connection. If it is connected to USB host, it will charge at 100mA. If host allows, the current will be 500mA. Most of the host will allow this case.
To detect charger connection(not USB host), the charger controller need to see data line at the stage of non-USB standard. Normally, Dp and Dm are not connected to each other. I think TI used this to detect.
Nook charging cable plays an important role too. I think it has some other contact compared to standard micro USB. I used standard cable. Nook will not show charging indicator. This is kind of show stoper for DIY charger from of the shelf components.
To detect charger connection(not USB host), the charger controller need to see data line at the stage of non-USB standard. Normally, Dp and Dm are not connected to each other. I think TI used this to detect.
Nook charging cable plays an important role too. I think it has some other contact compared to standard micro USB. I used standard cable. Nook will not show charging indicator. This is kind of show stoper for DIY charger from of the shelf components.
I don't recall the specifics but the NOOK cable has a longer microUSB connector on the Nook side so that the nook can detect additional pins and recognize the charging cable. When a standard microUSB cable is connected it connects to the standard set of USB pins and behaves as a normal USB cable would so far as both charging and data connection.
I took a look at TI's charge controller documentation, which answered a lot of the questions I've had about USB charging emulation in homebrew circuitry. When a device senses +5v on the power line, it sends 0.6v on D+, tests D- for a response, and does the same thing again, except backwards. Dedicated Charging Mode says that the D+- lines should be shorted together with an impedance of 200 ohms. There's also a Standard Downstream Port and Charging Downstream Port. The major differences between the types is how much amperage is available to the downstream device, however I can't find so far how to specifically control amperage draw within a specific charging profile.
i have a weird question
since the charger provides more than normal power, is it safe to plug in other usb cables or even charge with the nook cable on other devices for hopes of a faster charge?
since the charger provides more than normal power, is it safe to plug in other usb cables or even charge with the nook cable on other devices for hopes of a faster charge?
The answer is it depends. Here's the options:
NC, NC cable, NC charger - Life's good, 1.8A charging rate
NC, NC cable, other charger - Depends on the profile and circuitry of the charger, could be 500mA, 1.5A, or 1.8A.
NC, other cable, NC charger - You'd better use a heavier gauge wire, because even though you're not using the NC cable, USB spec says that the device may request up to 1.8A if available. NC will decide what it wants here.
NC, other cable, other charger - You'll get 500mA, 1.5A, or 1.8A, depending on the charger. Again, be careful of amperage on the cable
other device, NC cable, NC charger - *should* work, but I don't recommend it. I think ground carries a high voltage for some reason, since I've seen my USB hubs resetting and sparks coming from the connector at times
other device, NC cable, other charger - this really should work, but you're not going to get faster charge times, since again it depends on the output of the charger. I'd still be cautious since the NC cable has something wierd going on.
other device, other cable, NC charger - Go for it. I've gotten 1 hr full charge times on my phone with this method. You MUST use a heavy enough gauge USB cable.
other device, other cable, other charger - depends on device draw and charger profile mode
NC, NC cable, NC charger - Life's good, 1.8A charging rate
NC, NC cable, other charger - Depends on the profile and circuitry of the charger, could be 500mA, 1.5A, or 1.8A.
NC, other cable, NC charger - You'd better use a heavier gauge wire, because even though you're not using the NC cable, USB spec says that the device may request up to 1.8A if available. NC will decide what it wants here.
NC, other cable, other charger - You'll get 500mA, 1.5A, or 1.8A, depending on the charger. Again, be careful of amperage on the cable
other device, NC cable, NC charger - *should* work, but I don't recommend it. I think ground carries a high voltage for some reason, since I've seen my USB hubs resetting and sparks coming from the connector at times
other device, NC cable, other charger - this really should work, but you're not going to get faster charge times, since again it depends on the output of the charger. I'd still be cautious since the NC cable has something wierd going on.
other device, other cable, NC charger - Go for it. I've gotten 1 hr full charge times on my phone with this method. You MUST use a heavy enough gauge USB cable.
other device, other cable, other charger - depends on device draw and charger profile mode
Also, there's a difference between voltage and amperage. Voltage is the potential being pushed down the line forcibly, which should NEVER be anything but 5, 2.9, or 2 in a USB device. Amperage is available power that may not immediately be used. Watch out for power leeching devices not built to spec... a downstream USB device is supposed to not draw more power than is available, and some might.
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1chris89
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I'm charging mine with my note 2 2.0A 5v charger and it's been over 30 minutes and still on the battery too low to power on screen...
What's the Voltage Spec on the Nook Color charger?
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