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Technical details about nook HD+ charging

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By modelworks, Junior Member on 27th June 2014, 01:42 PM
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7th September 2014, 12:29 AM |#11  
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Quote:
Originally Posted by invinciblemo

I would like to ask does anyone knows, what is the voltage of a fully charged battery?

Lithium-ion cells are typically charged to 4.20V. The Nook HD+ uses that value, too. Nominal voltage is 3.7V. I forgot the cut-off voltage that the HD+ uses to decide that the battery is empty, but I think it was 3.4V or 3.5V.
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10th September 2014, 01:58 PM |#12  
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Quote:
Originally Posted by Tzul

Lithium-ion cells are typically charged to 4.20V. The Nook HD+ uses that value, too. Nominal voltage is 3.7V. I forgot the cut-off voltage that the HD+ uses to decide that the battery is empty, but I think it was 3.4V or 3.5V.

To add to that, make sure you put a load on the battery if you are measuring the voltage of the battery disconnected.
Something like a single 330 ohm resistor would be good.

Bad lithium batteries sometimes will appear charged until you place the load on it then it falls to 2 or lower volts.
Another quick check is to make sure the battery casing is completely flat, if the battery has bulges of more than a few millimeters the battery is about to fail and should be discarded immediately. Another trick you can use is smell the battery, I know sounds weird , but failing lithium batteries have a very unique odor , almost sweet, reminds me of the smell of bananas.
11th April 2015, 01:28 PM |#13  
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Quote:
Originally Posted by Tzul

[*]Nooks will only fast charge on dedicated charging ports, which are recognized by having their data pins shorted. That's more or less standard nowadays for generic USB chargers (USB Battery Charging Specification). However, some chargers still don't meet this requirement, and Apple has their own incompatible standard, naturally.[*]Don't use your tablet if you want to charge it from a low-power source (i.e. USB data connection on the Nook), because depending on the workload, the battery will be charged very slowly or will actually be discharged.

I have an HD+, which I have not been able to get to charge on a 3amp, 2amp or even a 1amp wallwart, but it does charge via its Nook wallwart. Does the above mean that were I to 'repurpose' a short USB extension and simply short the D- and D+ (clear of the +ve and ground) together in the USB lead, that I should then find it will charge via that lead? Please?
1st June 2015, 01:12 AM |#14  
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Quote:
Originally Posted by harrym1byt

Does the above mean that were I to 'repurpose' a short USB extension and simply short the D- and D+ (clear of the +ve and ground) together in the USB lead, that I should then find it will charge via that lead? Please?

Sorry for the late response.
Yes, that is correct, I have built such a cable myself and it does work.
5th June 2015, 10:31 PM |#15  
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Battery Issues
I have a Nook HD and it immediately dies as soon as it is unplugged, however there is no apparent damage to the battery, no bulges, leaks, or smells. After I plug it in and it reboots it goes from 10-20% charge to 100% charge within minutes. Is there a way other than removing the battery and charging it externally (outiside of my mechanical ability) to reset the battery to determine if it is a software issue or an issue with the battery itself. Currently running CM 10.2.1 stable.
27th May 2017, 07:31 AM |#16  
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Charging problem - solved
I had similar symptoms with my Nook HD+ : when plugged into charger the indicator light turned green, then orange, but only for a second, then went dark. When left on charger for many hours, the indicator would start blinking red. Nothing worked, until I read technical details in this thread.

The bottom line: if the battery voltage drops below 1.8 V, the stupid control chip assumes the battery is "bad" and refuses to pass the charging current; consistent with the observed symptoms. This gave me an idea on how to fix this:

Step 1: Open the Nook by prying the front panel to get access to mounting screws, then unscrew the back panel.
Step 2: Locate the battery cable composed of three red, three black, one blue, and one yellow wires.
Step 3: Locate the gold test points on circuit board _under_ the wires: "VBAT" under the red wires, "BAT-" under the black wires.
Step 4: You have to trick the control chip into "thinking" that the battery is still "good". For this, you'll need an external voltage source. I used my homemade adjustable DC power supply setting it to 2.5 V. I guess, any voltage between 1.8 - 3.7 should work.
Step 5: Connect the _positive_ lead from the external power source to the "VBAT" test point, connect _negative_ (or ground) lead to the "BAT-" test point.
Step 6: Plug your Nook into charger and wait a few seconds: the indicator light will now stay solid orange meaning the charging current is passing through. Yay! You should disconnect the external DC source; it's no longer needed.
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