Nexus 5 Users!! Texas Instruments BQ24192

[cybertronicify]

Hey all! I own a Nexus 5 that seems to love charging on its original 5v 1.8A Nexus charger. Only that charger will charge my nexus faster than 1 Amp. I figured that the charge controller chip says Vin Max is 17v. I can safely pump 12v into the phone? Charge controller chip:

http://www.ti.com/product/bq24192

[wraper]

Sure you can. Your phone will be dead though  .

[godFather89]

Might work. But would you risk damaging your phone? 
Let us know if you try.

[wraper]

The problem is, there is not only charging controller connected there. Moreover there should be TVS diode and fuse connected to this rail. In the best case only fuse will blow once TVS diode clamps the voltage. But it is useless anyway, because charging current is not determined by input voltage.

[cybertronicify]

I put 8v into it, it pulled 1.98 amps and it didn't smell very good. Everything still worked but im scared to go further. I did get the phone charge, in 10 minutes it went from 13% to 42%. Now thats fast charging, but I wouldn't suggest you try it.

[zapta]

I put 8v into it, it pulled 1.98 amps and it didn't smell very good. Everything still worked but im scared to go further. I did get the phone charge, in 10 minutes it went from 13% to 42%. Now thats fast charging, but I wouldn't suggest you try it.

How does this work? Vin is 8V, battery is 4V, something in between has 4V @ 2A. Does that charger IC use switching DC/DC?

BTW, I managed to charge my N5 at ~1A max, even when using a 2A (verified) 5V charger.

[amyk]

I put 8v into it, it pulled 1.98 amps and it didn't smell very good. Everything still worked but im scared to go further. I did get the phone charge, in 10 minutes it went from 13% to 42%. Now thats fast charging, but I wouldn't suggest you try it.

That was a ridiculously risky thing to do and I recommend you don't try it again since you probably damaged something in the process - including the battery.

Read the datasheet and you'll find that the current limit is configured via I2C, but can be overridden via an external resistor. Thus if you were really inclined to get a faster charge then look at the software side of things.

Also, lipo batteries are quite flammable.

[saturation]

A common annoyance in lower charger currents is typical USB data cables, they are not designed to deliver power and have a significant IR drop.  "Charger" USB cables use 24 AWG wire in the power line versus 28 AWG in standard data cables.  If the Nexus 5 charger cable is removable try that on your 'other' chargers and see if it improves the charge current.

You should label the power cables once you know identify them, there is no standard appearance, labels or coding, so they appear just like regular data cables.  A common difference however is they tend to be shorter than data cables, but there is no fixed length difference.

[mazurov]

You need to let your phone know that it is connected to a charger capable of delivering more than 500ma. For simple power sources this can be achieved by strategically placing resistors between data and power lines, see here -> http://www.usb.org/developers/docs/devclass_docs/ , under "Battery Charging".

[okashira]

Hello!

Bumping this old this old thread to ask a beginner question...

I have a nexus 5, and I'd like to modify the battery. However, the battery I want to use requires different voltages.

Would it be possible to reprogram the BQ24192 in the Nexus 5, or is this set on the board in hardware some how?

From the datasheet, programming the BQ24192 is done via the SCL and SDA pins on the chip. This is an "I2C" interface and programmed at address "6BH"

My question is, is this programmed at the factory, and the BQ24192 has an internal flash memory?
Or is it likely programmed at every use via the Nexus 5 Hardware (or Software?)

According to the datasheet, it says connect SCL and SDA to the logic rail via 10k resistors. On the board, it appears there are resistors connected to each pin indicating that it is connected on the nexus 5...

[zapta]

Hello!

Bumping this old this old thread to ask a beginner question...

I have a nexus 5, and I'd like to modify the battery. However, the battery I want to use requires different voltages.

From my limited and unqualified experience Nexus 5 works by applying the voltage (single cell) to its internal power input. Possibly you can have your external battery with a separate charger. 

BEWARE, lithium batteries are very dangerous and can cause fir, injury and death so make sure it is done by somebody that is qualified. Also, I am a non qualified layman so take everything I am saying with a grain of salt.

[okashira]

Hello!

Bumping this old this old thread to ask a beginner question...

I have a nexus 5, and I'd like to modify the battery. However, the battery I want to use requires different voltages.

From my limited and unqualified experience Nexus 5 works by applying the voltage (single cell) to its internal power input. Possibly you can have your external battery with a separate charger. 

BEWARE, lithium batteries are very dangerous and can cause fir, injury and death so make sure it is done by somebody that is qualified. Also, I am a non qualified layman so take everything I am saying with a grain of salt.

Very nice!!!! So you have connected an external power supply? For what purpose if you want to share? :-)

My problem is, the nexus 5 is designed for a battery with 3.0 - 4.35 volt.
I want to use a battery with set voltage of 2.8 - 4.1.
This can be done by reprogramming the BQ24192
But how...

Any battery connected will work from 3.0 - 4.35 (or 3.5 - 4.35?)
When controlled by the internal charger/discharger.

Are those terminals you found the positive and negative battery terminals?

By the way, my new battery is intended to be internal. shooting for 10,000mah and long calendar life/high temp resistance. :-D

I wonder why there are three battery terminals...

[zapta]

Did it many times, motivation was to measure power consumption with different software versions. Search for power play on github. I think the other wire(s) are for data and temp sensor.

Search YouTube for lipo fire, it can be dangerous.

[okashira]

Did it many times, motivation was to measure power consumption with different software versions. Search for power play on github. I think the other wire(s) are for data and temp sensor.

Search YouTube for lipo fire, it can be dangerous.

I am well aware.. won't be using lipo's

went ahead and did a test on the two terminals with a varaible power supply..

4.01 volts and the phone considered the batt 1/2 charged. Still ran at 3.6 volts. Cut out at 3.49 volts.
So it seems to operate at 4.35-3.5 as suspected.

I want to use Panasonic 18650's which will go 2.8V-4.15V, and also also much safer and more durable then lipo, but that will require reprogramming of the BQ24192.
I hope someone can provide a clue if this is possible.

Otherwise I will use LG 4.35V 18650's which aren't quite as good but will suffice for 3.5-4.35.

[zapta]

Use a boost DC/DC when the battery is too low? Not as elegant but may work. What percentage of your battery capacity is below the operating voltage? Maybe doesn't worth it.

[zapta]

The source files of android are available so maybe you can find an answer to your question there.

[okashira]

Use a boost DC/DC when the battery is too low? Not as elegant but may work. What percentage of your battery capacity is below the operating voltage? Maybe doesn't worth it.

If I were to use Panasonic's... like 40% of the capacity is below 3.5V.
But even worse, charging them to 4.35V would be terrible, they would not last long.

I've decided to go ahead and use the LG's. I'll get about 94% capacity to 4.35-3.5V with those.
They won't stand the heat (hot car in the south) like the Panny's would, but I should still get 3 yr out of them. Still safer then Lipos
Since my phone will have 9600mAh, I wonder how many amps the USB OTG is programmed to provide (also controlled by the BQ24192). My phone could be a power bank for other phones, even an ipad...!
I know the BQ24192 supports a full 2A for USB OTG...
Need to finish this mod first, getting ahead of myself...

I am still curious to know if the chip BQ24192 could be reprogrammed.

[okashira]

The source files of android are available so maybe you can find an answer to your question there.

My hunch is that it's not software controlled. Because the BQ24192 is designed to work without phone powered on at all or even working.
There is some hardware on the motherboard that sends the appropriate I2C signals to the chip... or it's factory programmed ?

[TheUnnamedNewbie]

My guess is that the loss in the dc/dc converter will be higher than the gained energy you can get out of the batteries

[okashira]

My guess is that the loss in the dc/dc converter will be higher than the gained energy you can get out of the batteries

Well, TI makes DC/DC 5V boost converters that are as good as 96%...
Also, the BQ24192 already performs the function of a boost converter for when battery voltage drops below specified system voltage, so it would be silly to run a double boost when the BQ24192 can already boost from 2.8 to 5V (or 3.3/whatever is set)
Which is why I either want to reprogram it ... or I will just have to use batteries with similar voltage profile... :-(

[cybertronicify]

The reason why the N5 took in soo much current was because of the charge controller chip. It is able to handle turbo charging the battery by using a higher voltage thus making the input wattage higher.

For example a cable can only handle 2 amps of current. 2 amps at 5v is only 10 watts. But 2 amps at 8v. thats a whopping 16 watts of power. But it still is 2 amps. So the cable doesn't get that much hotter than 2 amps at 5v.