My In-Dash Nexus 7 Project

[Monkey]

Has anyone experimented with something like this in place of using your phone as a hotspot: http://www.gumtree.com.au/s-ad/burpenga ... 1066731792
And if so, do you know whether this or equivalent models are locked to the carrier (Telstra, Optus, etc)?

[phly]

Has anyone experimented with something like this in place of using your phone as a hotspot: http://www.gumtree.com.au/s-ad/burpenga ... 1066731792
And if so, do you know whether this or equivalent models are locked to the carrier (Telstra, Optus, etc)?

I believe all the carrier labelled ones are locked to specific carriers. Their data plans are usually pretty pricey too. It should be cheaper hotspotting on your phone and increasing the data allowance rather than getting one of these cause you're effectively paying for another sim/plan.

[Monkey]

Has anyone experimented with something like this in place of using your phone as a hotspot: http://www.gumtree.com.au/s-ad/burpenga ... 1066731792
And if so, do you know whether this or equivalent models are locked to the carrier (Telstra, Optus, etc)?

I believe all the carrier labelled ones are locked to specific carriers. Their data plans are usually pretty pricey too. It should be cheaper hotspotting on your phone and increasing the data allowance rather than getting one of these cause you're effectively paying for another sim/plan.

Yeah cheers for that. I'm on Boost prepaid and have the top $40 package. Data can be added for $5-25 but it's either insufficient data or too expensive. I've been monitoring 3G data usage and one 3min song sucked 25MB of data with tablet connected to phone. That equates to up to 500MB p/h. And then there's the fact that hotspotting drains phone battery life pretty quick. So I'm just exploring options at the moment.

[psy]

Has anyone experimented with something like this in place of using your phone as a hotspot: http://www.gumtree.com.au/s-ad/burpenga ... 1066731792
And if so, do you know whether this or equivalent models are locked to the carrier (Telstra, Optus, etc)?

Should be no different to using your phone as a hotspot.
Thats a Telstra branded device,s o will be locked to their network Im guessing.

[gradg]

I've finally finished making a custom USB OTG Y cable and prelim charging results are very promising. I will give it a test with torque tomorrow, as that seemed to be the big battery drainer. WIFI etc worked while holding a 100% charge for host mode.

EDIT:

For those that haven't read through the whole topic, I had issues with the current carrying capacity of the OTG Y cables that I was trying from ebay. This included ones that claimed they could charge on the go. They did not. Seeing as I was running a heavy gauge USB cable (purchased from ergotron a 20/24G cable) I knew the bottle neck for the current was at the Y cable. The cable I've made myself is a Y with 20G power and 24G data cores so there's no issue with charging on the go.

I couldn't be happier that i've finally got this thing to work. Buying the cables from the cheap chinese vendors on ebay was getting tedious when they would not work.

Back to great quality audio!

Anyway.....

I realise that these charging Y cables may be hard to come by. So I'm willing to make them for anyone that wants them.

At the moment I'm looking to charge around the $30 mark posted, for something that is guaranteed to work. It won't be the prettiest cable you've ever seen (although it'll be heat shrunk etc to tidy things up) but it will work. The terminals on the USB plugs you get, to say they're tiny is an understatement, so these things take time.

All joints soldered and all terminals hot glued to prevent them wiggling free.

If anyone is interested just shoot me a PM. I'll probably make a few over the next week or so and throw em up in the for sale section.

Thank you to everyone that helped with their info throughout this! Much appreciated!

G

[Monkey]

Interested but what charge rates are you getting? Currently I'm getting only 900-1000mA Max from 2.1A cig lighter. I need ideally 1500mA

[bigBADbenny]

Yes please put me down for one of your mega OTG Y cables please

[HardwareBoB]

me too - I have an ebay one that seems to work, but better to be sure before I put it in!

[gradg]

Interested but what charge rates are you getting? Currently I'm getting only 900-1000mA Max from 2.1A cig lighter. I need ideally 1500mA

While I don't have a REALIABLE metering APP, I'm yet to test the current on my meter. After a lot of reading, the charge current apps that are available for android are quite finicky - as I found myself. Android apparently doesn't have an accurate command for measuring the charge current.

The cable worked okay on teh drive home today. Torque use on and off (exiting when it wasn't required) and mainly media playing, although I think I've got issues with the USB cable from the Y to the hub playing up. (Y cable charges, USB DAC works fine from any other source and the thumb drives I've tested in the hub tend to drop out) So there's an issue there I need to iron out before I'm 100% on these. I want to be sure my system works 100% before I can use it to test on, ya know?

Monkey, you won't get the current you require to run this system as well as a hub powering other devices and charging on the go - I feel - simply using power from the cig lighter.

I'm using a system where I've used the 12V DCDC which has a dual 5V supply. One supply goes to the powered USB hub, one supply to the Y cable to charge the tablet.

[Monkey]

CurrentWidget works well. I'm not yet running a hub, and I've read that the 2013 Nexus is more efficient and charges much quicker. Currently I'm getting 1% charge every 2 mins with everything on. But the discharge over night is more than 1% per hour in deep sleep. I believe 1500mA charge would mean my charge rate exceeds the discharge rate and I could complete the install.

[bigBADbenny]

Are you using Greenify or similar to hibernate services on the Nexus?

When I redo my interior (long term project), I'll be running front and rear power for dash cams.
I'm considering a Battery discharge prevention device / Uninterrupted power cable...
https://dashcamtalk.com/battery-discharge-prevention/

I like the model that has 12.4V cutoff option...

Something like this would be handy for my BtSsm host device, so I can implement car-off Titanium Backup sync over wifi as described here:
http://forum.xda-developers.com/showthr ... ?t=2552570

[Monkey]

Are you using Greenify or similar to hibernate services on the Nexus?

Timur's kernal hibernates the tablet when power is cut. Drain is still too high though if you don't turn off wifi/BT and GPS.
CBF doing another hack on it - I think increasing the charge rate is what will solve my problem since I only drive 15mins to work each way.

Interested but what charge rates are you getting? Currently I'm getting only 900-1000mA Max from 2.1A cig lighter. I need ideally 1500mA

While I don't have a REALIABLE metering APP, I'm yet to test the current on my meter. After a lot of reading, the charge current apps that are available for android are quite finicky - as I found myself. Android apparently doesn't have an accurate command for measuring the charge current.

As mentioned, I reckon CurrentWidget is good.

The cable worked okay on teh drive home today. Torque use on and off (exiting when it wasn't required) and mainly media playing, although I think I've got issues with the USB cable from the Y to the hub playing up. (Y cable charges, USB DAC works fine from any other source and the thumb drives I've tested in the hub tend to drop out) So there's an issue there I need to iron out before I'm 100% on these. I want to be sure my system works 100% before I can use it to test on, ya know?

Monkey, you won't get the current you require to run this system as well as a hub powering other devices and charging on the go - I feel - simply using power from the cig lighter.

Maybe. I'm currently using a 2.1A input, no hub but UCA202 and Timurs kernal which has fast (AC) charge mode. Tested today with a car USB hub with 2.4A output - no change - still around 900-1000mA mark.
Then I tested with wall plug 2A onput and got even less - 700-800mA. I then removed the OTG cable (direct to tablet) still using the wall plug 2A output and got 1100-1150 mA. So I'm thinking the OTG Y-cable is the bottleneck - if I can get a higher capacity OTG Y cable and a 2.4A charger (on order), I may just get close to my goal of 1500mA charge rate.

I have one more theory I'd like to test:
Connect OTG USB hub to tablet: http://stationery.auspost.com.au/techno ... eader.html
2 x USB male to USB male cables connected from power source to hub
3rd USB port for the DAC (none left for USB stick though).

I currently have a cig plug which is 2.1A + 1.0A. If this works, it would theoretically put 3.1A into the tablet (limited by cable capacity)
This wouldn't work with a normal USB hub, but I believe the OTG hubs are 2 way due to read/write capacity. Any thoughts on whether this would work?
My main concern is that, like my current OTG cable, the circuitry may well be limited to around 1000mA

I'm using a system where I've used the 12V DCDC which has a dual 5V supply. One supply goes to the powered USB hub, one supply to the Y cable to charge the tablet.

How does that work? Can you do a basic wiring diagram? If your DAC is plugged into the hub and not the OTG, you wouldn't get an audio signal. And if you were simply using the hub to plug in peripherals like a USB stick for music, it too wouldn't have a connection to the tablet. Or am I missing something? What amperage is the output per supply? Is it hard wired or USB?

[Viper]

HI chaps,

More info on all this stuff.

So the Nexus 7 2012 (Gen1) doesn't support the current monitoring apps, so you'll need to use a multimeter to get the amperage draw.

I had some issues measuring mine with the Nexus connected for some reason. Might have to get a new multimeter
Anyway. without the Nexus, the USB 3.0 hub + USB stick + DAC was pulling 1.6 amps.
So add in the 1.8 amps for fast charge and you'll be coming close to 3.4amps for that setup.

I also switched my power supply last night to the 15amp Buck type so we'll see if it fixes my issues.
In my bench tests the voltage provided was much more stable than the previous, so it should sufficient.
I'll post some pics over the weekend.

[Monkey]

So the Nexus 7 2013 doesn't support the current monitoring apps, so you'll need to use a multimeter to get the amperage draw.

My Nexus 7 2013 appears to show drain and charge rates using CurrentWidget (with update interval set to 1 sec)... unless this is wrong?
Drain appears to be between 200-600mA depending on what features are active and screen brightness
Charge rates appear to be between 200-1100mA depending on connection. Anything under 300mA charge will slowly discharge.

Screenshot_2015-01-30-10-37-47.jpg (122.58 KiB) Viewed 6029 times

Looking forward to more pics / updates on your setup!

[Viper]

So the Nexus 7 2013 doesn't support the current monitoring apps, so you'll need to use a multimeter to get the amperage draw.

My Nexus 7 2013 appears to show drain and charge rates using CurrentWidget (with update interval set to 1 sec)... unless this is wrong?
Drain appears to be between 200-600mA depending on what features are active and screen brightness
Charge rates appear to be between 200-1100mA depending on connection. Anything under 300mA charge will slowly discharge.

Screenshot_2015-01-30-10-37-47.jpg

Looking forward to more pics / updates on your setup!

Yep sorry, I meant the 2012 Gen1 model ;p
Haha.