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Advice for dedicated AA phone

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I basically did a similar thing with a tablet a long time ago. I think I used Automate and triggered off whether the phone was charging or not. It would also goto standby mode though I had to tweak some things to make sure nothing woke it up randomly. Since I was not mirroring and just connected to a charger. The main issue was that the device could not draw enough power to keep it charged.

I agree, the issue with mirroring, is that you use the same cable for charging as USB data. I'm not sure about split cable idea because it probably depends on a few things. The simplest 5A 500mA charge is obviously too low. I know of some chargers that will put on 5V 2A. The fast chargers will start upping the voltage. However, the phone needs to support this. Some fast charging technologies use the data lines to negotiate between the phone and charger to determine the charge rate. In the old days, I think if there was a data signal, it would default to 500mA.
Yes the car/charger needs to be able to supply the power, but the phone has to actually draw the power. That's a big unknown with a used phone.

Basically, I'm weighing this option with a AAWireless or Cardongle from indigogo
 

sosimple

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Aug 20, 2017
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If anyone is afraid to do the cable which redirect the voltage to a 2nd USB with a fast charger (i also was thats why i didn't keep it this way), then what i have already done is the best solution.
With the switch (on/of) i turn off android auto (disconnecting data and voltage) and connecting (voltage) to the 2nd USB with the fast charger, so when you don't use android auto, phone to charge fast.
The others way is actually simplier and working better as phone will always charge fast even when you use android auto, so battery never drain. You have the switch only to connect / disconnect one of the wires for data.
 

Lenster45

Senior Member
Oct 2, 2010
197
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Naples
I have a couple of phones I could use for this, but a question I have is: can I use the second phone for AA and still have my primary phone connected for handsfree phone calls?

Len
 

sosimple

Senior Member
Aug 20, 2017
2,135
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Greece
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I have a couple of phones I could use for this, but a question I have is: can I use the second phone for AA and still have my primary phone connected for handsfree phone calls?

Len
Now you can. Install AIO TWEAKER. It has an option not to use Bluetooth when connecting to android auto. This way you can be installed to android auto by one phone, and connect to Bluetooth by another. I tried, it works.
 

sosimple

Senior Member
Aug 20, 2017
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As i was writing above, i have a dedicated for android auto nexus 5x always in car. I use an on/off switch to enable / disable android auto. But i did have drain in battery. I modified a cable to do this.
I now try to improve it. I did what I was writing above.
Some facts i have learn and are useful to anyone who will try it:
A usb cable has 4 wires :
2 for data, and 2 for 5v voltage +-.
If you actually cut the cable you will probably find more wires. In my cable which it had a usb c which go to phone, i actually find 4 wires and the screening if i write it correct. It is the wire which goes around and around of all the others. At first i thought this doesn't play any role.
This is actually the voltage wire -
2 other wires i found out are actually 1. They are connected together probably so you can input usb c in both ways. Those are voltage +
There are 2 others without voltage. They are data wires.

So what i did to improve the system :
I cut the 2 voltage wires which go to PHONE and send voltage to phone by another usb fast charger which i actually have in car lighter.
The other 2 cutted voltage +- cables which go to car usb, goes nowhere.
So to car usb are going only the 2 wires for data.
Everything is working and now phone doesn't drain when i use android auto.
I connected the on/otf switch so to connect / disconnect one of data cables so to enable / disable android auto but although it mostly works there are some problems. I will move the switch so to connect/ disconnect the voltage + cable. It will work better. The 2 data wires will always be connected to car.
By connecting the 2 data wires to car, Android auto DOESNT WORK as i found out. Voltage should go to phone so that android auto start working. But it doesn't care if this voltage come from car usb (for android auto), or from anywhere else, as i found out.

I hope it is useful for someone. I searched in internet and didn't find anything. Everything i posted here i founded by myself.

I should add that i don't actually connect phone to car usb. I have a usb hub between (because car has only one usb and i wanted to connect phone and a usb for music).
I don't know if it has anything to do for everything to work fine, i don't think so.
Anyway if you are hard-core and want to reduce drain and everything to work more "professional", this is the way to go.

Car android auto, and voltage from external charger schediagram, for solve phone draining.
 
Last edited:

sosimple

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Aug 20, 2017
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My final custom cable with 3 positions switch.
Switch position:
A: Android auto ON (working) AND fast charging ON
Middle : Android auto OFF, fast charging OFF (not charging)
B: Android auto OFF, Fast charging ON

I don't write it in photo, but in B, i connecting the 2 wires Data +, and data -, with a resistor (i used a variable one like this: https://www.electronicscomp.com/10k-ohm-variable-resistor-trimpot-metal-preset).
I do this so connection with the car to fail, and have only phone fast charging.
I hope it is useful to someone. I spend many hours experimenting until i found the best solution.

Also in the previous schediagram photo i posted, i connecting voltage - ot fast charging and voltage - that goes to car. I had forgotten this to note it in the schediagram. So it's not entirely correct as i have posted it.

Android auto custom cable with fast charging and 3 position switch
 

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  • 1
    Hi there,

    since I don't want to root my main phone (don't want to hassle around with some apps that try to block on rooted phones, and also don't want to enable that stupid google voice assistant to use google maps and so on) I want to buy a phone just for Android Auto. This phone will be rooted and stay in the car all time, it could also get a custom ROM. Since I don't have any experience with AA mirror yet and also not that much experience with rooting, it would be great if you have some suggestions what I could get for this use case.

    From what I found here so far, the requirements seem to be:
    - easy to root
    - possible to install custom roms
    - will have the display turned on (for AA mirror) for several hours whenever traveling a longer distance
    -- maybe heat could be an issue?
    - should not have the cheapest battery since it will be charged for long times when traveling as well as not charged at all for several days
    -- unfortunately, there doesn't seem to be smartphones anymore that can be used with batteries pulled out
    -- is there anything to be considered because of the always-usb-connected use case
    - preferably a cheap model from a premium manufacturer

    Any suggestion for my decicion or experience with a dedicated phone would be helpful.
    1
    Have you considered a raspberry pi?
    There are plug n play rom do get that up and running as a AA display

    Sent from my SM-N960F using Tapatalk
    1
    D
    Deleted member 1198227
    I'll post it here also:
    I made a 4 minutes video displaying android auto mirroring in my car, with some apps and a dedicated phone with a switch for this. It may give some ideas:
    1
    D
    Deleted member 1198227
    Hi .
    What rom do you recommend for S5?
    You mean galaxy s5?, I don't have s5. I had it in past. I would install something similar to the rom i installed to nexus 5x i have.
    The lighter nougat rom with pico gapps.
    If it goes ok with battery consumpsion an especially standby time you keep it. If not try another one.
    1
    You mean galaxy s5?, I don't have s5. I had it in past. I would install something similar to the rom i installed to nexus 5x i have.
    The lighter nougat rom with pico gapps.
    If it goes ok with battery consumpsion an especially standby time you keep it. If not try another one.
    Thanks for the advice :bueno: