[MTCB Hardware Development] CaptShaft:
Hello folks! I wanted to explain the solution I came up with to the problem of the very lengthy startups on my android car radio.

Your typical car radio is wired like you see below:

https://drive.google.com/file/d/0B_X6EY6VJIXNRk8tR3VobmxOdUk/view?usp=sharing

With a OEM radio, your startup is just a few seconds for a modern Linux- or android-based car radio. Even some aftermarket radios like the mainline AVH Pioneer series are up and running in seconds.

Not so much with our favorite android aftermarket car radios. Boot up times are something on the order of 20 to 30 seconds. This isn’t too bad in and of itself, but if you’re the sort of individual that likes to “get up and go” this starts getting very annoying after a while. If you’re refueling your car then start up the motor when finished, that cuts the power to the radio and you witness another 30 seconds before everything is up and running, and that’s before the stereo does its media scan and the audio apps get loaded into the RAM. So you’re almost a minute on your drive before the tunes start.

A straightforward solution is what you see below:

https://drive.google.com/file/d/0B_X6EY6VJIXNcVFYZG1mamhVN00/view?usp=sharing

I’ve wired the ignition trigger line directly onto the positive. This keeps the radio on at all times. This eliminates the annoying boot up delay, however we run the risk of draining the car battery this way. I have seen discussions on this forum where standby power consumption for aftermarket android head units runs somewhere on the order of 25 mA, all the way up to 300 mA or more. I have not tested this out although it would make for an interesting study. The point is this is a potential problem if you plan to leave your vehicle parked somewhere for an extended period of time. You don’t want your car in the long term parking lot at the airport to have a dead battery when you arrive back late at night from your trip, because the android radio was running off your car battery for the days or weeks you were gone.

If you wish to eliminate the lengthy android boot up time and also save your car battery, allow me to propose the following solution:

https://drive.google.com/file/d/0B_X6EY6VJIXNV2pUUmNiN3RLMDg/view?usp=sharing

In this example, I have purchased a battery isolator and a very small auxiliary battery just the power the car radio. This involves the addition of some extra electronics in your trunk, and some extra 4-conductor wiring from this new battery and battery isolator up to the car radio. If you know what you are doing you can do this all in one afternoon, which was my experience.

You’ll need a few things in order to get this project rolling:

A 12V 18-amp-hour battery that is typically used in an uninterruptible power supply. $35:

https://www.amazon.com/ExpertPower-EXP12180-Rechargeable-Battery-Bolts/dp/B00A82A3RK/

Battery isolator:

https://www.amazon.com/NOCO-IGD140HP-140-Battery-Isolator/dp/B001DKRF2M/

or http://www.westmountainradio.com/product_info.php?products_id=iso_pwr

(There’s plenty of different choices here. Look around and see what you like. I chose the IsoPwr unit because it is solid-state diode-based and has no mechanical relay inside it.)

Four-conductor wire:

https://www.amazon.com/16AWG-4-Conductor-Speaker-White-Mediabridge/dp/B0193RRUBM/

Butt splices, and splicing tool.

Fish tape, for running the wire underneath the carpet in the car.

Toolset for removing the seats, center console, removing the radio, etc.

A stiff drink for when the trolls show up. (Just kidding! :D )

I also purchased a pair of trailer wire extension cables, which are four conductor wires with plugs.

https://www.amazon.com/Hopkins-48145-Wire-Extension-Length/dp/B0002RNSNM/

This works well for keeping the wiring in place in case I need to remove the battery or the radio.

https://drive.google.com/file/d/0B_X6EY6VJIXNbGswdW04V010akU/view?usp=sharing

https://drive.google.com/file/d/0B_X6EY6VJIXNTDhfY3hLT2Rlc3M/view?usp=sharing

https://drive.google.com/file/d/0B_X6EY6VJIXNVUc5TXJSMzN2STQ/view?usp=sharing

As you can see in the pictures, I fabricated a wooden stand to retain everything, and I had a plastic battery box laying around from an earlier car stereo installation.

https://drive.google.com/file/d/0B_X6EY6VJIXNNElSUDUtOGhDNXc/view?usp=sharing

The procedure is simple, you place the battery and isolator in the trunk and run the wire up to the car radio. You cut the power leads on your aftermarket car wire radio harness, and splicing your four conductor wire. This wire runs all the way and hooks up to your isolator in the trunk, which in turn is connected to the auxiliary battery.

https://drive.google.com/file/d/0B_X6EY6VJIXNVE9peGZGZF91MXM/view?usp=sharing

Also, an important point: LABEL YOUR WIRES!

https://drive.google.com/file/d/0B_X6EY6VJIXNaVhPVWg4OHlGMGs/view?usp=sharing

You really don't want to mis-wire anything and screw up your car.

An optional switch on the positive line running to the radio prevents discharge of the auxiliary battery, in case you’re parked for an exceptionally long amount of time.

If it seems like a lot of running around to get around a technical limitation on the part of the radio manufacturers, it really is. This was an experimental project on my part to expand my technical prowess in to give me the android car audio experience I desired minus the tire some waiting for the radio to boot up every time I got in the vehicle.

I’ve been running this for a few days now and the result is excellent. I can restart the car after filling up at the gas station, and now there is little delay other than the OS scanning the USB and MicroSD drives. And the radio works almost from the start first thing in the morning, before I even pull out of the driveway.

If you know what you are doing it can’t be beat.

Any questions?