USB hard-wire install
 

I'm using an old Galaxy S3 to run torque, Waze and listen to audio books. I have it mounted on a low profile mount in the top left corner of the windshield near the pillar.

I want to hard wire a usb cable, but I want to make sure I'm getting enough to maintain a charge and not just slow down the battery drain.

My plan is to cut a factory USB cable and short wires 2 and 3. Then connect to this: [ame="http://www.amazon.com/dp/B00A71CMDU/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1D8X B8X6N6PBF&coliid=I3MO6QIT1AV1U8"]Amazon.com: KEEDOX® DC/DC Converter 12V Step Down to 5V 3A Power Supply Module: Electronics[/ame]

and then use an add a fuse to the panel under the driver's side dash. I don't want constant power, only while the car is on. Run it up the pillar and down from the headliner, nice and clean and pretty.

Thoughts? Will this be sufficient?

Check the interior fuse box. Some slots only have power with ignition.

Yeah, that's the plan.

Ah I see. I interpreted that part as something else. :bonk:

It should easily be more than enough power though. I would crack the charger open to bypass the step down voltage regulator, and place it in line. Otherwise you would kill the battery. Or you can get a 12v charger if you want to avoid opening a wall charger.

Wait what? Don't I need the step down as USB is supposed to be 5V?

The car is 12v so yes you would still need a step down. It would be easier to just put a 12v (car) charger in line.

Honestly, I have no idea what actually does the charging. I wouldn't be surprised if the charge circuit is in the phone. Why do I say that? Because 5v is probably too much for a single cell. If this is the case, then any 5v source would work.

I would still play it safe and put a car charger in line.

There is a 12V cigarette lighter receptacle in the glove compartment.

Buy a $10 USB phone charger and plug it in there.

My dashcam is currently using that, and in the past when I've run USB cables that far it hasn't maintained enough juice to power my phones while using bluetooth and GPS.

Can you elucidate? I don't think I understand your terminology.

TBH for this I'd use a simple cigar socket splitter behind the glove box and run the dash cam and phone off it like boredom suggested, its gotta be simpler to try that first than the other route. Is the phone being setup to hibernate when not charging?

Ya I go all over the place sometimes. You were originally talking about cutting into the USB wire though. I was just going along with that initial condition.

Tap a 12v source
Hook car charger up to it
Splice charge supply wires into USB power wires

I've done this before and it then becomes insufficient for keeping the camera and the phone charged.

Yes, but over long drives the phone will die. I'm trying to get as close to 2100mA as possible and splitting will not achieve that. :(

Dual Power Auto,Dual USB Ports Car Charger
Its dual-port interface features one 5V/2.1A port which is ideal for ultra-fast charging devices such as Apple iPads and other tablets, and one 5V/1A port for Smartphones, iPod, GPS and other devices.

http://www.newegg.com/Product/Produc...140805151518:s

that looks cool