Hardwiring a car charger (USB 500mA vs 1A)

Smiert said:

I'm trying to figure out what the best way to implement a hardwired charger.. more specifically in terms of getting the most mA as I can. What I understand is that when the data pins on a USB charger are floating, the phone requests only for 500mA. When the data pins are shorted, the phone requests for 1A (or 1000mA). On any decent 5v ciglighter /wall outlet phone charger, I understand that the charger shorts these data pins, allowing for that full 1A charging capacity.

I plan to use one of these ebay 12v to 5v converters:
http://tinyurl.com/oogbhyn
..and splice a standard micro-usb connector to the 5v output, also connecting both data wires together.

If I understand this correctly, would this provide 1A to the phone? Does anyone see any implications?
Thanks!

Click to expand...

Click to collapse

In theory it should work OK.

I would recommend a few things. Make sure that dc-dc converter is easily accessible if you need to check it or smell a smoke in the car. Don't bury it too deeply where you will have to take too many things apart to get to it. I made plenty of mistakes in the past where years later wire cracks or connector is not making a good contact and I have to take the whole damn thing apart to get to it Also, I would STRONGLY recommend to add in-line blade fuse, like this: http://www.ebay.com/itm/Waterproof-..._Video_Fuses_Fuse_Holders&hash=item3f2dc85fa3

The last thing you want is to damage your phone if you get some in-rush spike. DC-DC converter looks ok, but you never know what could go wrong if it overheats and something shorts out. At least you will have a fuse to protect your 5V power supply line going to the phone. And since blade fuses are replaceable, you just pop in 1.5A or 2A, obviously don't use 10A that comes with it.

Once you done, comeback and post some DIY pics!!!

Smiert said:

I was planning to use these add-a-fuse circuit extensions. I'll be sure to pick up some 2A fuses (supposedly the smallest fuse for mini-fuses)!

I want to actually hardwire chargers for two things into my car; my phone, to the left of the steering wheel dash, and a recently acquired dashcam right next to the rearview mirror. I drive a little Mazda so space isn't plentiful. The fusebox is to the left of the driver's left foot, so I planned to wire two add-a-fuse circuits; bring one up 2~ feet before the windshield pillar (phone), and the other along the pillar, over the headliner, where it would go to the 5v converter, and then bring the mini-usb cable where the headliner and windshield connect. There really isn't much I can work with..

Do you think that sun damage would damage the exposed cable? Perhaps it would be better to have an exposed female-usb outlet "installed" and use adapters to charge the electronics?

Click to expand...

Click to collapse

I have my Passport X50 wired through a-pillar. It's not usb, but 12V tapped off cigarette lighter internal wires so I can use another usb converter plugged into a cigarette lighter.. l was able to run the wire under upholstery of my GS350, but it was kind of tricky. I actually used credit card to push it in along the edge. Otherwise it would not look clean, and will be exposed to a sun - in my opinion sun damage is a problem. Perhaps get one of those cigarette lighter to AC adapters and use something like that 40W 5-port Anker wall charger I just reviewed?

I want to do the same, but for a dashcam.
Can I tap in to the power line that goes to the auto dimming rear view mirror and connect something like this to it?
Does the converter comes with a fuse or do I need to add an additional fuse?
Thanks in advance