Adding USB power port to Tahoe

[MikeTheApeman]

Well, I had posted my attempts at adding a hardwired USB power source to my Tahoe in the Interior forum. Got no replies, but thought that some folks might be interested in this here.

Originally, I had a 3-port cig lighter adapter that had a USB port in it. Can find them all over eBay, but here's the one I had:
http://cgi.ebay.com/3-Ways-Triple-C...in_0?hash=item2302ad0ef2&_trksid=p3286.c0.m14
Very handy unit, since my phone uses a USB cable for charging, as did my TomTom before changing out the head unit to a nav one. BUT, I never used the cigarette lighter ports at all. I opened the unit up, saw that the USB portion was on its own circuit board, and got to tinkering. Tried to use the USB port on its own, wound up frying the circuit for some reason. (Upon inspection, it seems one of the resistors fried, which caused the capacitor to blow up...literally.)

My quest continued. I stumbled across this article online:
http://www.engadget.com/2006/06/13/how-to-add-usb-power-to-your-alarm-clock/
Went to PartsExpress and found I could get all the parts for about $10. Not bad at all, and seems like anyone with basic wiring ability could do this.
Then, before I got a chance to order the parts, I stumbled across this on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230372121904&ssPageName=STRK:MEWNX:IT
Hmmm....wound up about the same price after shipping. Gotta love eBay.
I have not gotten the item yet, but when I do I will let you all know how I installed in the event that anyone else wants to do this. Hardwired USB power without using the 12v outlet, should work just fine with HTC phones (i.e., AT&T Tilt or Fuze), Blackberry phones, any phone that uses a USB to charge, as well as GPS units.

I do still plan on ordering the parts to build a unit though. It's more a question of "can I build it myself?" kinda thing. If it works well, I might just go ahead and install the port in the trim somewhere. I still think it'd be kinda cool to have a USB port sitting right there in the dashboard. Maybe I'll use the cubby where some of you guys mount your Garmin's or backup camera monitors, make that a charging / switch panel.

 

[vatahoelt]

that would be pretty cool to put in there. add in 2 ac outlets there too.

 

[Eagle]

just make sure it does a couple of amps... not .5 like some of those chargers.

I know my old IPaq was 2 amp, the PSP is 1.5 amps, etc.

 

[MikeTheApeman]

If I was going to add an AC outlet, it'd basically involve gutting an inverter. If I were to do that, then I'd probably just start with a Kensington unit I found that has a USB port and outlet. Either that or buy a cheap powered USB hub and wire that into the inverter.

Starting to rethink this design though. I thought about something not previously put in my equation: heat. That 7805 will likely get pretty hot going from 12v to 5v, leading me to think the way to go is install the unit in the engine bay once built and just extend the wiring to put the port in the cubby. I might just build it and hook it to a 12v bench unit to test the heat tolerance. Might need to add a heat sink or even some kind of regulator. Time to bring in some engineer friends to figure this one out.

 

[RobertWYoung]

They get really hot, heat sink is a must. I'm also not sure how much current you can pull from them, wouldn't think it would be more then 1A.

I plan on doing an inverter in the back, don't think gut it though I'll just stick it in some cranny and run extension cords to a mounted receptacles.

 

[MikeTheApeman]

You're correct that the 7805 will only do 1A. I haven't found a quick and dirty one that will go higher. While 1A wouldn't work for a PSP or such, it should work okay for a cell phone.

and by 'gut it' I meant take the outlets out of the inverter and extend the wiring from the unit to mount it. There's no point in pulling anything else out, since they're designed pretty well.

 

[Eagle]

perhaps it would be easier to simply buy one of the 5v 2 amp lighter plug units and convert the lighter plug to hardwired, and the other connector from round to a USB?

 

[MikeTheApeman]

Yeah, but what fun would that be?

 

[Eagle]

true!