12VDC to 5V USB port.

[Colt45ws]

I was on a sudden and unexpected trip out of town the other day, and realized my phone was running low on charge. I went to the local WalMart and grabbed a cigarette lighter to dual USB adapter. Then I found a 140W inverter with a usb port for a couple bucks more so I grabbed that. Well, the inverter runs all the time. Huge parasitic draw for just a USB port.
I pulled it apart and traced it out, the 5V is coming off its own board and is just taking 12V from the board. The only thing that is being done is a pair of 16V 2200uf on the feed.
Could I take just the board and hard wire it up to my switched aux line I have in my car? Should I add a capacitor on the input, maybe a 470uf? I have a couple Chemi-con KMG 470uf 16v. Those twin 2200s are shared with the inverter section, so I dont think I need quite that much.

[Krankshaft]

Re: 12VDC to 5V USB port.

Why not just buy a charger for your phone that plugs into the cigarette lighter?

The USB section is just a 5 volt voltage regulator with a filter cap connected afterward. That is why they're so dirt cheap. This modification sounds very convoluted for what you're trying to accomplish.

To answer your question it won't hurt to have an input filter cap. 16 volt rated filter caps are a bit too close for comfort the alternator can put out around 14-15 volts when the engine is running. I would go up to the next standard voltage 25 volts.

[Colt45ws]

Re: 12VDC to 5V USB port.

Well, I would like to make it look like it is supposed to be there in the dash. Plus I would like to put it on my aux keyed acc/on line I already have run behind the dash for stuff like this.

[kaboom]

Re: 12VDC to 5V USB port.

A '140' watt inverter from whalemart is gonna need some help, the least of which will be a cap job.

https://www.badcaps.net/forum/showthread.php?t=13201

Try one of those USB backplates that's made to fit a rear expansion slot. Cut it to fit, paint it gray or black, mount it in the dash and be lookin sharp. A little 7805 ckt is perfect.

-Paul