Piston Slap: The Cigarette Lighter’s Enduring Appeal
Roger writes:
How can I make the USB ports hot when the vehicle is shut off?
Sajeev answers:
The easiest answer is to not do that. Instead, consider adding USB charging ports to your cigarette lighter. Re-wiring any part of a vehicle carries inherent risks, especially in modern times of multiplexes and electronic modules controlling everything. Buying a USB port for a standard automotive, 12-volt cigarette lighter is cheap, easy to install and gets the job done, as you can see here in my lovely Lincoln Continental. (Grabs phone, scurries to the garage…)
Cigarette USB chargers are available in a million different designs, some with extra features like a voltmeter, or bluetooth-to-FM modulation. Some also mount nearly flush, ensuring they fit behind an ashtray door or modesty panel. (I both have and recommend the flush ones, but the USB stick pictured here was free and this car was currently at my house.)
But perhaps your application doesn’t have a cigarette lighter. Or you don’t want anything else inside your cigarette lighter. Fine, I guess we need to continue this thought experiment!
I have my reservations publishing everything you shall see going forward, as you must find a way to run down a 12-volt wire down to 5-volts for a USB port. Or maybe not, but I am not electrically savvy enough to commit to either side of this discussion. Perhaps it’s worth a try, especially if you are comfortable replacing a USB port if it gets toasted in the process. So get your car’s wiring diagrams, disconnect your battery, throw out your factory warranty (if applicable), and proceed!
Once you bust out the factory schematics, find a power wire that is “always hot” from the fuse box, one that isn’t controlled by the ignition key (or push-button system). USB charging for smartphones is usually around 1-3 amps, so just about any source of fusebox power could work without blowing fuses, or damaging your fuse box.
Once the appropriate wire is found, splice into it and run a fresh wire to the USB. Before adding it to the USB charging port’s wiring harness (again, look at the wiring diagrams to find the correct wire!) consider installing an in-line fuse holder as close to the USB as possible and pop in a 3 amp fuse in it. Or perhaps this is mandatory? I’ll let the comments section handle that.
With the USB’s wiring harness at hand, cut the wire providing the current source of power and replace it with your new wire. Plug in the USB port to its harness, and reconnect the battery to test. Once you are confident the USB port is charging your phone and not cooking a wiring harness at the same time, carefully reinstall everything and hope you never have to go back in there.
Or, you know, just get a USB adapter for your cigarette lighter. It’s the right move.
Re: the comment about the cigarette lighter plug-ins being “cheap” (i.e. – inexpensive), that really depends. I’ve seen them from Dollar Store items to upwards of $12.99 just recently. I’m certain that if I cared to look, I could find “designer” brands that are even more. Now, not being even as “electrically non-savvy” as Sajeev claims to be, I’ve no idea why there is such a disparity in pricing – is there really a huge difference in quality? Dunno. Perhaps another commenter can throw some light on the discussion.
I’m always leery of wiring in “always hot” accessories, however. Not only is there a chance of parasitic draw, but on old cars, there are few safety systems built in to preclude frying something that’s got power in it while you are not even in the car. As Sajeev suggests, proceed with extreme caution, and ALWAYS fuse anything with a low-amp-sized fuse as you can get by with. You surely want a fuse to blow first before toasting a wiring harness, your dash cluster, or worse, your entire car.
A plug-in (cheap or otherwise) is simple, and simple is better. Unless you are a smoker of course, and regularly use the light for its original intended job. Then you might have worries about starting your car on fire other than just wiring!
If I can wait for something, usually I do not buy it at a retail location. This goes for repair parts (i.e. Rock Auto) but also for accessories. I bought a bunch of these USB cigarette lighters on eBay from a Chinese vendor for about $1.50 each. I should probably get some more, as I seem to have run out of them on my cars and giving them out to friends like party favors. 🙂
Two questions:
– got any red ones?
– throwing any parties soon?
😁
Only black or chrome here!
Ratz. But your loss, really. I make a killer tzatziki sauce for dipping pita bread.
And now I have regrets!
$1.50 Chinese eBay chargers sound about as sketchy as wiring an always hot USB port to a 1986 Escort.
Except they aren’t, they’ve lasted over 10 years in my case.
If I were interested in running an always hot USB port in my car (not entirely sure why this would be necessary), I would go out to the interwebs to find something that is already 12v powered with USB ports like this…
https://powerwerx.com/blue-sea-1016-dual-usb-panel-mount?utm_source=bing&utm_medium=cpc&utm_campaign=*Catch%20All%20-%20Shopping%20-%20%242,000%2Fmo&utm_term=4585444532081842&utm_content=All%20Products
I would then run hot and ground directly to the battery and leave the poor factory wiring alone. I would do the opposite of what is recommended above and install the fuse as close to the battery as possible. The purpose of circuit protection is not to burn the car down… not necessarily to protect the load. 3A fuse is probably reasonable. 1A @ 5v is something south of half an amp at 12V, but the example I posted has two ports, so you might need some extra margin.
The standalone USBs are a wonderful idea. I should have mentioned them, even though I was only thinking of car interiors where mounting such a device would be challenging. More challenging than the cigarette lighter USB.
Putting one of those in the bed of a truck is a great idea.
Most cigarette lighters and ports are not in good places most have lids and will not shut if you put an adapter in.
The best thing to do is get a spitter that plugs in place of a fuse and the fuse is retained in the splitter. No splicing , hacking or other thing is needed. The car can be fully restored.
You can get a port and mounts to the dash underside. Many tape on.
https://www.discountcarstereo.com/mini-tap.html?category_id=317
You can get whatever port you need USB or lighting.
Don’t cut wires unless needed.
I had no idea such things even existed. Interesting. Thanks for the link.
Many vehicles don’t have the cigarette lighter live when the ignition is off, so the cigarette lighter USB converter may not answer the question.
Wiring a 12USB from ebay is pretty simple I did it in a travel trailer and some of them come with a combination USB and cigarette lighter so you have options.
I would not want an always on USB as you may possibly drain the battery. The usb adapter for the 12v is simple and easy. Even on my newest cars I still use one as the 12v plug with a usb adapter can deliver more power than the USB alone and therefore charge quicker. Factory USB’s are usually current limited so they just can’t compete with a newer one designed for quick charging todays phones.
Kind of related, but not to the issue at hand. While (Whilst) searching for some 1995 Corvette parts recently, I came across a cigarette lighter in the form of a red “Eject” button. Of course I ordered it.