While driving to a car show a couple of weeks ago I plugged my iPod charger into the cigarette lighter of my 72 CS while driving there.

I had a whine through the radio speakers that reflected the acceleration.

I thought my antenna may have needed a better ground - I thought it would be better grounded to my amp.

After about 2 hours at the show the car wouldn't start for the trip home.

Troubleshooting led to a bad HEI ignition module (less than 6 months old).

After bumming a ride to the parts store and a new 4 pin module - she fired right up. Cussed Pertronix all the way home.


On the way to a car show today...

Plugged my iPod charger into the cigarette lighter and got a whine through the speakers that reflected acceleration.

Immediately unplugged it and apologized to Pertronix.



I know the obvious solution is: don't plug the iPod charger into the cigarette lighter.

But what's going on here? Anything I can do to make the lighter function as a charger?


Thanks for any input!

 

Just a thought here,don't mix todays technology with yesterdays .I'd bet you don't have that issue with the points setup.

 

Even 'tho lights don't flicker, the CS electrics probably supply a pretty "dirty" DC to the charge input.

 

How do you know that the iPod charger and whine, and the bad module were related?

- Eric

 

I get the same wine on my Harley when I use the cigarette lighter USB charger. No wine without it so I turn off the music until the Ipod is charged then I'm good to go. So it could very well be your charger's reaction to the current. There are noise suppressor's you can get for the circuit, I just haven't bothered yet.

 

My guess is the USB charger and whine are related because the current draw is so much larger with a USB charger plugged-into the cigar lighter than just the cigar lighter (when activated) -- higher current means stronger electromagnetic field, radio electronics not designed to counter that high a field

The bad module could be related as maybe the electrical system is not designed for such a large current draw to the cigar lighter, my understanding is the modules don't like large variations in current or voltage so maybe things are happening in the wiring

I think you're out-of-luck when it comes to charging unless you upgrade at least that circuit

 

Are you aware of how much current a USB charger draws?

The rated output of USB 1 and 2 is 0.5A at 5.0V. For USB 3 it's 0.9A.
For dedicated charging ports, it's 1.5A.

So the most your charger could be putting out is 1.5A x 5V = 7.5W, which, divided by your car's 13V supply, equals a 0.58A draw, hardly a "large current draw," especially when compared to the roughly 20A that the cigarette lighter would draw from the same socket.

This has nothing to do with current, but does have to do with unshielded RF interference created by the charger, which is being picked up by your radio, either through the antenna, or through the power supply wires or the speaker wires.

It may help to put an RF-filter capacitor between the hot of your lighter plug and ground, but it also may not.

Either way, if the charger was able to blast your HEI module, it'd be through some pretty funky esoteric RF feedback loop, which I think is very unlikely.

- Eric

 

Most unlikely that plugging something into the lighter socket killed an ignition module. Unless it's repeatable, every time, I am disinclined to link the two events.

 

My 67 wont even power up a usb charger, I ended up installing a stereo with a usb and have no problems with that.

 

I can't see how plugging in the charger would damage the ign module unless the charger is bad. I would think it more likely unplugging it could cause a problem from a collapsed field. This would put me in the camp of installing a capacitor (condenser) or trying a different charger.

 

I was thinking about this and since the noise changes with engine RPM, it must be the alternator noise that is getting into the USB / iPod circuitry.

Were you just charging a device or did you also have a device playing music through the stereo? There may be something not well grounded, or some wiring running too close to the noisy 12 Volt power source.

It could just be inadequate filtering in the USB charger that is letting the alternator noise into the system. Most car radios have good filtering, but I doubt the designer of an inexpensive USB charger put very much effort into power line filtering.

As stated previously, installing a high frequency filter on the cigar lighter power wire should stop the whine.

For anyone interested in the guts of a typical USB car charger:

http://www.ti.com/lit/an/slva464e/slva464e.pdf

 

Not much to it is there Ken.

I can see possibly a size or mechanical connection mismatch of the male end to the old cigarette lighter socket possibly causing a light or intermittent short. There was no standard to cigarette lighter components back then, different makes and models had different cig. lighter cartridges and sockets. I don't power any accessories through my cig lighter because when I tried it in the past it blew the fuse.

 

Thanks for all the input everyone!

A great think tank is one of the reasons I love this site so much. OK.gif


I'm not positive that it did, just relaying the facts as they happened.

I think that whine may have emotionally scarred me.



I think this discussion has led me to 2 options:

1. Never use the cig lighter as a charger
2. Run a separate 12v power point


Thanks again everyone!



Brain Fart Edit: My radio does have a USB port that may work as a charging port. doh.gif

 

3. Try a different USB charger.

Good luck!

- Eric