Need some wiring advice.

[north42g]

02 PR5 2.0L,
Has some kind of wiring issue. Trying to figure out what it is exactly.
My cigarette lighter/12 volt power supply is not working properly.
Any device that I plug in , instead of charging or supplying power to the Device, it instead DRAINS the power from the device.
It has ruined My GPS Unit , my IPod , and two cell phone!!!

I have all the wiring diagrams but I don't really know whats going on here. Have any of you ever heard of this?
I suspect I have some sort of Power Short.
I do have a complete aftermarket stereo system; ( two 12 inch subs are hooked into MA Audio HK-401SK 1800 Watt Amp, The 4 speakers in the doors are powered by a 4 channel Ma Audio 1000 watt Amp, The tweeter speakers mounted at the side view mirrors have been replaced with KICKER Tweeters and are powered by there own Amps.)
The whole system was installed professionally.(That doesn't mean it was done perfectly correct, but I think they did a very nice job.
Any ideas on what could be goin on?
It might be as simple as replacing the 12 volts power supply socket entirely...hopefully.

 

[memo79]

IDK about the install job, but I'd start with that stereo system. Shut it all off and see if your devices charge then.

 

[north42g]

yeah ......seriously I know right!?
I guess I was hoping that someone has seen some sort of reoccurring issue that I could just fix.
Know what I'm saying?

 

[pcb]

The cigarette lighter powers off with the ignition so there is no power to your charger when the key isn't in. Perhaps your charger is draining backwards because of poor design of the charger (many cars power-off the cig. outlet with ign. off).

You can fix that by cutting the positive feed wire to the lighter and rewiring it to the battery with a fuse (probably 10 amp unless you use a high power inverter in your car,... check the power drain on anything you might plug in).

That way your devices will keep charging when your not in the car (be careful not to kill your car battery. Keep an eye on the power drain. The charger will draw a lot less power when the device is fully charged but there is always some standby current).

I still find it odd that all the different things you plug in drain the device. The chargers should shut down when the ignition is turned off but they would all have to drain backwards to kill your batteries. Perhaps the chargers are over charging the devices and that is killing the batteries but that would mean that all the chargers are doing the same thing.
The only other thing I can think of is that the guys wired into the ACC. wire and that controls the relays for power on your amps. That could cause a reverse power drain. The ACC. wire normally goes "open" when the ignition is turned off which powers down the AMP relays but if the relays are waiting for power to turn back on then the chargers could feed back into it. That still means that all the chargers will drain backwards (a simple diode in the chargers circuit would prevent that) but maybe the manufacturers expect the ACC. feed to be completely open when there is no power, without the possibility of current flow to other circuits.

Either way, I think wiring the cig. lighter (and just the cig. lighter) to always hot may very well fix your problem as well as allow your devices to charge while the key is out.

PS If you send me the wiring diagrams, I may be able to help you out further. (That's a reference to the PM I sent you)(RTM)

 

[pcb]

I just measured my cigarette lighter and it is 0 V with ignition off and 12.34 V with ignition on. The resistance of the outlet, with the power OFF was around 15.5 k ohms and was floating because the meter sends voltage into the ACC. line and charges up some capacitors and coils on the ACC. circuit.
I'm guessing your resistance (with power off to the lighter) is a lot lower (because of your AMP relays) creating a much greater power drain if something plugged into can drain backwards.

 

[Installshield 2]

I have a very similar problem in an old Porsche 928...and i have narrowed down to a specific short.

if a 12v outlet is creating a draw on devices connected to it...it has to be a short, or a device that is wired in incorrectly to sort of create the same problem. The problem with a 'short', is that all kinds of things can create it. a failing relay technically can create a short, even though the circuit its controlling is completely in tact... there is no circuit in the car that will purposely pull power from anything but the battery, at least factory wise...so i'd start by detailing how your receiver and amplifiers are wired in...

I have an alpine stereo that uses a 4 channel 38 watt rms amplifier, and a rockford fosgate something (can't remember)...BOTH devices needed to be directly connected to the battery with their own fused line. If i didn't, the draw from the amplifiers would be enough to start pulling current from aux circuits in the harness, at least that is what the directions said...

so i'd pull the receiver out and closely go over how its receiving power. Most amplifiers need 2 power sources, and the factory radio harness already has that. One is the 'real' power line, which is controlled by the ignition switch...the other is a constant power line that keeps pre-set and clock memory fed...depending on the receiver, this could be handled differently that the factory radio does it. The factory radio is tied in with the constant line always hot, and the switched line turning it on when you turn the key. my alpine uses an internal switch, sort of the opposite. I have a big line that is used to fully turn it on as well as keep memory intact...and it uses the factory switched circuit to 'see' when its ok to turn on, much like a remote line for a sub amp works.

it would've been very easy for me to accidently switch those lines around...in which the amplifier(s) could actually be on with the key off, and start to put a draw on other circuits...but even then, the car battery should be able to power that stuff for hours...

the 12V cig lighter is pretty much its own switched circuit...nothing else should be on it (a reason many guys use that circuit to power aftermarket gauges)...so i'm sort of thinking whoever did your receiver wiring may've used that for power instead of the factory radio lines...or its own line (like i did)...

 

[pcb]

I have a very similar problem in an old Porsche 928...and i have narrowed down to a specific short.

if a 12v outlet is creating a draw on devices connected to it...it has to be a short, or a device that is wired in incorrectly to sort of create the same problem. The problem with a 'short', is that all kinds of things can create it. a failing relay technically can create a short, even though the circuit its controlling is completely in tact... there is no circuit in the car that will purposely pull power from anything but the battery, at least factory wise...so i'd start by detailing how your receiver and amplifiers are wired in...

I have an alpine stereo that uses a 4 channel 38 watt rms amplifier, and a rockford fosgate something (can't remember)...BOTH devices needed to be directly connected to the battery with their own fused line. If i didn't, the draw from the amplifiers would be enough to start pulling current from aux circuits in the harness, at least that is what the directions said...

so i'd pull the receiver out and closely go over how its receiving power. Most amplifiers need 2 power sources, and the factory radio harness already has that. One is the 'real' power line, which is controlled by the ignition switch...the other is a constant power line that keeps pre-set and clock memory fed...depending on the receiver, this could be handled differently that the factory radio does it. The factory radio is tied in with the constant line always hot, and the switched line turning it on when you turn the key. my alpine uses an internal switch, sort of the opposite. I have a big line that is used to fully turn it on as well as keep memory intact...and it uses the factory switched circuit to 'see' when its ok to turn on, much like a remote line for a sub amp works.

it would've been very easy for me to accidently switch those lines around...in which the amplifier(s) could actually be on with the key off, and start to put a draw on other circuits...but even then, the car battery should be able to power that stuff for hours...

the 12V cig lighter is pretty much its own switched circuit...nothing else should be on it (a reason many guys use that circuit to power aftermarket gauges)...so i'm sort of thinking whoever did your receiver wiring may've used that for power instead of the factory radio lines...or its own line (like i did)...

All that makes sense but I'm pretty sure the guys who installed it (professionals) did everything right.
Perhaps another way to look at it is if you were to apply 12 V to the lighter socket with the key out, you would be powering up all the circuits that are connected to that circuit. (ACC. 1 or ACC. 2 i forget which) but on my car, those circuits are a very high resistance (15.5 k ohms) which translates into only about 3/4 of a milliamp (.774 milliamp or 774 micro amps).

Those relays for all his amps can draw a significant amount of current. Not the current that they are switching but the current that runs through the little coil in the relay (not so little in a high current relay. Those relays handle a lot of power so the coil inside has to be bigger to operate the physically bigger mechanical switch inside them)

So instead of his cig. lighter circuit being 15.5 k ohms (like my stock car), it's probably a lot less. When the key is removed from the ignition, the device plugged into the lighter socket may then start to power all the relays,... perhaps not enough power to kick them on but enough for the battery in the plugged in device to run dead with a long period before the car is started again. Those batteries in the devices are quite small (amp hour wise) compared to a car battery. And the car battery is removed from the circuit with the ignition off so it's just the device battery feeding into the ACC. circuit.

It still boils down to why the plugged in device is allowed to drain backwards. north42g may very well have only one charger that he has used for all the affected devices. So the problem may be in that single device.

He could also put a diode on the cigarette lighter "hot" wire to make sure current only travels one way. (properly oriented and rated for the amps required by anything plugged into the socket).

 

[pcb]

I just grabbed a handful of little 12V relays at a wrecker a few days ago. All the terminals are either closed or open accept for the two "control" terminals that are connected to the little coil inside. Those would be the wires (+ & -) that would be connected to the ACC line in a car to switch high current devices on and off. They measured between 73 ohms and 108 ohms (with the smallest relay having the highest resistance).

Those four Amplifiers in north42g's car, almost certainly have similar internal relays. Each one would have the ACC wire connected to the "control" terminals of the relay and they would draw 600 milli amps. total (if they are the same internal resistance as my collection,... Those are high power amps so the control circuit drain would be quite high)

So if the ignition is off and the connected device is able to drain backwards, then the battery in the device sends voltage to the Amp relays. There is most likely some internal resistance of the charger that's plugged in and the reverse voltage would drop way down to the point where it is not enough to activate the relay but the current still flows until the battery in the device is dead. Then when the car is started, the battery is charged up again and eventually kills the battery in the device.


I'm pretty darn sure that a diode put on the positive of the cigarette lighter would solve this.


Installsheild 2,... does the cigarette lighter outlet power off with the ignition on your Porsche 928 ?? Do you leave the device plugged into the cig. outlet when the key is out ??

north42g,... did your devices get fried or was it just the batteries that were killed ?? (some devices crap out if the batteries go completely dead,... some lithium ion batteries have a "fuse" in them that "blows" if they go completely dead because they are almost a dead short when they get recharged so the charging circuits were heating up and catching fire so they added the fuse)

Both of you guys could check for voltage by unplugging your device after things are all charged up (the car has been running for a while) and check to see if there is voltage on the plug terminals of the of the device you plug in. If there is voltage there,... it's gonna go into the ACC. circuit,... It's not an open circuit so it will draw current (but it's not a short either, just a normal circuit with resistance that is operating normally).