[e90yyc]

I don't know any other way to say it, but I feel like the accessory (cig lighter) sockets in my car are gravely underpowered... Doesn't (and shouldn't) matter whether I use the one in the ashtray or the center console: the output is so shitty that my phone charges at a glacial pace, or if I'm using a GPS app, barely at all.

I'm just wondering if this has been anyone else's experience? I've tried different USB adapters and even a 120 watt power inverter (with a DC usb power adapted plugged in) but seem to get similar results no matter what I use.

Currently I have a 2A USB power adapter. Even if it's putting out closer to 1 amp, it should still be adequate to at least charge my phone at a reasonable pace. But it's terrible. Way worse than the 1A power adapter I have at home.

I don't have this issue in my GF's Q3.

Am I just using shitty adapters or what? I plan to do a little testing in the coming days using a multimeter in series with a USB cable I have in order to determine current. I'm expecting to see < 500mA.

[gbalthrop]

Originally Posted by e90yyc

I don't know any other way to say it, but I feel like the accessory (cig lighter) sockets in my car are gravely underpowered... Doesn't (and shouldn't) matter whether I use the one in the ashtray or the center console: the output is so shitty that my phone charges at a glacial pace, or if I'm using a GPS app, barely at all.

"Underpowered"? Here is the circuit diagram for the Lighter/Power sockets in the 2007 328xi (at least my E91 -- you don't give your chassis#):
https://www.newtis.info/tisv2/a/en/e...socket/akuLwb5

Note that all four sockets use the SAME fuse, F30 (20A), which is only active when ignition is ON (terminal 15 powered). Also note that the three sockets inside the cabin use the same Ground Point (X173) while the socket in the Cargo area/ Luggage Compartment uses X151. The TIS circuit diagrams are interactive, meaning you can click on any BLUE component ID# and get more information about that component, such as "Installation Location."

In electrical circuit terminology, POWER = watts = Volts & Amps. Also Volts = Amps x Resistance or Amps = Volts/Resistance. That means if resistance (such as from a bad ground) increases, Amps or current flow decreases (if voltage remains the same).

So you may have excessive resistance somewhere in the 12V+ Orange Wires between the fuse F30 (20A) and the center pin in the socket that results in voltage drop, OR you may have a corroded or loose Ground Wire (Brown) that restricts current flow.

I would begin by using a multimeter to test voltage at the center contact in EACH of the sockets, BOTH (a) with the ignition ON/ engine OFF (~12V), and (b) with engine running (~14V). Record the voltages at each socket.

Then measure resistance in reference to a good chassis ground of each socket outer cylinder (what the ground spring of your adapter touches). All FOUR sockets should read in the range of .01 Ohm (negligible resistance). Record those resistances at each socket (ignition OFF). Resistance should NOT vary whether engine running or ignition on or off, you just don't want to short out the socket & blow the fuse.

BTW, if you have a USB port in the center console, you can use a USB to Mini-USB cable to charge a phone or any other device with a Mini-USB charge port.

Please let us know what you find,
George

[e90yyc]

Many thanks George. Very helpful stuff. I will check resistance soon as I'm able and let you know my findings. I'll check voltages as well.

I do realize that what I'm saying sounds odd, and understand just enough about this stuff to know that it doesn't really make sense... I've looked at those very wiring diagrams previously and thought that none of this should be happening on a 20A circuit.

I don't have a USB port in center console, so that is a no-go for me.

***
You know, come to think about it, I did try to use the actual cigarette lighter once and it not only wouldn't stay 'engaged', but even when I held it in, it came out just barely hot, and far from glowing red. It also took forever to get there.

So now that I type this out, it does sound like I've certainly got an issue! Initially I was a bit unsure if the cheap Chinese adapters I was using were to blame, but it seemed like a bit of a stretch.

Thanks again man. I'll start chasing this down. Hopefully it's a simple enough fix.

[gbalthrop]

Originally Posted by e90yyc

...I'll start chasing this down. Hopefully it's a simple enough fix.

Perhaps quickest way to identify the problem is to use the trunk/cargo area power socket (which uses a different ground point) and see if that works perceptibly better than the interior sockets. If so, then almost certainly the interior ground point is the issue.

George

[e90yyc]

I don’t believe the E90’s have a socket in trunk?? I’m checking momentarily.

Diagram appears to say otherwise, but I can’t ever recall seeing one.

Edit:

I’ve got one in front ashtray and one in center console. None in rear and none in trunk.

[gbalthrop]

Originally Posted by e90yyc

I don’t believe the E90’s have a socket in trunk?? I’m checking momentarily...

Should have known from your "handle" that you had E90 -- here is same circuit for 2007 E90 328xi, and here is the "Installation Location" per TIS. My E91 has socket at left rear of cargo area. Don't know specifically about E90, but can't see why not.
https://www.newtis.info/tisv2/a/en/e...socket/akuLwb5
https://www.newtis.info/tisv2/a/en/e...xi-lim/SB1rrvK

George

[e90yyc]

LOL all good. I didn't think of that until now either.

Already took a peek at the diagram specific to my car. It seems to indicate there should be more than 2 cigarette lighter sockets, but my car does not have them. FWIW the diagram from your first response and the one that I am seeing when I put in my specific VIN are identical.

Can't seem to find that socket, though I do appreciate you posting the location.

Nonetheless, I will move forward with trying the resistance and voltage tests, and work from there. I've already done some looking as to where X173 is located etc, so I've got an idea of where to look if I have ground issues.

Also, is the 12V line not Green/Yellow per the diagram?

[ewicky]

Phones often charge slowly in the car because you aren't in the car very long, and because of the heat, people using them for GPS and music, etc. Also, the USB cable can make a difference. If you used a 120V inverter and it didn't beep at you "undervoltage" ie that it wasn' getting enough power, then it isn't the car's fault. Something is wrong with your phone, the cable, or your expectations.

It's a common issue for the cigarette lighter to not work well on a second-owner car. They work great when new, but whenever you put anything other than the BMW cigarette lighter in the socket (USB charger, radar detector, inverter, etc), you bend the contacts that are needed to time the heating of the cigarette lighter. That's why you're only supposed to use the center console for power, never the ash tray socket. That's also why the center console won't heat the cig lighter; they look the same and both provide 12v, but have different designs.

[e90yyc]

That makes sense -- appreciate the input.

I went against my better judgement by making this post PRIOR to doing testing of my own.

You'll be not-so-shocked to learn that when I took voltage, resistance, and current readings yesterday, everything was within spec.

The issue is that my 1A charging block--though it is indeed putting out 1A--is insufficient when my GPS is running. I knew the GPS was a power hog, but thought that surely 1A would be enough to at least charge it moderately during use. Sometimes it would actually lose a couple percent of charge when plugged in w/ GPS running, which I thought couldn't possibly be normal... but it is.

My phone also "seemed" to charge much slower than it did inside when plugged into a 1A adapter, but as you say, perhaps other factors influenced this. I'm also considerably less aware of my phone's charging rate inside.

I've now ordered a 2A adapter to charge my phone with. Not surprisingly, this is what was in my GF's Q3...

Sorry for wasting all your time! Had I done a bit more due diligence, this post would never have existed.

Thank you though for all the very helpful responses!!!