12 volt outlet

I am attempting to use the power plugs in my 2006 Boxster to charge my mobile phone using a standard USB 12V charger plug, The plug itself and the cable I am using appear to work as expected (and tested in the power plug of my other car). In the Boxster, however, the charge rate appears to be abnormally long (5 or 6 times longer as measured by an app on the phone and observed negative -- discharging when phone is actually used). The phone seems to know it is connected to a charger and the charger itself is powered as indicated by its LED. The phone itself knows that it connected to a charger and indicates charging is in progress. This aberration seems true of all three 12 volt outlets. I have tried both 1 amp and 2.1 amp chargers. Is this normal ?-- I can't think what might be the cause but it really cramps my cell phone usage in the car. Any suggestions as to what I can do to make this usable?

depends on many things, what type of device and charger are you using? - your phone battery could be faulty or could have depleted most of its life - your charger could be giving less than what is indicated ( up to 2.1A) - you are using your phone while charging, like steaming movies / music, downloading, brightness at max, etc. which consumes a lot of power i doubt it has something to do with the car. I always use this whenever i charge USB Charger Doctor Mobile Battery Tester Power Detector Voltage Current Meter SY | eBay it tells you the actual voltage and the ampere of the phone you are charging normally its 5.X v or 9.X v charge and ampere depends on the phone unit

Yeah, I don't see how the car could limit the charging rate, but agree using a tester would tell you exactly what's going on. Think I'll buy one of those - thanks for the tip.

Yes that would have been my thought as well. But the phone is OK (in fact I have tried with both mine and my wife's) - it charges correctly everywhere else (including on the two AC chargers I have and in my other car). The chargers and cables (I have tried 3 chargers and 2 different cables with the same result) are also apparently OK and work as expected in my other car. So the only thing I am left with is the car -- that is why I am asking. I will see if I can get the tester you recommend and try to figure out if something is awry with the car.

again, what phone are you using? i remember i had my iphone 5, it charges normally at 5V .8 amp. (4w total )and it was not enough to charge it fast, whenever i would watch movies or stream media, phone would drain very slowly instead of charge. i switched to samsung note 4 with fast charging at 9v 1.67amp (15W total) so it charges really fast even if i use it extensively

The phones are Moto G gen 1. Both phones charge normally (on any other charger -- in my Corolla or on a AC charger) in about 1.5- 2 hours from near depletion on a 1 amp charger and about 2/3 of that on a 2.1 amp charger (based on my reading of the specs it will draw maximum of 1.5 amps). In my tests the phone is on but doing nothing but cell phone standby. In the Boxster the estimated charge time is 3 to 4 (or as much as 5 to 6) times the normal rate (I have never actually charged to complete charge so not sure if the estimate is accurate but the change in charge seems to indicate that the estimate is correct). Actually when using the phone (especially for GPS function with screen displaying which is my normal use case in the car) the phone discharges faster than the charger in the Boxster keeps up resulting in depletion when attached. It is a mystery ... I ordered one of the testers mentioned above -- from Hong Kong though so maybe a few weeks before I get it -- maybe it will provide more clues.

My tester should arrive between Mon. May. 18 - Mon. Jun. 22, so it will be a while. I have used a 2.1A charger with my Cayman & HTC One and found that it was not charging much with the GPS map app running, so maybe there is something funny going on. If I get ambitious I'll cut apart a cable and see if I can measure charging current.

If your phone charges fine in another car, then your phone and charger are ok. The voltage source for charging will affect your charge rate. ....dramatically in some cases. I'd bet your voltage is lower in your Porsche .

my normal car battery is around 13v when on, 12v when engine off. but it should not affect the charge rate unless the port is bad. update us when you receive it. thanks

OK, cut apart a spare USB cable and made some measurements. I put a 0.1 ohm resistor in series with the charging wire (red) and made a few measurements charging my HTC One M7: - HTC One 1A charger: V = 4.82, I = 390mA - Generic 1A charger: V = 4.93, I = 430mA - Cayman using Scosche dual 1.2A charger in power tap between seats with car off (V=12.48V): V = 5.4, I = 536mA. The HTC One is currently around 94% charge, so maybe that slows down the charging rate. I'll repeat the measurements when the battery has discharged a bit, and also see what happens with the car running.

Those measurements would seem to be "normal"?

Drained my HTC One down to 46% battery, and got the following measurements using same procedure as above: - HTC One 1A charger: V = 4.91, I = 765mA - Generic 1A charger: V = 4.69, I = 450mA - Cayman using Scosche dual 1.2A charger in power tap between seats with car off (V=12.48V): V = 5.00, I = 738mA. I don't know how the phone decides how much current to draw, but I see no evidence my Cayman has a problem charging the phone. Maybe if I drained the battery near zero I would get charging currents closer to 1A - not sure. It does appear my generic 1A charger is weaker than the HTC 1A charger, but in both cases (94% charge and 46% charge) the 1.2A Scosche charger in the Cayman was the best. I did try both ports on the Scosche and got essentially the same results, although it might slump a bit if both USB ports had loads at the same time. I think everything is working as expected, so yes, I'd call this "normal".

During phone charging, the current should decrease over time as you charge your phone because the resistance (series of your .1 ohm resistor and your phone) is going up as you change the state of charge of your phone (i.e goes up). As the phone is charging, the current will asymptotically approach zero as you reach 100% charge. Conversely, if you start charging at a lower batter level, your current will be higher. Try charging the phone when it is at 10% charge. It will draw more than 738ma.

My Note 4 with its bigass 4.4V 3220 mAh battery charges like a champ in my CS using the center console outlet and a Motorola 12V fast charging cable I bought on eBay.

Eh, maybe, all depends on what the smarts in the phone is doing. Most smart chargers will attempt to charge at a constant current up until 100% charge is reached. Based on my 2 data points, you're probably right, the phone is not using a particularly sophisticated algorithm, probably limited by what it can do with the limitations of a USB port. My guess is it may simply limit the current based on how much droop it is getting from the supply. Although I used to work in cellphone development engineering, it was on the base station side, not the cellphone side, and we used very sophisticated algorithms to charge the back-up batteries as quickly as possible. Of course those were large single-cell lead-acid batteries, not lithium-ion. With respect to Brian's problem, it is possible the charging logic in his Moto G phones is somehow getting tricked into thinking the voltage source is weak and thus limiting the current to something much lower than what it could actually support. Not knowing how the algorithm works, I don't know what to suggest. Maybe adding some capacitance to the connector would help, but that is a wild guess. Another alternative would be to wire in something like this - http://www.amazon.com/DROK-Adapter-...rger/dp/B00F0CS1EK/ref=sr_1_6?ie=UTF8&qid=1430274607&sr=8-6&keywords=usb+supply . Not sure it would help, though.

I think you guys are shootin' blanks. It's pretty clear that the problem he's having is not caused by the phone. It is isolated to charging in the Porsche . So we ought to be concentrating on what could cause that. Using the center console cig lighted, OP - try plugging-in and using the cigarette lighter. If it can make the lighter coils glow red-hot, it is feeding plenty of current to the outlet. If this doesn't work, that's a big clue where the problem lies. Another possibility is that the charger is not making good contact in the Pcar's power outlet. I've heard that Porsche 's outlets are a little different (although I have not had any problem). So - examine the hot (center) contact in the outlet and make sure you are getting the charger plug in all the way into the outlet. Also make sure that the charger plug is making good contact with the metal on the side of the outlet (ground). Push real hard and hold it with your hand. I also wouldn't rule-out possible wiring problems in the circuit, but the center console outlet is a different circuit than the footwell one, so it is unlikely that both circuits would be bad. Finally, maybe the outlets aren't grounded properly to the chassis.