Bought this 12V USB dual Charger to hardwired into the car Show
Thanks I will downrate the cigarlighter fuse to 10A (from 15A) and use a 3A in this new circuit tomorrow ; so at least the combined value is less in total, than the stock fuse value. I am also going to labouriously check all the fuses in that particular fuse box, just to make sure someone didnt mix them up i.e. if there is a 15A f Use in this ‘fuel pump’ slot, ooooopps could the correct one (a 30A) be in a 15A slot. (Thats my worry). I think its only worth double checking all t He fuses in this fuse box located “behind the rear seat’s central parcel shelf” , as the the others are not nearby i.e. one in each end of the dash board, and two up front in the engine bay. Hopefully safe to assume if they mixed it up it would only be within the same fuse box. They didnt make a diesel S Class Coupe, so cant be that. I was wondering if the tracker engineer tapped into this circuit and pulled the fuse for safety while he installed it, and then couldnt find it and just stuffed anytging back in there. (as there has been no evidence of issues with the fuel pump). Or maybe an ECO downgraded the fuel pump fuse.
I think you are right Its pretty close to it. I just realised my Fluke multimeter has a Clamp DC Amps setting. At the USB end 4.91V to 5.2V unconnected. The Dashcam read 0.37A to 0.45A The totally flat iPad Air sucked 1.98A to 2.02A And at the fusebox 12V side It varied between 1.1A and 1.14A. So having a 3A fuse I used that in both the top and bottom pigtail fuse sockets. Originally it had A 15A fuse for the rear cigar lighter ... which the S Class Coupe doesnt have one ! So pretty safe to assume no one can overload that standard circuit as there is no outlet, other than my new USB charger. As this charger has two 3.1A outputs where one can deliver 6.2amps i.e. x 5V = 31 watts So 31 watts divided by 14.3V engine running = 2.167A x 1.2 = 2.6A. I upped it 20% as a magin of safety to account for the conversion inefficient from 12V to 5V ... guess its probably more like 10% loss so well covered. In reality the most it cou,d use is say charging 2 iPads, so 5V 4 amps = 20 watts / 14.3V = 1.4A on the 12V side. But she shares the same wiring loom as the S Class Saloon ... just that element are not connected
I doubt that you always get 14.3V with the engine on. Measure it at the end of a decent drive home with the headlights and windscreen heaters on. If the battery is full then it would normally charge at 13.8V and with an empty battery possibly 13.0V, you normally only see 14.3 from a few seconds after starting the engine up to around 5 minutes after. For the first few seconds after starting the engine, the alternator is normally off, and if you have a stop-start system it may also turn off for a while when it decides the battery is full.
Now thats an interesting point. I had fully charged the battery (6 months old) with a CTEK ‘Start Stop’ (max 14.8V and 3.56A) maintaining charger, till it got to “Care Maintenance Mode” and then left it on overnight. In that mode it charges at 13.8V and runs down to say 120mA. That morning the Battery was at 13.2V ... which dropped to 13V quickly as it lost its residual charge spike. So my tests were done with a completely full Battery . I am therefore surprised it wasnt charging, as you say at 13.8V. Unless it was recovering from having the doors open and door courtesy lights on. .? I know the electrical system is working perfectly, because Mobilo spent 4 hours completely checking everything. ( starter, Charging system, Battery, Batteryncontrol module etc.] Long story ... I got a new MB battery and it failed to start the next day. Long story short ... I got a new but intermittantly defective battery :-0 Once replaced, it was and remained all perfect again.
Is there a fuse for USB port in car?Check the Fuse Box
A blown fuse can shut down the circuit that feeds electricity to the USB port. Find the fuse panel (typically on the driver's side of the car) and the diagram that identifies what each fuse does. If there's no diagram or it's too small to read, a full drawing can be found in your owner's manual.
What size fuse do I need for USB socket?The 20 amp fuse protects the wiring between the battery and the socket in case a short develops there. Be sure to use a heavy enough wire! I would use 14 gauge or possibly larger than that if it is a considerable distance to the battery.
Why did my USB port stop working in my car?A failure in the functioning of your car's USB port can usually be traced back to a shortcoming in the hardware or software. Despite how powerful and useful they are, they're more prone to particles getting inside because they're open. As such, food, dust, and other debris can make their way into the port.
How many amps does a car USB port provide?Often they provide around 2.1 or 2.4 amps dependent upon the device, but check what you need. Car USB chargers providing 2.1 and 2.4amp are now common.
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