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Maxim's USB Emulator Consolidates In-Car Device Charging
11/5/2013

Comparison: Adjustment vs. non-adjustment with 3-meter cable
Blue line: End-of-cable voltage (with voltage compensation).  Red line: End-of-cable voltage (without voltage compensation). (Source: Maxim)
Blue line: End-of-cable voltage (with voltage compensation).
Red line: End-of-cable voltage (without voltage compensation).
(Source: Maxim)

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MeasurementBlues
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Charging in a car
MeasurementBlues   11/5/2013 9:27:00 PM
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>many consumers were frustrated when they tried to charge their portable devices in cars.

Well, it depends on how long you're in the car, doesn't it? If you take a 15 minute drive and you start with your phone at 20%, do you expect 100% in 15 minutes? Wou wonlt get that from a home charger. For less than about $15, you can get a dual charger that plugs into a cigarette lighter. I have a dual charger. Unless you're on a 2-hour drive, don't expect your phone to be fully charged.

 

MeasurementBlues
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Re: Charging in a car
MeasurementBlues   11/5/2013 9:28:09 PM
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I keep two Apple cables and a micro-USB cable on the car for charging.

Caleb Kraft
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Re: Charging in a car
Caleb Kraft   11/6/2013 10:15:39 AM
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I have one of those dual usb chargers.

I would assume that with smoking on the decline (it is isn't it?) that more manufacturers would simply put usb chargers in the place of the lighter. Hell, even if smoking isn't on the decline, energy sucking devices are obviously on the rise.

MeasurementBlues
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Re: Charging in a car
MeasurementBlues   11/6/2013 10:19:45 AM
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Well, my "new" car is a 2001 and my "old" one is a 1999. Both have lighters.

MeasurementBlues
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Re: Charging in a car
MeasurementBlues   11/6/2013 10:23:19 AM
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>more manufacturers would simply put usb chargers in the place of the lighter.

Don't take away my cigarette lighter socket even though I have never smoked and never will. Why, because what if you need to power something besides a phone charger? For example, my GPS plugs directly into the lighter socket. Now true, the other end of the cable is a mini-USB so I could use a mini-USB cable plugged into a USB socket, if my cars had them.

MeasurementBlues
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Re: Charging in a car
MeasurementBlues   11/6/2013 10:33:34 AM
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But speaking of mini-USB cables (see my post immediately below), did you know that they have five connections, not four? The fifth is for a pull-up resistor that lets the cable charge some devices. My daughter's MP3 player was one of those. The cable that came with it would only charge the player when connected to a computer USB port but not to a charger. Pin 4 needs a pull-up resistor so the charger knows there's something connected to it. PCB USB ports don't have that.



I have a blog about this that I can post here on request.

Caleb Kraft
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Re: Charging in a car
Caleb Kraft   11/6/2013 10:37:23 AM
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Sure, a lot of stuff exists that use that old cylindrical interface, but switching to a usb plug wouldn't be a big deal. I wonder what the cost difference is between the two types of plugs.

MeasurementBlues
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Re: Charging in a car
MeasurementBlues   11/6/2013 10:41:44 AM
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One advantage of the USB is it's smaller, taking up less dashboard space. But, you really need two or more, thereby killing any space savings. USB might cost more because it needs a DC/DC converter to get down to 5V. The cig lighter socket is just the 12V from the vehicle's electrical system and is thus more universal.

AndreiK
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USB please, two of them, but also keep the lighter plug
AndreiK   11/6/2013 11:01:13 AM
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Well... I'dd really like USB charging ports to be integrated on the dashboard, at least two USB ports, but I would not give up the ciggarete lighter plug...

I use it for my mini air compressor, in case the pressure in my tires needs adjusting, and for small cool box I sometimes take with me to picknicks or trips...

There are a lot of other devices that need 12V, and up to now I haven't seen any other conector in car to supply it (and with 10 or so amps).

But I would do one thing... I would replace it with someting more compact. Actualy none of my friends that smoke, use the cigarette lighter in the car.... they use the connector for chargers, SAT-nav and other gadgets...

jvn01
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Re: Charging in a car
jvn01   11/6/2013 11:54:25 AM
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The Iphone charging issue referred to is (I believe) due to the conventional USB charging current being limited to 0.5A. Most smartphones (Iphone and HTC, Samsung etc) require something nearer to 1A to provide both device operating power and battery charging power simultaneously, especially when running apps in the car like navigation. 

Some devices can be pursuaded to draw more than the maximum 0.5A by connecting the D+/D- lines together in the USB charging lead. This works on my HTC smartphone and enables me to use navigation apps on long journeys whilst charging the phone battery to 100%.. You do need to check that the car charger/USB adapter can supply the current needed first tho! Many of them are marked as rated up to 1A but will run very hot at this type of current level...

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