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I have a Acer Iconia A500 tablet. I want to plug it in, in the car, but it has a barrel plug and I don't want to buy an inverter. The car adapters are expensive for what they do.

I already have a 2.1 amp USB car charger meant for the iPad:

I want to use this USB cable from the 2.1 amp port to plug into the A500:

Here are the specs on the original wall charger if that helps:

The USB cable says it's 5v, but the original charger says it outputs 12v, and since it's just a cable, wasn't sure if that really made a whole lot of difference since it's only 1.5 amps from the wall charger.

Is it possible to use that USB cable through the powerbolt car charger, to charge the A500?

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up vote 3 down vote accepted

Even with an appropriate boost regulator, the car charger can't supply enough power (5V@2.1A, 10.5W) to charge the tablet (12V@1.5A, 18W). I would look at getting a 12V buck/boost regulator you could plug directly into the socket with a 2A fuse.

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The PowerBolt charger is a 5V source, since it's designed for USB devices. It'll still be a 5V source even if you plug your tablet into it. That probably won't be enough to operate or charge the tablet, though I doubt it'll cause damage. (But I don't know enough about your tablet, or electronics in general, to say for sure that it won't cause damage.)

Make sure the polarity of the barrel plug on that USB cable matches the polarity of the tablet's original charger. Getting the polarity reversed can potentially damage the tablet.

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ahh, didn't think about the polarity. How does one check that? – hwp08 Apr 12 '12 at 4:27
It should be marked on the cable or plug somewhere. Look for the symbol. – Wyzard Apr 12 '12 at 4:29

To directly answer your question, no, USB cables are meant to carry 5v, not 12v. Even if the cable could, your charger is only putting out 5v, so you can't use it to charge your tablet.

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