Advice sought on why 6.8A USB charger melted USB cable today

Danny D. · 2015-11-30T17:00:06+00:00

I would just like some advice since I melted a USB cable today and I realized I don't have the proper troubleshooting skills. I bought over a half-dozen "Hype Volt" 6.8Amp USB chargers for stuffing the Christmas stockings: I kept one for myself, but, when I used it last night on an iPad and on an Android phone, the iPad lightning cable melted! When I pulled it off the iPad, it was noticeably extremely hot, but it doesn't seem to have damaged the iPad (AFAIK). So, I'm just wondering what happened, and, more importantly, when I look at the specs for this device, they don't make sense to me, so, I have difficulty troubleshooting what the problem is/was. Here are all the specs off the package and off the device: DGL Group Ltd. Hype Volt HV-6PT Model: HC363-5U (also listed as HV-6PT-WHT) Input: AC 110VAC/60Hz - 220VAC/50Hz (800mA max) Output: DC 5V, 6.8A total Maximum Power: 40W Supercharge: 5V@2.4A maximum Universal: 5V@1A maximum Description: My questions are varied, because I don't understand how it works, nor how it could have overheated the cable to the tablet. Here's what it says on the package: "Smart USB Technology: This adapter automatically adjusts power output to fit your charging device. Tablets and e-readers require 2 Amp charging, and this adapter will reroute power to the appropriate USB port you use." "Charging Combinations: - 2 tablets + 3 mobile devices - 1 tablet + 4 mobile devices - 5 mobile devices - 3 tablets" I am confused about both the pure math and how this operates. Q1: Since 6.8A times 5VDC is only 34Watts (not 40 Watts), how can they very clearly label it as a 40Watt device? Q2: How does the device "know" to give tablets 2.4 Amps (12 Watts) but a "mobile device" only 1Amp (5 Watts). Q3: What if a mobile device "wants" more than 1 amp? Does the charger give more than 1A to the device?

Nov 30, 2015 161 Replies

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Brian Gregory 10 years ago

1% tolerance resistors are dirt cheap nowadays.

The last 0.1% ones didn't cost that much either.

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clare 10 years ago

It's what you call (in)efficiency.

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