WARNING on USB Charging Ports!
Just wanted to post a warning to everyone who has the built in USB charging ports on their camper/RV. We have a 2017 Grey Wolf 29BH that has 6 of these through out the camper, 3 of which are in the b...
Forum Discussion
Frozen001 wrote:You gonna keep us in suspense, or tell us the part number, and what they're counterfeiting? My suspicion is that it's a simple switching step-down voltage converter chip.
IC looking like a counterfeit from an manufacture with no website (www.xlsemi.com)
To others:
(this is for USB 2):
Responsibility for the current drawn is principally placed on the device drawing current. The source is supposed to enforce a limit, but it "cannot exceed 5.0 A" per USB 2.0 spec, which is more than any reasonable device can be expected to draw (it's more than the 1.5 A the common Type-A connectors are spec'd for) - it's to provide a fail safe and cover simple non-USB spec devices people will plug in which don't do anything but draw power, like fans, lights and coffee warmers (!). Baseline is a proper USB device can only draw 100 mA without doing anything else.
Next step is negotiating more power, which requires negotiating over the data lines - then the device can draw 500 mA. Most chargers don't have the intelligence to do that.
Then, there's the USB Battery Charging spec, which many chargers do use. It's pretty simple to do - short the data lines together (with 200 ohms in the most recent 1.2 spec) on the charger, which tells the device it can draw up to 1.5 A. There are other methods, a charger can be able to provide more, but any USB compliant powered device isn't allowed to draw more than 1.5A.
Beyond that, there are non-standard proprietary methods of negotiating more voltage and/or current - Qualcomm Quickcharge, Apple, Samsung, etc. Note that anything drawing more than 1.5A (including Apple iThings) is drawing more than the connector specifications allow. And even those expect the device drawing power to limit their power draw to a maximum.
USB 3 adds more methods, which allow higher voltages, and therefore more power, but the negotiation becomes more complex (and expensive), and devices and chargers are at the front of the bell curve. Current (common) RV USB ports certainly don't support USB 3 methods.
