Topic: TP-link MR3020 - USB WiFi not working when powered by car charger

Hello,

I've flashed OpenWRT and installed USB drivers for ralink 3070. All is setup and working great when using the power from the AC wall USB charger. I'm able to use the USB ralink WiFi adapter as a long range WiFi client and broadcast my own WiFi network using the internal WiFi all of which works great.

My issue is when i power the device using a car 12v ciggy adapter which outputs 2 x 5v USB ports (1 rated at 2.1A and the other at 1.2A) the device powers up and i can access the CLI using the internal WiFI but my external USB ralink adapter does not connect to any networks. The USB WiFI adapter is still listed in the interfaces section and i can see WiFi networks when i click "scan" but it just wont connect to any of those networks.

If i plug it back into a mains AC wall charger with the USB everything is working fine again so it seems to be a power issue. My thoughts are the car charger isnt giving out enough power for the USB WiFi to work? Any thoughts on what i would i need to get this working using a car adapter please? Is it as simple as finding a more powerful car charger or is something else needed?

Thanks

2 (edited by AndreL 2017-04-04 02:40:52)

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

Hi,

I don't have this router, but I know how much trouble USB power can have with some charger-device combinations.

1) Since you suspect this is a power issue, first of all, try different USB cables with the same chargers. Preferably, use a short cable. Many bad quality USB cables use thin wires that add too much voltage drop on the circuit.

2) Generic chargers with labeled 2.1A and 1A ports identify themselves as Apple chargers (which means they are not standard USB chargers) through pins D+/D- . Some devices care about this ID, some do not. You could check if your router doesn't like Apple-type charges by testing it with an Apple AC charger. If the same issue happens, then you could mod an USB cable this way:

https://www.youtube.com/watch?v=-9-rfImR86g

or this way (try the easiest first)

http://www.instructables.com/id/USB-Con … -contacts/

to tell the device (router) that the charger is a standard USB charger capable of supplying high current (first link) or a simple dumb 5V power supply (second link).

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

agree with bad charger idea

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

The 5 volts passes directly from the power inlet to the USB host port.  There is probably a lot of ripple on the 5 volt output, and its voltage is also not very precise.  This usually does not affect the router functions since they run on 3.3 volts from an additional regulator inside the router.  I have had USB dongles become permanently damaged by bad chargers.

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

Tried a bunch of adapters including a USB power bank since my original post all with the same results- the usb wifi fails to connect.

Whats even stranger is if i connect the car adapter to a 230v - 12v ie a mains AC to DC converter the same charger powers the tp-link fine and usb wifi connects.

They all measure 5v @ 4.2 amps on the USB ports which is exactly the same as the adapter connected to the wall AC so i'm really not sure what the issue here is.

I've ruled out the charger being the issue it works fine on AC. The only difference is one power source is AC and the other is DC @ 12v but i dont see why this would cause any issues since they are both converted down to 5v DC anyway.

Would love to figure this out before i go away in the van later this month but its looking like one of those life mysteries that i will never figure out.

6 (edited by tthreeoh 2017-04-20 20:09:30)

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

This router has power issues, use a powered usb hub between the router and the USB device.

Re: TP-link MR3020 - USB WiFi not working when powered by car charger

Thanks @tthreeoh, i used a self powered usb hub and its working now. Literally just plugged the usb hub directly in to the tp-link and the usb device into the hub and its working. The hub is self power so i have no idea how or why this is working.