USB ports not working?

[rob]

So I had a couple of 12v electrical issues this past weekend.



First issue (Friday night) was fixed easy enough.  A simple blown fuse.  Found it odd that it is only a 15 amp fuse but without it, no power to the other 12v outlets.  Didn't take a chance, so replaced the blown fuse with another 15 amp fuse.  Everything worked fine after that.



Sunday morning I woke up and was alerted by my daughter that her iPad didn't charge.  My wife also noticed that her Samsung smart phone didn't charge either.  Both were plugged into the USB ports.  I had charged my phone in the same USB ports earlier without issue, but double checked and the ports were now not working.  Changed the fuse and still nothing.



Reading online, several things may have caused the problem:



1.  Amp draw from iPad is too high;

2.  Amp draw from Samsung smart phone (on Samsung USB charger) is too high;

3.  Carelessness of my lovely family may have shorted the USB port by having a live USB cable touch the aluminium trailer;

4.  Combined amp draw may have blown the USB port; and/or,

5.  All of the above?


Is there a "reset" on the USB port (perhaps a GFI type)?  Could there be other causes?

[hdrehder]

We had issues with our ports. It seemed that sometimes they worked and sometimes not. Had them replaced under warrantee a month ago.

[charles]

My USB ports died to I replace with a power port, used OEM parts

http://www.amazon.com/gp/product/B003VAT1LA?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I have found that Livin Lite uses boat parts

[rob]

Had the same blown fuse this weekend.  It is the bottom 15 amp fuse.  When I replace it, a fan turns on.  I assume that it is the cooling fan for the converter.  Without it, I have no 12v power when not connected to shore power.

When I get home, I connect to 110v to recharge the battery.  Before leaving, I disconnect.

Am I perhaps doing something incorrectly?  I find it odd that it is only 15amp, since without it, there is no power.  I also find it odd that it has blown twice.



 

[charliem]

[font size="3"]So as I understand when you are connected to shore power you have full 12 operation even without the 15A fuse?

When on shore power you can charge the battery with or without the 15A fuse?

When not connected to shore power you only have 12 operation when the 15A fuse is good? Without the fuse you get no 12V operation?

The fan coming on when you replace the fuse bothers me. The converter fan should be powered internally from the converter; not run through the fuse panel.

I don't have a QS so can't speak from experience. Perhaps someone with a QS will jump in.
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[rob]

That appears to be correct....................or I haven't run the battery down yet.  I only use it for lights and to charge my phone.

[charliem]

[font size="3"]rob,

Do you know what model converter you have? On LL's website there is some indication the QSs use a WFCO 8712 or 8725converter or maybe an Elixer converter. How many fuse slots, used or unused, do you have? The WFCO documentation shows 5 fuses, the bottom one being the reverse protection fuse. How do you know the fuse in question should be 15A? Is it marked on the converter?

If you have a voltmeter you can verify the battery is being charged. It will read greater than 13 volts at the battery if it is being charged when on shore power.
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[rob]

It is a WF-8725-P converter

[a href="http://s94.photobucket.com/user/rwgill/media/12v%20circuit.jpg.html"]
I just plugged into shore power.  The fuse blew.  Changed it and it blew again.  Tried again and it blew just as the fan was starting up.  It never blows on 12v only.  Looking at the electrician's handwriting, one of the fuses should be 75 amps? 

[david]

That fuse is 7.5 amps, not 75 amps. Here are some additional thoughts on your problem:

The USB outlet has an internal circuit that converts the 12v DC supplied from the trailer's battery and/or converter through fuse #3, to the 5V DC that the USB spec calls for. If that circuitry is bad, it could either cause no power output at the USB outlet, or it could be a dead short. In the latter case I would expect it to blow fuse #3.

But you have a different problem. Fuse #4 is blowing. My guess is that fuse supplies power to the internal cooling fan for the converter. This may be caused by a wiring error to the internal fan or an internal circuit failure, but in either case it probably will require replacing the converter to fix it.

David

[charliem]

[font size="3"]I agree with David. The USB is a separate problem. When on shore power with the fuse removed do all other 12V things work? [/font][font size="3"]Have you verified the battery is charging by measuring greater than 13V at the battery when on shore power and the fuse is removed? I'm puzzled by the fan sound. [/font][font size="3"]Do you have a propane furnace? I don't know why the converter internal fan would be fed through an external fuse. If the above checks are good I'll join David in the faulty converter club.
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[rob]

There appears to be no charge. I remain at 12.4 v.

Reading the manual, there is a cooling fan. Its speed is dictated by usage.

While on shore power, all power sources work (less USB), with or without fuse.

When on battery only, no fuse in #4, no power. With fuse, everything works. I plug into shore power, fuse blows.

It worked fine my first trip out. I can charge the battery in the garage. Trailer is still under warranty.

[charliem]

[quote source="/post/13726/thread" timestamp="1438044842" author="@rob"]There appears to be no charge. I remain at 12.4 v.
[font color="e61944"][font size="3"]I assume this is measured at the battery [font color="e61944"]on shore power with the fuse removed?[/font][/font][/font]

Reading the manual, there is a cooling fan. Its speed is dictated by usage. 
[font color="e61944"][font size="3"]That's correct. I was just wondering if you also had a furnace.[/font][/font]

While on shore power, all power sources work (less USB), with or without fuse.

When on battery only, no fuse in #4, no power. With fuse, everything works. I plug into shore power, fuse blows.

It worked fine my first trip out. I can charge the battery in the garage. Trailer is still under warranty.

[font color="e61944"][font size="3"][font color="e61944"]It almost seems the #4 is wired or shorted back to the battery. [/font]That would cause it to blow rather quickly. The converter may sense the high current and try to start the fan.

It would be worth verifying again the battery is not reversed. [font color="e61944"]When not on shore power the lights don't care about polarity., [font color="e61944"]t[/font]he fan may or may not, but the USB [font color="e61944"]definitely[/font] will. Check this by disconnecting the battery, connect to shore power and insert[font color="e61944"] fuse[font color="e61944"] 4. If fuse 4 holds measure [font color="e61944"]at the disconnected battery cables and verify they are the correct polarity as you [font color="e61944"]would connect to the battery. The battery reversal fuses should catch this, but who knows.

[font color="e61944"]If everything worked fine your first trip, including charging the battery[/font], [font color="e61944"]and the battery is not reversed, I'd say bad converter.[/font]
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[rob]

Problem solved (at least for now).

Spoke with an electrician friend who repairs RVs from time to time.  He had come across similar problems before.  He stated that often a component manufacture suggests X, but final assemblers change it to Y and dealers adjust to Z.  He suggested that I try a 20 amp fuse.  If that blew, go with a 25 amp.  If that blew, we had a serious issue.

I bought some more 15 amp, some 20, 25 and 30 amp fuses.  At 20 amps, fan started and continue to run.  I tested the voltage and read 13.7v at battery.  Two hours later and the fan stopped.  Battery reads 13.7v.  Plugged in one light and it worked, with the fan coming on low.  

My friend will stop by on the weekend to properly test amperage.  He has a feeling that the fan is drawing 16+ amps at start up.

[david]

I would be shocked if that fan drew 16 amps, even for a few milliseconds at startup. Ask your friend to also check the wire gauge in that circuit. You will need 20 gauge or bigger to be protected by a 20 amp fuse.

David

[charliem]

[font size="3"]Rob and David,

I'm now thinking the trailer is miswired. [/font][font size="3"]I think what's happened is the converter DC output is connected to the bus via F4 instead of the 30A fuse.[/font][font size="3"] This would account for the presence or lack of function as Rob describes. I think the battery charging current, particularly when partially discharged, is between 15 and 20 Amps and that's why it now appears to be working. [/font][font size="3"]Somewhere else on this forum someone mentioned a 15A fuse that had to be in place to get 12V. I didn't pay much attention because it was a QS and I thought that probably was the reverse protection fuse. Now, after following this thread, the fog is clearing. That wiring error may be present in some/all of the QSs from the factory.
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The DC output of the converter should be directly connected to the DC bus through the 30A fuse. Fuses F1-F4 and the positive of the battery should also be directly connected to the DC bus. This allows the battery to power the bus and all 12V circuits. The converter output directly powers the bus providing 12V on shore power and battery charging. The 30A fuse only protects the converter circuitry. All 12V accessories remain connected to the battery even [/font][font size="3"]if the battery had been reversed at one time and [/font][font size="3"]the 30A fuse is gone. This may be a clue to the USB problem too.

If I'm correct it's easily corrected. Rob's friend with RV electrical experience should be able to fix it with the  WFCO info available on line. I started to draw all this out, but ran out of explicit knowledge and patience. I'll try again if needed.

EDIT: See later post for diagram.
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