Using the rear solar plug as a charging port?

[VanillaRice]

Hello. Long time lurker here. WTW has been an amazing resource for the purchase and build out of my Hawk shell. Can't thank y'all enough.

For fun I plugged my SAE to USB adapter ( I use to charge my phone on my motorcycle) into the rear solar port. To my surprise, it worked. My phone was getting juice. My question is.....is it ok to draw power that way? I didn't realize it was a 2-way street. I have a solar panel on top and a charge controller inside. Please forgive my rookie understanding of solar and such!

 

[Vic Harder]

I don't know if that surprises me too, if your camper is factory stock. Can you send some pics of your battery box wiring? I can only assume that there is a direct connection to the batteries from the SAE plug, which is the way it would be wired for plugging in a portable panel with its own controller.

 

[Old Crow]

Does it work at night?

(I'm guessing the phone charger was being powered by the solar panel during this test (not by the battery))

 

[Beach]

I think Old Crow might be on the right track there. Which could mean the phone is connected to the raw output voltage of the panel. I would put a meter on it and check.

 

[Wandering Sagebrush]

On some controllers (older?) isn’t there a connection for a load (I believe it was called “Light” on the controller
where I think I saw it. ) other than the battery? If so, could the rear plug be wired to it.?

 

[esimmers]

Following up on Old Crow and Beach's comments, you'll want to make sure that your "SAE to USB adapter" (USB charger) is designed for the voltage input from your panel's raw output voltage. Your USB charger is probably designed for 12 volt input (car or motorcycle battery) and outputs 5 volts for USB devices.

The rear charging port of your camper is probably hooked to the input side of your charge controller, same place as the roof panel output. So this raw voltage could be significantly higher voltage than 12 volts depending on the specs of your roof panel and the amount of sunlight falling on it. You don't want your USB charger to input higher voltage than what it's designed for or it could be damaged, possibly also damaging your cell phone or whatever else you have plugged into the USB charger's output.

 

[Outnabout]

The rear solar plug on my Grandby usually reads between 17-18 volts with my multimeter.

 

[craig333]

If you want to use it as it stated, should be simple enough to move the wires over to the output side of the controller or straight to the battery.

 

[PaulT]

The Powerwerx USB Buddy should meet your needs as that is its purpose. It can take 10-32 volts in and it outputs USB power of up to 3 amps for that purpose. Most any nominal 12 v solar panel should work. For full power out, I'd consider using a panel that puts out 3 amps. You would likely need to buy or make an adapter that goes between Anderson Powerpoles and whatever connector you use like the SAE 2 pin flat connector on the rear wall.

Instead of plugging directly to your phone, you could use the USB Buddy to charge cellphone portable power banks and charge the phone from them, That way, your phone is on your person while away from the camper and you can charge your phone at night from the portable power bank.

Paul

 

[Norsman]

Last I checked my rear SAE plug with a volt meter it read 49 volts and was highly variable... assuming it was from the solar panel on the roof.

 

[Old Crow]

Perhaps a diagram and a video will add to the discussion.... (Correct me if I get the explanation wrong, solar guys) The diagram isn't mine-- I'm pretty sure I got it from WTW and don't quite know where.

(Click to enlarge)



(The rectangular shape on lower left represents a Wago PushWire connector (I believe it's the 773-173 one). That's just an easy way for FWC to connect wires together. Strip and push in the reds from roof and rear-wall into the connector, then add another red wire to the connector and run that one toward toward the controller. Same for the black wires.)

And Stan explains the setup pretty nicely in this video. (And he adds something not shown in the diagram... the Load wires needed for their optional Overland Solar setup)

How to hook up your own solar system inside an FWC

Also-

So the roof and back-wall wires are connected together by FWC and once the controller's in, they're connected on through to the input side of the controller. And since the output side of the controller is connected to the auxiliary battery, one might wonder if electricity doesn't flow from the battery back to the rear-wall and roof plugs. However, the answer is no as the controller doesn't permit it. It doesn't allow electricity to flow 'backwards' from the battery back toward the solar panel(s) as that would drain the battery when panel voltage is lower than battery voltage.
.