Exterior SAE Connector as 12v Power on 400

manyman297 · November 2021

I believe I ran across a post by @Verna as it pertained to 12v fridges and how to run them at camp. She mentioned running one using her exterior SAE port that would typically be used for solar panels. It had never dawned on me to use that as a 12v power source. I'm assuming the 400 is wired directly to the battery as well, right? That means you could use this to power any 12v equipment externally. Awesome idea!

I've debated on installing a charge controller inside the 400 for that port (to use a solar suitcase) but I'm wondering now if it leaves more options to just install the charge controller on the solar suitcase (or buy one that has one installed already) and have that SAE port pulling double duty. Thoughts?

pthomas745 · November 2021

The SAE port can charge the battery from a solar controller, and can also provide 12V power to a 12V port. I have a cable that has an SAE on one end, and a 12V port on the other. Plug in an inverter, etc, and it can work. You would have to be careful with the amount of power you want to draw from port. My 2017 SAE port is not "fused", the newer SAE ports are (I think!). The SAE to 12V port cable I have is fused, though.

I've powered little things with this setup, so far the most useful was providing the USB power for a small HDMI TV antenna. I'm sure it could be useful for all sorts of things, including the small fridges.

I swear someone said a while back that even the 12V ports in the trailer are "2 way". You could attach a charging device to a 12V plug and it would charge the battery. I could be very wrong about this.....so if anyone else remembers, please set me straight!

BridgerSunset · November 2021

Watch polarity of the SAE prongs when thinking of what you can attach.

All the various suitcases and trickle solar panels I have fit the factory SAE polarity. But other 12V things may require you to use a crossover SAE connector. The things I was planning to plug in - like fan, compressor fridge, inflator - came wired mismatched relative to the factory SAE prongs (when I installed a backup port at the tub to get 12V power at the front of the camper).

Horigan · November 2021

Yep. SAE connectors are wired such that on a power source connector the positive terminal is female and protected. On a load connector the positive terminal is the exposed male terminal. The SAE port on T@bs are wired as a load connector, not a power source connector, since it is expecting a solar panel (power source) to be plugged into it. If you want to use the port as a power source, you'll need a crossover connector that reverses the polarity to connect any load to the T@b SAE port.

As alluded to above, make sure your load matches the wire gauge to the SAE port. Check the wire gauge (maybe 12 AWG?, which equates to 20 amps?) and confirm your load won't exceed the wire gauge rating. You can Google wire gauge amp ratings.

manyman297 · November 2021

Great tips here. I might utilize that port for a 12v cooler next season. Wish it was closer to the front of the trailer. I’ll just have to be mindful of voltage drop if I keep the fridge in the TV

Dutch061 · November 2021

Why not connect the cooler to the TV instead if you are going to put it in the bed of the truck? You can always move it when you get to camp, that would eliminate the added length of wiring. The alternator will keep the TV battery charged while driving. You could always add the wiring with the SAE connector (with a fuse of course) to the truck and route it to the bed.

Brad

AnOldUR · November 2021

Interesting discussion. I use a Renogy 100W suitcase without a controller. I have a Victron controller between the SAE port (mounted on the side of the tub) and the battery. I'm curious if the port could be used as a power source in this situation?

Dutch061 · November 2021

@AnOldUR, if you have a Solar Charge Controller between the port and the battery, the answer is no.

Brad

AnOldUR · November 2021

Dutch061 said:

@AnOldUR, if you have a Solar Charge Controller between the port and the battery, the answer is no.

That would have been my guess, but I have no idea what goes on in the controller. Does it act as a diode to only allow flow in one direction?

Dutch061 · November 2021

I suspect there would be some sort of diode array to prevent discharging when there is not input from the solar panel, otherwise it may function as a load instead of an input. Along with the function of making sure the output voltage is proper based on the setup.

I have never tried to locate a circuit diagram for one, maybe someone else has or is more familiar with the circuitry inside the "magic box".

Brad

AnOldUR · November 2021

Just went out and metered the SAE port and (as you said) there is no reading. I've always thought that my choice of the SAE port (as opposed to MK4) was a mistake because there was a potential for shock from both the panel side and the battery side. This meant that there would be an exposed hot wire at one side or the other, but if the positive wire coming from the controller is not live then it poses no risk.

pthomas745 · November 2021

The "load" output on all solar controllers is a 12V power source. It can send power from the battery to a 12V item. I know they can do simple things, and the controllers I have owned have convoluted timers and setup procedures. People use the "load" function to turn lights on and off at remote locations, run pumps on a timer, etc. I know the basics of them, but I don't know the limits.

@AnOldUR I can't picture how your solar controller is connected to the battery. You have a separate controller wired directly to the battery, not using the SAE port?

AnOldUR · November 2021

pthomas745 said:

I can't picture how your solar controller is connected to the battery. You have a separate controller wired directly to the battery, not using the SAE port?

Yes. Rather than upgrade the on-board 75|10 to handle both the rooftop and suitcase, I chose to add a second controller. It's a 75|15 and is wire directly (but fused) to the battery. My SAE port is wired to the PV connection on the 75|15.

pthomas745 said:

The "load" output on all solar controllers is a 12V power source. It can send power from the battery to a 12V item.

That's interesting. I have never used the LOAD side, but thought that it only drew power directly from the solar panel, not the battery.

Denny16 · November 2021

No, the load side of the Victron 75/15 draws power from battery, and/or solar panel, depending on the load and level,of power off the PV. It regulates the load to keep it under a set value based on amount of battery/solar power available. When the load exceeds the amount of energy available, it shuts down the load output to keep from over discharging the battery. This is a nice feature, and some RVs have their house load bus connected to the 75/15 load connection.

That said, nüCamp doesn’t use this feature, on their 75/15 installations. I plan to connect a cable with a 12VDC power port or Anderson connector to the load connection on the 75/15 I installed between the factory SAE solar port (which is next to my rear cargo port and battery location). I can open the door and pull the aux power cable out when needed, and the SAE port is connected to,the 75/15 for the portable solar panels.
Cheers

AnOldUR · November 2021

Denny16 said:

I plan to connect a cable with a 12VDC power port or Anderson connector to the load connection on the 75/15 ...

I was considering connecting my current SAE port directly to the battery for an outside power source and then adding an MC4 port for a solar suitcase to the PV connection on my 75|5. Are you saying that rather than have the SAE going directly to the battery it could go to the LOAD side of the controller? No conflicts with having a solar panel on PV and a LOAD connection at the same time? Any advantages to doing it this way?

Denny16 · November 2021

No, you connect the 75/15 between the SAE port and battery (SAE to PV connection and Battery to its connection. Then use the load connection for your accessory power connection. If you want the MC4 cable formthe PV panels, then connect the MC4 to the 75/15 PV connection, and the SAE to the load connection (with correct polarity for power output) to use for your accessory power source. I had considered doing this also, which is not a bad idea.
Cheers

ScottG · November 2021

Since all of this involves an additional cable anyway, is there some advantage to connecting that cable to to LOAD terminals on the controller as opposed to directly back to the battery (with an appropriate fuse)?

AnOldUR · November 2021

@ScottG I was wondering the same thing. Connecting the external power port to the load side may have the advangage of drawing directly from the solar panel along with the battery, but wouldn't it be indirectly doing the same connected directly to the battery since the battery will be charging from the panel?

CrabTab · November 2021

Connecting external power through the Load connectors will be limited by the Amperage rating of your Victron MPPT. It will work fine unless you plan to use an inverter or other high current draw device.

ScottG · November 2021

AnOldUR said:

@ScottG I was wondering the same thing. Connecting the external power port to the load side may have the advangage of drawing directly from the solar panel along with the battery, but wouldn't it be indirectly doing the same connected directly to the battery since the battery will be charging from the panel?

Yes. At least that is the way I understand it. Everything else in the camper is connected directly to the battery (i.e., not through the load port on the solar controller) so I don't see the advantage of connecting an external power port through the LOAD terminals.

I've always thought the LOAD terminals allowed the used of the panels as a stand-alone 12V power source (i.e., not connected to a battery). I may be wrong about this--admittedly I've never had any reason to use the LOAD terminals so never gave it a whole lot of thought.

manyman297 · December 2021

Dutch061 said:

Why not connect the cooler to the TV instead if you are going to put it in the bed of the truck? You can always move it when you get to camp, that would eliminate the added length of wiring. The alternator will keep the TV battery charged while driving. You could always add the wiring with the SAE connector (with a fuse of course) to the truck and route it to the bed.

Brad

I wouldn’t want to keep it on the driver’s side of the trailer…out of sight out of mind in a bad way.

I guess I could run the cable under the trailer over to the passenger side of the trailer.

The more I read about this the more I wonder about having a charge controller between this port and the battery. Having the flexibility to have an exterior power source could come in handy.

ScottG · December 2021

@manyman297, why not just install another port wired directly back to the battery? Then you could have the best of both worlds and use both your solar and your external power supply at the same time.

manyman297 · December 2021

@ScottG
Yeah, that's probably the obvious solution but we've yet to need the external port for solar and I didn't want to make any additional holes or do additional work until I know what we need/don't need. If I can use that port for both then I figure let's do that until I really know what our long-term needs are (if any). And if we realize we don't need solar then I haven't done anything too drastic.

Viajero · December 2021

One of the inspirations for getting the victron 12 12 9 dc to dc converter was a visit to the campsite of friends who pull their 400 with a Tesla model Y. They used that port to charge their T@B battery from the Teslas rear 12 volt accessory plug after running down the T@Bs battery while doing extended dry camping. Worked well. Put the Tesla in Camping mode which kept the accessory plug active. Limited to 9 amps from the Victron (and 16 amps max from the Tesla port).

We are building something similar...just in case.

. Still waiting for our trailer to arrive.

CrabTab · December 2021

@manyman297 I believe a thought from your first post is the simplest solution...

manyman297 said:

...(or buy one that has one installed already) and have that SAE port pulling double duty.

While it is true that an MPPT will slightly outperform the PWM controller that comes with many suitcases, you get a plug and play system that does what you want.

Viajero · December 2021

Where do you guys store that suitcase panel? That rest cargo area has a pretty small door.

manyman297 · December 2021

@Viajero
i was thinking of just putting it under our comforter on the bed when traveling. Assuming it has a case (that’s clean) it seems like the easiest way to store it while traveling at least.

AnOldUR · December 2021

CrabTab said:

@manyman297@manyman297 While it is true that an MPPT will slightly outperform the PWM controller that comes with many suitcases, you get a plug and play system that does what you want.

It's not just the performance differences between MPPT and PWM. If you use a second Victron MPPT it can be networked with the on-board controller for increased efficiency and the ability to be monitored through the app.

Viajero said:

Where do you guys store that suitcase panel? That rest cargo area has a pretty small door.

Our 100W has a small footprint (22"x22"x3") and weighs about 20lbs. It rides in the back of our TV (Jeep Wrangler 2D) next to our folding chairs or up on the roof rack. It is one more thing to load and worry about, but not that much of a concern as far as space.

CrabTab · December 2021

Viajero said:

Where do you guys store that suitcase panel? That rest cargo area has a pretty small door.

We have 2 100W Renogy Eclipse panels that ride in the bed of our truck (under a shell). They are a compact size, as @AnOldUR noted. They come with a nice protective case and could easily ride inside the T@B, as @manyman297 noted.

We don't take them on every trip, depending on how we are camping and the weather outlook.

manyman297 · December 2021

The networking feature of the Victron charge controllers is something to consider as @AnOldUR points out. And I'm not sure what IP rating of those are but I don't think they can be outside in the elements (mounted on the backside of a solar panel for example). I know Renogy might have an MPPT charge controller that's exterior rated but then you lose the networking feature.

ScottG · December 2021

Viajero said:

Where do you guys store that suitcase panel? That rest cargo area has a pretty small door.

I bungee mine (in its case) upright in one of the back seats of my king cab pickup. It always travels with me. If I don't need it, it stays out of the way in its assigned set for the duration of the trip.

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Exterior SAE Connector as 12v Power on 400

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