ecoflow delta solar plus 12v charging together?

[jeromekeating]

Hey am I about to make a big mistake? I have some basic electrical knowledge but I'm pretty new to solar and MPPT charge controllers etc.

My solar panels should arrive in a couple days, 2 PET panels x 200w each and it says they're 18V and I guess I'll connect them in series. I intend to use the built-in charge controller in the ecoflow delta.

I want to be able to charge my ecoflow delta off either solar OR 12V outlet in the truck but I didn't want to have to switch from one to the other.

So I made a little project box to combine the two inputs, with some diodes to prevent any current from the 12v outlet from feeding back into the solar panel, and to prevent any current from the 36V solar from feeding back into the truck's 12v outlet. I've tested this project box and it seems to work, I tried shorting one of the inputs while the other is connected to confirm that no voltage or current will flow the wrong way. I also added a couple ammeter/voltmeters so I can see what's happening.

So my understanding is that as long as the solar is outputting say 14 to 36 volts then no power will come from the truck's 12V outlet until the sun goes down and then the 12V outlet will charge the ecoflow.

Since the ecoflow delta has a mppt controller I'm wondering how this setup will work and if it's going to confuse the charger? Let's say the sun is dim and the solar isn't bringing in much power, will the output from the solar drop down possibly below 12V? If that happens, then some current would start flowing in from the truck's 12V outlet and at that point would the mppt controller handle that just fine? And whenever the solar is putting out more than 14V I am wondering will I get zero current from the truck's 12V outlet or is it possible the mppt would attempt to draw higher current causing the solar output V to drop down to 13-14V until the 12V outlet begins to contribute some current as well? Could I break my new ecoflow this way?

Option 2 - the solar panels come with a charge controller, maybe safer to use their charge controller to bring the output to 12V before combining with the truck power? But an mppt controller in the delta charging off another mppt controller doesn't sound like a good idea

 

[Mattb4]

I am not an expert, but I would be concerned about limiting current flow from your trucks outlet. While getting input from your solar panels the current is limited by max wattage of the panels whereas the current in your truck's system could be the max your alternator puts out. Something might give. If your power pack has a 12vDC auto supply port for recharge I imagine it bypasses the MPPT charge controller and limits current based on the normal capacity of such a plug system.

I agree you do not want to output from one MPPT controller to another. MPPT outputs are designed to charge at battery voltage after converting panel voltage.

Perhaps an expert can weigh in. Those are just my quick thoughts on the subject.

 

[jeromekeating]

just to clarify the power pack limits its draw from the 12V outlet.

I tested this little project box using an 18v battery:
Just to summarize I've got a 12V lighter socket input and a solar input joined together with diodes to prevent reverse current from one to the other, both feeding into the ecoflow mppt charging port. With switches to turn off each input and a couple ammeters to see whats going on. I did the following and here's what happened:
- 12V plugged in to the truck and charging the ecoflow, drawing almost 8A
- I join an 18V battery at the same time into my circuit. Immediately the ecoflow draw drops to 0A I guess because the ecoflow detected a sudden change in voltage
- after a couple seconds the ecoflow starts increasing draw from the 18V battery, still zero amps coming from the 12V input but getting up to several amps off the 18V
- when disconnecting the 18V battery the ecoflow immediately starts to draw a fraction of an amp on the 12V input. I waited half a minute and it did not increase its current draw beyond maybe 0.16A, only 2W.
- momentarily disconnect and reconnect the 12V supply, then the ecoflow tries again and realizes it's a 12V input and starts drawing amps again

So essentially that negates the need for a box to join both inputs with diodes, I might as well get a 2-pole 3-position switch to just manually switch from solar to 12V charging. In theory an auto transfer switch would have to be way too complex and intelligent to make it work.

That makes me wonder again how two mppt controllers would interact if one was feeding the other...

Anyone have any solutions to automatically switch from solar to 12V charging off the truck, for the ecoflow delta?

 

[Shiny]

Saw this video

and had similar thoughts.

From the video comments:

This won't work as you expected. The battery is only 12v but the solar panel is 21v. If you connect them the way you connected in the video, in parallel via adapter, the output will be close to 12v. It will be recognized as car charger by EcoFlow. The total input, allowed by EcoFlow, will be 100W in this case. I think you should use two batteries and connect them in series, so that the output of batteries will be 24v, then use the adapter you used in the video to connect to solar panel in parallel. Then the total output will be close to 22v. This setup should be recognized by EcoFlow as Solar. Hence the intake will be increased to 200W. One important thing to consider is, when you connect two different power source together you should consider connect a diode at the positive output of each power source, when the voltage is too different. The diode will make sure the current is only going one way. Otherwise, when the two power sources' voltage is too different. It will be like the high voltage source charging the low voltage one. Since the internal resistance of power source is low, this will cause over heating. In this case, diode will close up the low voltage power source to make sure the safety of the circuit.

Also

Good evening sir, let me share what I researched regarding charging my ecoflow delta mini. When plugged into sigarette adapter ecoflow will charge at around 100watts due to the ecoflow car charging limit of 8amp current(you can see it in the app). That's why when you connected solar and car battery at the same time it went up to only 102watts , basically it identified it as a sigarette connection and limits it at 100watts. They had 10amp limit before ,but they had to reduce it , because some cars have 10amp 120watt max outlets and pulling 10amps might blow fuses and melt the wires. You can connect two 12v sources of power using the adapter ,but ecoflow will recognize it as sigarette plug based on a 12-14volts output of these sources. Solar panels on the other hand can charge up to 200W 10-25Vdc 12A Max for river pro and 300W 11–75V DC 10A max for delta mini. I guess you know about parallel and series types of connections. With solar usually outputting about 60-80% of rated wattage you can go with slightly more like 300watts for pro and 400w for delta mini. Ecoflow actually recommends using 400w panel for the mini and they said that you can exceed the wattage slightly as long as you don't go over the max voltage. 200watt panel has 27volt max and it should be able to charge your river pro up to 170watts or so on a sunny day. If you don't want to use solar ,but need to charge your ecoflow faster from the car you can use 300w bestek pure sine inverter ,but you need to hardwire it directly to the battery or use alligator clips. You have to use proper gauge wires for this setup. This way you can feed up to 300w to the power station using ac charging from the bestek inverter. It's better to have a deep cycle battery connected to the car's main battery to reduce the load on the alternator. The best thing to do is to use a dc to dc charger with the built in mppt controller so you can keep your deep cycle battery charged from two sources simultaneously. Another way to charge faster is to connect two 12v batteries in series , this will increase voltage to 24-27 volts and ecoflow will think it's solar and will accept 200watts or even more. I'm still in the process of building my system and researching my options, but i wanted to share what I dug up so far. Hobotech has a video about bestek inverter ac charging,check it out. Feel free to ask any questions that you might have, also ecoflow chat is pretty helpful. Good luck.