Which Port for incoming from Solar Generator? And Why?

crosstrnr

I have an Ecoflow Delta 2 and a 220W Bifacial Solar Panel. I use this in places other than my T@B, but would like to use this as an alternate power source. The Delta 2 has several DC outputs at 12v and 10A -- standard cigarette lighter and the smaller DC-barrel connector.

If I wanted to feed this output into my existing system (2019 320s Boondock Edge with 100A Interstate lead-acid battery), what would be the best way to do so?

I am looking into an SAE port or an XT60 input. The panels themselves use MC4 connectors, but the only solar charge controller I have is in the Delta 2.

Looking for best practices and some "why's" to help me understand the "what."

SLJ

How many watt hours (WH) is the Delta 2?
The Interstate is 100AH?

crosstrnr

SLJ said:

How many watt hours (WH) is the Delta 2?
The Interstate is 100AH?

The Delta 2 is 1024Wh, which should be 85AH. The Interstate is 100AH.

Of course, I can plug the tab into the AC outlet of the Delta, but trying to avoid the losses by staying DC to DC. And very glad I have a three-way fridge!

pthomas745

In the "Anyone Carry A Spare Battery Thread, there are several ways to attach an "Extra Battery" to the trailer.  (The Ecoflow is a very impressive device but it is...a spare battery.) You can attach the Ecoflow to the 7 pin plug on the trailer with a simple modification.  I have attached a "spare battery" to the trailer by wiring a battery directly to a 12V port.  (A 12V port is a 2 way device: they can draw power or send power to the battery.  Another owner simply connected a Bluetti directly into the 12V system. 

Here is the "spare battery" thread, with pictures of various "extra battery" setups.  The 7 pin plug adapters are discussed, and the Bluetti attached directly into the trailer is on page 2.

https://tab-rv.vanillacommunity.com/discussion/7008/anyone-carry-a-spare-battery/p1

AnOldUR

Some of the 12V to 12V methods described are in effect connecting the batteries in parallel. From what I've read, it's not a good idea to do that with your lead acid battery and the LiFePO4 in your Delta 2.

"Different types of lithium batteries and lead-acid batteries are not recommended for use together, because the load characteristics and capabilities of the battery are different, which will lead to abnormal conditions and safety issues."

pthomas745

You can just turn off the battery switch to prevent any battery type from  from being in parallel if using the 7 pin adapter, or the USB ports.

rfuss928

When you plug the 7-pin into your TV, the TV battery is in parallel with the T@B's electrical system and its batteries.  It seems any "12v" source (battery, solar, generator...) should be safe to add to the system.  It is my understanding that most 12V LiFePO4  batteries come with a battery management system on board.  You are connecting to this management system and not directly to the LiFePO4 cells.  In many cases the Li batteries claim to be "drop in" replacements for some lead acid applications.

AnOldUR

This is the way I understand the explanation, but let me know if it's wrong. The problem is not with the LiFePO4. It's the lead acid battery that has a potential for "abnormal conditions and safety issues". When batteries are in parallel they try to equalize. A topped off LiFePO4 is at about 13.6V. The lead acid is about 12.9V. A charge controller will drop it's voltage as the battery reaches a full charge. When the batteries are in parallel there is nothing to stop the higher voltage LiFePO4 from overcharging the lead acid.

rfuss928

Typical float voltage for lead acid batteries is 13.8v.  No significant current will flow to the lead acid batteries with such a small voltage differential (12.9v to 13.6v) if they are fully charged.  If they are depleted, some charge current will likely flow doing no harm but not the most efficient energy use due to losses during charge/discharge cycles of all the batteries involved.

AnOldUR

I agree @rfuss928, probably not enough to do harm. Off topic, but what about using solar charging while traveling. You can't shut the battery switch off because of the emergency brakes. You could shut off charging in the Victron app, but then wouldn't be maintaining the lithium battery charge. The lithium charge voltage from solar is well above what should be sent to a lead acid, but voltage drop from the 7-pin to the tow vehicle battery may be enough to make that safe also.

crosstrnr

Thanks for all of the feedback! I have read the spare battery thread and agree with @pthomas745 that the Ecoflow is in fact a very nice spare battery!

I was not aware that DC was 2-way and that plugging into an existing port would work to charge. My plan is to put an XT60 port inside the T@B near the inverter and wire directly into the DC wiring there (with a fuse). I may later change out the battery switch to one that allows battery #1, #2, or both. The XT60 port allows me to use an existing cable that came with the Delta.

While I love the 7 pin idea, the Ecoflow is a very pricey extra battery, and I feel better keeping it inside the T@B.

I'll post some pics once done.

pthomas745

@crosstrnr Show us your setup and how you wired your Ecoflow when you are done. 

MarkAl

I am speculating but find it difficult to believe that connecting a Li Battery to a lead-acid battery is an acceptable idea in many situations - primarily a discharged <11V battery. The Li internal BMS (battery management system) controls charging and discharging (to in many cases) much higher discharges than can be tolerated by the Lead acid battery for long life.  The only way this makes sense is to as suggested, turn off the battery switch prior to connecting. As stated, do not drive with this configuration as the breakaway braking will be disabled unless some rewiring is done. No one would ever suggest directly connecting two so dissimilar battery technologies. If the Lead acid where fully charged or the Li was very discharged it would probably be safe to connect and the charging set for the lower charge rate of a Lead acid.

crosstrnr

I've got a physical question related to the wiring. Underneath the bench seat is the converter and associated wiring. The wiring heads to the junction box through a 2" black plastic pipe which goes under the wet bath to the front of the trailer. I can see these wires coming out of the bottom of the trailer through a gasket and then to the J-Box.

I would like to run a new wire from the J-Box to under the bench seat but for the life of me can't get anything to fish through. I can't clearly see the "in-between" space to be able to properly fish -- it's going somewhere, but not coming out under the seat.

Here is what I am trying to do:

Install a new three-way battery switch in the front box.

1. Battery 1 = Lead Acid that came from the tab. 
2. Battery 2 = The Ecoflow

The common output from the switch would go to the current red 10GA power wire through the J-Box and power the trailer as usual.

My rationale:

• The switch keeps the battery chemistry separate. The trailer is powered by Battery 1 or 2 only. (The switch has a "both" setting which I would not use.)
  
  
• I want to leave the battery switch in the current location. I could move it inside, but the current location allows me to easily check I have set it to Battery 1 before towing, thus keeping the trailer brakes operational.
  
  
• I want the Ecoflow inside the trailer to prevent theft and keep it dry. That's the purpose the wire from under the seat -- to bring the 12v hot back out to the switch in the storage tub.
  

While I'd love to figure out how to fish through the current tubing, I am open to other ideas to get the wire from one end to the other and keep it sealed against dust and water.

crosstrnr

I found this picture:



And this one:



In this thread: https://tab-rv.vanillacommunity.com/discussion/4597/running-wires-into-t-b

Going to give it one more try!

pthomas745

Did you find the Secret Life Of Wires thread?  With a description of "Magic Smoke"?  Getting a cable from the front of the trailer to the back has always been one of the great dreams of Tabdom.  Only a few have done the deed and lived to tell the tale. 

https://tab-rv.vanillacommunity.com/discussion/13824/the-secret-life-of-wires/p1

AnOldUR

Our batteries are still in tub and we installed an inverter under the drivers side bench. I added an outlet from the inverter to the kitchen/bath wall. Without much research I took a single strand 12AWG solid copper wire and pushed it toward the front from the opening in front on the wheel well. With a little effort, it came out in the opening near the water pump. Only minor yoga involved getting an arm down into the pump compartment.

This is in a 2020 320S ...
 

crosstrnr

pthomas745 said:

Did you find the Secret Life Of Wires thread?  With a description of "Magic Smoke"?  Getting a cable from the front of the trailer to the back has always been one of the great dreams of Tabdom.  Only a few have done the deed and lived to tell the tale. 

https://tab-rv.vanillacommunity.com/discussion/13824/the-secret-life-of-wires/p1

Yes. I found that one, too! Hopefully no magic smoke on my trip.

This has turned into an interesting project. Try as I might, I was not able to do the deed and so cannot tell the tale. But I did figure out an interesting alternative. (Actually, two alternatives.)

1. From the spare battery thread, I decided to make a 7-pin to cigarette lighter cable to allow me to power externally from the Ecoflow.



This was assembled from the following items:

- CURT 58150 Vehicle-Side 7-Pin RV Blade Trailer Wiring Harness Connector
(https://www.amazon.com/dp/B001EP0G72?psc=1&ref=ppx_yo2ov_dt_b_product_details)

- YCIND Heavy Duty 12AWG 30A Male to Male Cigarette Plug Cigarette Lighter Adapter Charger Cord With LED Lights 3ft (3FT) 
(https://www.amazon.com/dp/B0B2F9S698?ref=ppx_yo2ov_dt_b_product_details&th=1)

- Scotch 130c black rubber splicing tape
(https://www.lowes.com/pd/Scotch-130C-Black-Rubber-Splicing-Tape-30-ft-Black-Electrical-Tape/5014312885)

The tape is probably overkill, but it keeps everything tight and waterproof.

2) I decided to create permanent conduit using 3/4" Schedule 40 liquid-tight conduit. It will go from the front storage tub, above the corrugated plastic along the trailer frame, and then into an LB conduit box up through the floor under the seat.

I've added an XT60 connector to plug in the Ecoflow. That will go back out to a four-way battery disconnect switch in the storage tub. Power to the trailer will come in from the J-Box using the original wiring.



Still in progress, so no more pictures. I like the idea of easily fishing this conduit for future projects like a backup camera wired to the reverse lights on the 7-pin.

We're headed to Gulf Shores, Alabama for a week, so no T@B projects until I get back.