Am I Heading in the Right Direction? A Somewhat Unique FLA to LFP Conversion!

EricR

New Member
Hi All!

Please review and comment on this first stab at drawing up my oddball project. Greatly appreciated!

Background:

We have a Lance 2185 travel trailer that I want to upgrade from FLA to LFP.

Initially I was going to do a full solar plus hybrid inverter/charger build for our trailer. Then we bought a 2021 F150 Powerboost hybrid with the 7.2kw Pro Power on Board feature that can provide 120V 30A service for the trailer wherever we go! In a completely separate project I am running the 120V 30A from truck to the trailer such that it can be used while we are towing. 😲 Thus, the refrigerator can run on AC (vs propane) and our batteries can be charging - all while going down the road.

Note: When parked, the truck uses the hybrid battery to drive the Pro Power inverter most of the time. The engine runs for about 2 minutes to recharge the hybrid battery as needed. We no longer need the noisy portable generator.

Goals:
  • Keep things safe
  • Keep things simple and easy to install
  • Move the battery position to a closet at the back of the trailer (the soon to be gone FLAs are outside on the trailer tongue)
  • Allow use of 1 or 2 portable solar panels
Already Purchased:
The Idea:

The trailer's WFCO 8955 (converter/charger/AC & DC panel) isn't designed for LFP and "Lithium Ready" replacement converter/chargers don't seem to be much better. So, my idea is to use the WFCO 8955's 12VDC to power the DMT1250, and nothing else. The DMT1250 takes on the duty of charging the batteries when needed, or just being a 12V DC power supply to the existing 12V fuse panel otherwise. The 120V side will remain unchanged and handled by the WFCO 8955.

The DMT1250 includes 30A MPPT that we can use with portable solar panel(s). So if we are at a boondocking site for several days and going hiking/exploring for the day we can set up the panel(s) while we are gone to recover some power while out and about. At some point I may mount panels on the trailer roof, but for now I'll just keep it simple. I've not yet diagramed for PV input. I am hoping for feedback before I go any deeper into this.

Also, most of the time we are on 12V rather than 120V. On the occasions we want to run the air conditioner or microwave we can use the truck. So you will notice there is no inverter in the design.

Other:

Using the Energy Audit spreadsheet a rainy-stuck-in-the-trailer-all-day scenario came in at 104 Amp Hours (DC). If I'm thinking correctly, that means we should be able to go two days (without solar or running the truck). Right?

Note the distance from the existing WFCO 8955 to the rear closet is going to be 10-13 FT depending on how the wire routing goes. About 3 FT of that will be right next to existing 120V 10/2 Romex. I'm thinking 4 AWG for the two runs to the closet and back. Can I use this same wire for the connections within the rear closet?

Feedback, thoughts and help regarding the diagram would really be appreciated (especially wire sizing, fuses, breakers, etc.) Please spare me from bonehead mistakes! Any thoughts or feedback you have on the overall project would also be appreciated. Please let me know if you think it's just a bad approach, or I'm making things harder than needed! The DMT1250 isn't a must and can be returned. It just seems to fit the bill.

Initial Diagram (NOT drawn to scale):

Trailer_Diagram_2.jpg
Thanks so much!

-Eric

PS - If this is in the wrong area of the forum please let me know the correct area and I'll repost there.
 

Short_Shot

Photon Sorcerer
The wfco stuff is fine for lithium because it doesn't have a desulfation mode and it's maximum voltage under full load is only 14.2v, which will never overcharge proper lithium.

Normally it's only 13.6v, which will never overcharge your lithium either.

That said, you might see interesting conflicts trying to tie two chargers together depending on the other unit.

Tying two DC voltage sources together like that is also... inappropriate. They will sense one another's voltage and fight depending on each one's programming. That also doesn't represent the wfco properly.

The battery input and output of the wfco is the same set of wires. This is also the output for the converter. Correct me if I'm wrong of course, but I have a somewhat smaller wfco and there's only one set of battery wires to handle both.

The other outputs come off the wfcos 12v fuses, which are also fed by the converter and the battery connection.
 

eXodus

Solar Addict
With this drawing you are shorting the Input of the DMT1250 against it's output - you can see the WFCO as short in the circuit.

Remove the 12V Input line to the DMT1250 and call it a day. Should work.
 

eXodus

Solar Addict
Feedback, thoughts and help regarding the diagram would really be appreciated (especially wire sizing, fuses, breakers, etc.) Please spare me from bonehead mistakes! Any thoughts or feedback you have on the overall project would also be appreciated. Please let me know if you think it's just a bad approach, or I'm making things harder than needed! The DMT1250 isn't a must and can be returned. It just seems to fit the bill.
A regular MPPT charge controller would do the same job, since your primary 12v powersource (WFCO) is coming over 120V.

I mean you can keep the DMT1250, but you got a expensive piece of technology there for only using it to half of it's potential.
Get a EPEVER, Victron or something similar and buy another solar panel of the cost saved.

The DMT is primary used in self driving RVs for Alternator Charging. - you got a trailer.
 

Zwy

Solar Addict
Hi All!

Please review and comment on this first stab at drawing up my oddball project. Greatly appreciated!

Background:

We have a Lance 2185 travel trailer that I want to upgrade from FLA to LFP.

Initially I was going to do a full solar plus hybrid inverter/charger build for our trailer. Then we bought a 2021 F150 Powerboost hybrid with the 7.2kw Pro Power on Board feature that can provide 120V 30A service for the trailer wherever we go! In a completely separate project I am running the 120V 30A from truck to the trailer such that it can be used while we are towing. 😲 Thus, the refrigerator can run on AC (vs propane) and our batteries can be charging - all while going down the road.

Note: When parked, the truck uses the hybrid battery to drive the Pro Power inverter most of the time. The engine runs for about 2 minutes to recharge the hybrid battery as needed. We no longer need the noisy portable generator.

Goals:
  • Keep things safe
  • Keep things simple and easy to install
  • Move the battery position to a closet at the back of the trailer (the soon to be gone FLAs are outside on the trailer tongue)
  • Allow use of 1 or 2 portable solar panels
Already Purchased:
The Idea:

The trailer's WFCO 8955 (converter/charger/AC & DC panel) isn't designed for LFP and "Lithium Ready" replacement converter/chargers don't seem to be much better. So, my idea is to use the WFCO 8955's 12VDC to power the DMT1250, and nothing else. The DMT1250 takes on the duty of charging the batteries when needed, or just being a 12V DC power supply to the existing 12V fuse panel otherwise. The 120V side will remain unchanged and handled by the WFCO 8955.

The DMT1250 includes 30A MPPT that we can use with portable solar panel(s). So if we are at a boondocking site for several days and going hiking/exploring for the day we can set up the panel(s) while we are gone to recover some power while out and about. At some point I may mount panels on the trailer roof, but for now I'll just keep it simple. I've not yet diagramed for PV input. I am hoping for feedback before I go any deeper into this.

Also, most of the time we are on 12V rather than 120V. On the occasions we want to run the air conditioner or microwave we can use the truck. So you will notice there is no inverter in the design.

Other:

Using the Energy Audit spreadsheet a rainy-stuck-in-the-trailer-all-day scenario came in at 104 Amp Hours (DC). If I'm thinking correctly, that means we should be able to go two days (without solar or running the truck). Right?

Note the distance from the existing WFCO 8955 to the rear closet is going to be 10-13 FT depending on how the wire routing goes. About 3 FT of that will be right next to existing 120V 10/2 Romex. I'm thinking 4 AWG for the two runs to the closet and back. Can I use this same wire for the connections within the rear closet?

Feedback, thoughts and help regarding the diagram would really be appreciated (especially wire sizing, fuses, breakers, etc.) Please spare me from bonehead mistakes! Any thoughts or feedback you have on the overall project would also be appreciated. Please let me know if you think it's just a bad approach, or I'm making things harder than needed! The DMT1250 isn't a must and can be returned. It just seems to fit the bill.

Initial Diagram (NOT drawn to scale):

View attachment 64027
Thanks so much!

-Eric

PS - If this is in the wrong area of the forum please let me know the correct area and I'll repost there.
I'd simply buy an AC charger such as the Victron and just run a 120V AC power cord to the trailer bypassing the WFCO. I have a 250a aux alternator on my truck and intend to just install a 2000w inverter up front and AC power to the rear.
 

EricR

New Member
The wfco stuff is fine for lithium because it doesn't have a desulfation mode and it's maximum voltage under full load is only 14.2v, which will never overcharge proper lithium.

Normally it's only 13.6v, which will never overcharge your lithium either.

I've left out a key detail. My primary purpose is for added reliability / redundancy for DC power. It seems these WFCO converters seem to have a poor reputation. If all goes as planned my wife and I will be taking multiple cross country trips over the next couple of years. I'll disconnect the WFCO converter but leave it in place as a backup.

I agree the WFCO converter would probably be OK. I was on the fence about just using it until another on this forum reported their WFCO 9855 never left float voltage (13.2V) - ever. I selected the DMT1250 for two reasons: it charges at 50A, and you can easily configure the voltage and current. If I understand correctly, this allows for charging at a higher voltage to make sure the batteries can balance their cells and then dropping into a lower voltage power-supply mode as the batteries become mostly charged (via a current set-point).
 

EricR

New Member
That said, you might see interesting conflicts trying to tie two chargers together depending on the other unit.

Tying two DC voltage sources together like that is also... inappropriate. They will sense one another's voltage and fight depending on each one's programming. That also doesn't represent the wfco properly.

The battery input and output of the wfco is the same set of wires. This is also the output for the converter. Correct me if I'm wrong of course, but I have a somewhat smaller wfco and there's only one set of battery wires to handle both.

The other outputs come off the wfcos 12v fuses, which are also fed by the converter and the battery connection.
OK, you guys have me worried! Though I think my design will work.

The WFCO 8900 series has three parts: AC breaker panel, DC fuse panel, and a converter.

Let me clarify what I said in the first post: "So, my idea is to use the WFCO 8955's 12VDC converter to power the DMT1250, and nothing else." Does that help?

The plan is to go from this:
WFCO8955_Diagram.JPG

To This:
WFCO8955_&_DMT1250_Adaptation.jpg

Doesn't this design solve the two competing chargers issue?

Thanks for the input!

-Eric
 

EricR

New Member
With this drawing you are shorting the Input of the DMT1250 against it's output - you can see the WFCO as short in the circuit.

Remove the 12V Input line to the DMT1250 and call it a day. Should work.
Please see my reply to Short_Shot above and let me know if you think there is still a short.

Thanks for the input!

-Eric
 

EricR

New Member
A regular MPPT charge controller would do the same job, since your primary 12v powersource (WFCO) is coming over 120V.

I mean you can keep the DMT1250, but you got a expensive piece of technology there for only using it to half of it's potential.
Get a EPEVER, Victron or something similar and buy another solar panel of the cost saved.

The DMT is primary used in self driving RVs for Alternator Charging. - you got a trailer.
The DMT1250 was $300 delivered from Don Rowe. I'm happy with the value due to the redundancy gained, 50A charging, the simple (even if basic) programming, and that it includes a MPPT controller as well.

Thanks for the input, eXodus.

-Eric
 

EricR

New Member
I'd simply buy an AC charger such as the Victron and just run a 120V AC power cord to the trailer bypassing the WFCO. I have a 250a aux alternator on my truck and intend to just install a 2000w inverter up front and AC power to the rear.
Wow, up until reading your post, I somehow missed that by using the WFCO converter to power the DMT1250 I still have a single failure point. The DMT1250 can fail and I can fall back on charging with the WFCO. But if the WFCO converter fails... were soon in dark. :oops:

It looks like you have blown up my plan, and I really appreciate it!

Thanks Zwy,

-Eric
 

EricR

New Member
While my design failed to meet my redundancy requirement I would like to know if the design would have worked. Based on the clarifications I made to my original post, were the problems solved? Or, are there still issues mentioned like charger to charger conflict, shorts, etc.?

Thanks to everyone for your input.

-Eric
 

EricR

New Member
Also, say I went with something like a Victron Blue Smart IP22 12-Volt 30A 120V Charger. Can you suggest a straight forward way to add in our portable solar panel?

Thanks!
 

HRTKD

Boondocker
Also, say I went with something like a Victron Blue Smart IP22 12-Volt 30A 120V Charger. Can you suggest a straight forward way to add in our portable solar panel?

Thanks!

The solar charge controller would be wired to your common bus bar, just like the AC->DC charger.
 

eXodus

Solar Addict
Please see my reply to Short_Shot above and let me know if you think there is still a short.
I see, you are referring the WFCO power center and not the converter alone.

Yeah, when you disconnect that inside the power center between the charger and distribution you can remove the short issue.

Wow, up until reading your post, I somehow missed that by using the WFCO converter to power the DMT1250 I still have a single failure point. The DMT1250 can fail and I can fall back on charging with the WFCO. But if the WFCO converter fails... were soon in dark.

You would be still charging with the WFCO, I don't see a reason to go through the DMT from that one.

What you could do - is running a large 12V from your alternator to the hitch and use the input of the DMT for it's indented purpose.

You are already thinking about adding a 120V wire run from your truck to the Trailer - just throw in another pair when you already on it.

Also, say I went with something like a Victron Blue Smart IP22 12-Volt 30A 120V Charger. Can you suggest a straight forward way to add in our portable solar panel?
that would basically replace the WFCO Converter in your powercenter.
 
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