Trailer LifePo4 Upgrade + Add an Inverter + Solar in Future

[noblesin]

Hi all, We have a Jayco X23B Trailer that came with a WFCO 8735 Converter/Panel and a standard 60AH Battery. I recently ordered 8x 280AH Cells to build (2) 12V 280AH LifePo4 Batteries for a 560AH Upgrade. While doing some research, I have found out that our WFCO Converter/Panel will only charge the Lithium Batteries up to only 90%. Also, I'd like to add a 2000-3000W Inverter along w/ the LifePo4 Battery upgrade and possibly add Solar in the Future. I'd like to be able to also use standard AC Shore Power or a Generator to charge the batteries.

It seems the options I have are:

1) Use the existing WFCO 8735 + Add a 2000-3000W Inverter + Transfer Switch
2) Buy an all-in-one Inverter/Charger/Transfer Switch Solution and Use it in tandem w/ the WFCO but disable the Converter/Charger in the WFCO

I'm inclined towards Option # 2... Is this the right approach? Do you have any recommendations for a 2000W+ System? The ones I have looked at so far from AIMS, Victron etc. are in the $1000+ range.

Thanks for your feedback!

 

[HRTKD]

Option 2 is the easier, more elegant path, but more expensive. Disabling the existing converter can be as easy flipping a circuit breaker in the distribution panel.

 

[MisterSandals]

While doing some research, I have found out that our WFCO Converter/Panel will only charge the Lithium Batteries up to only 90%.

Can you point me to your research?
What metric do you use to determine 90%?
Assuming you researched LiFePO4 (lithium iron phosphate batteries).

 

[noblesin]

Can you point me to your research?
What metric do you use to determine 90%?
Assuming you researched LiFePO4 (lithium iron phosphate batteries).

I sent an email to WFCO:

"Hello, I have this Power Panel in my RV and I'm replacing my batteries with Lithium LifePo4 280AH Batteries. What are my options to replace this Power Panel or Converter to support the Lithium Batteries? Thanks!"

And this was their official response:

"The converter you have is not an actual lithium converter but will charge to approx.. 90%. We do not have a direct replacement converter that is lithium for this model at the present time."

 

[MisterSandals]

Ok so your research consisted of a sales pitch.
Do you know what the charge profile voltages are? That would be the most basic research i can think of.
Following up with what finding the charge profile of the unit they want to sell you should also affect your buying decision.

And 90% charge... i won’t even touch that one.

 

[noblesin]

Ok so your research consisted of a sales pitch.
Do you know what the charge profile voltages are? That would be the most basic research i can think of.
Following up with what finding the charge profile of the unit they want to sell you should also affect your buying decision.

And 90% charge... i won’t even touch that one.

I'm not trying to buy this... This is the WFCO 8735 unit that's in our RV already. I'm trying to replace it because of the fact that It'll only charge the batteries to 90%.

 

[HRTKD]

You don't have to replace the panel. All you need to replace is the converter that is in the bottom of the panel.

I have a WFCO panel. I replaced the OEM converter last year. The only issue there was that the new converter had a plug to go into a 110vac outlet and the old converter was wired directly into a circuit breaker. Not a big deal, I cut the plug off the new cord. However, some converter manufacturers will invalidate the warranty if the plug is cut off. When I put in a new LiFePO4 converter this month I added an outlet so I could plug the converter in instead of cutting off the plug.

 

[MisterSandals]

I'm not trying to buy this... This is the WFCO 8735 unit that's in our RV already. I'm trying to replace it because of the fact that It'll only charge the batteries to 90%.

I was in the same situation that you are in now. I have a PD4645 from 2011 that was made for lead acid batteries. I researched the charge profiles and found that the charge profile of the unit i have is more suited to how I want to charge my LiFePO4 batteries.
My personal preference is to charge conservatively because i have a LOT of battery capacity and i do not need to bang the voltage off the ceiling everyday. My preference is to charge to about 13.85v with solar. They quickly discharge 13.4v anyway. My capacity tests have shown i get 100% out of this, which is more than i expected (wanted really).
A recent trip where i was plugged into shore power looked like it was charging plenty, well above where my batteries settle when charging stops (sorry, i cannot recall the exact numbers now, i've put that worry out of my head and recovered the brain cells).

If you are going from 60ah of lead batteries to 560ah of LiFePO4, this should give you almost 20x the usable capacity. Charging to "only" 90%, even if true, will likely not even be noticeable unless your usage has increased exponentially as well.

Research the charge profiles, you'll need to know this eventually. You'll also need to come up with your charging strategy - there are many.

I'd say give it a go with your existing charger. Keep an eye on it until you think it can be trusted. Bench test thru as many cycles as you can if possible. Label your cells and take good notes.

I cannot help with the inverter part of your issue, sorry.

 

[HaldorEE]

I would much rather have it charge to 90% of capacity than 105% of capacity.

Biggest thing to be concerned about is, if the charger will ever try to "Condition" (desulfate) the battery. That will damage your cells if the BMS doesn't protect them from this.

What BMS are you going to use with your LiFePo4 cells?

 

[noblesin]

I would much rather have it charge to 90% of capacity than 105% of capacity.

Biggest thing to be concerned about is, if the charger will ever try to "Condition" (desulfate) the battery. That will damage your cells if the BMS doesn't protect them from this.

What BMS are you going to use with your LiFePo4 cells?

This one:

7.74US $ 10% OFF|Dykb Smart Bms 4s 12v 60a 80a 100a 120a Li-ion Lifepo4 Lithium Protection Board Balance High Current Bluetooth App Software Gprs - Battery Accessories & Charger Accessories - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[HaldorEE]

This one:

7.74US $ 10% OFF|Dykb Smart Bms 4s 12v 60a 80a 100a 120a Li-ion Lifepo4 Lithium Protection Board Balance High Current Bluetooth App Software Gprs - Battery Accessories & Charger Accessories - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

Configurable, that's good.

I am using a 7S Daly with my LiNMC pack. It isn't configurable, but I am only really depending on it to protect against unbalanced cells. All of the charge sources and my Inverter are Victron, plus I have a couple of DC Low Voltage Disconnect circuits for the DC loads.

My important DC loads (fridge and internal lights) have a lower disconnect voltage. The less important DC loads are set to disconnect at a higher voltage.

 

[noblesin]

Alright ... So I've made some progress on this:

1. I finished building my (2) 280AH LifePO4 Batteries w/ 120A BMS attached to each. I plan to attach these in Parallel to get my 560AH capacity.
2. I also purchased the All-In-One SUNGOLDPOWER 3000w Inverter/Charger/Transfer Switch.

In terms of hooking it all up together, Does this Diagram look correct below?

Some questions:
1. What gauge wire do you recommend for the connections below? Between the Batteries, From the Batteries to the Inverter/Charger and from/to the Inverter/Charger and the AC Panel and the AC Input.
2. What happens to the Power from the Tow Vehicle Plug? Just in case I needed to charge using that, Do I have to add an additional DC-DC Charger? Where would the Output from the DC-DC Charger go?
3. Do I need to add some Fuses/Transfer Switches/Power Blocks what have you in these connections?
4. To disable the existing Converter/Charger in my WFCO Panel.. I'm hoping It's easy as flipping a breaker or cutting it out completely.

I'm totally new to this so would appreciate any help figuring this out!

 

[MisterSandals]

What gauge wire do you recommend for the connections below?

You need to specify the amps, volts and distance (one way or round trip) to look up the wire size required.

 

[noblesin]

You need to specify the amps, volts and distance (one way or round trip) to look up the wire size required.

I've marked it on the Diagram.. Does this help? Thanks!

 

[MisterSandals]

Yes it does. I am using this site:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

120vac 12ft 30A needs 16awg to stay below 3% loss (assuming 12ft is one way)

Site with values filled in:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Are you good to calculate the rest?

 

[noblesin]

Thanks for that Calculator!

My brain is fried and I'm confused as hell but I think I'm making progress. I believe I have to run separate cables from the Batteries to the WFCO Panel to continue to support the existing DC Systems in the Trailer aside from the AC Input that will be provided by Shore Power/Inverter etc. I'll also need a 250A Fuse between the Batteries and the Inverter and use 2/0 Gauge cables for the connections between the Batteries and the Batteries and the Inverter. Will get back to this tomorrow. Still have no idea how the Tow Vehicle Charger will fit into the picture.

 

[noblesin]

Made some more Progress on this...

1) Added two 250A Bus Bars / Power Distribution Blocks to distribute Power between the DC side of the Panel and the Inverter/Charger
2) Also added a 250A Fuse to the + Side of the Battery before the Bus Bar to protect the Wires/Surges
3) Added a On/Off Switch to the + Side of the Battery before the Bus Bar in case I need to turn off the Power from the Batteries
4) Added a 50A Fuse to the Wires going from the Bus Bar to the DC Side of the Panel to protect the Wires/Surges

Still outstanding:

1) What to do with the Tow Vehicle Plug / Add a DC-DC Charger? Will the DC-DC Charger also accommodate Solar in the future? If so, Where do I wire in the DC-DC Charger into this overall System?
2) Does all this make sense?

 

[Dogsareloud]

Wow...this is really helpful...there are a lot of 8735's out there...I too called WFCO and asked the question...I called tech support, not sales...they told me the same but said it would only charge to 80% - said a new 8735Lis was coming out for Lithium... Anyway, thank you for posting all of this...I am trying to build a similar system - basically add solar package and integrate with the current WFCO 8735...what a pain...

 

[Supermo26]

Any pictures ?

 

[noblesin]

I will share more updates and pics as I move further along on this... I just haven't had time to work on it.