Converting to Lithium in Keystone RV with the SolarFlex 2001 package

[upontheridge]

I have a 2022 Keystone Carbon 338 with the SolarFlex 200i setup. That setup comes with a 200 watt solar panel on the roof and a Victron MPPT 75/15 Solar Controller. The RV also has a WFCO 9875 converter/charger that says it has a 13.6 Output. I want to add 2 Lithium 100amp-hour batteries and a 1000-watt inverter. My questions are as follows:

1. Do I need to replace the WFCO 9875 converter/charger or can I let it charge the LI batteries to 13.6 and then let the Victron Solar Controller handle topping off the LI batteries.
2. If I need to something other than the WFCO 9875 what would you recommend replacing it with? I have read the WFCO auto-detect is a less-than-optimal device.
3. Can I keep the WFCO device and purchase an inverter with ATS and charging capabilities? Can the LI batteries deal with charging come from the WFCO device, the inverter charger, and the solar charger?
4. For the LI batteries. I am considering Redodo batteries. My battery compartment is not in an insulated area. I don't plan to camp in sub 32 weather on a regular basis but may have a night or two that temps may drop below 32 degrees. I don't have a problem charging running a generator for power if temps drop below 32 degrees so I don't think i need a battery with built in heat but wondering if I need a battery with the 32 degree charging cut off as batteries would be connected to solar charging.
5. Trailer when stored may result in batteries experiencing below 32 degrees temps. Do I need to remove the LI batteries or will they be okay as long as they are partially charged and not being charged.

Thanks for your help.

 

[12VoltInstalls]

Trailer when stored may result in batteries experiencing below 32 degrees temps. Do I need to remove the LI batteries or will they be okay as long as they are partially charged and not being charged

If they are not heated batteries I would disconnect the solar panels via a proper-rated DC breaker while in storage, and also turn off the battery switch in storage.
Lithium batteries ‘can’ be stored at any partial state of charge, but best practice is to store them at ~75% state of charge. They will ‘hold’ safely at that state for probably years.

Do I need to replace the WFCO 9875 converter/charger or can I let it charge the LI batteries to 13.6 and then let the Victron Solar Controller handle topping off the LI batteries

Need is a funny word. But if budget isn’t compromised I would tend to want to disable it and instead use an AIO to handle ‘grid’ or generator charging. That gives you solar charging and an AC transfer switch as well as the 1000W inverter. See www.watts247.com for 1012LV
Seeing as you already have a Victron SCC you could do the charging with wfco as you suggested.

^^^That has an advantage imho. I likely would not buy a 1000W inverter. That will do most minor everyday things but a) a 1200W pure sine inverter will have a lot less overload shutdown potential but b) a 2000W pure sine wave inverter probably won’t object to a microwave or hair dryer and isn’t going to have much difference in idle watt consumption.

setup comes with a 200 watt solar panel on the roof

I would want to double that at least; 600W is going to be better imho, but 400W of flat panels is going to be much better for usage.

Can I keep the WFCO device and purchase an inverter with ATS and charging capabilities? Can the LI batteries deal with charging come from the WFCO device, the inverter charger, and the solar charger?

Yes, up to ~100A of charging

wondering if I need a battery with the 32 degree charging cut off as batteries would be connected to solar charging

i think that feature is inexpensive compared to damaged batteries

 

[upontheridge]

Thanks for your reply 12VoltInstalls. I will take your advice and move up to a 2000 watt pure sine wave inverter. Need to think through all the other stuff.

 

[12VoltInstalls]

move up to a 2000 watt pure sine wave inverter

Just keep in mind you will need to cable for at least 160-200A at 12V if you hadn’t already thought of that. Same/similar idea of using a 2000W inverter: it won’t get hot or as hot if it’s not being maxed out continuously.

 

[Rocketman]

If you have Victron smart mppt’s and you install a Victron Smartshunt or BMV712 - you can have the Smartshunt (with an optional temp unit) report the temp to the solar mppt’s- you can then set the mppt’s so they don’t charge under____(user setable) F - mine is set to 40 F.

Also if you get a Victron Multiplus inverter/charger- it comes with the temp cable.

 

[upontheridge]

Just keep in mind you will need to cable for at least 160-200A at 12V if you hadn’t already thought of that. Same/similar idea of using a 2000W inverter: it won’t get hot or as hot if it’s not being maxed out continuously.

So, looking at a couple of wire sizing charts. It looks like the 6 feet of cable that I will need from the batteries to the Inverter. I can run anything between 2/0 and 2 AWG depending on how much drop in voltage I want to deal with. What size would you recommend?

I ordered a KISAE SWXFR1220 2000W Pure Sine Inverter w/ Transfer and 2 Redodo 100 AH batteries with Heat and low temp cut-off. I am going to wait on changing my converter/charger and adding additional solar panels at this point and see how much I use the Inverter

 

[12VoltInstalls]

can run anything between 2/0 and 2 AWG depending on how much drop in voltage I want to deal with. What size would you recommend?

I would use 2/0
The high cost of 2/0 is a downer, but “in dollars” the difference between lighter gage and 2/0 is measured by a pizza or two so I consider that a non-factor. WindyNation is available on Amazon as made-up terminated cables or as roll-your-own.

When I assembled my first system- 200W solar, 1200W Giandel* psw inverter- I used 2/0 cables. Three upgrades later and the original cables are still in service with my 2000W QZRELB* psw inverter. So the idea of using ‘big’ cables has been less expensive in the long run.
So three advantages:
- efficiency (a beneficial side effect not a factor to sweat over)
- the cables have never gotten warm
- upgrade friendly at zero cost

So I’d recommend 2/0

*for inexpensive commodity inverters I’d recommend Giandel, QZRELB(Reliable Electric brand), or MPP brand; not others)

 

[mkaye]

remember when using cable length for size calculation, it is the total of both wires, not just 1

here is a drop-in replacement guide for the WFCO

Converter-Cross-Reference-Guide - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

 

[12VoltInstalls]

I’ve never understood the ‘converters’ for off-road use. Glamping RV’s, sure, but then we wouldn’t be talking solar.

I’ve either bought RV’s with no converter or removed them. Worked a bunch of trailer RV’s and the converter is just a power-hungry obstacle imho

Personally, I’ve had functional 120VAC in five RV’s with 12V systems and four of those were no-solar. Just batteries. I had a classic 1969 Westfalia with a starter solenoid and relay with an inverter that worked great 1998-2004-ish running a fridge, vcr, and computer.

With all our tech progress today I’d just AIO and ditch the converter. My current 24’ camper is on an AIO and no converter. It’s simpler, more efficient, and seamless.

 

[upontheridge]

I would use 2/0
The high cost of 2/0 is a downer, but “in dollars” the difference between lighter gage and 2/0 is measured by a pizza or two so I consider that a non-factor. WindyNation is available on Amazon as made-up terminated cables or as roll-your-own.

When I assembled my first system- 200W solar, 1200W Giandel* psw inverter- I used 2/0 cables. Three upgrades later and the original cables are still in service with my 2000W QZRELB* psw inverter. So the idea of using ‘big’ cables has been less expensive in the long run.
So three advantages:
- efficiency (a beneficial side effect not a factor to sweat over)
- the cables have never gotten warm
- upgrade friendly at zero cost

So I’d recommend 2/0

*for inexpensive commodity inverters I’d recommend Giandel, QZRELB(Reliable Electric brand), or MPP brand; not others)

Thanks. KISAE recommended 2/0 cable as well so. I went with that. Worked on getting most of it installed today.

 

[upontheridge]

remember when using cable length for size calculation, it is the total of both wires, not just 1

here is a drop-in replacement guide for the WFCO

Converter-Cross-Reference-Guide - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

Thanks for the PD cross-reference. I called WFCO and interestingly enough they don't make a Lithium only Converter/Charger. They only make the Auto detect unit. Reading up on those they don't seem to be working well.