Looking for tips and hints on my new solar system

[jondrew55]

My 2024 Flying Cloud bunk came with 300W of solar panels, 2 x 100 AH Battleborn batteries and a standard Victron display/controller. Looking for advice for add ons, maintenance etc. My FC is stored under cover, so generally it's not seeing sunlight. I also have 50 A power and generally leave it plugged in to run my AC (set to 80) and or a dehumidifier.

I know the "leaving it plugged in" all the time always generates different opinions. But as far as the expensive batteries go, what should I be doing? Should I let them run down occasionally? My thought is keeping LiIon batteries constantly topped off is not good for them.

What about a shunt/monitor upgrade? I don't think I have that in the standard system. Is that useful?

The fact is, we don't boondock, so typically the batteries don't get a lot of work.

Also, my tech told me during my orientation that unlike AGM batteries, I can run Li batteries "all the way down" with no issues. I'm pretty sure from experience with other Li batteries that is completely false. I'm not exactly sure how to manage the State of Charge yet, but I 'm starting to investigate that now. I definitely do not want to ruin these expensive batteries.

[LNBright]

What Victron display/controller do you have? There are several, and some of them are part of a shunt/ battery monitor. Lead/acid and AGM batteries, you should not discharge them past 50%; yes, you can discharge LiFePO4 batteries all the way down. (I might put the cutoff at 5% just because, but it won't kill the battery, unlike how going past 50% will definitely shorten a lead/acid battery's life.)

[JeffKim]

Looking at the 2024 manual, it appears you have a Victron Smart Shunt. So, you should be able to monitor batteries from your smart phone with the Victron app. It also recommends storing at 100% (for winterization). If you are plugged in and in storage then disconnecting them doesn't hurt so if there's a power failure it won't potentially totally discharge them. If you haven't checked it out, the Battle Born website also has a lot of information.

IMHO, these are the gold standard of batteries and if you're not doing any boondocking, etc. you shouldn't have to worry very much. They are rated for thousands of cycles which is many years of use, especially in your use case. The only big draw will be the refrigerator during transit, but it should be able to keep up if you're plugging in at the end of the day and with the 300W on the roof. Some people add a DC-DC charger, but I'd wait and see.

[jondrew55]

Thanks. Been busy since we picked it up last week. I’ll have a day or two of alone time to play with it on its maiden voyage this week. Hell,
I’ll even read the manuals.

By the way, I thought the 12v line from my truck powered the fridge during transit? Or is that an urban myth?

Originally Posted by JeffKim

Looking at the 2024 manual, it appears you have a Victron Smart Shunt. So, you should be able to monitor batteries from your smart phone with the Victron app. It also recommends storing at 100% (for winterization). If you are plugged in and in storage then disconnecting them doesn't hurt so if there's a power failure it won't potentially totally discharge them. If you haven't checked it out, the Battle Born website also has a lot of information.

IMHO, these are the gold standard of batteries and if you're not doing any boondocking, etc. you shouldn't have to worry very much. They are rated for thousands of cycles which is many years of use, especially in your use case. The only big draw will be the refrigerator during transit, but it should be able to keep up if you're plugging in at the end of the day and with the 300W on the roof. Some people add a DC-DC charger, but I'd wait and see.

[JBamadon]

The 12V fridge draws 4-5 amps when the compressor is running. I don't think the 9 pin plug from the truck will supply that much. We have a 2023 FC27 with 300 watts of factory solar and even on light overcast days, that keeps the batteries at 100% while traveling.

[JeffKim]

Originally Posted by JBamadon

The 12V fridge draws 4-5 amps when the compressor is running. I don't think the 9 pin plug from the truck will supply that much. We have a 2023 FC27 with 300 watts of factory solar and even on light overcast days, that keeps the batteries at 100% while traveling.

This comes up quite a bit in the forums. Here's a recent thread. There is a 10AWG charging wire from the 7-pin and it provides a limited amount of current and charging. How much is a good question and depends on the vehicle. Ours is fused to 15A (most vehicles are much higher). (I think the line has a 30A breaker at the positive bus bar.) I have our wire disconnected since it also provides a voltage that I suspect confuses the rooftop solar controller so that it doesn't always provide charging.

More importantly, with your expensive lithium batteries a DC-DC charger is a very good idea to provide the correct charging profile. Something like a Victron DC-DC 12-12|18 is what many people use connected to the charging line. It will provide 18A of charge and set to a lithium profile will charge the batteries correctly over 10AWG*. Other people have used beefier 30A chargers but they require separate wiring from the TV to the charger in the trailer.

The 2024 Trade Wind comes with the DC-DC charger, I don't know with the 2024 FC equipped with lithium if they do anything with the charging wire. In our 2023 GT it's a black wire in the DC junction box.

*FWIW, I can't use a Victron 18A charger since it blows the 15A fuse and it's hard to find lower amperage chargers with lithium charging. But there's a Renogy and Victron has a new configurable charger I'm considering.

[jondrew55]

Lots of good info below. Thanks!

Originally Posted by JeffKim

This comes up quite a bit in the forums. Here's a recent thread. There is a 10AWG charging wire from the 7-pin and it provides a limited amount of current and charging. How much is a good question and depends on the vehicle. Ours is fused to 15A (most vehicles are much higher). (I think the line has a 30A breaker at the positive bus bar.) I have our wire disconnected since it also provides a voltage that I suspect confuses the rooftop solar controller so that it doesn't always provide charging.

More importantly, with your expensive lithium batteries a DC-DC charger is a very good idea to provide the correct charging profile. Something like a Victron DC-DC 12-12|18 is what many people use connected to the charging line. It will provide 18A of charge and set to a lithium profile will charge the batteries correctly over 10AWG*. Other people have used beefier 30A chargers but they require separate wiring from the TV to the charger in the trailer.

The 2024 Trade Wind comes with the DC-DC charger, I don't know with the 2024 FC equipped with lithium if they do anything with the charging wire. In our 2023 GT it's a black wire in the DC junction box.

*FWIW, I can't use a Victron 18A charger since it blows the 15A fuse and it's hard to find lower amperage chargers with lithium charging. But there's a Renogy and Victron has a new configurable charger I'm considering.