2205S solar panels vs. battery disconnect

[Bob.n.Denise]

Just traded in our 2018 Rockwood Ultralight 2703WS for a 2023 Rockwood Mini Lite 2205S. This will be our first exposure to solar power.

When I put the trailer into storage, it appeared the 2 ea 200W solar panels on the roof were continuing to charge our house batteries (2 ea 12V deep cycle batteries) even though I had turned the battery disconnect to off.

So this trailer is wired so the solar panels can still feed the house batteries even if the batteries are turned to disconnect?

[Aussieguy]

Pretty normal


It's usually done that way so the solar has a chance to charge the battery
and you have a simple method to turn off 99% of the load to the battery.


NOTE to self ....... some items such as Carbon Monoxide and smoke detectors are not hooked to the battery disconnect. They can stay on all the time unless you physical remove a battery cable



as long as you have a solar controller the battery won't be over charged
and solar usually turns itself off each night (not sure why?)

[01tundra]

Yep ^ normal and how the solar controller should be wired.

[Bob.n.Denise]

Great news. Will be nice to start trips with 100% SOC.

New question - We travel about 250 miles per day and harvest host overnight for many days in a row. The new trailer has 2ea. 200W solar panels on roof and 2ea. 12V deep cycle batteries. Have the OEM 12V frig.

If this set up proves to be inadequate in supporting our quasi boondocking, what's next step? Add a portable solar kit (e.g. Renogy 200W briefcase) or replace batteries with Lithium? Or is the next choke point something like the inverter/converter/controller, etc...

Trying to understand electricity...

Bob

[stephndudb]

Lithium is a great combination with solar because of its ability to rapidly take a charge, and its ability to drain down to 10% or less state of charge without damage. The only downside to lithium (besides cost) is cold-weather performance. They can't be charged if the battery itself is below freezing. (Some have built-in heaters.)

[Aussieguy]

12v battery?

You probably have a cheap style lead acid.
Lead acid is ok... people have used them for years
use yours until they die or no longer provide enough power for your needs


400w of roof top should be adequate as long as you don't get a lot of shade
I would get a ground panel to supplement.

Hopefully you have plenty of time to decide on whether a battery upgrade is warranted


I would strongly suggest going Lithium too ... lots of posts already on the forum on how what to get to use lithium (Lifepo4)


search the forum for "Lithium" "lifepo4" , "GC2" "battery replacement"

[Camp1]

I’m interested in going to lithium myself when the lead/acid dies. Would the charge controller need to be replaced as well?

[TitanMike]

Originally Posted by Camp1

I’m interested in going to lithium myself when the lead/acid dies. Would the charge controller need to be replaced as well?

There is no need to change the solar charge controller if it has a Li/Lithium/LiFePo4 charge setting available. Check existing controller's manual for "setup" and if this setting is available change to it.

Also, no real need to change converter/charger. If it doesn't have a "lithium" setting the solar charging will provide the necessary "top off" charge (>14v) needed for cell balancing.

Since your RV is a recent model it's very likely both converter and solar charge controller are "lithium capable".

[Rhumblefish]

Originally Posted by Bob.n.Denise

Just traded in our 2018 Rockwood Ultralight 2703WS for a 2023 Rockwood Mini Lite 2205S. This will be our first exposure to solar power.

When I put the trailer into storage, it appeared the 2 ea 200W solar panels on the roof were continuing to charge our house batteries (2 ea 12V deep cycle batteries) even though I had turned the battery disconnect to off.

So this trailer is wired so the solar panels can still feed the house batteries even if the batteries are turned to disconnect?

Solar is generally wired straight to the batteries via a controller. "Battery disconnect" cuts most of the 12v going from the batteries to the rest of the coach (as others have mentioned, there are some 12v draws that are constant by design). Lithium doesn't like to be charged or used in extreme cold, so a disconnect to your panels is a good idea if you live/store in a cold environment. Here in the midwest, we do get ourselves some negative numbers in the wintertime, so I make sure my solar won't try to charge my batteries when stored for the off season (even when it's tucked away indoors).

[18LT]

I’m a big fan of lifepo4 and solar on our 2205S. That said, two lead acid batteries should do ok if you are doing harvest host stops enroute to your destination, and provided you have moderate sun while on the road.
Our 2205S with 12-volt refrigerator consumes at least 30 amp hours of energy from early evening until the panels begin to create measurable wattage in the morning. That’s about what two typical 60ah marine batteries will supply if you stick to the 50% discharge guideline.
Energy consumption will increase dramatically if you use the furnace, meaning you could get an elbow in the ribs at 3am when the batteries stop powering the furnace.
I’m a member of the “you can never have too much battery” club.

[Rhumblefish]

Originally Posted by 18LT

I’m a member of the “you can never have too much battery” club.

Team Overkill, unite! 600AH of LiFePo4 aboard and loving the 12v life.

[18LT]

Originally Posted by Rhumblefish

Team Overkill, unite! 600AH of LiFePo4 aboard and loving the 12v life.

500 amp hours here and I’ll be adding another 300 soon.

[Bob.n.Denise]

I’m sold on going to lifepo4 batteries. But not excited about replacing the 2 brand new Interstate 60ah marine batteries in a 2-week-old trailer.

But 18LT’s comment about the 12-volt refrigerator in the 2205S consuming both batteries to the 50% discharge guideline overnight is eye opening.

Assuming I arrive at the harvest host location at 100% SOC (solar panels + truck alternators), I’m still putting the batteries at risk every night.

So it looks like adding a portable solar panel suitcase at this time is useless.

My weak link is the house batteries.

Time to research lifepo4 options.

PS. Help me with the math. Will 30 amp hours of energy bring 2 ea. Interstate 60ah marine batteries to the 50% discharge guideline? Or is it 60 amp hours?

[18LT]

Two 60ah 12 volt batteries connected in parallel will provide 120 amp hours at 12 volts, so 50% would be 60 amp hours. And yeah, I made a mistake in my math in my previous post.
If you have two new Interstate batteries already, I think you should use them and see how they work for you.
As I mentioned, our 2205S will consistently consume 30 amp hours from around 6 in the evening to around 7 the next morning. That's the fridge, thermostat (yes, the thermostat is 12-volt powered), radio memory, and propane detector operating throughout that time. It also includes using the 12-volt lights until around 10pm. We don't use the awning, step or porch lights very much.
Keep in mind the water heater ignition is 12-volt powered and if you use the furnace, it will run batteries down in a big hurry.
Regardless of which batteries you use, I highly recommend a state of charge meter. You'll definitely need one if you go with lithium iron phosphate batteries.
I have an inexpensive one but I'm a cheapskate.
https://www.amazon.com/QWORK-Battery...mX25leHQ&psc=1

[18LT]

P.S. A friend of mine has an Interstate in his new camper. His battery has an 80 amp hour rating so be sure to look at the stickers on the top of your batteries to find out the amp hour ratings.

[Aussieguy]

charge the batteries and camp in the driveway

turn on the fridge and other stuff ......................see how long they'll last
then see how long the solar takes to replenish


IMHO Tow vehicle alternator charging is not in the equation
especially if you camp for days in one spot



----------------------------------------------------------------------

You can always post the batteries for sale in Craigslist or Marketplace
use the boating sections.

[Bob.n.Denise]

Realize I just bought this trailer and have not actually used it yet…

18LT – Regarding the state of charge meter. Isn’t the Go Power panel in my 2023 2205S a state of charge device? When I cycle through “B” button, I get a percentage number (assume battery SOC), an “Ah” number (assume # of amp hours in batteries), voltage and an “A” number (assume amps coming into solar panel).

Is this sufficient information?

I do have a brand new/in the box Victron energy battery monitor BMV-712 Smart in the garage. Never installed it because electricity is not my friend. Is that much better?

[Bob.n.Denise]

Aussieguy –

HOA makes bringing the RV into the neighborhood a “challenge”. Can bring it to the house for a couple hours – that’s it.

Wife & I travel using harvest host. Generally 200-250 miles per day and overnight at a winery or golf course. 3-5 days on the road. Then full hookup at destination, for 3-5 days. Then back home.

Will definitely experiment as time goes on. But getting a big head start by seeing what the experts have to say.

[IPcamper]

The Go Power panel most like will only tell you what the solar is putting into the batteries. The Victron Battery monitor will measure the amount of power going in and out of your batteries. It will be more accurate and have more useful information.

[Bob.n.Denise]

IPCamper - Isn't this my battery's state of charge? Tells me the batteries are 100% full (and estimating 176 Ah remaining)?