Should I rewire instead of going from DC-AC-DC for RV 12V appliances? (Solved)

[eXodus]

Current Setup:
Battery Bank -> Growatt/Transformer -> Main 240V Circuit Panel -> -> 120V Sub Panel -> TT 120V Circuit Panel -> 12V Appliances

While this is probably better, is it worth while?
Battery Bank -> Victron 48V-12V Converter - >12V Appliances

I got the Growatt - 120V - 12V route and it works perfect for a long time. I think it gives more redundancy.
The amount my 12V appliances use is minimal. 100-300wh in a day. Even when you go from 70% efficiency the 48v - 120V - 12V system has to the 90-95% 48V - 12V presumable is doing. That's not much savings, you are saving ONE 1 AH a day or so..

 

[kjswiley]

Appreciate it, everything looks great now that I have the fridge and water heater on propane. While I do think something is wrong with that fridge, I grossly underestimated how inefficient RV fridges were on AC. I will leave the wiring as I have it now that I know what was going on.

 

[jberger]

The spikes look a defrost mode, does your model have auto defrosting?

 

[kjswiley]

The spikes look a defrost mode, does your model have auto defrosting?

You know I have no idea, but the freezer has not gotten that cold on 7 and the freezer doesn't even have a layer of frost which I hadn't noticed or thought about.

Regardless, since the TT will be permanent I bought a cheap Residential AC Fridge to put in and be done with it. Now that the water heater is running off propane and the fridge has been replaced I have plenty of battery hours available.

 

[Bobert]

Great I will leave it as is, the fridge/AC are the only real draws I have anyway.

When I renovated my travel trailer I discovered that my fridge was improperly installed. The rear of the fridge is supposed to be 1” or less from the rv wall and the top needs to not have cavities over the fridge that can cause turbulence. If your fridge is not properly installed it won’t give good performance in hot humid weather.
https://myrvworks.com/ has a great deal of information about rv fridges. If you have a problem of this nature fixing it could save you a bunch of propane.

 

[kjswiley]

When I renovated my travel trailer I discovered that my fridge was improperly installed. The rear of the fridge is supposed to be 1” or less from the rv wall and the top needs to not have cavities over the fridge that can cause turbulence. If your fridge is not properly installed it won’t give good performance in hot humid weather.
https://myrvworks.com/ has a great deal of information about rv fridges. If you have a problem of this nature fixing it could save you a bunch of propane.

Hey thanks, since I bought a small cheap residential I am going to put the RV fridge up on craigslist. The new one has the same footprint but the interior feels huge compared to the old one, and it uses a fraction of the power. I am leaving for Mexico soon, and the RV fridge is old enough where I do not want to be down there and have an issue which forces me to replace the unit. If the residential goes I am only out 350$ and can get one down there easily.

My freezer didn't freeze at 7 (of 10), maybe thats too low, maybe the fridge isn't right.

 

[kjswiley]

For anyone who is thinking of ditching the RV fridge/ doesn't want to rely on propane though it is very efficient....here is a graph with the old fridge (and water heater) vs just the new fridge. As you can see this plays much nicer with my system.

The RV was using 335W on average for longer durations, while the new fridge uses 90W on average and much briefer periods. This is ignoring minimal loads light laptops and LED lights, so those numbers are a bit high.

Old Fridge:
You can see when I finally turned off the electric from the water heater and switched to propane thanks to time2roll's tip on the rocker switch.


New fridge:

 

[12VoltInstalls]

anyone who is thinking of ditching the RV fridge/ doesn't want to rely on propane though it is very efficient....here is a graph with the old fridge (and water heater) vs just the new fridge.

My only regret is not buying in the 10CF range. 5CF is problematic for weeks one buys more meats, fish, a few juice containers and a gallon of milk.

What surprises me is why RV mfgrs haven’t jumped on solar yet. I guess maybe cuz propane doesn’t require interaction- it just works- but cloudy days are an issue that would bring crowds of warranty complaints.

The key is to not buy a frost-free fridge unless your system can take the hit.

 

[jberger]

"What surprises me is why RV mfgrs haven’t jumped on solar yet"
Have you seen the roofs of most RV's? I'm surprised the AC units hang up there.
They put a 10watt panel on there and call it solar powered.
The majority of the RV/Trailer market is all about shine over substance, and they know they can't sell the rooftop like they can cabinetry.

 

[time2roll]

RVs are primarily designed to plug in at the RV park.

 

[jberger]

There are plenty of us who boondock with our RV's.

 

[12VoltInstalls]

There are plenty of us who boondock with our RV's.

But the manufacturers can’t see you

 

[Bobert]

But the manufacturers can’t see you

Actually many manufacturers have solar options now. I believe keystone has it on almost all of their new trailers now.

 

[12VoltInstalls]

Actually many manufacturers have solar options now. I believe keystone has it on almost all of their new trailers now.

Maybe they exist. I’ve been out of that industry for two years.

The ‘solar ready’ RVs I had come before me were an SAE socket and some folding panels with an integrated pwm for a max of 150W or 10A, whichever was lower. This one customer paid $750 ‘including installation’ which must have meant adding a second battery and putting the panel tote in a closet because they all came with the sae plugin and a single battery according to the sales lit.

Yes, I’m pessimistic on RVs with solar. Sorry.

 

[Bobert]

Maybe they exist. I’ve been out of that industry for two years.

The ‘solar ready’ RVs I had come before me were an SAE socket and some folding panels with an integrated pwm for a max of 150W or 10A, whichever was lower. This one customer paid $750 ‘including installation’ which must have meant adding a second battery and putting the panel tote in a closet because they all came with the sae plugin and a single battery according to the sales lit.

Yes, I’m pessimistic on RVs with solar. Sorry.

Yeah I can understand that but the majority of campers these days want to be able to go for a few days without a dead battery. Keystone has a 200watt system with a lead acid battery standard ( basically to keep your battery charged while setting) there’s factory options using dragonfly batteries ( the commercial version of battleborn) and Victron equipment all the way up to 1200 watts of solar on the roof. For a “small” additional fee

 

[12VoltInstalls]

to 1200 watts of solar on the roof. For a “small” additional fee

Well maybe it’s coming around.

One younger couple came in with a non-working solar system installed by one of the largest regional RV dealers “here.” $3500 upgrade. They’d been back to them five or six times with no joy.

They had a generic mod-sine 5000W inverter, two flooded marine batteries, and 250W of foldable panels. 4ga battery cables to inverter. Turning on inverter powered up the converter. I told my boss it was a $1500-$2000 fix at $70/hr plus the needed equipment purchases; he told them $2500 but they didn’t schedule.

I have no love for RV dealers or manufacturers.

 

[chrisski]

For anyone who is thinking of ditching the RV fridge/ doesn't want to rely on propane though it is very efficient....here is a graph with the old fridge (and water heater) vs just the new fridge. As you can see this plays much nicer with my system.

The RV was using 335W on average for longer durations, while the new fridge uses 90W on average and much briefer periods. This is ignoring minimal loads light laptops and LED lights, so those numbers are a bit high.

Old Fridge:
You can see when I finally turned off the electric from the water heater and switched to propane thanks to time2roll's tip on the rocker switch.
View attachment 82873

New fridge:
View attachment 82872

I appreciate the graphs.

Can you tell me how many WH per day your new fridge versus the old fridge? Looking at your graph my estimate is 8 kwh per day with the old, and less than 1 kwh with the new.

I have a propane fridge running in electric mode right now ane the temp is comfortable 65 F outside. My fridge uses 350w to 400w when on, and when I run it on electric, it takes 5 kwh to power it. I think in the summer the fridge would use much, much more power.

 

[Bobert]

Well maybe it’s coming around.

One younger couple came in with a non-working solar system installed by one of the largest regional RV dealers “here.” $3500 upgrade. They’d been back to them five or six times with no joy.

They had a generic mod-sine 5000W inverter, two flooded marine batteries, and 250W of foldable panels. 4ga battery cables to inverter. Turning on inverter powered up the converter. I told my boss it was a $1500-$2000 fix at $70/hr plus the needed equipment purchases; he told them $2500 but they didn’t schedule.

I have no love for RV dealers or manufacturers.

Wow what a mess. No wonder Keystone is having paint by number systems pre engineered. It’s hard to believe they could mess it up that badly. It’s probably a blessing that it doesn’t work.

 

[12VoltInstalls]

probably a blessing that it doesn’t work.

No, it worked. For 10 or 15 minutes

 

[Bobert]

No, it worked. For 10 or 15 minutes

That’s what happens when you wire in a 5000 watt inverter where a standalone 500 watt unit belongs