Community Forums

Rg8043 · 12-08-2021, 08:49 PM

I had my pre-delivery walkthrough today on a Sunstar 27p. I have previously rented rvs, and they had refrigerators that to my understanding used propane when the engine was off and not connected to shore power or a generator.

I was told that the refrigerator in the RV that I am purchasing (norcold) only runs on dc. The RV comes with 1 solar panel and a battery charger. I was reading some posts trying to figure this out since I know next to nothing at this point about the power requirements of the various components. Based on my reading of various posts on this forum, it seems to me that I have to figure out how many watts of power the solar panel produces, and how many watts of power the fridge requires, I can't seem to find this out by referring to the manuals provided by Winnebago, so how does one determine the actual power requirements?

Since I would like to boondock occasionally, If the solar isn't enough to keep batteries charged and fridge cool, is my only alternative to use the generator?

I also noticed that several people replaced their older fridges with all electric power, if there an advantage to going this route and not having to use propane?

Thanks in advance for your help, and guidance.

Old-Biscuit · 12-09-2021, 08:18 AM

Sounds like you will have a Norcold N10DC Fridge
12VDC Compressor Fridge
*Runs on 120VAC to DC via converter OR DC from battery

DC Compressor pulls 8.3A (Standard Mode or 6.2A (placed in Night Mode)

As for Solar Panel........What is its rating?

While driving...battery maintained by vehicle Alternator
While parked.......shore/gen power to maintain battery OR Solar

cruizerEd · 12-10-2021, 01:30 PM

You need a lot of solar to reliably support an electric refridgerator. Panels rarely put out the full wattage and never for more than 6 hours a day. We have a compressor fridge and it is fantastic but it does use a lot of power relative to normal RV power usage.

If your fridge uses 7A and runs 60% (14.4 hours) of the time you will need 100AH just for the fridge. 100AH over lets say 5 hours of prime solar production is going to require 20A an hour or 240Watts. Now lets say you can get 80% of your rated solar capacity. 240W/.8 is 300Watts of solar. This also assumes no other loses and there are other loses. Under these assumptions just your fridge is going to need 300W of solar and although the fridge is probably the biggest load there will be a significant draw from other loads.

Frankly getting 80% of your solar for 5 hours a day is a bit optomistic if you travel year around and all over the US. I have 2000W of solar and there are time when clouds and trees keep me from keeping up with the coach loads including the electric fridge.

Don't count on your solar. Use your generator. If you don't have one get a nice quite honda generator.

You'll have to spend a fortune on solar and batteries to match what you can accomplish with a $1200 generator.

Why do I have solar? We're full time and dry camp alot. I hate running the generator. I don't want to have to be at the coach during generator hours. I want to be able to camp in no generator parks. It is all a life style choice, no echonomics in it at all.

Finally I am learning that solar panels don't survive well on RV's. I have it from an industry insider that RV should expect 10 years not 30 years from panels. As for the warranty, read them, they're worthless. This makes solar even more expensive.

twinboat · 12-10-2021, 03:26 PM

If you fridge runs 30 to 40% of the time, a more accurate assumption, then you can figure a lower AH use.

cruizerEd · 12-11-2021, 07:32 AM

Quote:

Originally Posted by twinboat

If you fridge runs 30 to 40% of the time, a more accurate assumption, then you can figure a lower AH use.

I measured my refridgerator usage over two years and the average WattHours was 95WH.

SuperGewl · 12-11-2021, 02:51 PM

Quote:

Originally Posted by Rg8043

I had my pre-delivery walkthrough today on a Sunstar 27p. I have previously rented rvs, and they had refrigerators that to my understanding used propane when the engine was off and not connected to shore power or a generator.

I was told that the refrigerator in the RV that I am purchasing (norcold) only runs on dc. The RV comes with 1 solar panel and a battery charger. I was reading some posts trying to figure this out since I know next to nothing at this point about the power requirements of the various components. Based on my reading of various posts on this forum, it seems to me that I have to figure out how many watts of power the solar panel produces, and how many watts of power the fridge requires, I can't seem to find this out by referring to the manuals provided by Winnebago, so how does one determine the actual power requirements?

Since I would like to boondock occasionally, If the solar isn't enough to keep batteries charged and fridge cool, is my only alternative to use the generator?

I also noticed that several people replaced their older fridges with all electric power, if there an advantage to going this route and not having to use propane?

Thanks in advance for your help, and guidance.

More information about the RV, Model # would allot in this situation.

Rg8043 · 12-12-2021, 08:17 AM

my rv is a sun star 27 p, after reviewing these posts, I now am a bit confused on the use of the inverter. the person who gave us the tour and explanation of the systems on the RV when we picked it up told me that I should turn the inverter off if I’m not using the 110 outlets, but now I wonder if that’s the correct advice if the refrigerator will be using the DC power. as I mentioned above, the only experience I have with an RV refrigerator was from renting rvs, which used propane when not plugged into shore power.

Mudfrog · 12-12-2021, 09:06 AM

Quote:

Originally Posted by Rg8043

my rv is a sun star 27 p, after reviewing these posts, I now am a bit confused on the use of the inverter. the person who gave us the tour and explanation of the systems on the RV when we picked it up told me that I should turn the inverter off if I’m not using the 110 outlets, but now I wonder if that’s the correct advice if the refrigerator will be using the DC power. as I mentioned above, the only experience I have with an RV refrigerator was from renting rvs, which used propane when not plugged into shore power.

I don't have a built in inverter but from what I have read on here a few times, is that it draws power even when it's sitting idle. It's best to turn them off when not in use to keep from draining your batteries, if not plugged into shore power.

On the frig, if it is a DC model, such as the example given by Old Biscuit above, then I don't think the inverter is needed.

wolfe10 · 12-12-2021, 09:13 AM

Please tell us what model refrigerator you have. That will insure answer are correct for YOUR refrigerator. Some are 12 VDC only, others use 12 VDC as one of three heat sources and some use 12 VDC only to power the PC board, ignitor and propane valve.

The INVERTER takes 12 VDC from your battery bank and powers some 120 VAC thing (the smaller draw ones). Again, please tell us what inverter you have-- some are just inverters, some are inverter/chargers.

And, yes if you are not on shore power or generator, and not using 120 VAC from any of the inverter-supplied things, leave it OFF. Inverters take a small amount of power from the battery bank just to be in "stand-by" mode.

Old-Biscuit · 12-12-2021, 09:13 AM

INverter........takes 12VDC from battery and turns it into 120VAC for the AC System
*used when no AC power is available...Shore power or Generator

When connected to AC Power source INverter charges/maintains battery voltage.
Battery supplies the DC System whether on AC Power or Not.

DC fridge draws power from battery......INverter on or off will not affect fridge operation
Just affects battery draw of INverter is supplying the AC System (NO AC Power source). Then battery draw can drain battery

Marine359 · 12-12-2021, 09:28 AM

If you have a Norcold N10dc, that’s a 10cf 12v compressor model. It uses 5 amps when the compressor is running. But it really doesn’t matter as much about how much it draws compared to the cycle time and frequency. My Dometic compressor uses 30-50 amp/hr per day depending on ambient temperature and sidewall shading. So, you can expect to average 50 ah/day with the Norcold. Therefore you must plan on replacing that much juice with solar, or run a small generator to charge batteries that much. You didn’t indicate what kind of batteries you have, which makes a huge difference in how long you can go without using gennie, and how long it takes to recharge. If there’s no sun, I can go for two days on a full charge, then run my small gennie for two hours to get back to 100% SOC.

IMHO, rv manufacturers have been switching to dc only fridges to save on costs. A dc fridge cost half of what a dc/lp absorption fridge costs, and they also save huge on build because they don’t have to install venting or propane lines/valves etc. The compressor fridges are very nice, big and efficient, so it’s likely the trend will continue, but it places a unspoken burden on the buyer to install expensive upgrades (LiFePo4 and solar) to be able to boondock for extended periods.

cbeierl · 12-12-2021, 04:02 PM

Quote:

Originally Posted by Old-Biscuit

...
When connected to AC Power source INverter charges/maintains battery voltage.
Battery supplies the DC System whether on AC Power or Not.
...

ONLY if it is an INVERTER/CHARGER. If it's just an INVERTER it won't be involved in charging or maintaining the batteries. In that case there is presumably a separate CONVERTER which handles that job.

Persistent · 12-12-2021, 04:42 PM

Old Biscuit gives good advice. Trust him.

The make and model of the refrigerator is the needed information, not the RV make and model. Appliances installed in RV's are independently designed and manufactured. The RV builder buys and installs, but many RV manufacturers use the same make and model of appliance.

RV builders shift what they install in their line of RV's depending on cost and availability. Thus the make and model of the refrigerator is needed.

The 12 volt refrigerator runs from battery power. Batteries are recharged in different ways. Some were listed above. They can all work together, or one at a time.

In summer weather you can probably dry camp for 5 days if you have 200 amp hours of battery. Add a 12 volt refrigerator and you may get only 3 days. Add running a 12 volt furnace fan and you may get 1 to 2 days.

Recharging is needed to replenish what is used. A 100 watt solar panel won't keep up even in Arizona. You would need shore power, engine charging, solar, and/or generator.

After batteries are depleted you will need at least 14 hours of shore power to fully recharge. Batteries will accept a lot of power in the first 2 to 4 hours of charging but periodically need a full 14 to 18 hour charge.

A generator can power your RV and charge your batteries using your built in charger. My charger is a 30 amp model. Yours may be bigger. Running the generator for 4 hours can bring batteries up to about 80% state of charge.

Solar can produce a little power in morning light. It will not help much. By 10 am on a sunny day it can start to approach full output. By 4 in the afternoon solar output will have dropped a lot.

100 watt solar panel can produce 8 amps more or less at full power. A good rule of thumb is you can harvest about 6 hours at 8 amps. So if your refrigerator uses 8 amps for 6 hours per day, the solar will provide the power to the battery to replace what it used.

When the sun does not shine strong, you may get very little. Now the solar is getting behind and does not have the capacity to catch up.

I would guess you need a solar array of about 300 watts to keep ahead of rainy days. You need a large battery bank to hold that power until you need it.

Of course you can run the generator on rainy days to do that job. Just keep in mind that charging lead acid batteries takes a significant amount of time and periodically needs a full 14 to 18 hour charge for long service life.

Many of us would like to know how this all plays out for you. Feel free to test your new system and post results here. Make and model of panels, solar charger, refrigerator, and other involved components are greatly appreciated. Pictures are worth a 1000 words.

I wish you good luck and happy trails ahead.

Marine359 · 12-14-2021, 09:34 AM

In real world use, for a travel trailer, having a 12v compressor fridge almost necessitates switching to LiFePo4 batteries. They charge to 100% SOC in a fraction of the time when paired with a good inverter/charger or a high end progressive charger, and accept full solar charge amperage at any SOC. And their weight is less than 1/2 of FLA. That’s huge for TT owners. Maybe not as much an issue for a Sunstar. Not the least expensive option, but by far the best option.