Community Forums

whiterhino · 08-07-2017, 09:06 PM

I've started reading multiple threads and get confused with terms that I don't understand. So, if I can ask this in laymen's terms and get laymen answers back, I'd really appreciate it.

We have always had dual power fridges in our RV's. We are looking at making a change and several units we like have residential fridges in them, and we don't really trust the knowledge of salesmen. We boondock for 2-3 days at a time and don't know how long a residential fridge will last on battery/solar power. NOTE: I do not know the amp draw of the residential fridge's listed. So we need to do a basic SWAG here.

Is it feasible to run 100% on solar power? If so, at what investment? Or is a 50/50 option practical?
Can I expect to not drain my battery overnight? (assuming (1) 12v battery)
How much run time can I expect to need from my genny to recharge? (my experience with my motorhome is that the chassis alternator charges way faster than the genny)
Also, if the RV is wired to have a 12v feed from the truck, will it sufficiently power the inverter while driving?

I struggled with putting this in the GREEN section or the appliance section. Decided I might get better help here.

Thanks in advance,
Jim

BFlinn181 · 08-07-2017, 09:24 PM

A lot would depend on the number and quality of your house batteries. Another variable is how big a solar array do you have planned? I don't understand how a generator would take longer to charge batteries than a truck alternator.

dandrhill · 08-07-2017, 10:22 PM

We replaced our Norcold with a Whirlpool residential fridge about a year ago. In layman's terms, we also installed enough batteries to run the Whirlpool for about 2 days without damaging the batteries and enough solar panels to recharge the batteries in about a day. Cost for the solar system was about $900 for the panels, $500 for the charge controller, and about $400 for cables, mounts, and other bits and pieces. I did the install myself so no labor cost included.

There are lots of variables in providing answers for your specific use. My objective was to run just the refer off the batteries and charge those batteries with solar so I could leave the coach unplugged in a parking lot for several days and not need to turn off the refrigerator. A happy side effect is that we are usually able to boondock several days without running the genny.

Most likely you will need more than 1 battery. In my case there are 4 12v deep cycle batteries with a total of about 500amp hours of capacity. Also realize that the solar panels need to be in direct sunlight. Shade on the panels drastically reduces the amount of electricity being generated so if you usually boondock under trees beside the lake, you probably won't generate enough to keep the batteries charged.

Your question about how quickly the batteries charge using the generator is really a question about how big is the battery charger in your rig. The generator usually doesn't charge the batteries directly, it provides power to the same battery charger that is used when you connect to shore power at home or in a campground. As a result, your batteries will take the same amount of time to charge when running the generator that it takes to charge when connected to shore power.

Your observation that the engine alternator charges faster than the generator is likely correct. Motorhomes often have very large alternators to meet all the electricity demands when traveling down the road and make sure the batteries are fully charged when you arrive at the campground. Unless it has a large combined inverter/charger, it probably has a simple 12v converter (the same one used when on shore power) that is pretty slow charging the batteries.

BFlinn181 · 08-07-2017, 10:33 PM

The engine alternator will charge faster when the RV is moving, but at idle while boondocking I don't think it will do the job. Adding a bigger charger could speed up the time to bring batteries up and reduce generator time, unless you also want the generator to power A/C units and other large amp items.

dandrhill · 08-07-2017, 10:35 PM

Just a couple of other thoughts. If you are considering a new rig that has a factory installed residential fridge it probably has upgraded batteries and charging capacity. I have seen units that even had a battery bank and inverter/charger dedicated just to the refrigerator.

Also, for lots of reasons, I doubt if the 12V charge line in a regular 7 pin RV connection will keep up with the demand from the inverter. I do know people with residential refrigerators who simply turn it off when traveling. These things are very well insulated and will stay cold all day if you don't open it.

whiterhino · 08-08-2017, 04:26 AM

Thanks for the quick responses. I really appreciate the mature and polite responses. I've been on some forums where the newbie with dumb questions gets lambasted.

A couple more items as I currently see it. Yes, my Ford alternator did a good job of charging my two 6v house batteries. 20 - 30 minutes of idling twice a day usually does a good job to run the current setup with the propane fridge and ancillary items. If it's really cold and the furnaces run a lot, it may be different. On the other hand, the genny would power a trickle charger and 30 minutes of run time wouldn't do much for the batteries. But that's behind us since the motorhome sold last night.

Our campsite in northern Michigan is mostly shaded. It may be that I will need the panels on a portable tripod, but that adds more claptrap to store, setup and tear down. Not sure how that will play out.

Now that I have some comfort level in the possibility of this working, I need to find out what the details are of the unit that my wife has fallen in love with.

After all, happy wife = happy life.

Updates to follow.
Jim

Winemaker2 · 08-08-2017, 05:30 AM

Freeze a few jugs of water while hooked up and place in fridge while traveling to help reduce the run time & load.

computerguy · 08-08-2017, 05:56 AM

Quote:

Originally Posted by whiterhino

I've started reading multiple threads and get confused with terms that I don't understand. So, if I can ask this in laymen's terms and get laymen answers back, I'd really appreciate it.

We have always had dual power fridges in our RV's. We are looking at making a change and several units we like have residential fridges in them, and we don't really trust the knowledge of salesmen. We boondock for 2-3 days at a time and don't know how long a residential fridge will last on battery/solar power. NOTE: I do not know the amp draw of the residential fridge's listed. So we need to do a basic SWAG here.

Is it feasible to run 100% on solar power? If so, at what investment? Or is a 50/50 option practical?
Can I expect to not drain my battery overnight? (assuming (1) 12v battery)
How much run time can I expect to need from my genny to recharge? (my experience with my motorhome is that the chassis alternator charges way faster than the genny)
Also, if the RV is wired to have a 12v feed from the truck, will it sufficiently power the inverter while driving?

I struggled with putting this in the GREEN section or the appliance section. Decided I might get better help here.

Thanks in advance,
Jim

Don't trust salesmen is correct. EVER. If their lips are moving they are not telling you the truth.
Think of batteries as a bucket of water. If you need water, you can only take so much out until it is gone.
1 x 12v battery Flooded Lead Acid (FLA) will not last long when using it on an inverter that will power your residential refer.
6v FLA deep cycle batteries are better. Basically they have more lead and will perform better today and over the long term.
Not knowing any specs on the battery or the residential refer I am guessing 4 hours will be the life (1 x 12v) until you need to be charging again.
As an example I had 4 x 6v FLA batteries in my motorhome before I upgraded. It would handle overnight but by 8AM it needed to be charged.
Genny to recharge regular FLA batteries is not very efficient. It doesn't only depend on the genny but also the charger (how many amps it is). Also, FLA batteries are not charged efficiently (lots of loss to heat). When you get to about 80-90% charge they don't allow much charge to go in so it slows the process tremendously. FLA needs to be fully charged regularly to have any sort of life to them. Run time will directly depend on the battery and charger. I can't even guesstimate here. To do it properly though you are talking hours not minutes. If you don't charge the batts properly they WILL die prematurely.
Sounds like you will be using a truck to tow a trailer. Not going into the details here but it would work if wired correctly. Correctly is the operative word here. You can't expect a 16 ga wire to power your rv and charge your batteries from the truck alternator. The distance and amperage is just too much.
Tried to simplify it for you. But reality is there is no simple answer. One needs to know specifics about all the items to provide a real answer.
It is possible to run 100% on solar. It is not a cheap route though. To properly answer the question a lot more information is needed as there is no one size fits all.

whiterhino · 08-08-2017, 07:09 AM

Quote:

Originally Posted by computerguy

Don't trust salesmen is correct. EVER. If their lips are moving they are not telling you the truth.
Think of batteries as a bucket of water. If you need water, you can only take so much out until it is gone.
1 x 12v battery Flooded Lead Acid (FLA) will not last long when using it on an inverter that will power your residential refer.
6v FLA deep cycle batteries are better. Basically they have more lead and will perform better today and over the long term.
Not knowing any specs on the battery or the residential refer I am guessing 4 hours will be the life (1 x 12v) until you need to be charging again.
As an example I had 4 x 6v FLA batteries in my motorhome before I upgraded. It would handle overnight but by 8AM it needed to be charged.
Genny to recharge regular FLA batteries is not very efficient. It doesn't only depend on the genny but also the charger (how many amps it is). Also, FLA batteries are not charged efficiently (lots of loss to heat). When you get to about 80-90% charge they don't allow much charge to go in so it slows the process tremendously. FLA needs to be fully charged regularly to have any sort of life to them. Run time will directly depend on the battery and charger. I can't even guesstimate here. To do it properly though you are talking hours not minutes. If you don't charge the batts properly they WILL die prematurely.
Sounds like you will be using a truck to tow a trailer. Not going into the details here but it would work if wired correctly. Correctly is the operative word here. You can't expect a 16 ga wire to power your rv and charge your batteries from the truck alternator. The distance and amperage is just too much.
Tried to simplify it for you. But reality is there is no simple answer. One needs to know specifics about all the items to provide a real answer.
It is possible to run 100% on solar. It is not a cheap route though. To properly answer the question a lot more information is needed as there is no one size fits all.

Thanks for the input. I understand that there is not enough information to get SPECIFIC answers but you guys are giving me what I need to know at this point.................. can I rustic camp with a residential fridge or can't I?

The answer is yes, with some limitations or some investment. That's OK, at least it gets me going in the right direction. Yes, I will be towing a 5th wheel with a GM 350 Duramax .

Now that I know it is feasible, it's time for me to find out what the specifics of the RV are. We have an appointment at the RV store at noon.

garbonz · 08-08-2017, 07:50 AM

Sometimes you can find a mobile RV tech that can be paid an hours or so to help you design a system that works for you.

The best route to go IMO is to use a generator in the morning with a GOOD charger (like a prog ind high amp converter) to restore most of the charge used during the night and then a medium sized solar system to top up the batteries during the day and run the frig. # of batteries and panels will depend on the details of your situation.

harryn · 08-12-2017, 09:44 PM

Quote:

Originally Posted by garbonz

Sometimes you can find a mobile RV tech that can be paid an hours or so to help you design a system that works for you.

The best route to go IMO is to use a generator in the morning with a GOOD charger (like a prog ind high amp converter) to restore most of the charge used during the night and then a medium sized solar system to top up the batteries during the day and run the frig. # of batteries and panels will depend on the details of your situation.

Very good advice.

YC1 · 08-13-2017, 05:29 PM

Solar is great but you need to be in the sun of course. In many cases getting in the shade is really important.

I carried a 1000 watt Honda gas generator for several years to top things off but a 2000 watt would have been better. That is another story to explain IF the generator would handle the load.

Our onboard 8000 watt diesel generator was fine when it was really hot and we wanted to run the AC's. The little generator could be set behind a tree and an extension cord run so the noise level was extremely low.

I too suspect any rv using a residential refer will have more than one battery or a very small refer.

nothermark · 08-13-2017, 06:10 PM

When residentials hit the C market we found out through other peoples problems that it took 2 batteries to make it through the night. One for the coach and one for the refer. Some folks just shut the refrigerator off as a way to manage. That is roughly 8 hours.

It seemed then that the designers were going to depend on the Automatic Generator Start to pick up the slack. If one programmed quiet hours the battery died. If the generator started @ 2 AM a lot of folks were not happy. Two batteries more or less solved the problem. That will give you a fairly coarse idea of a minimum.

You need to weigh your unit against that of people giving you advice. Anyone running a Ford chassis will have battery space problems. The 45 ft DP folks have a lot more roof space for solar and bay space for batteries. There is also the balance of how much you want to spend. We have folks ranging from shoestring to whatever it costs is OK if I get what I want.

whiterhino · 08-14-2017, 05:14 AM

Thanks for all the advice everyone. Well, our shopping journey took us a different direction. We found a pre-owned 5'er that fits our bill with a dual power residential size fridge, OB Genny and dual 6v batteries. Even though the fridge will run on propane, I'm going to take the advice here and move forward with a solar setup to help maintain the batteries.