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Old 04-26-2021, 07:14 AM   #1
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Refrigerator and Solar Power

2020 View D:
Greetings. Our View has 200 watts of solar and non lithium batteries. We will fully charge the batteries via shore power prior to our departure to the Florida Keys and not have our toad.

We plan on disconnecting from our site and spending the day snorkeling at Bahia Honda Park. We are wondering if the batteries will be able to effectively power the refrigerator for + 8 hours until we arrive back at the site later in the afternoon? Thankfully we are planning on upgrading to 510 solar watts and lithium in July.

I appreciate your replies,
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Old 04-26-2021, 07:29 AM   #2
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It might. The 200W of solar, in good sun, should give you around 8A-10A of replenishing charge to the batteries, which power the fridge. However, if the inside of the coach heats up to 80F-90F the fridge may struggle to keep things cool, which means compressor on more often, and the result is faster draw down on your batteries. It's a catch 22, if you park in the shade the inside of the coach might stay cool enough to reduce fridge compressor on time, but that reduces sun time to the panels. If you park in good sun, the coach may heat up inside drawing more power overall. So, it might.
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Old 04-26-2021, 07:39 AM   #3
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Lots of variables there. Too many to provide a definitive answer. I’ve found that you can only learn the RV’s capabilities by actual experience. It “should” work out fine but you’ll only really know after the fact.
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Old 04-26-2021, 07:39 AM   #4
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Lots of variables there. Too many to provide a definitive answer. I’ve found that you can only learn the RV’s capabilities by actual experience. It “should” work out fine but you’ll only really know after the fact.
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Old 04-26-2021, 09:04 AM   #5
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How i think in term of dc-amp-hours

I'll take a crack...

Hedge your bet:

* Do what Winterbagoal said, and park in the shade. (Leave your awning out if it's not windy.)

* If you did a refrigerator conversion and have large air vents... tape them off from the inside so hot air will not get in.

* If you have water or soda in your frig that will act as a cooling source that will help a little, but not much.

MATH


First, it sounds like you don't know your FLA House battery should only be depleted by 50% if you want them to last more than 1 year. So your 200AH is really only good for 100AH.

With batteries in excellent shape, on your first day out you might 100AH of battery storage, but on your next recharge cycle your battery SOC will only be ~90% even though your SOC meter will read 100%.

So you really are working with 40% (90%-50%) of useful battery storage. And 40% of 200AH is 80AH. (That's all... plus the cost to run your generator for 6 hours to recharge them -- offset by how much solar you have.)

A battery will only take so much charge and as it get full the internal resistance increases. I.e., your battery will charge rapidly when is low and slowly when it is above 85% SOC.

The best time to check your battery SOC is between 5AM-6AM, before the sun rises, when all your systems have been turned-off for a while, and your solar cells are not charging.

TIP: Keep thinking in terms of Amp-Hours or just Amps. Why? Because Watts make the numbers bigger and it gets more confusing.

* If you have an AC appliance that takes 1A to run, then think of this as 10A of DC current pulled from you house battery.

==> So a refrigerator that averages 1.5A for 6 hours/day x10 = 90Adc/day
===> And when it's hot outside your refrigerator may run 10 hours, which equates to 150A of DC battery storage/day.

You did not say what size refrigerator you have, but I bet it runs between 1A-1.5A/day on average, which includes a 3x "rush current" to start the compressor.

All this is theory. So you really have to do what CreativePart said, you have to try it and see what works for your set-up!

SOLAR

If you have the Renogy 100W type solar panel then you will get ~4 to 5A/panel (max). So your 200W is only going to contribute an average of 6 hours/day at 10A or 60AH/day. (This which takes into account the intensity of the sun on a clear day; I.e., max power.)

If you have 400W of Solar, MPPT Controller, you will get 20A output. So you have the potential to get 120AH/day, which is just barely enough to keep up with the residential refrigerator I have, but I seldom get that much power out of my solar panel. I think it's more like 80AH-100AH/day based on how much I run my generator.

Summary

Having solar helps, but not by much. And I'm afraid adding 200W to an RV is not more of a selling function vs. a practical solution. ...And then you find out you have to buy a better solar controller, because Winnie put on a cheap one you can't upgrade to 400W.

I have 400W of solar on my 40' roof, but I need 800W.

This is why many are doubling their battery storage by removing their FLA battery bank and buying LiFeO4 batteries.

Upgrade Option For Us Older RVs

I have a 2004 Itasca Horizon 40AD and it comes with 420AH of battery storage, which is good for 210AH if we follow the 50% rule. I like my FLA batteries if you call cheap $500 to replace them.

In my RV I have a Dimensions 2000W Inverter Charger, which is a good LOW FREQUENCY "quasi-sine" inverter I don't want to get rid of because a new one will cost me a lot of money to replace.

However, It would be nice to have 200W of LiFeO4. And I'm thinking of building a separate power grid, with a separate Pure Sine High Frequency Inverter, and separate charger by Victron so I don't need to mount a panel display inside my coach, because I can use my phone to monitor the charging of these LiFeO4 batteries, and the only thing it will run is my refrigerator and maybe one other plug for my TV and computer. ...And when I find shore power I will use a separate 20A extension cord.

This approach will allow me to hide the LiFeO4 batteries in the center of my basement, out of sight and out of mind, and I think this upgrade will run under $2,000.

So what is stopping me? Answer: I like to vacation where I need air conditioning and where you need to run your generator you don't care about how may AH of battery storage you have or how much it costs to buy those expensive LiFeO4 batteries. ...Because you air conditioner needs 10A-20A of AC power to run and no battery bank will do that for very long!

So is spending all the money on LiFeO4 worth it? ...To some it is.

One Last Point People Forget To Talk About

Your 12V system will use 50-80A of DC current per day to run all the 12V stuff you have in your RV, like lights, steps, stereo, etc. So don't forget to add this to your daily power usage and you will see it's real hard for me to boondock more than a day with my residential refrigerator, 420AH of FLA batteries, and 400W of solar on my roof.

...And this is just another reason why people almost always buy a bigger RV, among other reasons.

==> IMO, if you only have room for two house batteries, the only thing you can do to increase your AH of battery storage is to remove your FLA batteries and replace them with two LiFeO4 batteries to double your battery storage capacity... and then if you have room for 400W of solar on your roof that helps.
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Old 04-26-2021, 01:48 PM   #6
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Worst case you may have to run the generator every other day to keep the batteries above 50% SOC. Of course if you plan to replace the factory battereries in July then drawing them down to 30% SOC should not be a concern.

With our new 2021 Navion I had the fridge and freezer at 36 degrees and 10 degrees respecdively and with no other main draws on the batteries and with the doors left shut and temperatures in the RV ranging from 40 degrees at night to 60 degrees during the day, after 48 hours the two lead acid batteries were at 50% SOC.

The problem with the lead acid in part is that they take 4 times as long to recharge and so the panels that may be providing a high charge for 4-5 hours a day are not particularly effective. I found that when the lead acid batteries were are 50% SOC it took nearly 4 hours of generator run time to get them back to 100% as compared to less than an hour with the lithium batteries.
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Old 04-26-2021, 02:39 PM   #7
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Sure , it will be OK . The refrig will be cold and even if the batteries only last 4 or 5 hours nothing will spoil in that time . Many people shut their refrigs down anytime they move .
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Old 04-26-2021, 05:12 PM   #8
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Thanks to all for the input. We will cool all items down and monitor all the variables the first day. That will help us determine the next day’s strategy.We will definitely use a Yeti to keep our drinks cold!

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Old 04-27-2021, 08:59 AM   #9
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And think about running your genset to and from your snorkeling site. Every little bit helps. Running a genset while driving isn't an issue.

This will allow you to also run your house A/C while traveling.
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Old 04-29-2021, 11:37 AM   #10
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One thing about the Onan is that the manufacturer recommends a 200 hour break-in and to run the generator under 50% load.
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Old 04-29-2021, 03:49 PM   #11
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Another thing to do is freeze some water bottles on the way and put some in the fridge and leave the rest in the freezer. Repeat for the next day, putting them in the freezer and split again the next day. This well easy the load on the fridge and batteries
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Old 05-02-2021, 04:34 PM   #12
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I don’t know about the View, but my Horizon is all electric with a residential fridge.
Winnie told me I could go 72 hours without plugging in if I just use the fridge parked.
I do know it was ok to spend the night at the Iowa 80 Truck stop back last September.
But I just stopped to sleep in the Rv parking area. Didn’t run anything but the fridge. Got up at about 5:30 to take off east.
I didn’t run the generator at all.
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Old 05-02-2021, 06:20 PM   #13
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I'm with creativepart

I agree with creativepart - too many variables and not knowing the true condition of your stock coach batteries, no one can really tell you.

One thing you can do is a trial run. I'm not sure if your current location is anything like the weather in the Keys, but still, you can still get a decent idea if your batteries will last 4, 6, or 8 hours or more before they reach critical level of 12.06 volts.

There are other "adjustments" that you can do; keep the refrigerator at a lower number ( 2 or 3). The refrigerator won't work as much. Keep the inside of the coach as cool as possible. The warmer the interior, the harder the refrigerator and compressor have to work so parking in the shade as recommended by others and venting the coach via windows if the weather allows.

Lastly, I truly recommend a Victron BMV. The Victron works like the fuel gauge for your batteries. The Victron will let you know how much has been taken from the batteries and what has been put back in (solar, alternator or converter charger). Regardless of the age of your batteries, the Victron provides information on the SOC. It is an instrument worth having regardless of the battery chemistry if you routinely depend on the coach batteries.

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Old 05-02-2021, 06:51 PM   #14
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Quote:
Originally Posted by butch50 View Post
Another thing to do is freeze some water bottles on the way and put some in the fridge and leave the rest in the freezer. Repeat for the next day, putting them in the freezer and split again the next day. This well easy the load on the fridge and batteries
I'm not the original poster but that's a great idea that I never thought of. In fact now you got me thinking about buying a couple of large Blue Ice packs.
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Old 05-02-2021, 07:43 PM   #15
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Your solar charging watts are pretty irrelevant - when what you really need for RVing is good house battery capacity. You did not specify what that is, so hard to answer your questions as that is the data we really need.

Let me offer this - we live as full timers in a larger Class A. Upgraded our house electrical system to 400 Ah of Lithium batteries 2 summers ago after fighting for years with lead-acid batteries which just did not hold up very well. Those took forever to charge, I could only use 1/2 their stated capacity, and they seemed to drop voltage very quickly - which then shut off the inverter due to low voltage. So upgrading from 480 Ah of SLA batteries (240Ah usable) to 400Ah of Lithium (~360 AH usable), plus saved about 160 lbs in battery weight - now gives me a much more usable battery system which runs at higher voltage and charges so much faster.

We also have 600 watts solar - which works great when parked in full, direct sunlight. But that's the problem - Don't want to be parked in direct sunlight in the summer as it can get too hot in the RV. Would prefer to park under shade tress - but then no solar. Solar also pretty useless on cloudy/rainy days. We rarely stay at RV parks any more, so rarely have hookups. So we run the generator when we have to, and I installed a DC-DC charger to enable charging off the engine alternator while driving.

Bottom line in all this is - what you really need for great RVing is a strong house battery system. Install as many batteries as you can, and make them Lithium if at all possible. Solar is nice to have - but it is unreliable as a charging source.
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Old 05-02-2021, 07:59 PM   #16
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Originally Posted by Elkman View Post
One thing about the Onan is that the manufacturer recommends a 200 hour break-in and to run the generator under 50% load.
I think you have a typo in your post...
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Old 05-02-2021, 10:55 PM   #17
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The manual for my 2020 Onan diesel generator states not to exceed 70% of rated power during the first 20 hours of operation.Either the convection oven or the AC alone would provide a 35-50 percent load if the fridge was not also operating.



Onan recommends "exercising" the generator once a month by running it for 2 hours with a 1/2 rated power load. Two hours seems excessive. The standby generator at my house runs every two weeks for a period of 10 minutes. A diesel engine usually reaches it operating temperature after 30 minutes unless the ambient temperature is below freezing.
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Old 05-03-2021, 10:24 AM   #18
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imnprsd gave us a very nice summary with great information. One design rule which cannot be over-emphasized is the battery internal resistance during charging. We can charge from 50%-85% fairly quickly and in a nearly linear fashion. While it is possible to design solar charging to accommodate large discharges, it really is not the best use of solar. Solar is perfect for that 85-100% slow absorption/float charging.

Running the genset for 90 minutes every morning, while dealing with large loads (hot water, coffee maker, etc) will allow your charger to to replenish a large portion of the overnight fridge draw. Then your solar can top things off and offset the daytime loads.
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Old 05-03-2021, 11:56 AM   #19
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With the OP having the lead acid batteries and running the DC fridge all they can do is monitor the battery status and run the generator as needed to get the batteries in the 85% SOC range.

Power consumption with the fridge can be minimized by not using the freezer and setting it at 40 degrees and the by having the refrigerator section at 45 degrees. Food will have a shorter life but not a problem if the fridge is not overstocked.

Adding one or two 1-gallon or even 1/2 gallon plastic containers filled with water that is pre-chilled at home or with the motorhome plugged into shore power will help minimize the run time for the fridge as when the door is opened all the cold air flows out and is replaced with very warm air from inside the RV. Or one can place frozen food in the fridge and let it thaw which will also keep it cooler.

Bottomline is that the new Winnebago Class C motorhomes are designed for people who will be plugged into shorepower while staying at an RV campground. They are not designed for people who want to dry camp for more than a couple of days. I would expect that the product managers have done surveys and believe that very few people dry camp and they are probably correct, at least in the long run.
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Old 05-03-2021, 12:05 PM   #20
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Surface Charge - How To Get Rid Of It So You Can Determine SOC

Thanks MadMaxWinnie.

The other day I pulled over to spend the night at a rest stop, and by habit I pushed my Battery Display Switch.

Naturally, there was a lot of "surface charge" and the display indicated 13.1V, which is impossible, because no 12V battery or 4x6V battery bank can have more than 12.8V-12.9V at rest.

Then I pulled some leftovers out of the refrigerator to heat in the micro wave when I got an idea. What if I run the microwave for 30 seconds? ...And then can I check my battery voltage?

Sure enough it worked! ...And the voltage never climbed.

So no you know you don't have to wait until morning if you want to check your SOC!

CHARGING

It's easier to read the 12V voltage of a battery than it is to take an hydrometer and measure the electrolyte inside each cell. So that's what most of us do.

Each battery cell is ~2.15v. So a 12V battery will have 6 cells connected in series just like you do when you load a flashlight up with batteries (in series); and then you add the voltage of the batteries together to get the total voltage.

In this case 2.15 x 6 cells = 12.9V, and anything above that is called "surface charge."

My point is that if you could measure each battery cell then you would get a graph like the one below that emphasizes MadMaxWinnie's points: Batteries will charge rapidly at first and then take a long time to charge the last 10%.

==> And old batteries, that are sulfated, will have so much internal resistance you will never be able to recharge them back to 100%.

So that 420AH bank is now only good for 280AH, and as it ages it will drop to around 250AH. This has to do with the number of charge cycles and for me other factors, like:

* Do you leave your batteries in freezing cold temperatures WITHOUT a battery maintainer?

* Are you always changing your batteries from your alternator?

* How good is your Solar Charge Controller, which is also a smart battery charger?

* Are you equalizing your batteries often enough, and not too often, and are you completing the equalization phase?

In general, most owners, especially me, do NOT treat their batteries very well. This is why I bought a 17A Victron Supplemental Charger/Battery Maintainer; and why I will be looking into a smart DC-DC converter in place of my KeyLine VSR, because when I take my RV out for 3-4 months/year I am always driving, and that means I am not reconditioning my batteries like I should be doing.

MICROWAVE TEST - USE IT TO CONVIRM IT IS TIME TO REPLACE YOUR HOUSE BATTERIES.

Last summer my 420AH died. These batteries were only 1.5 years old and over the last 2 months of using them, my SOC over-night would drop rapidly, and my inverter would shut down before I woke-up in the morning.

My batteries load tested good at the Interstate Battery Store; and when I measured the electrolyte all was normal. So, what then?

I refused to think my batteries were bad, but they were!

...Then I started troubleshooting my inverter thinking that old Dimensions is going to be recommissioned as a lead anchor and I'm finally going to get me a newer PSW inverter.

... Turns out that was just foolish talk, and after I researched the new High Frequency Inverters vs. the cost for a good Low Frequency Inverter, I decided to replace all 4 of my 6V golf cart batteries for $400 at Costco.

(Not to mention there are a lot of junky PSW inverters you should not buy for your RV, but that's a different subject.)

...So, as I said, I bought 4 new 6V batteries and all was back to normal.

These points listed above are best summed up in the charts below.

TAKEAWAYS

* Specific gravity of SOC voltage checks cannot be used to determine a battery's capacity."

* The best battery test to know if your house batteries are SULFATED can be preformed by doing the Microwave Test listed above.

* Always replenish your distilled water in the battery bank. (I use a DEF funnel for all my fluids. So then next time you are at a service station you should check the trash. I have 3. One for my oil, one for me diesel additives, and one for my distilled water jug, which I also use for my windshield washer reservoir.

* Be sure your inverter temperature probe is connected to the NEG battery post and not the POS post.

* Clean your 300A fuse to your inverter after 10 years of service. It's normally mounted next to the batteries, on the side wall.

* Make a conscience decision to properly maintain your batteries in storage; or "BEAT THE SH*T OUT OF THEM AND DEAL WITH YOUR BATTERY WARRANTY EVERY YEAR."

Note: One problem with this warranty approach is that when you encounter a short: A) You might be camping and now your inverter will not work; and B) You only short one battery. ...It's hard to say?

==> And you can't throw a new battery in with old batteries and expect good results for very long! So I try my best to take care of mine since I have 4 house batteries to deal with.

==> And I don't know about you, but dealing with 240 lbs of batteries is a real PITA.

==> Best solution, go with lighter LiFeO4 batteries... when the price comes down some more! (Maybe this year!)

==> However, when I had a gasser Class A with only 1 or 2 12V-house batteries, then yes... I would "BEAT THE SH*T OUT OF THEM" and take my chances. Plus the 12V batteries are not as durable as the 6V golf cart batteries, so they say.

==> Batteries also have impedance characteristics and if you like getting nerdy you can check out this website to find everything you really don't need to know about battery physics: https://batteryuniversity.com/index....surface_charge
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