Solar and Walmart Campground

[uncle_bob]

Originally Posted by stevejones

Our 2019 Globetrotter only had two 80AH AGM batteries (not 100AH). At 50% max discharge for AGM that is only 80AH usable. The OP probably has the same batteries.

I was initially a fan of the factory solar install but now feel it is more of a marketing thing. It will help charge your batteries but I don't think it has enough capacity to fully charge them if you've discharged them down to 50%. I guess if you keep your power usage low and your trailer is in direct sunlight, it can maintain your batteries enough to provide the basics for the 12V systems. But I wouldn't use the inverter much. Don't run your furnace or fantastic fan all night. And constantly check your battery voltage.

Steve

Hi

The factory solar *will* indeed fully charge the stock (or any other) batteries. Regardless of the type of charge system, lead acid's take a *long* time to charge. That's just how they work. There is no magic way around that.

The factory solar will hit nearly 200W of output with a Victron controller on it and the stock wiring. With the stock wire and two more factory panels you can hit nearly 400W. The panels are fine, the stock controller is ok, but not the best.

With the stock controller the two panels can deliver just over 12A at 13V to the batteries on a sunny day. My guess is that is where the "160W" number comes from.

Again, the problem comes from the assumption that if you have 10A available for four hours that will take your 80AH batteries from 50% to 100%. Instead what happens with any charger is that you go from 50% to 80% at the 10A rate (in a bit under 3 hours). It then will take *much* longer (at lower current) to bring them up to full charge.

======

First step is a power budget - how much are you going to use in a day? That could be 100AH. It could be something very different. It is a number you manage with your usage. If you go with "I don't care" that's not a budget.

Next step is to work out what part of the country you will be in and when. If you are in the northeast, you might only get 5 hours of peak solar equivalent on a good day. If you are in the southwest, you could do much better.

If you assume 13V and 100AH, you will need 1.3KWH into your system a day. At the 5 hour number, that would be 260W of panels at 100% efficiency and all the power being used as it becomes available.

That works on a perfect day in a perfect setting at 100% effeciency . On a cloudy rainy day in the shade, you might get 100WH. If you want to be able to handle four days of rain, get 400AH of batteries.

If you still want to camp when you only have sun every few days, double or triple the amount of solar. If you want to charge the batteries without long charge times, go with lithium instead of lead acid.

So no, it's not simple / easy / you can ignore it sort of stuff. You can *easily* get into the 150AH a day range without much effort. ( = 80AH batteries dead in < 12 hours). That's why the first step is a good battery monitor.

Bob

[jcanavera]

I guess I just don't get the Walmart thing. I guess if you drive till you're tired then it may be your only resolution. I like to plan ahead my stops. Typically I determine how many miles I plan to drive on a day and then check out the campgrounds within that driving distance. Never has failed me to find a suitable campground stop, and on locales that are busy, I make reservations ahead.

Keep in mind that some WalMarts have local jurisdictions that do not allow camping overnight. The local WalMart by me has signs posted. Secondly and more concerning is the locales where some of these WalMarts are located. While I don't believe we've had anyone on the forum who has reported difficulties, I personally would not stop there, especially being familiar with some of the WalMarts in my metro area. Seems like the bad guys are getting more emboldened carrying their own weapons. Even if you are packing heat, the last thing I would like to see is a gun battle. No one wins there. And those aluminum walls don't give you much protection. To those who say Walmart has camera's and good security, I had a friend whose car was damaged in the parking lot. When he asked management about getting a picture, he was told that the camera's range was close to the entry and not designed to reach the far reaches of the lot (where usually you are asked to park).

Jack

[AlinCal]

Add me to the group that does not get it.
I understand there are many ways to Airstream but calling a Walmart lot a "campground" is past me. I can see in a pinch where you might have no other choice, but if you have the energy to sit inside and consume electricity watching tv while in a Walmart lot I would rather keep driving.

[AirMiles]

My comments on this thread don't have anything to do with Walmart. My comments, and most others, are to help a fellow forum member determine how much power can be used when parked in a location without shore power with a solar powered Airstream. Sure, Walmart's don't have shore power, but neither do many of the most beautiful places where we like to stay in our Airstream including most National Forest Campgrounds, National Park Campgrounds, County Park Campgrounds, BLM land/campgrounds . . . Very little commentary on this thread is about Walmart except from those who want to drag this thread into the mud. Let's save our mud throwing for when we get stuck at a great boondocking location in our solar powered Airstreams.

Notice there are no power cords in this picture from the non-electric Jeff Busby Campground on the Natchez Trace Parkway:

[featherbedder]

Originally Posted by jcanavera

I guess I just don't get the Walmart thing. I guess if you drive till you're tired then it may be your only resolution. I like to plan ahead my stops. Typically I determine how many miles I plan to drive on a day and then check out the campgrounds within that driving distance. Never has failed me to find a suitable campground stop, and on locales that are busy, I make reservations ahead.

Keep in mind that some WalMarts have local jurisdictions that do not allow camping overnight. The local WalMart by me has signs posted. Secondly and more concerning is the locales where some of these WalMarts are located. While I don't believe we've had anyone on the forum who has reported difficulties, I personally would not stop there, especially being familiar with some of the WalMarts in my metro area. Seems like the bad guys are getting more emboldened carrying their own weapons. Even if you are packing heat, the last thing I would like to see is a gun battle. No one wins there. And those aluminum walls don't give you much protection. To those who say Walmart has camera's and good security, I had a friend whose car was damaged in the parking lot. When he asked management about getting a picture, he was told that the camera's range was close to the entry and not designed to reach the far reaches of the lot (where usually you are asked to park).

Jack

Not only bad guys w/guns at walmart. A off duty in plain clothes dep.sheriff pulled a weapon on mo. pregnant woman for no valid reason except he was upset because her husband pushed him away from her lady is white husb. black internal investigation results county board approved $20,000 for esteem of dept?? Couple filed fed lawsuit still don't no results of suit. Our local walmart is not in bad area, now they have posted signs no over nite parking, as far as me I would not even think of staying over nite at wally world except extreme emergency. This Elected sheriff was defeated last election, I won't say any further about his term in office but many ?

[AirMiles]

Here is another great example of a non-electric camping location for our solar powered Airstreams. It’s at Alabama Hills BLM with Mt. Whitney in the background.

[featherbedder]

Originally Posted by featherbedder

Not only bad guys w/guns at walmart. A off duty in plain clothes dep.sheriff pulled a weapon on mo. pregnant woman for no valid reason except he was upset because her husband pushed him away from her lady is white husb. black internal investigation results county board approved $20,000 for esteem of dept?? Couple filed fed lawsuit still don't no results of suit. Our local walmart is not in bad area, now they have posted signs no over nite parking, as far as me I would not even think of staying over nite at wally world except extreme emergency. This Elected sheriff was defeated last election, I won't say any further about his term in office but many ?

The lady was 9mo. understand why hubby upset.

[AlinCal]

Here's a pretty good reason to not camp at Walmart..http://www.airforums.com/forums/f415...st-193921.html

[stevejones]

Originally Posted by uncle_bob

With the stock controller the two panels can deliver just over 12A at 13V to the batteries on a sunny day. My guess is that is where the "160W" number comes from.

The 160W number comes from there being two 80 watt panels.

Steve

[uncle_bob]

Originally Posted by stevejones

The 160W number comes from there being two 80 watt panels.

Steve

Hi

If they are 80W panels then why do two of then put out 200W and 4 of them put out 400W? Since you also get a lot of posts about "my 100W panels only put out 90W", it's not at all clear the 80W units are any different than the ones we call 100W.

Bob

[uncle_bob]

Originally Posted by AirMiles

.....

Notice there are no power cords in this picture from the non-electric Jeff Busby Campground on the Natchez Trace Parkway:

Hi

Been there and done that at that campground and many similar ones. Solar is not a big help while you are parked there. I have empirical data .... That kind of site is what pushed us to the 400A battery bank.

For solar to do well for you, you need to be out in the full blazing sun. No shade, no clouds all day long. It does not do a giant blast all at once, so hours and hours of sun are what matter.

In most of the east (other than the beach I'm on right now) the campsites are likely to be shaded. Parking lots (Walmart or Harvest Hosts or Cracker Barrel or ...) may be less shaded. Counting on solar without a lot of info on the site can be risky.

Again, the only *practical* way to do this is to put in a good battery monitor. Without something like a BMV-712 there is no way to keep up with what's going on. Trying to do it by "this pulls that and it's been a while" simply is not accurate enough. Voltages, even with temperature charts (which nobody uses), are not good enough to tell you when you are fully charged or when you should stop using the battery.

It is amazingly easy to damage a lead acid battery by over discharge. It is probably the number one thing people run into doing this stuff for the first time. I would bet there are over a thousand posts here from people who trashed their batteries this way.

Bob

[stevejones]

Originally Posted by uncle_bob

Hi

If they are 80W panels then why do two of then put out 200W and 4 of them put out 400W? Since you also get a lot of posts about "my 100W panels only put out 90W", it's not at all clear the 80W units are any different than the ones we call 100W.

Bob

If someone has four panels, they aren't the factory installed panels since AS only puts up two. In this screen shot below from the AS parts list, they are listed as 80 watt panels. Perhaps they are capable of more, but if so I would think AS would market them as such.

[uncle_bob]

Originally Posted by stevejones

If someone has four panels, they aren't the factory installed panels since AS only puts up two. In this screen shot below from the AS parts list, they are listed as 80 watt panels. Perhaps they are capable of more, but if so I would think AS would market them as such.

Hi

Well, don't tell the guys at Jackson Center that put them on top of my Classic about three weeks back about that .....

Indeed there *was* a bit of conversation about "we only do three" vs "I want six". Four was a compromise.

Bob