3 Batteries?

[jauguston]

To answer the second part of your question in a general way. Providing you have sufficient AC power available and you do with your 7500 Onan the time it will take to recharge will depend on the output capacity of your converter. I have the same generator and a Magnum Energy ME2012 inverter/converter that will charge my 6-6v AGM house batteries at a starting rate in the morning after a normal evening and night C-PAP use of just over 100a. It is a 100a rated converter. I don't have any fancy meters to track anything but volts and amps. My C-PAP with a humidifier and a heated hose draws about 6a at 12v.

Jim

[Groovy]

Davdeb1 - I'm hardly an expert. We've just lived with this stuff for a long time so we have a real world perspective.

The weird thing about 6v batteries is they are given an Ah rating for when they are placed in series as 12v pairs. So two of them gives you 220, four give you 440 and eight will give you 880.

There is a fabulous discussion of batteries by battery experts here.

You can get very caught up in the details and math with these things, but the overall question is still simply -- am I using more power every day than I can reasonably get back into my batteries? Do my batteries make it into "Float" mode at least every 2nd or 3rd day? ("Float" is that trickle charge state the controller goes into when the batteries throw up their hands and yell, "We're full!!!").

Whether you divide by 10 or 12 for the inefficiency of an inverter is important theoretically, but we generally deal with things like, "Am I parking near a tree that will partly shade a panel for 3 hours (effectively knocking that panel out of commission for those hours)." Or, in January when the days are short anyways, "Is it going to be cloudy for the next week... ?"

Speaking of real world, it dawned on me last night -- don't you need to run the oxygen concentrator 24/7? If so, then calculating for just 8 sleeping hours isn't quite accurate...

As for the cost of the system, a 1000 watt system is not necessarily all that bad. If you went 24 volt (which we did on our sailboat), you could get four 240 watt panels for $1200, a charge controller for $550, combiner box/breakers for $150 and cabling/connectors for maybe $400, and 8 6v batteries for $1,200, so it would cost around $3300 if you did it yourself or maybe $5000 if you hired an installer (totally wild guess at an installer's fee).

The freedom you'd gain is priceless. Your system could pay for itself in overnight park fees within a year.

You could always give the folks at Wind and Sun a call and talk to them about your particular needs. We've always found they are more than happy to answer questions and were very helpful to us.

[Davdeb1]

Groovy,
Thanks for your info. I sleep with the big concentrator because it has continuous flow and doesn't have the annoying "pulse" noise that my portable has. The rest of the time I carry around a portable that uses about 5 amps DC. I am very active and mobile, I refuse to just sit at home. That's why we go full time starting in October. We will be doing most of our dry camping during the winter out west. It has been pointed out that I will need to tilt these panels when I set up camp. It is difficult to, climb, bend over, stoop or keep my arms over my head. So checking batteries, climbing up ladders and the such are difficult, in fact exhausting. I can walk, golf, paint, cook, and other things, but if I have to go into the bay, get the hose, go hook it up, that is completely exhausting. The bending a pulling the cord, pushing it in to the outlet when hooking up to shore power is exhausting.

I only tell you this so you know why I will use AGM batteries, and an inverter that will automatically do three stage charging. I am even thinking of getting a auto-start system for the Genny. Is there a solar system that can be installed that will not require tilting in the winter? I have room for 4 batteries so I may just do 4 300 AH batteries and watch my usage of the 300w concentrator. Also, we do use our computers a lot, and watch a lot of TV.

I am assuming that if I have 600AH batteries, and I discharge them 300AH, I will have to charge them at 100 amps at 3 hours to bring them up to full charge. I think this is why you are suggesting a 1000 watt solar system.

I could set up and install this whole system on paper, but physically trying to install everything would not be possible for me. Batteries will be 2400, ms2012 inverter, 1500-2000, and meters, wires etc, will cost a total of about 5000 I figure. I know it will save me campground fees, but this is not about the money. I do have limited resources, whack is why I bought a 2000 Endeavour instead of a new one. The thought of staying in these "trailer park" cookie-cutter RV RESORTS, more than 6-8 days a month is disturbing. I will use these places to fill water, dump tanks, recharge, do laundry and the like, but 20 days a month I want to dry camp and enjoy this lifestyle. This is why I am willing to spend money on batteries and inverters to get to this point. I felt if I had to run the genny 4 hours a day to keep batteries charged, it would be worth it. If I have to run it 8 or more hours a day, then I will have to make solar work.

[jauguston]

Don't let anyone talk you into setting up panels to tilt. Bad idea. Lots of unnecessary complication for minimal gain. Inorder for tilting to work you have to be able to orient your coach to maximize the suns exposure. That will dramatically limit the sites you will be able to use. Then there is climbing up on the roof twice every time you get where you are going. I am a relatively healthy 73 year old and I would NEVER consider panel tilting. If I was going to spend months in one location in the desert maybe. If I had your health issues no way. Rather than tilting add one more panel. The results will be about the same and it won't matter what direction you park and you don't have to get on the roof.

My solar system will put out 40-42a on a sunny day. My panels are flat with a 2" air space under them wired with 4 ga welding cable down to the Blue Sky Solar Boost 3024i controller and on to my 6-6v AGM Fullriver batteries. I have my system wired 12v with 10 ga wire going from each panel to a combiner junction at the refer vent where the 4 ga starts down the refer vent.

Jim

[Davdeb1]

Thanks Jim, I'm glad you told me that. I am now one step closer to going solar. The thought of tilting and untilting them with every move was one thing seriously making me hesitant about going solar. I'm going to have the batteries, inverter, battery meter, and all the other stuff necessary installed. I can spend next winter getting a handle on how many amps I use everyday, then I can have a educated decision on how much solar I need.

I really want to dry camp, but I might find out after 6 months I would prefer to stay in parks. You never know how you will feel about something till you do it. If that were the case, the solar would be a waste

[Groovy]

Davdeb1 - I think you will enjoy the freedom of dry camping, and you are blessed to have the budget to stay in parks when you wish as well.

Jim's got a great setup, and like he said, you sure don't have to tilt the panels. Ours don't tilt. They are flat mounted with 2" underneath also. They follow the roofline (it's a fifth wheel so the roof is not exactly parallel to the ground)..

The difference with tilting is biggest in the winter when the sun rides very low in sky. Look out at noon today and see where the sun is -- it's not very high!

In the open desert in the southwest, folks with tilting panels typically orient them with the long side parallel to the long side of the rig, and then they park so the driver's or passenger's side faces south. It's easy to park that way because there is so much room.

We did a comparison in Arizona one winter with another fifth wheel that had 360 watts of solar panels (ours has 490), but theirs tilted. Throughout the day they typically got 25% more charge.

Of course that was not a scientific test, as we don't know if their batteries were more discharged (and hungrier for current) than ours at the start of the day (not likely!)... but it gave us an idea of the difference. It is more than we thought.

But we still don't tilt our panels! And those folks bought another panel and stopped tilting theirs (he's a spry 78 but was tired of climbing on the roof).

So, the very easy solution is simply to have a bigger array of panels. Also, since you have an onboard genny, if you find yourself falling short after a week, then run the genny for a few hours to get the batteries up to full charge.

[Ed-Sommers]

I personally like to be able to tilt my panels, or at least some of them. Out of 1200 watts on the roof (with air space), 1050 worth of them are tilted.

If designed properly, tilting can be accomplished by just standing on a ladder (I use a 12 foot telescoping ladder), and without climbing on the roof of the RV, raise the panels in only minutes.

Better yet, with just a little ingenuity, a system that uses only a push of a button can be designed to raise or lower the panels. Something I have given a lot of thought to, and have begun assembling parts. I am 70 plus myself.

While the statement that the addition of a panel or two can replace the need for raising the panels, I like to have my satt TV on , my satt Starband Internet unit running, with at least one but maybe two laptops on line, be using the clothes washer, and still have the battery's topped off even if the sky is not completely clear, and do so in Dec and Jan. But then that's just me.


Ed
Navy Ret.

[jauguston]

One other thing to consider when solar is not optimum, cloudy or partially obscured. Rather than relying on your solar system to replace what you have used in the morning use your generator to start the recharge process. Your battery bank voltage will be low and your converter will put out its maximum rated output. This initial charge boost doesn't have to be very long maybe 30 minutes or so but will really help your solar system finish up the recharging. We do that most every morning running the Onan QD 7500 because DW's latte maker doesn't like the inverter circuit. While she is making her latte I see 102-104a charge from the Magnum. If the conditions are real bad for solar the Honda EU 1000 in the box goes to work feeding the Magnum for a 40a output.

[Groovy]

Ed, I'm with you on the tilting... after comparing our solar collection with our friends, even though their reaction was "we'll get another panel," mine was "I want tilting brackets!" But our panels were already mounted, and my sweet hubby didn't particularly want to redo his work... On the NEXT rig (smile), we'll have tilting brackets... with your push-button system!!!!

And the idea of the morning boost charge jaugoston mentioned has worked for us on our boat too. If our batteries are lower than we like at dawn, we'll run the engine for a little while (it has a high output alternator, and the boat doesn't have a generator). Then the solar panels have a much easier time getting the batteries up to the bulk charging voltage of 14.4 volts...

[Davdeb1]

I think the cost of each motor and assembly has to be put into the equation. Is it cheaper to install another panel, or put in all the tilting mechanism. I'm sure manual ones would be cheap, but for someone like me, I would go the motorized route, possibly wireless with a remote. I bet the extra panel would be cheaper. I'm also toying with the idea of having them all installed with a one inch tilt built in. 3inch brackets curbside, and two inch brackets streetside. Then when boon docking I will alway.s park with the street side facing the south. (in the winter anyway) In the summer I will be back in the Cleveland area, and there aren't too many places to dry camp there. In fact, I will probably only dry camp less than 6 months out of the year, because with coming back to see family and camping what it is in the Northeast, there aren't too many opportunities to Dry camp. I started a thread about boon docking in the Northeast. I was curious as to how many are able to do it. Very few responses tells me what I suspected. Very little boon docking or Dry camping going on east of the Mississippi.

Sorry to digress, I will just probably install them with a one inch tilt.

I do have another thought, hope it's not to dumb a question, why couldn't you just put on 24V panels, and at would make up for the inefficiency?