I just don't get it

[Van Lady]

T-105's are not AGM batteries. but you can substitute AGM batteries instead of the T-105's. highdesertranger

So if I want AGM only, and I want to store enough power for the following items, what ah battery (batteries) should I get? I cannot figure it out and I will be ready to purchase in about a month:

Use 24/7.....additional insulation will be used...draw will not be consistent so how do I know what to estimate

Use 9 hours daily for 6 months....draw will not be consistent again

Use 9 hours daily for 6 months ....same inconsistent draw

Use 8 hours daily

Use a lot, could be 24/7 - 6 months of year

My estimates are on the high side as to have enough power in worse case scenario.
Is this even possible?
My plan is for a D/C only powered van.

What ah batteries do I get? I was figuring on getting two, but what ah size?

Your thoughts please.

Thank you!

 

[jimindenver]

So the generator salesman said that solar isn't effective eh. lol

What you have listed so far is pretty limited for the size of roof that you have. That said a generator as a back up is a good idea. I haven't used ours since we got solar but we own it.

 

[RevDen]

Dennis,

You don't sound like a chump to me.  You sound very reasonable.  Reasonable needs and reasonable confusion.

Despite what anyone might tell you, this stuff ain't simple or straightforward.  Anybody who says otherwise is trying to blow their own horn.  I'm no laggard when it comes to understanding stuff, learning, seeking my own answers, etc., and I'm struggling.  That can be made harder by the fact that some people (not here necessarily, but solar forums, etc) seem to delight in writing a full volume of IEEE standards every time you ask a question and thus making everything as complex as they can make it.  Fortunately, some people are better.  You've encountered a few here.

In total seriousness, from the reading and discussing that I've done over the last year, off and on, I've come to my own conclusion that there are really only four feasible options to get solar power in your van/truck/RV/house ... listed in order of decreasing pain:

1)  Go back to school and get an EE degree with a major in solar energy.

2)  Throw wads of cash at some solar vendor and tell them what you want.

3)  Get qualified volunteer help to do the full needs analysis that most here have been recommending and then design and install a system, piece-by-piece, that meets those needs.

4)  Take a recommendation like Bob's above, buy a few common things, slap them together, start using them, and discover along the way what's good, what's bad, what needs upgrading, etc.  Make allowances for some disappointment and premature replacement costs.

Each one has pros and cons.  If there's a fifth option, I'm not aware of it.

At the present state of technology, people who would score less on the SAT than your dog can buy a very complex smart phone and use it, without understanding CDMA or 4G protocols.  That is the way technology should be for users.

Sadly, solar energy just isn't there yet.  However, just in the time I've been learning about it, it has gotten a bit better, almost as if someone in the solar/battery industries understands what I just said and is trying to fix it.  Still, in my opinion, that will be long, slow improvement ... not in time for us.

You might feel lost, but it's a well-worn, and mostly unavoidable path. 

Vagabound

that makes sense to even me.

 

[GotSmart]

I have a 2014 GMC Sierra PU and KZ travel trailer that is 27'.  I use a C-Pap at night, lots of computer time, I'd like to watch TV some and then there is the normal cooking and living stuff.  I think that boondocking will be more my thing.  As far as charging batteries, I don't have a clue!  I was told that solar panels aren't very effective so I guess I need to buy a generator but I don't have a clue about what kind.  So, I really want to know about generators and what kind of  batteries would be most effective.

What Bob recommended will work great for your use.  

akrvbob Wrote: 
okay, here is what I recommend for the great majority of vandwellers and unless you have some special needs, should work for you:
1) Renogy 200 watt solar kit
2) Pair of T105 Trojan  golf carts
3) Cobra 400 watt inverter.
Most vandwellers will be very happy with this setup.

I have 200W of Renogy monocrystalline  panels, and no matter how much I use my appliances, the batteries are always full by 10 AM.  Even on cloudy days.

 

[Vagabound]

(michele0203) Are the Pair of T105 Trojan  golf carts batteries AGM batteries? I think I feel safer with AGM batteries.

-and-

(highdesertranger) T-105's are not AGM batteries. but you can substitute AGM batteries instead of the T-105's.

 
Practically speaking, HDR is right.  The T-105s that everyone is talking about are not AGM.  But, because you asked, I'll mention that there is a T-105 AGM battery.  It costs 2-3 times as much as the non-AGM, more common version.

(GotSmart) I have 200W of Renogy monocrystalline  panels, and no matter how much I use my appliances, the batteries are always full by 10 AM.  Even on cloudy days.

And that's what I call "news you can use"

Vagabound

 

[Spaceman Spiff]

I have 200W of Renogy monocrystalline  panels, and no matter how much I use my appliances, the batteries are always full by 10 AM.  Even on cloudy days.

X 2

200 W solar, 208 AH of batteries and run an old refrigerator (~ 40 AH/day), Maxxfan (~ 5 AH/day), LED lights (~ 1 AH/day), and charge my mac and iPhone periodically (usually do that when driving).  Batteries are seldom below 85% in morning and usually back to 100% by noon.

 -- Spiff

 

[highdesertranger]

but they are throwing in an electric blanket, an electric mattress, a CPAP machine. and we don't know what type of computer and how much it draws. we need more info. we need to add up all this stuff. what is the amphour use of the computer and CPAP. and anything else like lights, RV heater, RV refer, etc. I hope you realize heating anything with electricity is very inefficient. highdesertranger

 

[jimindenver]

RevDen

generators are pretty simple to handle, at least compared to solar. there are too basic categories, loud and even louder. The ones that are just annoyingly loud are called inverter generators that can slow their throttle when the load is low. The even louder run at one high speed all the time and you generally don't want to be within 50-100 ft of them.

More on those two later. Lets talk about sizing. You size the generator by the largest load or combination of loads that you want to run. So if you want to run 30 100 watt bulbs you need a generator that can consistently provide 3000w. Roof top air conditioners usually fall into the 3000 series of inverter generators and the 3000-3500w running non inverter generators. ( the louder of the two) Microwaves can be handled with a 2000 series/ 2000w. Coffee maker and lower with 1000 series/watt. (there are also options like combining two 2000 inverter generators to run larger loads like the A/C.)

So if you want the quietest generator that can run your air conditioner, you would buy the Honda EU3000is. It is the quietest of all when at idle and 50 db. 58 Db at full load. It runs somewhere around $2000. The same size Yamaha is close in both noise and cost. Champions big inverters are a bit louder but not much. They cost half as much and are a little more powerful, especially the new 3500w inverter.

All three of those brands in the 2000w range have the same general noise levels at low speed. The champion again is half the price but a bit less powerful while a bit louder under full load. The same goes for the 1000w series.

So, the least expensive to run the roof A/C is the Champion 3500/4000 at $300. It sounds like a good sized lawn mower at high RPM's, I know because it is what I own. It's fine out in the boonies alone as long as you are in the trailer with the A/C and TV on. I would never subject other people to its ear splitting roar.

Efficiency depends. A large inverter generator running at full speed is likely to use just as much gas as the same sized non inverter pushing the same load. The inverter model only become more efficient when the loads are reduced allowing it to slow down.

The last thing is altitude and heat affect a generators output. Mine loses 40% of its power at 10,000 ft on a hot day, which is why we have such a large non inverter generator. There were no 3000 series inverter generators that could run the A/C above 8000 ft when I bought. ( still aren't)


Whew. Now you know why I use solar.

 

[akrvbob]

You do have pretty high expectations of solar. Using it for heating is much more expensive because that's a big draw at night. Big draws at night require a big battery bank. Big battery banks require big solar to rechage them i the winter and in the rain.

Forget the electric blankets and go with propane heaters and a good sleeping bag.

If you can't do that then get this:

400 Watt Renogy kit
4 AGM deep cycle batteries. (I like Full River if there is a dealer nearby)
400 watt Cobra inverter.

Be sure to measure the roof and know you can fit the panels on it.
Bob

 

[GotSmart]

but they are throwing in an electric blanket,  an electric mattress,  a CPAP machine.  and we don't know what type of computer and how much it draws.  we need more info.  we need to add up all this stuff.  what is the amphour use of the computer and CPAP.  and anything else like lights,  RV heater,  RV refer,  etc.  I hope you realize heating anything with electricity is very inefficient.   highdesertranger

My original reason for my set up was a CPAP.  

Instead of electric blankets, mattress, and heater I use a cat...

 

[RevDen]

What Bob recommended will work great for your use.  




I have 200W of Renogy monocrystalline  panels, and no matter how much I use my appliances, the batteries are always full by 10 AM.  Even on cloudy days.

If we ever meet up, I'd love to buy you dinner!  Thanks so much.  I do have a follow-up question if I might.  The batteries you suggested are 6 v but I thought the trailer was 12 v.  Sup with that?

 

[jimindenver]

You use two 6v batteries in series to create one large 12v battery.

 

[GotSmart]

If we ever meet up, I'd love to buy you dinner!  Thanks so much.  I do have a follow-up question if I might.  The batteries you suggested are 6 v but I thought the trailer was 12 v.  Sup with that?

Here is my battery set up.  I have 4 6 volt batteries set up in series ~ parallel.  

Two sets of 6v combined into 12v.  The two 12 volt units are tied to the same controller.  Positive on the top, negative on the bottom.  Positive wires go to the source, negative to ground. 

Because I got a huge deal on the batteries, I bought more than I need.  You never have too much solar or batteries.  

Look at it this way. a 12v  battery cell is 1X size, and puts out 2 volts.  A 6 volt battery cell size is 2X sized, and puts out 2 volts.  The 2X unit is more efficient than the 1X unit. More than twice as efficient.  It works.  

Any of the members that gave advice on this thread can be trusted to design a top grade system.  They might do it differently, but the end product will work extremely well. 

More information to follow after you completely understand this. 

Look up the different threads in the solar section of this forum.

 

[BradKW]

I feel people are getting a bit ahead of the curve suggesting specific panel and battery size...that c-pap machine and PC are serious unknowns. Bob did an interview with a fellow using a mobile powered C-pap, maybe he could re-post it.

A good place to start is getting a Kilowatt meter and seeing how much draw your machines require. 

Not too long ago I build a high performance PC in a mini chassis, designed to be very efficient for mobile use...normal desktop PCs are power hogs because historically, the easiest way to solve many design challenges has been to throw more power at it...

 

[GotSmart]

My CPAP uses 6.67A @ 12V

The type of computer does make a difference.  A lap top typically uses 1/10 the power a desk top. 

http://www.wholesalesolar.com/solar-information/how-to-save-energy/power-table

 

[RevDen]

I'm amazed that so many of you chimed in to help. My plan is to study all of this carefully, be a minimalist for a while and learn a little at a time.

 

[GotSmart]

I started out with just the batteries, hooked up to a solenoid.  I charged them while driving.  I had a Blue Seas distribution box, and one 12V cig style outlet.  I had a yard sale inverter to run the CPAP off of.  6 months later I was able to get the first Renogy panel.  

Baby steps.

It is possible to build a system the Johnny Cash method.  One Piece At A Time.