Reply
 
Thread Tools Display Modes
Old 10-18-2016, 01:12 PM   #11
Wanderer
 
Spacecasey's Avatar
 
Join Date: Oct 2016
Posts: 10
I am still trying to decide what Four (4) 12V Group 31 AGM Batteries in Lithium equivalency is.. Any idea? Because GT 12V 525 Lithium Amp Hours 8DR Case Module is 135lbs..
__________________

__________________
Navy/Army Disabled Veteran
Little Guy 6x10 Silver Shadow Limited
Spacecasey is online now   Reply With Quote
Old 10-18-2016, 04:03 PM   #12
GM
 
bclemens's Avatar
 
Join Date: May 2011
Location: Elkhart, IN
Posts: 5,130
Each of our group 31's are 105 AH and roughly 70lbs each.

Set of (4) would then be at least 280 lbs plus cabling weight with a theoretical 420 Amp Hours.

Right now...a single Li-Ion battery to replace (2) group 31 AGM's is about double the cost. Or roughly 4 times the cost of flooded...
__________________

__________________
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).
bclemens is online now   Reply With Quote
Old 10-18-2016, 04:22 PM   #13
Senior Member
 
Join Date: May 2012
Posts: 382
I think that you're starting your solar project in the middle instead of the beginning. Before you can correctly judge battery capacity and solar output, you need to determine what your expected usage will be. Running an AC unit for five hours can easily use 6000W of power. Add 30 minutes of Microwave use, 500W, and a couple of hours of television, 200W and you're approaching 7000W of power a day. This is close to 600A at 12V. Six 100AH batteries will meet this load if you are willing to fully discharge them and can fully charge them the next day. If you follow the 50% capacity rule, you'll need 1200A of batteries.

Once you figure out how much battery power you'll need, you can size the solar array to charge the batteries. If you draw 600A from the batteries each day, you'll need at least 660A of energy from your panels to account for losses during charging. At five hours a day of power from the panels (an optimistic estimate for non-tilted panels), you're looking at around 112A or 1.2kw of output from the panels. At that power level, you'll want to use an MPPT controller and connect panels in series to decrease wire size from the panels to a reasonable size.

Running high power usage devices, especially air conditioners off of batteries is a daunting task.

Phil
__________________
pmsherman is offline   Reply With Quote
Old 10-18-2016, 04:32 PM   #14
Wanderer
 
Spacecasey's Avatar
 
Join Date: Oct 2016
Posts: 10
See, that is what I need.. I need the estimates of the math needed, then a parts list.. And I know what I can work with..
All I have are our habits.. Sleep with A/C or Heater on.. Plug in 5 devices (USB), watch tv about 3 hours a day, run the fridge, an induction cook top, hot water on demand, and listen to music. A coffee maker running about 10 minutes a day. Microwave for about 4 minutes a day to reheat cold coffee.. Also we will be getting a dehumidifier, and I need to run a CPAP while sleeping. Sleep is about 6-8 hours.
I was hoping to have the solar charge the batteries, a generator on the engine to charge the batteries, and shore power sometimes..

What will I need?
__________________
Navy/Army Disabled Veteran
Little Guy 6x10 Silver Shadow Limited
Spacecasey is online now   Reply With Quote
Old 10-18-2016, 04:54 PM   #15
Senior Member
 
FOURWHL's Avatar
 
Join Date: Mar 2016
Posts: 217
You're asking for a pretty detailed design, not sure somebody but you can answer all those questions. I can tell you though there's lots of good information out that that I'd recommend immersing yourself in. If you just want the quick answer though I'm sure some solar shop will give it to you and even sell/install the system.

I've been researching this all on and off for going on 6 mo now and I still have questions but the puzzle pieces are beginning to fit together.

If you plan to run AC off battery that's the first thing I'd start with because there's a whole lot more to not destroying your batteries than just having enough power.
__________________
2016 Dynamax DX3 - Big Blue
FOURWHL is online now   Reply With Quote
Old 10-18-2016, 05:02 PM   #16
Wanderer
 
Spacecasey's Avatar
 
Join Date: Oct 2016
Posts: 10
That's the thing, isn't it? There aren't many shops out there, just standard kits, but if the needs vary, who do you go to? That is why I ask here, because I will be getting an 5 in about a month or so.
__________________
Navy/Army Disabled Veteran
Little Guy 6x10 Silver Shadow Limited
Spacecasey is online now   Reply With Quote
Old 10-19-2016, 08:25 AM   #17
Member
 
Join Date: Oct 2015
Location: St. Charles County, MO
Posts: 40
If you start searching google you can find a lot of answers. I have talked with Backwoods out of Idaho. They design and sell solar arrays and products. You can swap out your residential fridge for a 12 volt fridge as well. 12volt units come in very similar sizes as the residential units provided by the manufacturer. There is another web site by a couple that goes by the name Technomadia. They live in a vintage bus and have been on the road for many years. They test solar panels, batteries, wifi options, appliances, etc. They are currently testing lithium batteries.

Research is key to correctly designing and building a trouble free solar array. If you bypass the research element you chance spending a lot of money and not reaping the best reward.

There are many other sites that provide good info.
__________________
Explorer1016 is online now   Reply With Quote
Old 10-19-2016, 09:33 AM   #18
Senior Member
 
Join Date: May 2012
Posts: 382
Quote:
Originally Posted by Spacecasey View Post
See, that is what I need.. I need the estimates of the math needed, then a parts list.. And I know what I can work with..
All I have are our habits.. Sleep with A/C or Heater on.. Plug in 5 devices (USB), watch tv about 3 hours a day, run the fridge, an induction cook top, hot water on demand, and listen to music. A coffee maker running about 10 minutes a day. Microwave for about 4 minutes a day to reheat cold coffee.. Also we will be getting a dehumidifier, and I need to run a CPAP while sleeping. Sleep is about 6-8 hours.
I was hoping to have the solar charge the batteries, a generator on the engine to charge the batteries, and shore power sometimes..

What will I need?
If you run the A/C at night and use induction cooking, I doubt you'll be successful with a solar system and batteries. An induction cooking stove is a very heavy electric usage device and, if you want to use the stove while running the A/C, I'd suspect you will need at least a 5kw inverter, possibly larger. Running an A/C and a single "burner" on stove should allow using a smaller AC power source. For heat at night, the RV furnace uses propane but still uses 12V power for the furnace fan. Electric space heaters can draw 1200 - 1700W per hour and aren't suitable for use when drawing on a 12V battery for power.

From your usage, your best bet might be a pair of 2kw Honda (or similar) gasoline powered inverter generators that can be wired together to give you 4kw of power. They're very quiet and you could also build a knock down soundproofing enclosure to further quiet them. With only 4kw available, you probably won't be able to cook and run the A/C at the same time but that would be manageable.

An alternative is to plan on always spending nights at RV parks or other facilities where you will have electrical power available.

In my 2011 Georgetown 327DS, 200A of battery is barely enough to run the (propane) furnace at night when outside temperatures drop below 20F. A four season rig would be easier to heat/cool at night because the double pane windows are much better at lowering heat transfer than my single pane ones. They also leak a lot less air than mine.

Phil
__________________
pmsherman is offline   Reply With Quote
Old 10-20-2016, 02:23 AM   #19
Learning a lot as I go...
 
Join Date: Aug 2015
Posts: 205
Quote:
Originally Posted by Spacecasey View Post
See, that is what I need.. I need the estimates of the math needed, then a parts list.. And I know what I can work with..
All I have are our habits.. Sleep with A/C or Heater on.. Plug in 5 devices (USB), watch tv about 3 hours a day, run the fridge, an induction cook top, hot water on demand, and listen to music. A coffee maker running about 10 minutes a day. Microwave for about 4 minutes a day to reheat cold coffee.. Also we will be getting a dehumidifier, and I need to run a CPAP while sleeping. Sleep is about 6-8 hours.
I was hoping to have the solar charge the batteries, a generator on the engine to charge the batteries, and shore power sometimes..

What will I need?
Short form? I will 2X the recommendation of just getting a generator.

The USB chargers? The refrigerator if it is propane powered? Even many of today's LED TVs? All quite doable on battery/solar power. Everything else you list there is probably too much for a battery/solar system unless you either write somebody a really big check or invest the time to learn and write a bunch of checks.

Deal is every device you buy has either a manual or a sticker which tells you how much power it pulls. A/C is a big draw, figure 15A of 120V. Induction cook top I am not sure but believe it may be even worse than A/C so figure at least 20A. Anything that generates heat will be a big draw. Really most 120V stuff will be a heavy lift for a 12V system.

So start out your planning by reading and researching what you have to figure out what it draws. Then put that into a spreadsheet or table so you can put how long you plan on using it in another column. Calculate out the watt hours (amps x voltage = watts, watts x time = watt hours). Add a 20% fudge factor. This is what you need to generate and that 480 Watt 12V solar system will not be even close.

The other issue you have is to provide 15A of 120V power takes 150A of 12V power (ignoring conversion losses). Do you know what size copper it takes to carry 150A without melting? That is huge and heavy and very expensive.

Once you take a solar system above about 400 Watts you need to really start running panels in series to reduce the size of copper you need to run. Regular solar panels produce ~15V and dropping this to ~13V by turning it on/off really fast (what PWM does) works pretty well. But when you put those panels in series you run 30V into the solar converter and just turning it on/off does not work so well anymore. At this point you need MPPT solar converters which actually convert the voltage. So smaller wire from panel to controller with serial and MPPT but still very large wire from controller to battery array.

And we are talking about a bunch of batteries because they have to be able to absorb all the power/current so they can provide it back out.

Having looked at this and bought some hardware, IMHO if you want to adjust your life style for low power then solar can be a great alternative. But if you want to live the same way off grid as you would on grid... get a generator instead.
__________________

__________________
2015 Rockwood 2604WS (sold as 2016)
2014 Ford F-150 Ecoboost
stevejahr is offline   Reply With Quote
Reply

Tags
solar

« Moving On | DX3 4x4 »
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




» Virginia Campgrounds

Reviews provided by




ForestRiverForums.com is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 09:02 AM.