I am in the planning/budgeting phase to add solar to our coach and would be interested in hearing from others while trying to figure out what I need (and don't need). A phased approach (maybe batteries first? or not?)
My goal would be to use:
1. well supported, off the shelf, standard electronics (i.e. Victron, Magnum) and Lithium Iron Phosphate batteries (non-flammable?).
2. Inverter/solar charging system capable of charging batteries from solar panels, 50A pedistal hookup, generator or via Cummins M11 alternator (not sure 160Amp?) when available with surge suppression (lightening?) cutoff switches/fuses to isolate/protect different areas of the system.
3. be able to power devices from both legs of the breaker box (50amp)
4. sized to support at least one night's use of one AC (at a time) plus TVs, interior LED lighting, water pump (microwave, hair dryer optional, still have propane cooktop/refrigerator).
5. 99 U320 36ft (diesel 431/12 AH, Isuzu 10Kw generator).
6. Need the system to easy to understand and support. 12vdc not 24-48vdc based system complexities. Solar panels can be parallel/series.
My use:
1. Part time not full time use.
2. Coach is inside with full hookups when stored.
3. To boondock with the Q gang.
4. To stay overnight in Crackerbarrel, permitted rest areas, relative's driveway... without hookups for a night or be able to run one AC while traveling without the generator. Dash AC works but would like the option of running one AC when driving on hot days for anyone that might be in the back.
You will need lots of amp hr.'s of batteries for the overnight a/c use and an appropriate inverter.
I have a Hughes power watchdog that monitors watt and energy used from the 50amp connection. Is it as easy as starting the app, running the devices and using that number to determine the amp/hrs needed for a given ambient temperature? Oh and both AC's have SoftStarts. Craneman, are you able to run your AC off your battery bank at night?
If I wired it I could get maybe 3 hrs. of a/c At 150 amp hours at 12 volts gets 3 hours drawing 450 amps out of my 600 amp's of batteries. Not something I would do. That doesn't take into account the other draws of the system.
So how do you use your system? What does your 2000W/600Amp Solar system support (refrigerator, microwave, water pump)? Also, is the solar system interconnected with the alternator charging system? If so, what additional components were used?
Walt,
We have had some Forum members install some pretty sophisticated high power solar + lithium battery systems. I think some of them have had the capability of running at least one A/C unit for a limited time. Use the Forum search tool to pull up recent threads on this subject. You can try a variety of search parameters to see what pops up. Set the search order to "most recent topics first" to get the most up-to-date info.
You are asking about a very tech heavy and complicated subject. Searching for already existing threads will save members having to rehash topics they have already covered in great detail.
Here is one current thread to get you started:
Battery Updates and Charging - Solar - Inverters (https://www.foreforums.com/index.php?topic=42231.0)
Thanks Chuck. I have read several of those "complex" solar system design articles but have not run across any basic articles. I appreciate the link you shared and look forward to reading it. I apologize if I am aggravating anyone. Definitely not my intention. I look up to you senior members and appreciate your continued offer share your knowledge and experience with the rest of us. It is what make owning a Foretravel and being a ForeForum special.
Solar systems are rated at the maximum output. That will seldom happen. Using the residential refrigerator, satellite, microwave and coffee maker each day without having to use the generator was my objective. I do have a B2B charger to use the alternator to charge also. Like the other Chuck posted there is a ton of information done by much smarter people than me on the forum.
You are not aggravating anyone. I am simply pointing out the fact that the answers to most of your questions already exist in previous threads. You may have to sift through a lot of extraneous information to
find those answers, but in many cases it is still quicker than waiting around for members to answer you. For instance:
Lithium Battery Insights from New Install (https://www.foreforums.com/index.php?topic=41886)
Seeking advice on several solar install aspects... (https://www.foreforums.com/index.php?topic=41476)
ROOF AC QUESTION (https://www.foreforums.com/index.php?topic=38842)
Thanks Chuck and craneman! I am reading the articles but am trying to get my arms around all the interconnections... Chuck, I read your alternator/isolator/8DAGM install and ATS removal article. Wow, great article. My biggest concern regarding solar is focusing in one area and then burn or damage something else because I didn't think it through. Example: 200amp alternator -> pos excitor/+ cable to 8DAGM. Somehow I missed how you can restrict current flow to 8D battery to prevent overcharging. Off topic of solar but should one design end-to-end (alt/pnls/charger/inverter/ATS) :-* Kind of like when a nameless shop in NAC installed my ride height valve and never took the time to adjust all ride heights to 8" bag height (foretravel spec) and made sure the rod wasn't going to fall out of the boot! Just installed the one valve and said good to go. Then I read that out of adjustment ride height can affect transmission yoke bearing. Yikes. Paying someone else and not doing it yourself has consequences. Sorry about the rant, just trying to communicate the "why" behind why I am posing the solar question. By the way, I now do my own ride height valve replacements and adjustments. Thanks to this forum. Now back to read those next recommended articles.
Walter, this all boils down to a balance between how much power you use each day, how much usable storage capacity do you have and how to you replenish the power you use.
The first part of that balance is quite important. Before you start spending lots of money and changing system you relly should have a good idea of how much power you use. And then if you are going to add a residential refrig what does that do? And if you want to run AC for say 3 hrs a day, what does that do to the total.
Usable storage capacity is how much can you extract from your batteries? For AGM or GEL batteries you commonly use 50% of the rated capacity. You can use more but it reduces battery life. Using only 25% of rated capacity can almost double the battery life. With LiFePO4 batteries you can can generally use up to 100% of the rated capacity.
AGM or GEL batteries need to be recharged every cycle to 100% or you start losing capacity. LiFePO4 batteries are much easier and faster to recharge and while most should be recharged to 100% when you can it is not required for maintaining capacity.
And you can recharge with solar, land line, or generator. We have 1200 watts of solar panels on the coach. About 60% of the days we will get at least 2400 watts of charge back into the batteries. on about 50% of days during the year we will generate as much as we use each day.
If you want to run AC without running the generator then you need to increase battery capacity and solar charge capacity.
We run our residential refrigerator and everything else in the coach and if the solar conditions are OK we can go 10 days to 2 weeks (waste tank capacity limit) on battery and solar alone.
If we are at an RV park and plugged in then it is used for running the microwave and the AH for 2-3 hrs a day. Everything else is powered by batteries and solar. The amount of power we use is 1/4 to 1/3 what we would use without solar.
We rarely charge the LiFePO4 batteries using the alternator while driving, solar is almost always enough.
Power is power no matter what voltage you use, 12,24, or 48 volts. Unless there is an overwhelming reason to do so chnging from 12v increases complexity and cost.
And finally, LiFePO4 batteries will outlast AGM or GEL batteries by a factor of 2-3 times. That makes a big difference in the economic considerations.
Any other question? Keep asking and learning, happy to help where I can.
Thanks Roger for summarizing. Makes sense. Also, just finished reading (and re-reading) that great article from FloridaRandy that Chuck recommended. Wow, spot on and something I could understand regarding his system size and how he is using it. What great information. Thank you all for sharing.
For solar or Foretraveling in general, simple is best. We invert from 12V and our AGMs are going on 13 years old with only a hose used to wash the tops in all that time. Even when shaded by trees, it only takes a little longer to bring them to float. We use a high draw latte machine along with the MW in the morning before the sun hits the roof but the batteries seem able to recover easily. Also almost 1200 potential watts up top.
The biggest secret in long battery life is keeping the voltage up when the coach is not being used. So many battery banks have been ruined by letting the batteries go flat.
Battery expenditure is dependent on the price of the coach and what you use it for. I can see high cost batteries in an expensive coach. Ours on the other hand, is a $20K coach with a lucky purchase of AGMs for little money. Lots of other hobbies and interests make the simplest devices for our coach the best.
Pierce
Our solar installer's ( thanks Bill ) motto was TOO MUCH is just right. after using it for a year,, I couldn't agree more.
It's nice for the DW to not have to ask, can I do this or can I do that without starting the geny.
Walter, if you would like to see my hardware sometime let me know, I've got 1455 watts on the roof...
Keith
48v is really good for running him amp loads off the inverter. The extra cost of getting from 48v to 12v to run the coach is minimal.
Pretty good short read.
Why does a 48-volt battery bank make sense? - RV Nerds (https://rvnerds.com/2016/01/19/why-does-a-48-volt-battery-bank-make-sense/)