My brain is on solar overload

allyson

Hi T@b forum!

I own a 2013 T@b Clamshell with wet bath and am trying to figure out the optimal solar configuration for my use pattern.  I have read all the forum posts on the topic, and frankly it is great re-affirmation on why I didn't get a degree in electrical engineering.  I'm hoping to get some assist from the forum.

Usage:  We are long weekend campers, and I don't see us wanting to boondock for more than 4 days as we will be limited by our water tank usage anyway.  We have the 12V refrigerator and use some lighting, run the fantastic fan all night, and occasionally watch and hour or two of TV.  I have never turned on the AC in the Pacific NW simply because the fan provides enough cooling at night. 

Power goal: My experience is that the power from my standard battery will last me if we're lucky 2 days. I'd like to double that length of time either through another battery solution that fits into the standard battery box or into a simple solar solution or combo.  I

Nomad

I do a lot of boondocking and as long as there's sun my 120 watts handles everything easily for however long I want to be out. My stay depends on my food supply, not my power.

Now the buts: I don't have TV but do have other devices. I can run them on battery or plugged into DC. I don't ever use the fantastic fan after the sun goes down and the solar is no longer producing. It's one big battery drainer as far as my experience. Somewhere here in the forums there's a link to a more efficient one - you replace the motor and guts as I recall. The other thing I don't leave on is the outside light. Forgot a couple times and woke up to a fairly low battery. Not depleted but lower than I like.

DABWCA

PXLated - Are you using the Zamp 120 unit for boondocking?

Nomad

Yep, Zamp 120
Even when I'm not boondocking and in a campground I rely on solar - Have only been hooked up a few times in six months. I do have a generator for those rainy or overcast stretches.

mawebb

The fantastic fan would be a significant draw, as well as the fridge. Is the fridge a compressor based unit like an ARB or an evaporative like the Norcold? Compressor based electrics are far more efficient. 

Lisa33

That is pretty heavy usage with running the fan all night along with the refrigerator.  As PXLated suggested, I'd look to upgrade the fan to the 7350, which will cut your power consumption (there is an informative thread on this topic on the LG forum ).   http://littleguy.vanillaforums.com/discussion/comment/40968/#Comment_40968

I'd also suggest upgrading your battery to something like 2 group 24's or 2 6v golf cart batteries or a single larger battery.  The energy produced by the solar panels needs somewhere to be stored.  As far as the panels are concerned, go as big as is practical for you.  Basic rule of thumb (I know I'm a broken record!) is one watt of solar per amp hour of battery capacity.  I oversized mine to compensate for parking in the shade and other factors like travel when days are shorter, etc.

If you decide not to mess with upgrading the batteries and just want a suggestion for a panel size, I'd suggest getting something in the 100-120 range.  Your battery is probably somewhere around 75 amp hours and going any bigger on the panels won't really help you because of the storage capacity limitation of the battery.  If you go that route, you'll need to cut down on your power consumption while boondocking by running the fan for only a short time and turning off your fridge at night.  

wizard1880

I believe the 2013 CS models come with the norcold 12v models. Our 2014 CS does, and I measured the power draw, when the compressor is running, to be between 5 and 6 amps @12.4v. Not sure if the 2013 models use a different fridge, but ours has a blue LED light inside.

Ratkity

I set up my 2009 5 wide Reverse Teardrop (in 2010) with an 85W rigid solar panel on the slope side (perfect angle - sacrificed the radio antenna and upgraded the itty bitty screen to watch movies). I had an 85 ah battery capacity, good deep cycle battery as well as short & heavy-duty wire runs, great controller and charger located appropriately close to the battery. Sounds like I knew exactly what I was doing, huh? Nope, just dumb luck at the time. It just so happened that solar panel prices came down drastically in 2010 and I wanted to experiment given the low amperage needs of the RT - the fantastic fan taking up most of the battery amps, along with a periodically used 12V blanket for winter feet warming before bed (45min cut off, variable setting). There was also no phantom power draw in the RT. Worked perfectly! Did battery equalization periodically, checked distilled water levels.. life was good. Now my needs have changed!

I have a 2015 Tabitha T@B now. Things aren't so simple. I think RV dealers put the lowest amperage deep cycle battery in that they can find. I know there are phantom loads in the T@B and way greater power needs (not even counting the air conditioner). I've set up the Trimetric meter (see info websites below on how this meter is important) to watch how the T@B's converter is charging things and what is pulling a load while not on shore power. I'm going to have to measure the plastic bin area again, but I think I can put a class 27 deep cycle battery in the plastic bin (and at least put a bottom and some sort of vented back to the bin while I'm at it to keep things from escaping). With a bigger battery, there will be an additional 10# of weight to the tongue, but worth it for the extra amp capacity. Keep in mind that 2x 6V golf deep cycle batteries weigh much more and won't fit into the factory-supplied bin. That's adding a lot of forward weight to the tongue (plus you have to lift those suckers into the box). Just two 85 amp class 24's weigh about 53 lbs a piece.

Remember how you stuffed a huge tent into its bag? At first it goes in easily, but the last bit can be challenging and slow - especially if air gets trapped in the fabric. That's a lot like a battery. The initial charge goes in easily and quickly (bulk charge), then it slows down as you stuff more power in (absorption charge) and you get to about 80-85% charged up. It's the last 15% that takes the longest to get a battery to 100% (float charge). Stuffing in that last 15% is important when you have limited amp capacity and it's slow-going (it's a physics thing and the websites below can explain why it has to be so slow). That 15% is also important to the lifespan and optimal use of the battery. 

Even with a battery that will be more than double the amp capacity of the current one in there, I believe I'm still going to need a hybrid system if I decide to add solar. Getting a low decibel generator (Honda 2k is my choice right now) to help with keeping the battery semi-charged when boondocking for more than a week's time is what I'm contemplating. Don't even talk to me about the Zamp solar system. Nice idea, bad controller placement with the potential for the panels to walk away - then add the insufficient gauge wiring that causes more than a 3% drop in power from the panels to the battery. Solar is already a trickle charge. All panels rarely run at 100% capacity and expect 4-5 hours of optimal charging on a beautiful sunny day (panels facing south and angled correctly and no shadows, of course). 

Just to throw your brain into more overload, here are some off-grid heavy solar user experience and expertise: 

HandyBob's website -  https://handybobsolar.wordpress.com/ The electrical information is spot on as well as the typical efficiency of panels. Most of his stuff is for way larger systems that have a basement storage area that can handle 6V golf deep cycle battery banks and also use inverters (12V to AC current). Semi-flexible thin solar panels in 2017 are more efficient than he indicates in some of his older notes and some even have diodes so that that the entire panel doesn't shut off if one of the 36 cells are shaded (36 cells are 12V typically and 72 cell is 24V - there are now semi-flexible panels with smaller and more cells, but still 12V). You don’t have a 4x battery bank of 6V golf deep cycle batteries or an inverter, so don’t even consider paying extra for a 24V system, even if your controller can step everything down to 12V. T@Bs are limited by their battery amp storage capacity. Look at Bob's pictures of poor flat roof setups (on big Class A RVs) where a tiny bit of shade from an antenna shuts down the entire 185-220W panel. Also, thin solar panels used to suffer a problem when it was hot outside. Panels and batteries run optimally at 77F. As the old thin flexible panels heated up to 95F on a bright sunny day, their efficiency dropped to 0.1% of their original wattage. I don't know if flexible panels still suffer with this problem. I've been reading about semi-flexible panels and they seem the way to go.

Where to buy Trimetric meter (TM2030) and companion solar charger for high amperage deep cycle battery (12V): http://www.solarseller.com/ - I didn't put the meter in my living area as the display is bright red LED. It's under the sink in my Tabitha.

Everything you need to know about living with solar efficiently - mostly refers to Class A RVs, but does give a good primer on all electrical and solar workings in general regarding wattage drops, amps, etc. http://www.jackdanmayer.com/links_and_files.htm

This is his off grid living guide: http://www.jackdanmayer.com/Files/Presentation%20HDT%20RV%20Electrical%2010_17_2011.pdf

Cheers!

Nomad

Wow - My dinky little 24 with the Zamp 120w have treated my 7-months of boondocking needs just fine and all I had to do was plug it in - This makes my brain hurt ;-)

Ratkity

PXLated said:

Wow - My dinky little 24 with the Zamp 120w have treated my 7-months of boondocking needs just fine and all I had to do was plug it in - This makes my brain hurt ;-)

Keep in mind that my LG RT worked wonderfully on 85W for 5 years (battery was new in 2010). Never a problem at all boondocking for days on end. 

I think the complexity with the fully-loaded T@B I have has to do more with the amp draw from phantom power, too-small-no-name battery to start with and finally, just cumulative amps draw even if running frig and the heat/hot water Alde system on propane. There's still the water pump, heat pump, fantastic fan on low, light (usually just one), frig, radio, going to charge that ipad or phone or kindle?, igniters (even the frig won't ignite propane correctly when the battery is too low)... I think it just adds up and I don't think I can get that long-time boondocking advantage I had with the RT. I could always just live efficiently and not use stuff while working from a small solar panel, but then, why'd I buy it?

I guess I'm thinking more long run - if I decide to chuck everything in the house and full-time in the T@B without commercial campground stays, can I boondock in one place with my only limitation being tank limits on gray and black water (extra fresh water and propane are easily carried)? Not worrying about power and generator noise would be great. My quandary is how to set up the system right the first time, so my only worry on a limited income would be pre-planning gas money for trips and balance it with groceries (with a small reserve left over for an emergency). Just dreaming, I guess. 

Nomad

I'm not trying to dissuade you but I'm full-time and do a lot of boondocking, run all that stuff and charge all my toys (computer, iPad, iPhone, camera batteries, bluetooth speaker, mini-vac, etc) with just a 24 and the Zamp 120w system. I have a Honda 2000i for backup when those rainy days invade or when I'm doing heavy duty photo editing and need the computer charged fully for long periods. I do wish the dealer had installed a 27 as I requested as I can be a little low (12.2) in the morning but then the solar kicks in and all is well. The Zamp was easy, plug-n-play, has worked well and didn't give me a headache thinking about it :-)
But there are plenty of folks here on the forum that have beefed up their systems to megawatts of storage and solar so it's not uncommon.

Ratkity

PXLated said:

I'm not trying to dissuade you but I'm full-time and do a lot of boondocking, run all that stuff and charge all my toys (computer, iPad, iPhone, camera batteries, bluetooth speaker, mini-vac, etc) with just a 24 and the Zamp 120w system. I have a Honda 2000i for backup when those rainy days invade or when I'm doing heavy duty photo editing and need the computer charged fully for long periods. I do wish the dealer had installed a 27 as I requested as I can be a little low (12.2) in the morning but then the solar kicks in and all is well. The Zamp was easy, plug-n-play, has worked well and didn't give me a headache thinking about it :-)
But there are plenty of folks here on the forum that have beefed up their systems to megawatts of storage and solar so it's not uncommon.

Yup PX, that's exactly what I want. Not necessarily the megawatts, but efficiency dollar/solar panel effectiveness due to limited roof space, the curved roof problem and shading (why park in the sun if you don't have to?). Efficient solar per dollar and also have a backup for cloudy rainy days. As an east-coaster, there isn't always the luxury of parking in full sun and >50% of the time where I currently camp has some sort of shade - the east coast does have the largest deciduous forest in the U.S.  I also want permanent solar installation - not because of the campsites/places I currently go to, but because I don't live in a not-so-great neighborhood right now (spontaneous walk-away factor).  I booted the tire on the RT because of that. 

If 11.4V-11.5V is essentially a dead battery (<20% charge) and 12.8V is 100%, you only have about 1.3 amps to play with per "deep cycle". Dropping to 12.2 is around 50% (deep cycles are meant to do this - but there's a finite amount of cycles these can take - depends on the battery manufacturer and you get what you pay for). If your Zamp is getting you to 85% in a couple/few hours during your bulk charging cycling while you are out playing/photographing, you are doing pretty good. When that battery stops charging >12.4V (you'll never reach a full 12.8V with constant phantom loads), you'll probably think about investing in your class 27. Since those batteries can be pricey, I'd rather not replace one every or every other season, so that's why I was doing the solar-head-exploding research - that, and I'm a scientist, so I can't help it.  A good battery charger (or solar controller), bulk charges at an adjustable rate of 14.4-14.8V (depends on the battery, battery  type and manufacturer) and has an equalizer. Most car chargers and solar chargers on the market are set at 13.8V to prevent overcharging and excessive outgassing on lead batteries while also considering the lower charging requirements of  AGM and Gel batteries. Consumer protection thing, methinks. Protecting a human life trumps extending the life of a battery.

BTW, jealous of your full-timing! BTW, where do you put your generator when running it? Did you get the 2000 Honda with the 30A plug? I know locks are for honest people and someone who wants something bad enough is going to get it, but it does prevent that spontaneous "walk-away" factor with the genny. Do you lock it somewhere when running and also when not in use?

Thanks for all the replies!! It's fun to read where your playground is at (other thread). 

Cheers!

Rad

Wow!  You sure have more knowledge about batteries and solar than I do.  

However, there are two things I do know from actual experience of members here on the site; two 6v batteries will fit in the compartment and the additional tongue  weight is not a problem.  

Ratkity

Rad said:

Wow!  You sure have more knowledge about batteries and solar than I do.  

However, there are two things I do know from actual experience of members here on the site; two 6v batteries will fit in the compartment and the additional tongue  weight is not a problem.  

Depends on the TV and weight distribution inside your trailer. Helps if you have a sway bar on the hitch. Hitch weight should be about 10% trailer weight. To be honest, I've not pulled a light trailer with an excessive hitch weight with my TV, so I can't tell you how it handles with my Rav4.

What concerns me is that one 6V golf battery is 63 lbs. You need 2 for 12V (the little class 24 I have is 53#). Adding a 2nd 20# propane tank and 2x 6V batteries will push the weight to almost an additional 100# on the hitch/front end of the trailer over what it comes standard on the T@B. I'd love to put all of that on the front end, but am scared to. Of course, I'd have a different battery box setup and the cute little plastic cowl would be history. Propane would be separated. I know it's done a lot, but why put one thing that explodes so close to something that creates a spark?

Anyone have experience adding that much extra weight to the front end of a light trailer and how it tracks and travels with a vehicle? Would the trailer bounce a lot in the back end?  If it's getting close to the max hitch weight of the TV, will the suspension bottom out?

Cheers!

mash2

I had an issue with the weight on the front end so I moved AGM batteries to the wheel wells inside the T@B (2 12 v 100 amp batteries in parallel).  I have one AGM over the axle on each side of the T@B.  It definitely lightened the tongue weight (I'm using a Forester which didn't like that much weight up front).  
Moving them inside worked extremely well for me (and the solar hookup wasn't an issue at the new location).  Since my solar is permanent, the whole system was definitely an issue with the heavier tongue weight.  

Ratkity

mash2 said:

I had an issue with the weight on the front end so I moved AGM batteries to the wheel wells inside the T@B (2 12 v 100 amp batteries in parallel).  I have one AGM over the axle on each side of the T@B.  It definitely lightened the tongue weight (I'm using a Forester which didn't like that much weight up front).  
Moving them inside worked extremely well for me (and the solar hookup wasn't an issue at the new location).  Since my solar is permanent, the whole system was definitely an issue with the heavier tongue weight.  

Thanks Mash! Your info totally helped. Did you have to move any water or electrical lines on the driver's side for the battery? There's plenty of storage room on the passenger side over the axel. Do you have your setup in a thread somewhere?

Cheers!

mash2

I have an 06.  Did not need to move anything.  I bought two battery boxes with vents and they fit in between the wheel wells and the wooden cabinetry of the seats on both sides.  I use 2 gage wire to link them together (a bit overkill), switched the outside cabling to the inside in the seat (drilled a hole and caulked when done).  I'm about 9 months into this setup and have had no issues since I moved it.  It definitely lighted the tongue weight (which was weighing down my forester -- which doesn't have the greatest rear shocks).  For me it has been like night and day.  I threw some pictures in a while back of the setup.

mash2

Photos are here.    http://tab-rv.vanillaforums.com/discussion/comment/7924/#Comment_7924

T@Balong

Perhaps this issue has been addressed somewhere but can't locate it.   My new Zamp Solar 120w panels were delivered recently and I'll be trying them out for a long Memorial Day weekend here.   We don't intend to stay in the campground and keep the panels company all weekend so I'm looking for suggestions as to how you folks secured your panels so they didn't walk away somewhere.

Verna

Norm, I think the 120 watt has single legs, rather than the triangle legs that my 80 watt has. Is there enough of a lip on the aluminum surrounding the panels to be able to drill a hole for a padlock?  I bought a 15' heavy duty bike cable from Lowe's and that is what I intended to use with my panels last winter--padlock it to my tongue or my truck. It turned out that I never used the cable because the one day I was worried, I didn't put the panel out until I got back from shopping. I always put it away every evening in the BLM campground, and one other campground. I didn't worry about it in other campgrounds because I was surrounded by friends. 

Nomad

There is room to drill a hole - yes, there are just single legs on the 120s.
I've left mine out unsecured and unattended most of the time as in the campgrounds I've been in there are a bunch of panels deployed. It hasn't been unusual to see 30% with solar. Don't see many if they are weekend type campers though. People leave so much stuff out unattended that the panels are just one more thing. I do put them away if I'm boondocking but that also kind of depends on what's around me. If the other campers are in good shape and the people look "normal" I might not bother. Since I rely on dolor, it does me no good to not have them deployed.
Thought about drilling a hole and securing them but a good tin snip could cut through the aluminum pretty easily. Maybe a long cable threaded through the legs would do it. I do secure my generator to the corner handles on the T@B.