Solar battery "maintainer?" - thunderbolt

[Mustang65]

Here is an easy way of figuring out your power needs. WATTS is the same whether it is AC or DC voltage. It is the basic part of your equation. A 110VAC Tv may be rated at 200 watts (usually posted on the back of the Tv) @ 110VAC. So if you hook that up to an inverter the AC side of the inverter still needs to put out 200 watts of 110VAC for the Tv. Look at your electrical things and get their watt usage, they post it on the transformers product itself and on their websites under specifications... just keep adding them for your total and about how much time they are in the on position.

Now look at the 12Volt DC side of the inverter. It needs to produce 200 watts to satisfy the inverters output, BUT those 200 watts will be produced by the 12VDC battery. So how many Amps is that? How many Ah is that? Easy to figure Amps = Watts / Volts.

Tv 200 watts on 110VAC:
200 watts / 110VAC = 1.81 Amps needed

Tv 200 watts running off of the inverter:
200 watts / 12VDC = 16.6 Amps of power from you batteries

If you have an 80 Ah battery, that gives you 40 Ah to work with. Each hour of watching Tv will cost your battery 16.6 Ah. So, if you watch 2 hours of Tv you have used 33 of your 40Ah. That means you have 7Ah left for your overnight heating system fan. Your battery voltage was probably down to a couple volts if you made it 2 weeks boon docking... not good for your batteries lifecycle.

In a few of the other posts it was mentioned that about getting a 100 watt SOLAR panel, I recommend that as a starting point on a system that can be expanded (like Renogy systems, a lot of the members have purchased these and have expanded them to meet their needs). I recommend no less than a 200-250 watt SOLAR system for any dry-camping as there are a lot of cloudy/ partly cloudy days out there, and when it gets to fall/winter/spring your panel(s) do not produce at full capacity for as many hours each day, unless of course you live here in Florida where I am still hitting FLOAT by 2pm.

If you mount your panels on the roof of your TT, you can say good by to camp sites that are under trees as shade will KILL your output.

The Digital Display Monitor only uses me, but you can unplug it and check the voltage in the morning/noon/evening.

I know just a few more things to think about

Don

[rsday75]

I really like this new kit from Renogy. It is a 100 watt portable, so you can set it in the sun and still have the RV in the shade. Controller is 30 amp, so you can add more panels later, maybe even a high-bred of a roof mount and a portable...

https://www.renogy.com/renogy-100-watt-portable-rv-kit/

[Mustang65]

Originally Posted by rsday75

I really like this new kit from Renogy. It is a 100 watt portable, so you can set it in the sun and still have the RV in the shade. Controller is 30 amp, so you can add more panels later, maybe even a high-bred of a roof mount and a portable...

https://www.renogy.com/renogy-100-watt-portable-rv-kit/

Renogy makes a great product.

The only thing to remember about expanding a SOLAR system is that the panel output voltage needs to be within 1% of the other panel voltages.. That is why it is recommended that once you purchase a panel you stick with the same make and model (voltage output) most systems used on RV's are 24Volt panels, where as the high voltage ones used in residence (like the one I chose) is 36+ volts. You can add a higher voltage one to your existing low voltage system, but it would need a separate SOLAR Charge controller. Voltage is the key, wattage does not matter in a parallel.

Don

[JEFF1963]

OK - another naïve question from this Thread's originator. I've taken all the good advice about "solar" properties and have done some web shopping. What I seem to find consistently are panels, kits, etc., while trying to find WATERPROOF products, are descriptions including the verbiage "water RESISTANT", never WATERPROOF. Now for the naïve question - without losing, breaking or otherwise inhibiting the panel's efficiency, would Saran Wrap on/around the panel work? - and if not, why not - heat, condensation, what? Have at me people - I said it was naïve. And oh by the bye Screwby, I consider all y'alls advice in my best interest and would never (probably) be offended by it. And pursuant to your "experiment" idea, I agree: no matter what I decide to do, I'll try that little 1.5W panel - if for no other reason than to provide feedback to both this Forum and the friend who loaned it to me (claiming it would be sufficient). Again, I thank everyone offering expertise/experience and advice.

[Screwby]

I'm sure there will be an exemption in knock off "cheap" kits but any respectable panel is waterproof. You have to consider panels sit out in pouring rain, ice, snow, and sleet all the time. It's the charge controllers on the portable kits that are made water resistant as a precaution. Most manufacturers mount the charge controller on the underside of the panel so the panel acts as a shelter for the controller so it doesn't get wet at all. The wiring and connectors on Renogys kits are "weather resistant". They have to say water resistant because somewhere/sometime somebody will manage to get a kit submerged and be mad when the controller or wiring shorts out.

[JEFF1963]

Disregarding the charge controllers for the moment, may I assume you're telling me the actual panel facing is NORMALLY water proof (I won't hold you to it)? What about my query regarding the Saran Wrap? Screwby - you gotta get a hobby instead of helping me so much! Really and actually, I appreciate your assistance - Jeff

[Screwby]

Yes, panels are waterproof. Most panels are just a thin wafer of photoelectric material sandwiched between glass and a backer. There is nothing for water to hurt as far as the panel goes aside from getting into the wiring which is sealed behind the panel itself. The frames even have "weep holes" to drain off extra water as they assume they are going to get drenched. I think the Saran Wrap would degrade the ability to gather energy because even a dusty panel loses collection rate so I keep mine squeaky clean. Unless your some super Saran Wrap guru who gets no wrinkles lol


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[Mustang65]

Saran Wrap will mess with the sun rays. Rain-X is not even recommended for SOLAR panels. Cleaning should only be done with a soft cloth water and a soap that does not have any abrasives in it, no Windex with Amonia D in it. I use a solution of Vinegar and water and a soft cloth... works fine... so far now scratches.

Yes, the panels are totally water proof. If you buy a SOLAR kit with the PWM SOLAR charge controller mounted on the panel, you may want to relocate the charge controller to near the battery. I am not sure if they are water proof, but by relocating it the PWM controller's performance will be increased as the higher voltage will be on the longer length of cable between the panel and the SOLAR charge controller (less voltage drop), and the shorter length of cable (lower voltage) will be between the charge controller and the battery(s).

Don

[Isaacs]

Perhaps I can be of some help.

First of all, your 1.5 watt charger from Harbor Freight is probably 1.5 amps. That would translate into 18 watts which is not enough to do much other than stop your battery from running down in, say, a car or boat in storage. Harbor Freight also sells a 45 watt charger which I would stay away from. I suspect it's old polycrystalline technology which is inefficient. You want monocrystalline.

Something like this would probably be just what you need:

https://www.amazon.com/gp/offer-list...&condition=new

If you start looking for one, make sure you get one with a charge controller. Or you can just buy the parts at someplace like solarblvd.com and make it up yourself.

The following is a little spreadsheet I made up to see what the power draws were on my camper. I estimated the amount of time I would be using each item to come up with total ampere hours. I actually measured the amount of current each item drew so it should be pretty accurate. Keep in mind that my lights were the old incandescent style which I have since switched out to led which draws next to nothing.

Appliance Draw Amperage Hours/Day Daily Draw]

Radio Memory & Propane Detector 0.10 24.00 2.40
Radio Playing 0.40 3.00 1.20
Refrigerator 0.30 24.00 7.20
1 - Light (Double) 3.25 1.00 3.25
1 - Light (Single) 1.60 1.00 1.60
Furnace 3.90 0.00 0.00
Water Pump 5.60 0.60 3.36
Range Hood Fan 1.36 0.00 0.00
Bathroom Fan 1.80 0.00 0.00

Total Daily Draw 19.01 ampere/hours

You can use my numbers to make up your own spreadsheet and come up with a pretty accurate number of ampere/hours for yourself.

Personally, I have a 130 watt panel mounted on the roof of my camper and I love it. I usually camp for two weeks in a spot that is shady in the morning and sunny in the afternoon and have never had a problem. On cool evenings before bed and in early morning we run the furnace a bit; again, no problem. Sure beats dragging batteries down to the campground marina to charge them!

Your portable unit will be more efficient than mine because you can keep it pointed at the sun. Just be sure nobody walks off with it!

Good luck, Bob

[Isaacs]

Oops, I tried to make that chart nice and neat but the forum decided to take out all my extra spaces. Oh well...

[JEFF1963]

It can be done. My friend and I went boondocking with 2 class-24 marine batteries - no generator and only the Thunderbolt 1.5 amp solar "maintainer" with which I began this Thread. We camped for 9 days conserving our power, using only 1 LED light for 2 hours each evening, very little water pump usage, furnace fan 20 minutes in AM and that's about it. Admittedly the temps were 25 - 65 with mean about 45 - so not very cold. My first battery metered 12.67 to 12.25 during the 7 days for daily average usage rate of .006V I then replaced it with the 2nd battery - just to insure the lights didn't go out during dinner. The second battery, starting at 12.54V demonstrated the same consumption given similar consumption for 2 more days. I understand and realize different results might have occurred had the temps been colder. However, because of this "experiment" and recent past experience, I'm confident one may boondock without the necessity of scaring away game (or other RV-ers) with generator noise or a high powered solar array - IF you can dispense with the "necessities" one finds at home.

[SecretCoveDave]

Interesting results. Thanks for the research.

[Mustang65]

Originally Posted by JEFF1963

It can be done..... IF you can dispense with the "necessities" one finds at home.

We would be dead in the water by the first morning... that is great that you can camp this way.... the basics

Don

[NVGun40]

Originally Posted by JEFF1963

It can be done. Snip - IF you can dispense with the "necessities" one finds at home.

Good job my shallow water navy Brother. While my rig is larger than yours, still, I to have been able to make the 7 days and more boondock trips utilizing just batteries. Like you, I have two batteries. A difference beside trailer size (based on what you describe) is that I have both my batteries hooked up (in parallel) all the time.
I while I utilize a 100W solar panel; as you may or may not know, during my hunt this year with two friends (one retired Army, the other still active RAF), I did not utilize my solar panel once. We managed just fine. Same as you, judicious usage of power, water heater on only for the time in take first thing in the morning to heat the water and at night during dinner, water pump on only when utilizing water, only using one overhead like in the trailer, etc. we also don't use leave the onboard furnace on (even on a low temp setting). We use a Buddy heater in the morning and evening primarily, used the on board heater one day just to get things warmed up quicker. Temps at night went below freezing, but things inside stayed nice and warm. We also utilized the refrigerator.
-- So, like you said, it can be done

The technical information in this thread is great and can be dizzying. But all that information cannot factor in all the variables you will encounter in the field. Sometimes you have to just DAMN the specs and go out and see what you can do.

If a satellite which was considered lost in 1969, can all of a sudden start transmitting again even though experts say the onboard batteries are completely fried.....



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