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William, I may have over exaggerated a bit above lol, I was just talking the concepts of energy conservation etc. in general. That being said, the “additional drag” caused by a small wind generator while driving would be extremely small so to supplement the engines alternator, sure it can help IF its worth the expense of purchase and installation?? But, when setting there parked if the wind is blowing IM ALL FOR IT.
John T
William, two friends have those fold up suitcase style portable solar panels AND THEY WORK GREAT. Here’s their HUGE advantage (if you are there and take a minute or two a few times a day) they can be kept at the maximum harvest angle and kept pointed direct to the sun UNLIKE a flat roof mounted unit ESPECIALLY if you have maybe a 25 ft or so extension cord for extra portability. HOWEVER Id use a good heavy gauge say 12 Gauge cord to reduce voltage drop. In my experience a 150 watt portable panel, if you move it a few times a day for the best angle to the sun, will harvest as much as say 300 watt flat rooftop mounted panels. One minor disadvantage is they usually come equipped with a cheap PWM solar charge controller which doesn’t work quite as efficient as a slightly more expensive MPPT solar charge controller but that’s nothing too much to worry about.
YES $500 budget (if you self install) is a good solar start. I bought my last three 235 Watt panels for 90 cents per watt, but I spent around two hundred bucks for a 4 stage MPPT Smart solar charge controller.
No problem with your present batteries, I’m ONLY saying if you ever upgrade and go bigger Id opt for true deep cycle golf cart batteries (like Trojan T -105 at 225 Amp Hours or equivalent etc)
Good luck and best wishes
John T Long retired electrical engineer
William, sure the energy produced by turning a wind generator while driving down the road could be used for another purpose such as say charge a battery. HOWEVER, there’s no free lunch, you cant create or destroy energy ONLY change its form (Laws of Physics). It takes energy in the form of wind resistance and drag, friction and heat, to turn the wind generator and its NOT 100% efficient IE there are heat and friction losses involved. In short its energy output is NOT free, due to wind resistance and drag etc. it requires the engines HP in order to make the turbine turn. NOW if you’re just parked and the wind turns the generator that’s one thing, its sort of free as far as you’re concerned, but you must use energy to drive the RV to turn the wind generator as its NOT sitting there turning (absent ambient wind forces) UNLESS you use energy to propel the RV down the road to turn the generator.
No problem in using one and trying it, it may or may not be as efficient as using the engine driven alternator to help charge coach batteries while driving. The measurements and formulas for force and wind and drag and resistance and engine HP calculations required to see how efficient it is overall (say versus using the alternator) would take a rocket scientist to compute lol
Remember you cant create or destroy energy,,, Heat lost = Heat gained and NO mechanical device is 100% efficient due to heat and friction and other losses.
Still it would be fun to experiment and sure the energy produced by a wind generator requires energy INPUT by the RV engine and one wouldn’t be able to ever calculate if its more efficient then just letting the alternator charge house batteries while driving, BUT ITS STILL FUN EVEN IF PHYSICS TELLS US YOURE NOT GONNA CREATE OR DESTORY ENERGY. When parked if you have solar panels or a wind turbine mother earth supplies the energy NOT the RV engine, see the difference???
John T Retired Electrical Enginer
Gary, if indeed your talking about your “Solar Charge Controller”, I agree with the Pipster, as its surely already capable of handling whatever voltage and wattage your panels can produce and charge a 12 volt battery or batteries. I strongly agree you’re better off using true deep cycle 6 volt golf cart type batteries (two in series) versus those 12 volt so called RV/Marine batteries which I consider as semi or quasi deep cycles at best. If you were to upgrade to a so called “Smart” 3 or 4 stage battery charger (if you don’t already have) your batteries would thank you and live longer.
John T Retired Electrical Engineer
To measure current draw you need an “ammeter” its a pass through series device that either hard wires in the circuit in between the source and the load or can be an induction or clamp on unit that works by placement in contact with the conductor or has a horseshoe type loop placed around the conductor. A cheap multi meter which is good to measure voltage or resistance (ohms) may or may not have an “ammeter” feature. If so, one lead connects to the source and the other to the load. One place to series tap into a circuit may be where the DC power distribution panel is located and the fuse to that load is located. Often the nameplate on say a furnace blower motor or a vent fan etc states the current but such is often not visible. Another way where its easier to attach and use an ammeter is right at the battery and you would have to have all loads EXCEPT say the fan in question isolated and OFF and then be able to turn the fan on and off and read the current draw.
That 300 Amp Hours of battery energy storage is a decent start for dry camping although I consider 12 volt so called RV/Marine batteries as semi or quasi deep cycle compared to true deep cycle 6 volt golf cart batteries. 300 battery Amp Hours and 200 watts of solar is a good what Id consider a minimum start. Unless size and location is a problem its no harder to install say a 200 watt panel versus only a 100 and four Trojans would give you the 450 Amp Hours I get by fine with.
John T Retired Electrical Engineer in Indiana
Pat, its impractical for long term dry camping to power a “relatively large” residential 120 VAC Compressor type of fridge (NOT an LP Gas Ammonia Absorption) using Solar. Sure, its “possible” if you have a huge battery bank, a ton of solar panels plus are exposed to good sunlight for long time periods. I have a very small dorm room size Haier 120 VAC compressor fridge I run 24/7 but also 450 battery Amp Hours (Four Trojan T-105’s) and 470 solar watts. Of course, it all depends on the size of the fridge, your solar wattage, total battery amp Hours and sunlight. I cant provide any details not knowing more about the fridge and all the other variables, but 400 to 500 battery Amp Hours and maybe 500 or so solar watts is at least a starting point but likely NOT enough if its a large residential size fridge.
John T Retired Electrical Engineer in Indiana
PS its true phone and computer chargers etc might have at least “some degree” of safety built in having their own 120 VAC to 5 VDC USB or 12 VDC charging control circuits, BUT RV fridge (such as eyebrow panels) and furnace and other devices may have LESS built in protection are still susceptible to damage caused by line voltage spikes and surges, even though a 12 volt DC battery certainly serves as good buffer. I may buy one in the future but got by 40 years without, but must admit there’s more sensitive electronics in use nowadays???
Still your call
John T
Depending on the climate, location and especially dust you’re exposed to, it sure don’t hurt to wash them just like the RV with mild soap and water and/or Windex etc. maybe once every week or two??? More dirt = less light = less energy harvest capacity.
John T
Retired Electrical EngineerYES they are expensive YES they can work to prevent serious damage to any sensitive electronics in the RV caused by power surges.
Do you really need one??? Thats your call and decision. FWIW I’ve RV’d for 40 years and got by without one to date, but am considering one since smart phones and tablets and laptops are also expensive ????
MUCH MUCH MUCH CHEAPER but cant protect against surges is to at least insure the RV parks pedestal receptacle is wired correct using a cheap plug in tester which looks for reverse wiring and presence of Ground and Neutral etc.
John T
Retired Electrical Engineer in IndianaUsing a cigarette lighter plug may or may not work, the answer is IT DEPENDS ON HOW MUCH POWER YOURE TRANSMITTING, heres the deal:
Typical cigarette lighter 12 volt outlets and plugs may be rated for say around 200 to 300 Watts. At 12 volts that’s 17 to 25 amps MAX, less current at higher voltage WELL DUH.
SO WHAT IS THE TOTAL WATTAGE OF YOUR SOLAR PANELS????????
If you had lets say two 100 Watt panels, that’s 200 watts, so a 300 watt rated cigarette lighter plug and outlet WILL WORK. DONT SCRIMP ON WIRE SIZE if you’re transmitting 25 amps I would likely use 8 gauge (40 amp) wire versus 10 Gauge (30 amp) to reduce line voltage drop.
NOTE the two panels may be wired in SERIES (doubles voltage) or PARALLEL (same voltage but current can double). If there’s any chance of one panel getting shaded out versus the other, I would use a parallel configuration.
NOTE panels may be 12 or 24 volt?? and can be wired in series or parallel!!! A proper selected and equipped solar charge controller (not all) can detect the voltage and still charge a 12 volt battery accordingly. The voltage withstand rating of a typical so called 12 volt cigarette lighter is likely much higher then 12 volts anyway, check the specs to see.
The answer DEPENDS on how much total solar power you want to connect using cigarette lighter (may be 200 to 300 watts rated) outlets and plugs.
John T
Retired Electrical Engineer in IndianaFor much dry camping at all, I would consider the very MINIMUM would be:
200 Watts of Solar and Two 6 volt True Deep Cycle Golf Cart batteries in series (around 225 Amp Hours). I just purchased a 235 Watt 24/30 volt panel for 90 cents per watt which measures 39″ x 54″.
The next step up system which I have is TWO of those 235 watt panels (470 total watts) and Four Trojan T-105’s wired in Series/Parallel for 450 Amp hours.
HOWEVER these are flat rooftop mounted panels. Its my experience if you use a 100 Watt portable suitcase set out panel AND KEEP IT AIMED DIRECT AT THE SUN ALL DAY you might harvest almost as much energy as 200 watts permanently flat mounted on the roof. THAT BEING SAID I guess you could revise my very MINIMUM system recommendations to be a 100 Watt portable suitcase panel and two 6 volt true deep cycle golf cart batteries.
Of course, a couple series connected true deep cycle 6 volt golf cart batteries is far superior to the cheaper semi deep cycle so called “RV/Marine” batteries sold at Walmart for extended dry camping.
To greatly extend battery life I suggest use of a so called “Smart” 3 or 4 stage (Bulk, Absorption, Float, 4th Equalize Cycle) charger and likewise a “Smart 3/4 Stage Solar Charge Controller when dry camping.
John T
Retired Electrical Engineer in IndianaRV HOUSE BATTERIES
Here’s the deal in my opinion. An RV may come equipped with or RV Joe will purchase a cheaper 12 Volt so called “RV/Marine” battery at Walmart, and while sure they will “work” they are at best a semi Deep Cycle NOT a full true Deep Cycle battery such as a 6 volt Golf Cart Battery (Trojan, Sams Club, Interstate, Costco) that has thicker plates and is designed to better withstand deep discharges before recharging AND IS SUPERIOR FOR DRY CAMPING. The cheaper so called “RV/Marine” semi deep cycle battery is sort of a hybrid (auto starting battery and deep cycle battery) since it must have BOTH the capacity to start a large 200 HP marine engine and then perhaps power a trolling motor the rest of the day.
Of course, two of the 6 volt Deep Cycle Golf cart batteries must be connected in series to attain the necessary 12 volts, so room for mounting two batteries must be taken into consideration.
When batteries are connected in series, the voltage is additive (6 + 6 = 12) while the available Amps or Amp Hours (a measure of stored energy) is NOT. If you need more stored energy, when batteries are connected in parallel, voltage is NOT additive, but Amps and Amp Hours (stored energy) IS additive.
True Deep Cycle Golf Cart batteries are rated for so many “Life Cycles” (discharge and recharge) so if they are kept better charged (Solar or Charger or Engines Alternator) you’re NOT using up a “Life Cycle”. Its best to NOT let a battery become discharged more then 50% of its rated capacity (I don’t like to go more then 30%), IE a fully charged 12.6 volt series pair of 225 Amp Hour Trojan T-105’s shouldn’t be used for more then 112.5 Amp Hours (around 12.0 volts for two in series) before its fully recharged. To extend battery life a so called “Smart Charger” which may have 3 or 4 stages (Bulk, Absorption, Float, 4th Equalize) is far superior to the old style cheap noisy humming buzzing high heat Converter/Chargers which function more like a constant 13.4 to 13.6 voltage source.
So, if you’re into serious long term dry camping I suggest you invest in true Deep Cycle Golf Cart batteries versus cheaper RV/Marine batteries and use a so called “Smart” 3/4 Stage Charger or Solar Panels with a “Smart” Solar Charge Controller to keep the batteries charged as best possible to extend their life by NOT using up too many of their finite number of “Life Cycles”
John T in Indiana
Retired Electrical Engineer
RV user over 40 years
29 Ft Class C
470 Rooftop mounted Solar Watts (Two 235 Watt, 24/30 volt panels in parallel)
Four Trojan T-105’s in Series/Parallel for 450 Amp Hours of stored energy
2000 Watt Pure Sine Wave (PSW) Inverter
4 KW Genset
