new streamlite trailer, need dry camping advice

We plan to dry camp with our new streamlite 22fb this summer. We have a 12 volt group 27 battery. We want to get a solar panel and golf cart batteries to replace the 12 volt. We can run our fridge on propane but some power is required for the fridge electronics. We would also like to use the water pump a bit and some lights. How many batteries should I get, and how big a solar panel? Any advice would be welcome. A two night trial run ran the battery low in a day. We gave it light charges with our toyota 4runner, and turned the fridge off overnight. Boy!! We need some good advice. Thanks, Joan
P.S. This is way better than our old tent and are committed to dry camping for now.

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: new streamlite trailer, need dry camping advice

    joan,
    i am not the rv specialist here, but i can generalize somewhat. you will have to have some idea of the power requirements of everything you wish to run and for how long. without this info it's all guessing. i don't believe running your group 27 battery down like that was good as no battery (with an exception or 2) should be more than 50% depleted. this stresses a battery and takes away from its lifespan. i believe you may be happier with an agm battery and they are maintenence free with almost no gassing(better for confined spaces), but they cost more.
    once you know the watthours you will need per day you will have to derate from pv wattages as much as 30% due to efficiency factors and other losses and multiply that by the full sun hours you would receive in your location.
    i'm probably making this sound more complex than it is. do know it's good for you to have this interest and i do advise you becoming more familiar with pvs and systems in general by reading in the forum so you have a much better idea of the terminology and technical aspects involved. it is an expensive undertaking so we do like everybody to become more educated before buying. even if some of the others who know the aspects of rving better than i answer you even with a specific recommendation of a system, read as much as you can before doing anything. no, we don't expect you to read everything and we will still be here to answer some questions that may arrise. do keep in mind that we aren't employed by naws, but we do love the subject matter. :-D
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: new streamlite trailer, need dry camping advice

    You have not said how much basic electrical knowledge you have... So, it is hard to figure out where to start. Try reading this link and see what you questions you have next. All things 12 volts RV:

    http://www.ccis.com/home/mnemeth/12volt/12volt.htm

    The basic answer is that you probably are using much more electricity than you think you are, and don't have a good feeling about how long it would take to recharge the battery from your truck through the trailer wiring...

    Just to give you a feel, a group 27 battery has around 100amp*hours (100amp*hour*12 volts=1,200 watt hours)--or about $0.10-$015 of electricity in your home... And you should only use about half of that so-as not to damage the battery.

    Or, a simple 1 amp 12 volt bulb like a brake light on your truck (12 watts, or about 1/3 the 40 watt light in your oven), you can safely leave that on for about 50 hours (2 days) solid before recharging your battery. Or 4 days to drain the battery to flat... Throw a couple appliances into that and you can see that you can easily drain the battery flat in 1 day of use.

    To charge a 100 amp*hour battery... Assume that you get about 10 amps from your truck through your trailer wiring (SWAG--your numbers may be higher or lower):

    Time = (100amp*hr / 10 amps) / 80% efficiency = 12.5 hours of running your engine to completely recharge the battery... Even running it for an hour is only 8%... Not a good way to start.

    Size of solar panel to make up 1 day usage of a 100amp*hour battery system: Assume 5 hours of "sun" (sunny days of the year) and 70% panel efficiency (panel ratings are wildly optimistic) and 80% charging efficiency:

    Panel = (100amp*hrs / day) * 12v * 1/80% /5 hours per day = 300 watts of panels (just a really rough estimate)

    And, you should have at least two group 27 batteries per day of use (at your current energy usage--assuming you recharge each day from solar or generator--if you want to go two or three days, then more batteries)...

    First, list and understand all of your loads. Remember that a pump taking 10 amps for 1 minute every hour (example) is = 10a*1min/60minutes per hour= 1.67 0.167 amp*hours [fix decimal point]. That one lone constant 12 volt light is 1a*1hr=1 amp*hour or 6x the energy hog of the intermintant water pump.

    Second is conservation... Look at the big amp*hour loads (lights, fridge, stereo) that may run for hours/days on end and see if they are the most energy efficient that they can be... 12 volt filament bulbs should be replaced with LEDs or Flourescent fixtures--and don't over size. Just enough is enough.

    Also, to understand sizing things like lights... Remember that your eyes are logarithmic, not linear. A 12 watt bulb does not look twice as bright to you as a 6 watt bulb [fix thought]. In fact, you can hardly see the difference--all other things equal.... Place small task lights where they are needed, not one big light in the middle of the room, etc. Turn on/off only what is needed.

    Third is charging... Fast charging will probably require a dedicated charger... Will you have a generator or other power source (shore power) handy at times? Just attempting to use the truck is not going to be very fuel efficient or truck friendly. Solar is great--but you are talking about (using the current estimated load) 300 watts of panels, or, approximately $1,500 to $2,000+ just for them. Also, they will need their own charge controller too (most likely). Solar is nice for a long stay in no-where--but a properly setup generator and one gallon of gas would run your place for approximately 5 days (~5-6kWhrs or ~400-500 amp*hrs (at 12vdc) per gallon of gas, charging a couple hours per day).

    For storage, AGM batteries are for many folks, almost the ideal battery. The can take high charge currents (not overcharging though--every battery will die from overcharging as well, just as bad as running flat), no water to add, low self discharge rate, no spills, long life, etc. However, they are expensive. Try to not discharge below 50% of battery capacity (100amp*hr batt=> use 50amp*hrs).

    Hope that you get a few ideas of what to look for as you read up on the subject.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: new streamlite trailer, need dry camping advice

    Thanks for the replies. I printed the link you gave me Bill for my bed time reading tonight. (Might put me right to sleep) I have a lot to learn about this. I have considered a generator but am thinking of the noise, getting the thing started, smell of gas etc. The solar/battery route seems more peaceful. :? I guess the 80 watt kyocera solar panel I looked at isn't likely to do the job. Now I need to figure out how much power I may need. I guess I need to get the fridge and water pump manuals out and see what they draw. I actually thought a fridge running on propane wouldn't use power. (Surprise!) I love the trailer and I'm going to figure all this out. Thanks again. Joan
  • System2System2 Posts: 6,290 admin
    Re: new streamlite trailer, need dry camping advice

    Joan--Most of the folks here know a lot more than I do about solar/electrical stuff....But I have about 25 years of dry camping experience with various rv's. It is my experience that flooded cell batteries work best in rvs---see what Northern Arizona....says about this. Second, one group 27 is not enough, but 2 "true deep cycle group 27's" will be as good as a pair of deep cycle 6 volts. I currently have 2 golf cart 6 volts in my Safari Trek Motorhome, but they give me little more power than my previous 105 amp/hr 27's did. My solar system consists of an 80 watt Kyocera panel wirh a Morningstar Sunsaver 10 controller, 2 110 amp/hr 6 volt batts. I can run indefinately on this setup during the summer (just did 2 weeks). My wife, daughter and I are careful with our power resources--we use lights, pump, and fridge---no stereo, tv, etc. (camp in an area where these are not available anyway). For a time, I had the panel mounted on my previous truck camper, but have found that I get a lot more solar energy by placing my panel in a suitable remote location---I am about to build a remote mount for the panel which will allow for periodic adjustments for angle. I find that it is far more important to limit power usage as opposed to increasing capacities---easier too!!! Ki8nda like getting better fuel mileage--reducing consumption is easier by far than increasing capacity. If you are reasonably careful, 2 good 6 or 12 volt batteries and a 80-100 watt panel will serve you well for dry camping.......ChuckD
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: new streamlite trailer, need dry camping advice

    chuckd,
    keep in mind that other people's requirements and conservation efforts will differ from yours. she may in fact be able to do as you do and the results may be different. i was going strictly by the fact that she had drained her battery in less than a day to know that her needs are much greater than she thought and greater than your needs. if you wish to share particulars with her on how you made it work for you please share it with her. she still may need more batteries and pvs for her needs than you as it depends on the appliance draws and for how long. her appliances may draw more than yours and she may have need of them for a longer period of time than you, but the general conservation effort you cite to her will give her good insight on how to better handle this so please elaborate to her on your efforts.
  • System2System2 Posts: 6,290 admin
    Re: new streamlite trailer, need dry camping advice
    BB wrote:
    70% panel efficiency (panel ratings are wildly optimistic) Bill

    Oh, you've noticed! LOL
    Yeah, I agree, there is a disconnect between reality and the "advertised specs" of PV's.
    My GE 110 watt PV's would lead some to expect perhaps 110/12= 9.2 Amps
    Reality is an average of 5 amps in full sun. 5X12= 60 watts! So much for the advertised 110 Watts.
    Ands yes, I know they spin the numbers, so they can't exactly be accused of fraud, but their numbers and the real world, are two different things.
    Oh, don't think I'm picking on GE. All manufacturers do the same thing. It's much like the HP ratings of modern air compressors. Go to your local Home Depot and check one out, you'll find it apparently puts out anywhere from 2 to 5 times more power then it consumes. Yeah, Right!
    It's my opinion that PV's should be rated in amps at 12 volts, for example and not in stretched watts.
    You don't buy a 150 watt battery charger for your car battery, you buy an 8 amp charger.
    The alternator in your car is rated in amps, not watts, that way you know what it's doing to the battery.
    End of another rant. LOL
    Wayne
  • System2System2 Posts: 6,290 admin
    Re: new streamlite trailer, need dry camping advice

    Niel--I did not intend to step on anyones toes here---I'm simply relating my experiences using the requirements Joan specified, which appear similiar to my own.
    JOAN--I do not know what group 27 battery you have, but many RV dealers stick in department store batteries which are NOT true deep cycle batteries---and many of these have been sitting on a shelf a couple of years nearly discharged. This is not good, of course...I would srongly suggest that when you buy batteries (regardless of type) that you buy good fresh batteries from a battery dealer. Your battery should not have discharged so quickly, so this brings up a couple of questions: 1) Did you run your refrigerator on 12 volts on your way camping (for 3 way refrigerators). I would recommend against this for a couple of reasons. When set on DC, these relatively inefficient gas absorbtion refrigerators use more energy than you can replace from your charge line. Second, it is easy to forget to change it over to LP, which will rapidly deplete your battery. 2) Did you make certain that the battery was fully charged? The so-called monitors in rvs do not give a good indication of charge, at least those with  the "good", "fair", and "poor" lights.I would suggest you find out from other folks on this site the best way to assure fully charged batteries.
    Another potential problem can lie with your charging system/convertor. Unfortunately, most rv manufacturers put in very inexpensive convertors with "trickle" chargers, putting out a couple amp hours, which again leads to incomplete charging. Finally, the charge line from your vehicle is frequently too small to keep up with your demands, which make charging from the vehicle unlikely.
    If you want to stay with a convertor, Progessive Dynamics makes some relatively inexpensive convertors with a "charge wizard" which allows the convertor to operate as a 3 stage charger. I have found these to be pretty good systems. I am now using an Inverter with a 3 stage charging system, which is what was in my recently purchased motorhome.
    If you use your furnace much, it will take a toll on your power resources--I camp year round here in Oregon, so use an Olympian Cat Heater instead of the furnace when it is cold.
    As your trailer is 22' (right), your appliences should draw less DC than those in my 28' motorhome--mine has a large (10 cubic foot) refer, 35,000 BTU furnace, etc, so as long as your use is as you indicate (lights, pump, refrigerator (on LP)) you would do fine on the equipment you first considered--you can always add a panel later. The convertor may well be necessary, and money well spent (about $250 for a 9145), and is very easy to replace. You can find more info about this stuff as relates to RVs on www.rv.net . Also look up a site called "the 12volt side of life". This is not to take away from anyone here, who obviously know thier stuff, but relates more to RVs. The issues you have had are far too common, but are easily resolved, and will lead to carefree camping experiences. Best of luck....ChuckD
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: new streamlite trailer, need dry camping advice

    no need to worry as no toes were stepped on as i'm just making sure you are aware that identical situations can have different results and i'm encouraging you to share your's with her so that she may pick up some pointers from you.
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