HELP I have a plan but not a lot of technical knowledge

bbbbbb9
bbbbbb9 Registered Users Posts: 2
in Off Grid Solar & Battery Systems #1
I'm building a teardrop trailer to pull behind my corolla so it must be lightweight. With that in mind I bought an "eDrenaline" 12volt 7.8amphour sealed cell lead battery. When we camp we don't need a lot of electrical luxuries. Until the very recent past we really used none, so we want a few lights (1157 type bulbs) and a few cig lighter outlets for dvd player and a hotpot (keeps already hot liquids hot). We will be very conservative with usage.

I have a 1.8 watt solar battery maintainer and an idea that the two extra blower motors from a 1964 Dodge Dart may just work as wind generators if mounted correctly under the trailer. I know I'll need to figure out how much they can generate but not sure how.

Second, how would I wire them all together and what charge controller should I use?

Thanks in advance
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: HELP I have a plan but not a lot of technical knowledge

    Your best bet is to revisit your loads/power estimates.

    An 1157 bulb uses around 0.59 amps (tail light) to 2.1 amps on high (brake light filament).

    An 8 AH battery will be dead in less than 4 hours on high.

    The LED version may use 1/4 that amount of current.

    And many of the small 12 volt heating appliances pull something like 10 amps (10 amps * 12 volts = 120 Watts)... Again, way too much for such a small battery.

    For measuring DC Loads, one of these DC AmpHour/WattHour meters is really handy.

    Anyway, before we go down the road of designing your system--We should look at your loads/power expectations.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bbbbbb9
    bbbbbb9 Registered Users Posts: 2
    #3
    Re: HELP I have a plan but not a lot of technical knowledge

    10-4, I'll work on that. I thought the "hotpot" took far less amps than that as it is insulated and you put already hot liquids in it. But I'll list the loads soon. Thanks
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: HELP I have a plan but not a lot of technical knowledge

    Use a good thermos and add insulation. We make coffee the night before, put it into an insulated carafe, then cover it with a freeze "cap" . Coffee is hot to drink 8 hours later.

    Like Bill says, look carefully at your loads, as all issues derive from the load calcs.

    Welcome and keep in touch.

    Tony
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  • fix_it_guy
    fix_it_guy Solar Expert Posts: 26 ✭
    #5
    Re: HELP I have a plan but not a lot of technical knowledge

    It's funny that the coffee hot plate came up, just today I was thinking about how much energy that stupid hot plate uses to keep my coffee hot. I drink a lot BTW, so that thing is on most of the day. I was considering designing a small solar hot water "hot plate" that just circulates hot water from a small panel over my kitchen. maybe a small pump that runs from a small panel. How many times did I just say small? Anyways maybe it would work for your trailer to.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
    Re: HELP I have a plan but not a lot of technical knowledge

    A solution in search of a problem! A goo thermoset, especially with a wrap aroun sit will keep coffee hot all day. I even use a 12 oz thermos cup most of the time' so I can sip all day! My previous post, I should note, that our coffee says hot over night at room temps that can get into the 40s in the middle of the winter. (it helps to preheat the carafe with boiling water for a few minutes before filling with the coffee.)

    Te lessons learned from the coffee pot apply to the house,, insulate, insulate insulate. We carry ice cream back from town, 3+ hours in the middle of the summer, wrapped in a fleece jacket, and stuffed in a cooler. Hard as a brick when we get home. The idea of burning 25-50 watts simple to do what a thermos would do is just plain silly.
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