Camping question

SchoolboySchoolboy Registered Users Posts: 2
I'm not sure if this is where to post this question but here goes. I have a small camping outfit trailer that i want to run a small frig in (1.65amp @120AC). I have a 700 watt inverter and want to mount a battery on the front of so i can charge while going down the road (this is may main goal - to have it powered while traveling). With a 100AH battery (deep cycle) how long would the battery last once i turned off the vehicle? Is what i want to do realistic?

Anyone's thoughts?

Comments

  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    Re: Inverters
    Schoolboy wrote: »
    I'm not sure if this is where to post this question but here goes. I have a small camping outfit trailer that i want to run a small frig in (1.65amp @120AC). I have a 700 watt inverter and want to mount a battery on the front of so i can charge while going down the road (this is may main goal - to have it powered while traveling). With a 100AH battery (deep cycle) how long would the battery last once i turned off the vehicle? Is what i want to do realistic?

    Anyone's thoughts?

    at 50% Depth of Discharge you have 50AH to work with. What's the cycle rate on the appliance?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Inverters

    Welcome to the forum. I've moved this to its own thread as it's a different question.

    To expand on what Alaska Man said, 50 Amp hours @ 12 Volts is roughly 600 Watt hours. Your 'frige specs indicate about 198 Watts (which is probably wrong as my 16 cu. ft. one doesn't draw that). So if it were to run constantly you'd get 600/198 or about 3 hours use.

    Now here's where it gets technical. The inverter will consume some power itself, and there is a conversion efficiency to consider. So you won't have 600 Watt hours available. On the bright side the refrigerator probably does not use 198 Watts running and doesn't run all the time so you would have longer running time.

    Unfortunately the 700 Watt inverter probably won't start the refrigerator as the start-up surge for those things tends to be 1kW+ and small inverters notoriously can't handle the demand regardless of their surge rating (especially 12 Volt units, and/or MSW type).
  • drraptordrraptor Solar Expert Posts: 205 ✭✭
    Re: Inverters

    what I have heard is pure sine wave inverter have higher rate of self consumption, is it true ? if yes what is reason for that ?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Inverters
    drraptor wrote: »
    what I have heard is pure sine wave inverter have higher rate of self consumption, is it true ? if yes what is reason for that ?

    As a rule, yes a PSW inverter will use more power for itself for any given Watt capacity. Simply put, it takes more components to 'clean up' the output waveform to pure sine specifications and more components use more power.
  • SchoolboySchoolboy Registered Users Posts: 2
    Re: Inverters

    Okay thanks. The 1.6amps at 120 are right from the tag on the appliance - I wonder if that is correct also but its all I have to go on now. This 12v vs 120v stuff just confuses the heck out of me if its not already obvious. I appreciate your advice. The inverter I have is a MSW type....I'll look for a pure sine wave inverter. I may also just hook it up and see what happens. Or maybe I just need to hook direct to the vehicle with an isolator switch and only run while going down the road.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Inverters
    drraptor wrote: »
    what I have heard is pure sine wave inverter have higher rate of self consumption, is it true ? if yes what is reason for that ?
    While true, any non resistance loads will run much more efficient and cooler on PSW, so you get the extra wattage back and then some. Most refrigerators sound like a bee hive on MSW inverter. You can hardly stay in the same room with a Fan or A/C running on one. I had one for 20 years and never did get use to it.
  • drraptordrraptor Solar Expert Posts: 205 ✭✭
    Re: Inverters
    While true, any non resistance loads will run much more efficient and cooler on PSW, so you get the extra wattage back and then some. Most refrigerators sound like a bee hive on MSW inverter. You can hardly stay in the same room with a Fan or A/C running on one. I had one for 20 years and never did get use to it.
    IMHO, it depends on the quality or some particular characteristics of the Load and Inverter. Right now, I sitting under a fan (relatively new) running on MSW inverter/UPS, noise is still bearable, compared to another fan which is almost 30 years old.

    P.S I'm looking for a PSW inverter/UPS. In order to run my Computer and other sensitive equipment.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Inverters

    Yes, not all MSW inverters are alike. They range in quality from square wave to pretty close to sine.

    BTW computers are actually one of the things that are not picky about power quality, contrary to popular belief. Due to the sensitive nature of the electronics inside they tend to have power supplies that can clean up pretty lousy waveforms. Can't say the same for their peripherals though.

    To the OP: usually the tags on equipment show a maximum running current. Pretty much a work of science fiction. To be sure, get a Kill-A-Watt and measure the power usage. You won't see the start-up surge but the running power and total Watt hours for a given period of time will be quite accurate.
  • AuricTechAuricTech Solar Expert Posts: 140 ✭✭
    Re: Inverters

    Keep in mind that charging a trailer's house battery through the towing umbilical cord can be a problem due to issues such as voltage drop (long wire run from the tow vehicle's alternator to the battery).
  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    Re: Camping question

    Why not buy one of those new little 4 stroke gennies and strap it down next to the fridge? You can probably go all night on a couple gallons of fuel and the things are pretty dang quiet. I can stand right next to my 3000ei and have a conversation in a normal volume of voice.

    They are so much better than a screaming two cylinder and worlds better than a stinky, noisy old diesel.

    Just a thought.
  • TucsonAZTucsonAZ Solar Expert Posts: 136 ✭✭
    Re: Camping question

    700w inverter is really low for the start up surge which I'm guessing is just about 1,400 watts. You may want to also look into a more efficient appliance if nothing else can be changed.
  • kellylippkellylipp Registered Users Posts: 21 ✭✭
    Re: Camping question

    Why not use a propane fridge (typical for campers...)? You can run a propane fridge on a single propane bottle for a very long time.

    I have a honking solar/battery/inverter system in my RV. I also have a propane/AC fridge. In AC mode, that dang fridge will drain my four batteries in no time flat. Sure, it runs just fine during the day when my honking solar system is producing power but at night...

    Now, I understand that most of us would prefer a residential fridge in our RV but from a practical standpoint we are really stuck with the crappy Dometic (etc.)...

    Thanks,

    Kelly
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Camping question
    kellylipp wrote: »
    Why not use a propane fridge (typical for campers...)? You can run a propane fridge on a single propane bottle for a very long time.

    I have a honking solar/battery/inverter system in my RV. I also have a propane/AC fridge. In AC mode, that dang fridge will drain my four batteries in no time flat. Sure, it runs just fine during the day when my honking solar system is producing power but at night...

    Now, I understand that most of us would prefer a residential fridge in our RV but from a practical standpoint we are really stuck with the crappy Dometic (etc.)...

    Thanks,

    Kelly

    Yeah a propane/AC 'frige is pretty inefficient on AC because it uses the power to run a heating element to do the job the propane would do.

    A standard AC refrigerator is far more efficient than this. The more time you spend using the installation, the more efficient the AC refrigeration becomes vs. propane.
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