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GlennWest

Khw meter use

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Interesting talk when picking up package at office. She made comment about our low electric use. So she gave me readouts. June 685, May 611, April 519, March 372. Can I use this info for inverter sizing. 

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Yes done wattage conversion and came up with 951 watts per hour. That's average. But that just don't figure up. 

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Glenn, I'm sure you have a handle on this, but for anyone who doesn't,  lets get back to the basics.

Instantaneous POWER in Watts = Volts x Amps. An Inverter has to have enough capacity to supply the biggest total POWER load (all appliances which might be on at the same time) placed on it any given time. For example if an AC plus a Microwave plus a heater or crock pot etc etc were all running, the Inverter has to supply that much peak POWER.   

ENERGY, like the Kwh the power company charges, is Volt x Amps x Time........

Therefore the total Kwh of ENERGY (V x A x T) used in a month isn't the same as the max peak POWER the Inverter must be capable of delivering.

 Got it ??? Power = Volts x Amps        Energy = Volts x Amps x Time

John T Retired n rusty engineer but this is still so as far as I know lol

 

 

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Here is an example scenario. It is made up, but should illustrate peak vs. average:  

Say that you have one busy hour in the evening where your A/C's are running, electric skillet is on, water heater is heating, etc.  That all totals 5000 watts and it happens for a solid hour. So you would use 5000 watt-hours during that hour (5000 watts for one hour).  The rest of your day is up and down, but you average 775 watts for the remaining hours.  Your usage for the day would total 22,825 watt hours, which averages out to your 951 "watts per hour" figure. 

But as you can see, your peak usage would be 5000 watts and that would control how your power system is scaled.  The numbers are certainly more variable and complex than my example, but I think you can see that average over the day is not an indicator of peak. 

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I didn't understand how power company does this. Thanks. Hostess told me we use way less than most and close to lowest I'm park. All my figures come up to just over 7k. But that's everything. People are telling me 2 3k inverters will suffice. 

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12 hours ago, GlennWest said:

I didn't understand how power company does this. Thanks

You're welcome, Hey Glenn, that's  what they do, hopefully you understand it better now. How many Watts you use for how many Hours computes to Watt Hours they charge you for.........Easy Peasey right ?  Power in Watts = Volts x Amps,,,, Energy = Volts x Amps x Time 

 

12 hours ago, GlennWest said:

People are telling me 2 3k inverters will suffice

To my way of thinking, absent YOUR energy audit of YOUR energy requirements and peak load,,, what those "people" are telling you isn't very definitive. How do you know what those "people" require is the same as you ????   THAT BEING SAID I have to agree 6000 WATTS  IN AN RV IS AN AWFUL LOT and may well (subject to your energy use) suffice for you as well as those other "people" whoever they are and whatever THEIR loads may be.

Its not hard to sit down and add up the total power of all the appliances (AC, Microwave, Crockpot, Coffee Maker,  Hair Dryer etc etc etc) you want to be able to run at THE SAME TIME . I would take that number of Watts and maybe add at least 20% to 25% for safety and good engineering THERE'S HOW BIG OF AN INVERTER YOU NEED. Then your ENERGY use will again be Watts x Hours of use

Remember you said I could plug to your system !!!!!!!! You have enough to power you own zip code lol

I enjoy helping and spending YOUR money Glenn, CONGRATULATIONS and Happy Birthday America

John T

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Well I added up everything and 7758 came up. But fridge doesn't run at full output always. dryer work part of time.air fyer and microwave onlly work when cooking. But tv, mini splits, hepa units, are all constant. 

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14 hours ago, GlennWest said:

I didn't understand how power company does this.

A way to explain the power company supplying your electrical needs is some hours of the day your useage  is high as mentioned above. Then they have all the generators (will call it Dogs and Ponies also) running.

Now you have a big truck and we many people have big truck's so they can stop. Like wise they like the highcube engine to get up to speed of over the hill. That is when your calling all the Dogs and Ponies to help, but do you use all or any of the Dogs and Ponies traveling across the flat land?

Size the convertor to get you peak Electrical useage normally the afternoon but could be the morning if you run a electric heater

Clay after 33 years in an electric utility

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Mornings my breakfast is 5 minutes micowave for oatmeal. DW doesn't eat a hot breakfast. Cooking is our big draw. DW rarely uses gas top. Air fryer and convention on microwave.Dryer used in evening.I have figured 1400 for dryer, Can't fit a meter on it. Researched it and came up with that. Everthing else is low draw. Do induction clamp on kill-o-watt meters work? Only way I can get an accurate draw on mini spilts.

 

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6 hours ago, GlennWest said:

Do induction clamp on kill-o-watt meters work?

Current transformers around conductors can be a way to measure CURRENT FLOW. Then a Kill o Watt meter will measure the amount of ENERGY consumed which is again Watts x Time. 

 

7 hours ago, GlennWest said:

Well I added up everything and 7758 came up.

If your peak power usage is that ???? you need an Inverter big enough to supply that number of watts, you have answered your question. Remember peak power is what you will draw if/when all of certain appliances are running at THE SAME TIME  The Inverter has to be big enough to supply that. That IS NOT THE SAME as how much ENERGY (Watts x Time) you might use in a day.

 Just add up the total watts of every appliance you need to be running AT THE SAME TIME to size your Inverter (plus allowing for extra and safety) piece of cake, you got this Glenn

 NOTE I'm rusty on this having long retired as an Electrical Power Distribution Design Engineer but believe its still true YET NO WARRANTY LOL 

John T

Edited by oldjohnt

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