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Guest Post - Amps Times Volts Equals Watts
Amps Times Volts Equals Watts
By
Mrs. Cog
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It seems a bit backwards that we Cogs have spent this cold, snowy week immersed in learning about the pros and cons of solar energy. Too windy to cut wood and too wet and slippery to be outside except for chores, Cog began tackling the tricky issue of using a solar powered system as a backup power supply for our well. The devil is in the details he carefully explained. “Amps times volts equals watts.”
Gently teasing me about my status as a former urban princess, meaning one who expects to have things work at the flip of a switch and to pay someone to fix it when it breaks, Cog pointed out I came into this homesteading experience with little to no technical understanding of household systems. Electrical, plumbing and structural concepts were for the specialists, not homeowners who don’t even know that ‘amps times volts equals watts’.
Having relocated to our mountain in order to live a more self-sufficient lifestyle, it has not been lost on me that relying upon ourselves means becoming a generalist who can evaluate, design, build, and maintain many systems at a basic proficiency level. The learning curve has been steep and often comical as I have tackled becoming a gardener, cook, and herbalist. But these tasks have paled in comparison to the knowledge Cog teaches me about the modification and upkeep of our home. It has been particularly difficult for me to remember that amps times volts equal watts.
Why can’t I remember that? Amps are carefully considered when calculating the electrical surge needed to start an electric motor, a brief and sometimes very powerful draw of energy. Volts are kept in mind when powering the typical household device or appliance we use. We plug regular things into a 120 Volt outlet. The dryer, stove and well pump are each on a 240 Volt line, thus the funny plug on the appliance and the big clunky outlet it gets plugged into. I thought I finally understood it all since I had now scribbled it on a sticky: amps times volts equals watts.
So we simply needed to set up a solar collection system with enough watts to meet our goal, which in this case was to run the well pump. Although our well is shallower than others on the mountain it is still quite deep, nearly 250 feet down. Hand or simple electric suction pumps do not work at that depth. So during a long term power outage, when our backup generator runs out of propane, it would be wonderful to switch the well pump to solar energy for a sustainable water source. Easy-peasy because amps times volts equals watts.
As I asked more questions Cog vacillated between feelings of frustration and laughing out loud at my Star Trek impression of “Make it so Number One.” It seems that in my enthusiasm to find a quick and easy solution I managed to oversimplify the whole matter in much the same way people who are used to writing a check to pay the contractor often do when they don’t want their heads filled with details, but just want the damn thing to work. Still in the mindset I learned in Consumerism 101, Cog offered up “it’s not just about the watts honey.” No, it is! That’s what it says on my sticky: amps times volts equals watts!
It was during the back and forth with Cog as I continued my solar education that my talents as an expert word-maker-upper came into play. I discovered that the technical jargon could be altered to better describe the process or function, something which still makes us both laugh each time it is used. In this way we can smile over what was previously a dry and serious matter. In fact, the new lingo came about as Cog was showing me that while amps are all equal, some amps are more equal than others.
The exisitng very small solar setup.
To illustrate the problem Cog outlined this issue of amps as I grabbed a legal pad and began scribbling notes. The sun shines on the solar panels where energy is collected and funneled into batteries via a charge controller. The tricky part comes in converting that stored battery power to run a household electrical device. For that you need an inverter. Solar inverters are very touchy as to ‘watt’ quantity of amps you need to draw.
The motor in our well pump needs a swift kick of amps to get it started, a temporary surge if you will. Cog explained to me this electrical kick is called an “in rush” and he bought a pricey clamp meter to not only measure the current in a wire from the outside, but to measure the surge to start the pump. He was so funny, almost excited when the UPS guy brought his new toy. With this we would discover ‘which’ amps times volts equals watts.
As we tackled the measuring of the surge with Cog’s new “in rush meter thingy” we turned on various faucets to force the well pump to kick in. Move over Doc Brown because our well pump’s “in rush” of amps might as well have been 1.21 giga-watts after watching Cog’s reaction. For approximately 2/10ths of a second the pump required 57.5 amps to start the motor. Doing the math, 57.5 amps times 240 volts equals 13,800 watts. We’re gonna need a bigger flux capacitor.
Typical quality (and pricey) inverters provide around 4 to 5,000 watts of continuous power with maybe an 8 to 10,000 watt ‘surge’ capacity. So a quality inverter that could handle our well pump would be a seriously expensive upgrade. Thank goodness Cog is stubborn and continued making phone calls as he searched for answers to our new dilemma. He discovered a gadget called a “soft start” controller which basically stretched out the time of the initial energy surge required to start the motor, thereby reducing the amps needed all at once. I dubbed this the “in rush slower-downer.” Perhaps with this device we would need less amps times volts to equal fewer watts?
But alas, a subsequent conversation with an expert at the manufacturer of our well pump confirmed the well pump motor would not last long with the in rush slower-downer, aka the soft start controller, in place. The electronics and capacitors inside the ‘standard’ well pump motor require a massive jolt of amps to turn the motor over and overcome the water pressure already in the pipe running to the surface and onward to the house. Essentially it would quickly burn out the motor. With the solar collection system we were considering, sometimes there just aren’t enough amps <sigh>.
Cog did discover that the same company who manufacturers our well pump also offers deep well pump systems already set up for solar with a type of soft start device designed in. Unfortunately, the cost is on par with the flux capacitor inverter we would need for the 13,800 watt surge in our initial design. Watt to do, watt to do?
So, for the immediate future our backup water supply remains a clear babbling creek, inconveniently located several hundred feet down a steep and uneven logging road at the foot of our property on the edge of the mountain. While this actually helps comfort me in my process of emotional bargaining, consoling myself that we have alternatives in place should we need to actually become sustainably self-sufficient for a long period of time, we need to find a way to get our water to the top of our mountain. For now, the power to do that remains locked in the simple formula: amps times volts equals watts.
Mrs. Cog
11-27-2014
What's a watt?

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This and your link above are very interesting. I was looking at this (below) and was told not to use it, but it is varying voltage, not frequency. Interesting.
http://www.grainger.com/product/SCHNEIDER-ELECTRIC-Soft-Start-6VMD3?nls_...
Amps times volts doesn't equal watts. That's just too damn complex for the modern USSA. It equals "volt-amps". Dumbass.
The first few times I saw electrical power expressed in "volt-amps" I felt like I was stupid, coz I'd never heard of it in all my years working with batteries. Took me a while to realize I wasn't the stupid one.
I like windmills for pumping water. Where they work they work well for years.
How deep will they pump?
I have wind most of the time up here on the mountain. Was thinking about a small wind turbine here as well as solar.
Both are good ideas.
The windmill water pump is like the very small dc pump ie.. as in they don't pump much volume but they pump all day long if the wind is blowing.
Having a large water reservoir on the property is like having a reserve in gold. they are both a bank for the future.
Aeromotor windmill co been around a hundred years or so. They might be the guys to talk to. I helped fix one once busted bolt. Its a worthy piece. The one I worked on was older than me, other than the bolt it was fine. I bet they got a pump you could live with.
I doubt its cheap but good stuff is like that most times. Stuff you could rebuild yourself for 50 years and then some?
amps * volts * cosine(phase angle)
Now, you're just making it complicated. Bringing complex variables in and stuff.
Anyway, Xantrex (Schneider) is supposed to handle that kind of stuff.
On first read I thought you said Xanax was suppose to handle this kind of stuff. lol
Heh, Xanax might help if you're not interested in learning why e2πi = 1.
We can thank Leonhard Euler for that one. Some of the most brilliant shit ever.
Mrs. Cog's avatar brings to mind, Thunderbolts.
Funny how much easier it is to grasp the ideas of the electric universe than those required to power the well pump with energy from the sun.
There are a couple of way to solve the surge problem, the way most people do it is with a bank of batteries (although you still need an inverter with enough surge capability) Another way to look at the problem is to pump less water for a longer period of time into a tank (a battery for water). This requires a lower wattage pump.
Over the last few days I have thought of several methods to accomplish the task. However.........after costing them all out they all require roughtly the same amount of money either to build new, rebuild old ir combine both. And that total is always three times our budget.
Yes the pumping problem is expensive. One way to get around the high cost of a 240vac inverter is to use a isolation transformer 2 to 1 with a 120vac inverter which you can find for much cheaper than a 240vac inverter. In the long run if you are serious I would recommend a Grundfos solar pump which will run off whatever you throw at it. ac/dc high voltage low voltage etc.
this is an interesting possibility;
http://www.survivalunlimited.com/deepwellpump.htm
Gives both hand and electric operation, you would need a tank and boost pump to your home but if you cant get the amp x volts you can still get some water.
I was looking at Grundfos yesterday. Made me tingle all over.
Ultimately if I am going to make this sustainable I must be able to put into the system, and store what I put in, at least as much as what I am taking out day after day. Which means lots of solar panels and deep cycle storage batteries.
I talked the other day with the tech rep at Outback about the isolation transformer. He strongly advised against it and informed me it would void the warranty. Xantrex confirmed the warranty issue with their equipment as well.
You could just buy a less expensive inverter and dedicate it to the pump. I don't know why they would object to a transformer attached to their equipment when virtually everything you plug into it has some sort of transformer attached to it. I sell and install outback and service the equipment. They don't ask about what is attached to your load when you have a warranty problem in my experience. If you have an fx inverter consider adding another one and you will have the 240 you need.
I don't know why they would object to the transformer on the load side. I certainly wouldn't tell them unless they were water boarding me. But I was in ask question mode and wanted answers. When I asked about a transformer both of them went into meltdown.
Please direct me towards a less expensive (pure sine) inverter that will surge to 13,800 watts every few minutes while the water is running and the pump is cycling. Regardless, I need enough batteries to provide the power to be surged (when water is needed) for years if need be.
The locked rotor current for a typical 1hp motor is 45amps. Typical starting currents are 75% of this value or 33 amps. This is about 7500 watts. If your pump is using more than this maybe the pump needs to be replaced. There is also considerable resistance for 600 ft of #10 wire if that is what you have in your well. This will also serve to limit surge currents.
I talked with Franklin, the pump manufacturer. The motor is 3/4 HP and is listed as 6.8 amps. I am a little concerned that it is drawing over 8 amps continuously and will call Franklin back for a talk. But during my first conversation I mentioned the 57 amp surge and he said that was about normal for that specific model number. He did ask about the wire, which is a 10 gauge, and the run, which is about 400 feet max total.
The pump is just over two years old BTW. I will continue the conversation with Franklin and the installer if need be.
You can get around the high surge current by ramping up the motor with a varible speed motor drive like this one;
http://www.ebay.com/itm/1-5-hp-variable-speed-controller-ac-drive-phase-...
You can program it to start your motor however you want to. What is the model number of the deep well pump?
You may not need a pure sine wave for your pump motor.
Ask your outback guy why they sell this transformer if you can't use one? I've installed these for customers;
The OutBack PSX-240
http://outbacksolarproducts.com/transformer.html
I do appreciate the in-the-field informed advice. I am always wary of listening to 'experts' that don't get their feet wet. I shall look into both your links.
The pump model is Franklin Electric 7JR07P4-2W230
7GPM, Plastic, 3/4 HP, 2 Wire, 230 V
AMP 6.8 S.F. Max Amp 8.0
Gotta do turkiey day. Happy happy!
Perhaps you may wish to consider rigging up an old fashioned stripper type pump for your water well?
The counterweight completely negates the weight of the water in the 250 foot pipe and pumping is as easy as pie.
Preferably pedal or crank operated just and then you can use the solar to make ice without the need of an invertor or battery.
Just sayin'...
http://www.energyindustryphotos.com/small%20Texas%20oil%20pump%20jack%20...
Hilarious. We can take turns pumping while the other showers. As soon as I'm done I'll be ready for the shower anyway. One of us will always be in a perpetual state of stink. :-)
On the other hand the drones will have a great landmark reference for their bombing runs.
Pump it 30 feet higher (280 feet) into a tank up the hill and you can gravity feed shower together... albeit with 15 PSI.
It's insanely simple technology.. you're going to kick yourself CD ;)
(Nice cabin BTW...)
Oh. Yeah, nice cabin. I meant to say that.
Thank you. I spent over a month this fall sealing the logs in the cabin plus the two car detached garage/workshop and another outbuilding. Then applying 32 tubes of special caulking to fill all the checks in the logs in the cabin. The outbuildings will be caulked in the spring.
Not fun particularly when it was getting progressively colder and wetter and the pressure was on to get er done. Log cabins are super high maintenance but real purdy.
It gets better. They got different kinds of electrons. Like ben and jerry ice cream.
LOL
I didn't have the heart to tell her. She only has so many stickies to spare and we are already at our project limit. :-)
If it were a DC motor in the well, you wouldn't need a flux capacitor, a regular one would do.
But I have the impression the well has a regular old 60Hz 110 (or 220) volt motor.
Oh and as you know by now, at 220 you only need half as many amps.
Agreed with what you are saying. The problem is money, not ways to do it.
I can either buy a bigger solar system and use the existing well pump or I change out the pump and go with a smaller solar system. Total dollars are the same.......much more then we want to spend. If we were to go bigger solar it would make more sense because then we would have more capacity to run other things in the house. We need to pass the hat and take up a collection. ;-)
Oh, by the way, and you aren't going to want to hear this, but ...
I have been recommending NiFe batteries every time I get a chance. Yes, they are more expensive per watt-hour. They are less efficient, and heavier, though you won't care about the weight, since you're not building a solar airplane. And you'll have to consult with Schneider or Outback on system settings for your charge controller.
But for long term off-grid, they are better IMNSHO.
http://www.nickel-iron-battery.com/
http://www.zappworks.com/index.htm
http://ironedison.com/
A well pump is a single purpose device, whereas the solar system is multi-purpose.
A less expensive alternative, particularly if you already have a backwashing filter, the filter media in the tank can (almost) always be adjusted to appropriately treat well water and stream or rainwater with different characteristics (once you have identified the actual composition of each water source).
We are already talking about rain water collection and a cistern. No existing back-washing filter on the premises which again brings the total price back up. As the article states the stream on our property is a long way down the side of the mountain. Pumping up from there (at least 200 feet below house level) is as bad as the well. Looks like we will have to sell the first born for the extra cash. :-)
https://www.youtube.com/watch?v=_jBrgVqyVLA there's a much greater selection of 110v inverters, than 240v does the well pump require pure sine wave. the modified sine wave operate electric motors just fine. the moving water in the creek is also a powerful energy source. ( pelton wheel)
Some electric motors deal with mod sine power better than others. It often depends upon the electronic controls within the motor or driving the motor that make a difference.
In the case of our well pump, we are certain the well pump will work on mod sine power. The question is......for how long. Many people in the business have advised me that it varies between manufacturers and the pumps they make. The cheaper pumps are less likely to hold up for long. And those pumps designed for special conditions with lots of electronics as well.
There is a world of difference between a modern deep well submersible pump inside a 4" casing and a bigger industrial motor turning a lathe. If I must implement this backup to the backup I want some degree of assurance it will work more than a month before my solution causes the next problem.
Safe storage for drinking water available in various sizes
http://www.tractorsupply.com/en/store/water-storage-tank-1500-gal
$1099.00
Hey Cog, you can get a purely mechanical system which click click chug chus its way up to a resevoir. A pump can only actually pump about 25 feet before the vacuum in the pump causes the water to boil due to fewer atmospheres and thus fails to pump. Mrs Cog said your well is 250 feet deep but presumably the water fills it to under 25 feet?
My little pump knowledge may be evident but I have seen the mechanical water damns in operation.
My well is 40 feet deep with 25 feet of water and has a hand pump for emergencies so I haven't fully explored these alternatives.
Actually the well was drilled to 300 feet. The well pump is set at around 250 feet and the head or top of the water is about 18-20 feet higher, or about 230-232 feet. No hand pump will work unfortunately.
Our SimplePump hand pump works great at 250 feet, sitting above our electrical primary pump at 275 feet.
http://www.simplepump.com/OUR-PUMPS/Hand-Operated.html
Thank you. An elegant solution to a real problem.
Now, about the shower attachment. :-)
With my SimplePump I can pressurize my storage tank and hot water heaters, so I can use my regular shower and faucets. I hear their solar systems are also very good.
http://www.simplepump.com/OUR-PUMPS/Solar.html
nice
Where I am (sometimes) in SW VA the roof collection water was almost as clean as the 1000ft well (other than the PH which was fixed by throwing a simple log in the rainwater cistern) so you can always manually filter just the drinking water, but a cistern might cost your second born as well, after installation :-(
If you go with simple above-ground vertical water tanks you should be able to hit $1/gal at around a 200 gallon tank from stock at a local plumbing warehouse/farm supply/specialty tank dealer. Avoid the 55-gallon and purpose-built/decorative "rain barrels" like the yuppie/sucker plague they are (Mrs. Cog might kill you if she has to constantly wait 5 minutes to fill a simple garden watering can from the 3/4" gravity outlet rain barrel), and stick with simple EPA green or black potable water tanks (they can always be "decorated" or camouflaged with lattice and something edible or medicinal trained to them) . My experience has been that fewer and bigger tanks is simpler and cheaper (i.e don't worry about the front downspouts, and if TSHTF, and you need more than 1000 gallons a month from 1/2 of that roof, connect a discharge hose to the front downspout and run it downhill).
Nice house BTW, Happy Thanksgiving!
I used the term 'cistern' generically. I was thinking large water tanks of several 100 gals. I agree that smaller 50 gal are not very practical in the long run.
I think there are good reasons why the total is always coming in at three times your theoretical budget. Sub MOA has a point. You are trying retrofit and overcome an initial engineering spec that didn't fully account for future needs/desires, minimize human intervention and inconvenience, and do all this for less than the ~$750 for a quality inverter. Any project can be date driven, outcome driven, or cost driven. One can usually successfully implement a project with two constraints (but in a ZIRP/FED environment that other primary constraint is necessarily time). However, one can almost never succeed at a date, outcome and cost driven project, without having started with obscenely incorrect and inflated allowances, and/or cutting corners to reach the finish line. The questions of what do you have, what do you want, and what are you willing to spend (financially/time/convenience) are critical to optimizing the outcome.
For example, if you already have a potable water rated utility pump, then the cost of some appropriately sized hose and the fittings for a branched input to your existing house plumbing would be negligible (<$100) in addition to rainwater collection tanks. However, that initial hookup effort is more than the effort to manually bleed the water stack in the existing well if you ever have to use your existing pump and inverter. Alternatively, you could prioritize versatility and efficiency and minimize cost priority and borrow Hedgeless' gold card for one of those $1500 hand pumps and several hundred more for an appropriate DC motor for that pump in conjunction with your existing solar setup. But without properly understanding your priorities we are all shooting in the dark (fortunately, given how many of us there are - we are bound to hit something, even if it is less than "ideal").
What was it Donald Rumsfeld once said? You fight with the military you have, not with what you want?
Yes, it is always a compromise and you work with what you have and factor in what you can add and the labor you are willing to do......including labor involved with bleeding the water stack in the existing well.
I can just see Mrs. Cog out there on a January morning doing that. :-)
The article was Mrs. Cog's idea to have some fun. We really weren't expecting anyone to offer suggestions....at least not Mrs. Cog. Nor to actually come up with the perfect solution since it is we that must decide on the compromises involved.
This is a backup to the backup system. If everything goes very wrong and the world, or at least our corner of the US, has gone to hell and the power grid has either gone down or is too expensive to purchase power off of, we wanted an alternative.
There are many ways to skin this cat. All it takes is some money, time and labor.
I think that's the correct decision, too. A bigger solar system, and you can add appliances to the system.
If you get a 'softer' well pump, then you won't be able to run more stuff later ... like a woodshop or a welding rig. Never know what you might want later.
[edit]
And, I congratulate you Cogs on your choice(s) of spouse, and getting off the grid. Also feeling a bit of off-grid envy.