Power and Energy - Watts vs Watt Hours, Energy Cost and Battery Capacity
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- Опубликовано: 15 май 2024
- Watts vs Watt Hours
Amp Hours to Watt Hours
Power is the rate at which electricity is used, energy is the total amount used over a certain period of time.
Includes example calculations for the total energy and cost used, and the capacity of batteries. 
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Love how this channel has almost no dead time and you can learn a lot in the time that you spend on it. No waffle or life story business. Straight to teaching.
I hope the BBC are watching and their people can learn the difference between kW and kWh
I hope government ministers are watching too !
Don't hold your breath :-)
Have you seen the BBC broadcast this concept inaccurately? If so, please say when and what programme.
@@keithmclean3151 Local news on BBC News app today concerning a new solar farm in Dorset: “It would have capacity to generate up to 300 MW of renewable electricity, with 400 MW of battery storage capacity close to the existing substation at Chickerell.”
@@JezCunningham Yes, that is dissapointing. So we don't know how long it will take the new solar farm to provide 300MW power delivery. Could be 1 minute or 1 day ;-) But seriously, would it be fair to say that in a statement like this one could assume it meant per hour? Then as more people get to realise the difference between power & energy they will understand that a time factor must be associated with power delivery. In my discussions I like to use the term of a 'power' man walking along the street. Most of us have the energy to walk to the bus stop however far less of us have the energy to run to the bus stop so miss the bus because of not getting there in 'time'. I start there because most non-tech people do not know what a Watt is. It only gets worst when you then introduce voltage & current to the discussion. ;-) As John Ward intimated, water, fuel etc are tactile substances but electricity isn't.
I like the flowing water analogy for electricity. A lightbulb is a dribble, a kettle is the tap on full.
An EV charging at 150kw - the water main outside in the street after someone has dug through it with a digger, and it's spraying like a fountain.
As an electrical engineer, this is an excellent presentation. I have explained this to the young ones over the years in a similarly fashion with exhibits and examples so they really understand the terms. I don’t know what they teach them at college these days. Well done for taking the time to put this up along with the rest of your educational videos.
I am captivated now not just by John and his voice, but by THAT CAT PORTRAIT
Would be doubly cat-tivating If the cat was wearing the same style of glasses as John, .....
Been watch you for years now John. You helped me get through my electrical college qualifications and electrical inspectionand testingcourse, so just wanted to say thanks 👍
As always John, a brilliant and clear explanation. I wouldn't be surprised if you are doing teaching on the side! I also swear you are getting younger! Lovely to get a video pop-up from you, hope you are keeping well.
Great timing! I've been trying to get my head around battery storage & inverters recently. This comes across as clear and easy to understand; maths has never been my strong point. Very helpful, thank you.
Very useful and straightforward, thanks!
Great video clear and concise excellent job John.
John, As always your presentation was professional and informative. I thoroughly enjoyed it. Thank you.
Excellent as always J.W. Thank you.
Nice seen you again Mr John. I hope you will make more videos . Welcome back 🙏
Fortunately, most people are like JW.Possessing honesty, integrity & enough intelligence to understanding that buying a new kettle will not reduce the amount of power needed to bring water to 100c.
Glad you've lifted the lid on the murkey world of exotic units of battery measurements.
My friend makes electric skateboards with a (huge number)something battery and a 3kW motor (unlikely as it looks like something from a battery drill) whereas my 48v electric bike that mostly gathers dust has a 12 Ah eBay battery and a 1.5kW motor. Trying to make comparisons felt futile at that moment.
So clear - So helpful - Many thanks !
Thank you for a good back to basics explanation
Well explained John.
Great video John.
A kettle is a great way of demonstrating power and power over time. They are extremely efficient devices that use a very large amount of power to boil the water, but the total power used is miniscule really. You almost certainly use more electricity cooking something in the 2kW oven than you do making several cups of tea with your 3kW kettle. I also got into the habit of putting my tea/coffee into a thermos flask as I kept microwaving cold coffee which surely is a waste of money.
Watt was that?
Yes JW I do have the power to watch your videos, and you have the power to make them.... Keep up the good work
Dude. They made that joke a felony, and they want to add time to the sentence. I won't call the cops on you, because I still owe a lot of amends for some that I've just randomly thrown around, and I've hurt a lot of people, but I just thought you should know. By the way, most of them believe pretty strongly in the right of self-defense, and a lot of them own guns. They support the death penalty for puns.
@@eveningstarnm3107 ohm dear 🤣
The problem with most kettles is that the minimum amount they are designed to boil is about twice a regular mug of water. So if you're making a single brew you have no choice but to waste energy. A partial solution is to keep a thermos flask next to the kettle and pour the excess water into it after you've poured out your brew. Then when filling the kettle, use the water in the thermos. This way the water in the kettle is already hot and so takes less energy to boil. However, this is only really fully effective in the summer, during the winter if you have heating on, whatever energy you use in the home will end up as heat and thus reduce the amount of work your heating system has to do, so that extra energy is never really wasted.
Nearly every kettle sold nowadays has a flat element which means a half cup can be safely boiled
@@djhvideo Mine has a flat element on the bottom too. But if I try to boil a single mug's worth of water it sounds awful, all hissy and crackly. Every flat element kettle I've had has been the same like this. Maybe it's perfectly fine but it certainly doesn't sound like it. Also, the minimum fill level marked on the kettle is only reached at about 1.5 mug's worth of water and even then it sounds nasty, needs a little more to sound right.
Overfilling a kettle is not the huge waste of energy that the tabloid media likes to lead us to believe, the heat in the unused water simply dissipates into the room and supplements the central heating.
There's a big media campaign right now, likely sponsored by the greedy energy companies, to make the people blame themselves and each other for the rise in energy bills., and so much bad advice being passed around on social media. Whilst we're all fighting amongst ourselves, big corporate has free reign to keep charging more and more and more.
Great explinations!
Sound energy can be used to boil water if the amplification, frequency and duration are right. I used sound to boil a cup of water, but I had to shout at the kettle for 5 years...I think electricity is better 😄
🤣😂🤣😂 ah that made me laugh, on this premise I think my jack Russell could boil a kettle in seven seconds everytime the postman delivers a letter. 🤪👍😁
Very good video mate
I missed most of this video.....had to keep running to the toilet😵💫
John, great show. Even as a power engineer, this was a sweet refresher. It would be a very good topic to do the numbers on electric cars. Also, get a lot of views showing the truth. Topics: Charging times, costs, damage to batteries, temperature effects, etc. So many people have no idea about the costs. My quick analysis showed that my 30mpg car at USA $3.15/gallon gas, did better than the 50 kwh battery in your example, using your .35 pound/kw in England. Don't stop putting up videos. They are appreciated.
There will be more videos on this.
Gas / petrol in the USA is ridiculously cheap compared to the UK, where it's currently around 150p per litre, equivalent of nearly US$7 per US gallon.
Thank you very much!
Pro tip: "Power and Energy - Watts vs Watt Hours" is a great title. The cover picture says it the opposite way, "Energy and Power". So, would that be "Watt Hours vs Watts"? You want it to click with the audience right away. Make it easy for them. Keep the wording in graphical content consistent. It's just a minor detail, but thanks for your work. This is good stuff.
Really grinds my gears when people mix up kilowatts and kilowatt-hours - both Gary and Joe have done it recently on eFixx videos.
Maybe we should switch to using Joules instead of kilowatt-hours?
kWh to joules is a direct conversion, but using joules would result in some very large numbers.
Yes, it’d have to be mega joules really, wouldn’t it? I suppose my point is that the confusion comes because, to the layman the words are similar enough to cause confusion
@@The_Real_Pope1J = 1 Ws
1 kW = 1000 W
1 h = 60 min/h x 60 s/min = 3 600 s
So 1 kWh = 3 600 000 Ws = 3.6 MJ
100%
People understand liters, liters/sec & meters, meters/sec.....scales really easily km/h
watts & kwh are made up units, and only confuse people
nobody has to make videos to explain distance or speed of travel
we have more important things to be doing than explaining what a kwh is
Great videos, when is the next one. Can’t wait. Keep up the good work. Alan
Should be later this week.
Great video as always John, do you have any videos on hot tubs on PME supplies
John all okay at your end?
Havent seen a new video in nearlly a year.
Please upload videos they are fun to watch in my college breaks:)
Thanks John.
Hi
John, not related to this video but have you considered covering solar/battery ‘ESS’ systems and how to plan for and implement island mode? Your comprehensive approach would be perfect for this far from straightforward provision (given the usually limited kW capability of the ESS together with the need to establish a new TN-S).
A subject that social media has subjected to a layer of ‘ministry of misinformation’ dangerously incorrect advice and one that many ‘solar installers’ shy away from.
Hi JW - @4:58 I did listen and understand your maths as you did explained what you did - But as you wrote 2 / 60 - I question why did you not complete the division 2 / 60 = 0.033 infin 3 OR if the division was not needed why did you write 2 / 60 when you could have used 2 x 3 = 6 to derive your 6 / 60 = 0.1 example, Or at least cross the 60 and kW out to put emphasis on the 2 x 3 .Your maths written description would not make it easy for a lay student to follow if they did not speak English.
John . I have watched your videos over the years , but you dont seem to have done one on stanby generator setup and bonding etc , to household consumer units .Would be interested on your slant on the subject
I have a breville one cup kettle, it only boils one mug, takes about 30-40 seconds, 2800w
Ideal, as that only heats the water you use.
I have used one of those breville one cup kettles for many years. It only boils to 95°C so saves in two ways.
Such sad times that we are thinking of the cost of boiling a kettle
The media right now is being extremely misleading about power/energy consumption, the truth needs to get out a little bit more as I can see old people sitting in the dark this winter, whilst wasting huge amounts of energy on things which they don't know use a lot of energy over time.
John we need a video/test on how thermal insulation effect the CCC of cable.. because I think it's serious things we need to look at
Thanks Ross
Hi
John ward why dont you upload anymore?
I always see you posting on other platforms.
I wanna hear some "hello Im JW"
Also should there be resistance between neutral and earth on a tt system? And how much resistance?
Thanks Mr John ward.
Great video John - thanks. Often hear of kVA. Is that just the same as kW?
Enter power factor correction and angry DSOs
Generally speaking with rechargeable batteries you can only use a percentage of their stated capacity. Power banks have electronic monitoring to avoid over discharge. Lead acid should not be discharged bellow 12 to 11 volts, which is about ½ their stated capacity.
AFAIK.
What is the basic unit of measurement for electrical energy? A lot of the units we use are per time as a flowing energy.
Is there one that isn't "some unit per hour"?
The basic unit for energy is the Joule, but that is rarely used for electricity as 1J is a very small unit, and not of much use in the real world.
en.wikipedia.org/wiki/Joule
@@jwflame Yeah that makes sense, what with electricity being moving magnetic fields/electrons/whatever depending on which catchy RUclips video you watch on the topic. Just felt a bit weird measuring the capacity of a battery using a "per hour" measurement.
For fun you can convert joules to calories, and watt hours to joules... so you could work out how many calories are in an EV battery... or how many watt hours are in a marsbar 😆
I was looking into SI (the only truly international units) the other day and it's based on kilogram, metre, second and so on.
So a Joule is a Watt-second. Don't bother trying to get energy companies to use SI units, though :-)
I have converted by a factor of 3600 so often that I almost forgot why I do it :-)
I appreciste the vid's simple arithmetic, but it's worth pointing out that old school lead-acid batteries have had capacity rated in Amp-hours for many years, and it's misleading.
A rule of thumb is to use 1/2 of their capacity, but recent tests suggest that they don't produce their rated charge capacity unless you over-discharge them to about 1V per cell, slowly over 20 hours. No modern inverter I've seen would run with the voltage that low anyway, so it's pie in the sky.
For storage, I never use more than 1/3 of rated lead-acid capacity, and because of the slowly drooping voltage, you get even less energy in Watt-hours than that 1/3 suggests.
This is one reason that LifePO4 batteries are getting more popular, despite the higher price--you can use a lot more of the claimed capacity in real life.
Don't be afraid of saying that cattle can be turned on for 3 hours.
I've heard that builders using for kettles in each room to steam up and remove wallpaper. They are typing switches so the cattle stays on until the water runs out
Save a little bit of power by only boiling kettle to 95°C. Switch off when very close to boil. Reduces condensation every time.
My mate Paul told me watts are rubbish, he said jewels are the the real measure of hotness.
He said something about cool lambs(?) as well but I didn't understand.
A Joules is a unit of energy and is a Watt-Second. it is very important unit for Electrical Engineer's but is a very small unit indeed Much better to keep it simple and talk in kWh as that is the unit of electricity we all know and love. its a nice big unit
But if JW would like to take us deep into electrical principles that would be very interesting indeed to me eg heat power charge capacitors HP calories etc
Takes me back 50 year to technical collage days Never had to use most of it since but from time to time a bit of deep thinking has to be done and the calculator has to be deployed Remember the old Log book and all those horrible questions
Keep up the good work JW thanks
Watt does JW have on the top of his sponge desert after dinner?
Electreacle
No offence John but this is like the programs they used to play late at night on BBC2 when only the people with a brain would watch them (But learn a great deal in the process!) please keep up the good work
HI John,
I have a Timeguard RCD socket that has only one side working. Are you still accepting people sending items into you for a inspection on the fault? Would you like me to send it in and if so where do I send it... or should I goahead and put it in the WEEE waste..
Hi
I hope it's OK if I ask an unrelated question:
I replaced my electric 'focal fire' years ago, and I decided to just wire a plug onto the old one and use it in another room.
I believe the fuse in my consumer unit is 16A for the focal fire. I've used a 13A fuse in the plug that I attached to the old fire.
The problem is the plug seems to heat up, and I don't know why. A wattmeter shows the fire only drawing (?) about 8 amps on the highest setting, so I assume the 13A fuse is correct and gives me the 'headroom' that I need.
Why would the plug heat up...? Incorrect rating of the flex cord used maybe...?
Thanks.
Loose or damaged connection. Either the wire terminals, the fuse clips, or less likely is the socket it's plugged into. Some poor quality plugs overheat regardless of what's done with them.
The fuse will get warm in use, but certainly not hot.
If it's definitely the plug overheating (and not the socket which can transfer heat to the plug pins), then replace the plug with a new one. Cut about 5cm off of the end of the flex and reterminate, as overheated copper will be too soft to make a proper connection ever again.
@@jwflame I rewired it just to make sure all the connections were good, and I replaced the fuse too. The fuse clips seem nice and tight.
After doing this, it seems maybe slightly less warm, but still warm. I also noticed it's mainly (if not completely) the live prong (if that's what it's called) that is generating most (if not all) the heat. Does that make any difference to the diagnosis...?
I'm ready to just buy a new plug, but how do you know when you're getting quality? The current one cost £2.50 off Amazon, but the most expensive one at B&Q is only £3. It seems like every plug is a cheap plug, unless you know where to get a guaranteed quality one from...?
Thanks again.
I've now replaced the plug with the aforementioned B&Q "Diall" branded plug.
Still experiencing the same heating up of the live prong.
I'm going to see if it happens when I plug it directly into the wall socket. Currently it's plugged into a 6 way gang plug.
(I have a 1 hour battery charger where the instructions say never to plug it into a gang extension lead. Not sure why that's a problem, but I'm wondering if it applies here...?)
@@kye903 multi-gang sockets (parallel circuits) can lead to much lower resistance values and consequently greater current flow and localised heating. This should only be a problem if you are using most of the available sockets with several high current draw appliances simultaneously.
@@baldyslapnut. I've discovered that it happens even when I plug it directly into the wall socket. So I'm still none the wiser.
👍🏻
Jw im subscribed to your patreon since 2021 and you dont upload anymore:(
What is your view on smart meters
For most people today they have no benefit. Being able to see real time energy consumption isn't of much use to most people, and that can be done without a smart meter anyway.
Eventually they will allow time of use pricing, where electricity is priced according to demand and generation availability, and allow devices in the home to respond to that. That can be done in a limited way today with various trial schemes available, but they are not yet widespread and it will be a very long time before that is something that most people can benefit from.
Good video, of course I think most of your viewers will know but a 3kw heater won't necessarily use 3kwh and hour, due to the thermostat (especially in a confined place like a car)
Huge fan. watt a guy 😬
The latest Artisan Electrics video - “today the customer has generated 14 kilowatts of energy”
🤢🤢🤢🤢🤢🤢🤢
That kettle being on for 2 minutes which is 1/30th of an hour and 3.5p for 1/10th of an hour at 35p per Kwh don't match up.
3kW x 1/30h = 0.1 kWh
0.1kWh x 35p/kWh= 3.5p
Yes it does.
You’re forgetting that the kettle is using 3kW, not 1kW, so the numbers do add up
It highlights what a load of rubbish the EU were spouting, over limiting the size of vacuums and kettles. If the rate of work is reduced, then you just have to do it for longer. The cost in power and money is the same, but less convenient. Their level of understanding about this, is probably a measure of how much they actually know about the climate.
That whole thing was mostly about creating a monopoly for the European manufacturers, because it was only I think Dyson who were producing hoovers over 1600watts. The EU isn't what most people think it is, it's a federation run by unelected people who have their own goals and interests.
Yes. You have to use the low wattage vacuum cleaner for twice as long. It was a stupid idea that UK parliament got going in Brussels to reduce wattage.
Are you pretty much done with Utube? Are you posting content elsewhere?
There will be more videos here, and possibly on other platforms.
Thanks I will keep an eye out, I find your content helpful and informative, keep up the great work.
John, for someone known to critique the use of technical English, your use of the term “rate” is wrong. Rate of what? In physics force X distance = work done. Increase the force or the distance then you do more work. You increase the rate of work done. So what you should have said is that increasing the power means you increase the rate of doing work. Using the term ‘rate’ alone is not only grammatically incorrect, but it is physically meaningless. In electrical terms Work Done is Volts X Amps. Increase either and you increase the rate of doing work (= Power). In your water example it would have been useful to use a jug of water. That would have enabled you to explain that energy is the volume of water in the jug. Although perhaps outside the scope of this video, even better if you were to raise the jug of water to increase its potential energy and then draw similarities to why voltage is a potential difference between two points.
The video wasn’t about voltage potential. And the use of rate was in monetary terms and correct.
Would be much easier to understand energy bills if everyone just used J/s. I did a comparision between the increased prices in my country between petrol, natural gas and electricity and it actually makes sense, they are all the same in MJ.
Wow, 35pence for a kWh is a lot. I live in Ohio and pay only 9 cents. The bacon and beer sucks, though.
⠀
Most Americans would be poor in this country
why we do not get electrocuted when we touch a pan on electric stove?help
The heating element is electrically insulated from the outer element casing.
@@jwflame Thank you for the replay.....but there is bare resistance wire (Nickel-chromium alloy wire) stove on which we can see the glowing wire just under the pan and touching it
Hi
ρɾσɱσʂɱ
I'll mess up a bit. I will only touch on the topic of heating water in a kettle.
According to the formula for calculating energy consumption for heating water (from website How to Calculate Time to Heat Water) where (SHC*liquid weight*temperature difference)/time in sec. SHC is Specific Heat capacity and for water it is 4.2kJ/kg, liquid weight - for water it is generally assumed that 1l=1kg, the difference in temperature, i.e. let's say you pour water into a kettle from mains which is 15stC and heat it to 100stC, so the difference is 85 degrees. So let's assume that we want to boil 1l of water, let's assume the time in the video is 2min (i.e. 120sec). So we substitute into the formula and we get (4.2*1*85)/120 = 2.97kJ/s. kJ/s is watts, which is 2.96kW. A little more than 0.1kW. hmm. Okay, let's do it differently. Let's calculate how much time it takes to boil 1 liter of water, knowing the power of the kettle is (3kW). Substitute into the formula (4.2*1*85)/3kW gives us 119sec or 1m and 58.8sec.
In the video it is stated that it consumes 0.1kW of power, but for what? For how much water? In what period of time? I think that when converting to the duration of power consumption of a light bulb, pump or other device, it is correct as in the video, but in the case of water heating, it is not accurate and can mislead people. I would advise you to buy Energy Saving Power Meter Socket and see for yourself about the amount of energy consumption.
I dislike Wh, kWh or Ws and much prefer J or KJ.
So 1 W = 1J/s so 1Ws is simply 1J
Talk the talk but don’t answer any questions can’t be bothered or what Watt
Thanks, Been using & refining similar water analogy to teach students for years, your explanation gorgeous. Well done.
Looking forward to next in series "determine how much energy things do actually use"