Why do we still confuse KW and KWH?

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martyscholes

Well-known member
Joined
Dec 12, 2018
Messages
52
Location
Colorado Springs
I just read a thread where a poster conflated KW and KWH. That seems to be a regular mistake, despite EVs being more common than ever. What does it take to stop the confusion? The two really are a different as horsepower and a gallon of gasoline.

So that it's noted, a coulomb is a large number (some 6.24 x 10^18) of electrons. One coulomb passing through one volt of electrical potential is a joule. A joule is a (small) unit of work. One joule per second is a watt. One thousand joules per second is a kilowatt. One thousand joules per second for an hour (3600 seconds) is a kilowatt hour, which is equivalent to 3.6 megajoules. It is a shame that KW and KWH are so similar sounding and in writing, but a KW is a thousand joules per second and a KHW is 3.6 megajoules (regardless of time).

What does it take to get this right? Am I just too pedantic?
 
The language is dying. Millennials and Millennial wannabes start every sentence with "So..." It is annoying when people screw up simple terms but it is only going to 'sort of get worse' rather than better. Cwerdna is ever-vigilant about energy and power terms, if that's any consolation...
 
I long thought that adoption of EVs would bring a better awareness of electrical terms. But as time goes on I think it's going to become common for people to simply use kW when they mean kWH, and the reader/listener will be expected to resolve with context.
 
martyscholes said:
I just read a thread where a poster conflated KW and KWH. That seems to be a regular mistake, despite EVs being more common than ever. What does it take to stop the confusion? The two really are a different as horsepower and a gallon of gasoline.
...
What does it take to get this right? Am I just too pedantic?
It drives me nuts. It happens here, on other EV boards and on various EV FB groups. No on the last question.

I usually step in to correct or to seek clarification. Unfortunately, sometimes (often ignorant) folks will attack me for it. :roll:

People got really pissed off and annoyed at the cluster#$$% I pointed to at https://mynissanleaf.com/viewtopic.php?p=564743#p564743. What's scary and surprising is what Randy pointed out at https://mynissanleaf.com/viewtopic.php?p=565245#p565245. :shock:
 
cwerdna said:
martyscholes said:
I just read a thread where a poster conflated KW and KWH. That seems to be a regular mistake, despite EVs being more common than ever. What does it take to stop the confusion? The two really are a different as horsepower and a gallon of gasoline.
...
What does it take to get this right? Am I just too pedantic?
It drives me nuts. It happens here, on other EV boards and on various EV FB groups. No on the last question.

I usually step in to correct or to seek clarification. Unfortunately, sometimes (often ignorant) folks will attack me for it. :roll:

People got really pissed off and annoyed at the cluster#$$% I pointed to at https://mynissanleaf.com/viewtopic.php?p=564743#p564743. What's scary and surprising is what Randy pointed out at https://mynissanleaf.com/viewtopic.php?p=565245#p565245. :shock:

Your ;( overreacting. Or is it you’re overreacting? Calling folks ignorant doesn’t help.
 
Flyct said:
cwerdna said:
martyscholes said:
I just read a thread where a poster conflated KW and KWH.
What? They conflated kelvin watts with kelvin watt henries? That's terrible!

Electrical energy is commonly measured in units of kWh (kilowatt hours, lower case k and lower case h). Case matters too!

It irks me that when corrected, offenders feel offended, and claim "it's just one letter, therefore it's no big deal!" Well, it is a big deal. No-one would say it's 100 miles per hour from Boston to New York, if they meant 100 miles. (I have no idea of the actual distance, and only a vague idea of what a mile is). It just gets confusing. Maybe they actually meant that there is now some mode of transport that can actually average 100 mph between these cities? Perhaps fast rail has finally come to the USA?

I really hope that this present phase of lazy typing (units, spelling, grammar) is a passing fad. Humanity is better than that.

[/pedant]

[ Edit: corrected Kelvin -> kelvin, penant -> pedant. Sigh. ]
 
Flyct said:
Your ;( overreacting. Or is it you’re overreacting? Calling folks ignorant doesn’t help.
It would be you're. Well, unfortunately, that's what some of those attackers are. :(

In the case of kW vs. kWh, I don't care that much if folks get the case wrong. I let that go. I'm MUCH more concerned about using the right units.
 
cwerdna said:
In the case of kW vs. kWh, I don't care that much if folks get the case wrong. I let that go.
Ah. Then perhaps you have already pardoned me for my earlier gaff, the kelvin (which I used a capital K for). I did a quick search, and they all capitalized the K. Sigh. I'll go edit my shame now,
 
There are so many misconceptions and misunderstandings about all kinds of things, so confusion over kW vs kWh is relatively forgivable in my opinion.

I'm a lot more worried that some people still think that the earth is flat, or that there is zero gravity in space, or that the sun is actually yellow, or that science is a collection of irrefutable facts and so any "mistakes" that past scientists made, which are later refuted, somehow utterly disproves all scientific understanding and achievement (detractors of the theory of evolution love that argument).
 
cwerdna said:
LeftieBiker said:
LeafSpy Pro + Konnwei KW902 ELM327 BT OBDII dongle

Isn't that the BAD OBDII dongle...?
Yes. Of that model, some of them are bad. Some aren't. The ones that are bad can be fixed.

It may not be a good idea to advertise them in a signature line, though. Better to promote the ones that work 100%, and trash your CANBUS 0% of the time...
 
A lot of the confusion seems to come from laziness, and no small amount of arrogance that ignorance should be tolerated. Irony that.

As to *why* people have difficulty, I think it comes from trying to match the pattern of gallons, and gallons per time. This is why it is common to see kW/h: the presumption is that gallons are to kW as gallons/h are to kW/h. My wife and I have discussed this more times than I care to count. She understands that one of the units is an amount and the other unit is amount per time ... yet her mind refuses to accept that a rate is not written as something *per time.*
It does no good to write for her
(amount/time)*time, or to explain to her that the watt unit is a ratio by definition. She accepts the algebra as correct but cannot translate the meaning into everyday usage.
She finds her inability to use the units easily VERY frustrating. In her case it is not from lack of effort.

The Australians use the mega-Joule instead of the kWh to denote an energy amount. They lose some calculation convenience but I suspect have less confusion in the units.
 
SageBrush,
I think you've touched on the root of the confusion.
Most "rate units" have time in the denominator (miles/hr, km/hr, ft/sec) and kW just feels wrong to people who aren't interested in analyzing it.

If megajoules were the currency of choice I suspect people would be far more comfortable with it. Example; My battery holds 108 MJ when fully charged. My car consumes 14.8 MJ/hr when I'm traveling at 60 mph.

P.S.: You're a gm-volt forum alumnus, right? Tdiclub as well?
 
Flyct said:
To add to the confusion about units of measurement and which is TRULY correct.

There are countries that use the the metric system and then there is the country that went to the moon.

Flame suit on.

Fortunately, the subject of this rant is all SI units. It would be worse if we were characterizing things in Btu and horsepower.
 
css28 said:
P.S.: You're a gm-volt forum alumnus, right? Tdiclub as well?
I have posted in both those forums in the past.
Many would have been happy if I had not. Just like here :lol:

I wasted a lot of time on those forums but one person actually corrected some confusion on my part about COP and explained the thermodynamic basis. I'm indebted to that person. It might actually have been you.
 
css28 said:
It would be worse if we were characterizing things in Btu and horsepower.
I get nauseated just hearing those units.

I'm always amused by home heating and cooling conventions in Btu. The actual unit being measured is Btu/hour.
Somewhere along the line the industry bowed to ignorance.
 
Flyct said:
To add to the confusion about units of measurement and which is TRULY correct.
There are countries that use the the metric system and then there is the country that went to the moon.
The imperial system is correct, that is not the point. The point is that it is cumbersome.
As for your presumption, it is wrong. Electrical engineering went metric before I was born. I'm less sure about rocketry engineering but physics went metric long ago.
 
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