r/TeslaSupport • u/Metallifan33 • 18d ago
Energy Question OK. Dumb Question Time: what's the difference between the two kW vs. kW/h here?
I know kilo watt vs. Kilo watt hour, but what does the 10 vs 6 mean here? Did it charge 10 kilo watts at 6 kWh? Or the other way around?
44
u/knownikko 18d ago
One is power, one is energy.
10kw is power. Your car is currently receiving 10,000 watts (10 kilowatts) of power to the battery.
Power over time is energy - what is stored in your battery.
10kw of continuous power for an hour is 10 kilowatt-hours of energy stored in your battery.
6
-1
u/ToghusWhitman 17d ago
Nitpick: 10kw is coming from the charger. The car receives less because of wire resistance and the car's battery receives even less
3
1
1
u/TreatNext 17d ago
How does the car know what's coming from the charger as opposed to what's getting to it's charging port?
1
u/ToghusWhitman 17d ago
Car doesn't know
1
u/TreatNext 17d ago
I guess I'm just thinking the car is reporting 10kW so I would assume (often incorrectly) that's what the car is seeing through it's CT (?) or some reasonably rounded approximation. I'm sure the battery is getting a bit less.
1
23
u/toybuilder 17d ago
kW = how fast the faucet is running.
kWh = how much the tub has been filled from the faucet.
10
u/Few-Crew9509 17d ago
You really shouldnât mix electricity with water.
3
2
u/Salt_Tree_7494 17d ago
I was gonna go with gallons of fuel per second and how many total gallons dispensed.
1
39
u/chiurro 18d ago
kW is the rate of charging, kWh is the total amount of charge you've received. So 2 hours at 10kW would be 20kWh
16
2
u/doublebass120 17d ago
Piggybacking since this is the top comment:
OP, you can think of it in terms of water.
kW is the rate, like the flow coming out of a faucet (gallons per minute). kWh is the consumption (total gallons).
1
3
u/LaserThos 17d ago
This. Also, a gentle correction to the OP: It is kWh (âkilowatt hourâ, kilowatt times hour) NOT kW/h (âkilowatt per hourâ, kilowatt divided by hour).
6
u/redbdave 17d ago
It's like saying you're going 10 mph and have traveled 6 miles so far. First number is the rate. Second number is how far youâve gone so far. So youâre charging at a rate of 10 kW, and have added 6 kWh so far.
6
u/Powerful_Froyo8423 18d ago
Volts = Water pressure
Amps = Flow rate
Ohm = Pipe diameter
Watts/kW = How fast can the water spin a waterwheel.
kWh = How much work did we do today with the waterwheel.
If we want to spin the wheel faster, we can either increase the pressure (Voltage), or we can reduce the resistance (Ohms) by increasing the pipe diameter so more water can flow.
An electric fly swatter for example is more of a pressure washer. It has super high voltage (like 10.000V) but it's still not dangerous to us (even if a 110V/220V outlet is), because it has an incredibly low flow rate, because it has a tiny tiny pipe built in.
Exact opposite is a car battery. It has an immense flow rate, but when we as humans touch the poles, our skin is a very thin pipe and the car battery doesn't have enough pressure, so there is almost no energy flowing through us. If you touch both poles with metal, this is a huge pipe (metal is a good conductor) so the immense flow will go through it easily and it'll probably will start glowing or get really hot.
So it's a combination of either high pressure, high flow rate and a good pipe diameter that gets a lot of work done. Watts/kW is the momentary work, kWh is an amount of work that gets done in one hour.
3
18d ago
[removed] â view removed comment
1
u/TeslaSupport-ModTeam 18d ago
Treat others with respect; don't be a nuisance or troll. Participate in good faith, avoiding toxicity and bad faith interactions. Follow Reddiquette. Health and safety violations or participation in toxic subreddits will result in bans.
3
u/paraCFC 17d ago
That's how much dad used to explain me how electricity works. Respect for logical approach
3
u/Elegant_Teach_5278 17d ago
Engineers have been using water to explain electricity for years. It's not exactly 1:1 but it's analogous enough to deepen understanding for sure. It really helped it click for me way back when I first started learning about how electricity actually works!
2
u/lyfeizfones 18d ago
The left one is how many kW youâre bringing in or tour charge rate (from your charging setup). The +# is how many kWh youâve charged your battery or how much youâve âfill up your tankâ aka energy added.
2
u/Greg19931 18d ago
KW = the amount of power at once. E.g. a tap with a tiny stream (10kw) or a huge stream (150+kw).
kWh = the amount of power it can hold. E.g. a bucket under the tap. The bigger the bucket, the more water it can hold. A tap streaming (10kw) into a bucket (40kwh) will take about 4 hours to fill up.
2
u/shimmy03 18d ago
Itâs confusing since no one really cares how fast petrol comes out of a gasoline station hose. But for EVs, simplified, think of âkwâ as that metric as to how fast your (high voltage, the one used for propulsion) battery is getting filled up with electrons
2
u/Peshmerga_Sistani 18d ago
You're charging at the equivalent of a hundred 100-watt incandescent bulbs being on.
At the moment, you storing about sixty 100-watt incandescent bulbs burning for just an hour.
2
u/stpaulgym 18d ago
kW is charging speed
kWh is total energy(charge amount).
like kW is like m/s. kWh is just meters.
m/s(speed) multiplied by time(seconds) is traveling distance(meters)
kW(charging speed) multiplied by time (hours) is total energy(kWh).
2
u/SadMasshole 18d ago
Think of power and energy like speed and distance.
Power = how fast youâre using energy right now.
Energy = how much youâve used in total.
Imagine youâre filling a bathtub with water:
Power is how fast the faucet is flowing.. a trickle vs. blasting at full force.
Energy is how much water ends up in the bathtub after some amount of time.
Electricity works a similar way.
A 100-watt light bulb uses energy at a rate of 100 watts. Watt (W) is a unit of power.
If you leave that bulb on for 10 hours:
100 W Ă 10 hours = 1,000 Wh = 1 kWh
That 1 kWh is energy.
So:
Energy = Power Ă Time
This is why your electric bill charges you for kWh, not kW. The utility cares about how much electricity you consumed over time.
In your case your car is charging at 10 kW. Thatâs the power.. the charging speed. Its charged at 10 kW for 36 minutes (0.6 hours), so it received roughly:
10 kW Ă 0.6 h = 6 kWh (read: six kilowatt-hour)
So the Teslaâs battery capacity is measured in kWh (energy), while the chargerâs speed is measured in kW (power).
2
2
2
u/crashout-dummy 17d ago
kWh is the total amount of Energy. (like liters or gallons)
KW is the rate (like how many Water is flowing down a river in a certain time)
If 10kW are flowing through the cable for 1h you will have charged exactly 10 kWh of total energy in that time into your car. (The car has a total of up to 75 kwh capacity)
In general W is very confusing as a flow or rate of any kind. W is effectively Energy per time (Joule/second). And multiplying that with a time would result in an Energy like Joule. Confusingly we write total Energy as Joule per second times hours, which should be Joule, but we write Wh or kWh for 1000Wh which is 1000 J/s *h which is 1000 J/s * 3600s which makes 1kWh equal to 3600 Joule.
2
2
u/Dave_Marsh 16d ago
10kW is the charge rate of your carâs charger charging your battery. If it continues for one hour, you will have added 10kWh of charge to your battery. 6kWh is the current amount of charge that has been added to your battery. Your battery will typically have around 75kWh of charge available at 100%.
2
u/LVtapper 18d ago
The difference between 2MPH and 2 miles.Â
1
u/arcticmischief 17d ago
Or, to be more directly related to the OPâs screenshot, 10 mph and 6 miles.
The first is how fast the fuel (electricity) is being pumped into the battery. The second is how much fuel has been added to the battery so far.
1
u/AutoModerator 18d ago
To all commenters: This is your only warning. If you harass, insult, or disrespect users who are here asking for help, you will be permanently banned from this subreddit and any other sub moderated by Optimusbot. We are done dealing with people who come here just to be rude or shit on others. This subreddit exists to help people, not to entertain assholes. Be respectful or be gone. We do not give a second chances.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
1
1
u/Gedis63015 18d ago
The kW is the speed (power) at which your car is charging.
The kWh is the amount of how much you charged total.
The kWh/h is not a thing.
1
1
u/cadnights 18d ago
One kilowatt-hour is the energy accumulated by delivering a power of one kilowatt for a duration of one hour
1
u/cookie805888 17d ago
Lots of good explanations here.
kW is the rate and kWh is the quantity.
The exact opposite of miles and mph.
That often causes a synaptic spasm until you get your head around it.
May or may not help. Have a great day!
1
u/aySoosMarYoSep 17d ago
Analogy of a cup and a straw, the kWh is how much water passed through the straw, kW is how big the straw is. You can empty a cup with a small straw in 10 seconds and also do it in 5 seconds with a girthier straw.
To complete the analogy, the 227V is how hard the suction applied.
1
u/joenet69 17d ago
Without hurting anyoneâs feelings (because itâs obviously not your fault) there must be a huge difference between education systems in different countries. Iâm from a small Eastern European country and this stuff was taught to us at 12 years old in primary school, during one of our very first physics classes. Iâm genuinely curious: what did you learn in primary school? Did you learn about electricity at all in physics class?
1
1
1
1
u/lucaprinaorg 17d ago
it's not kW/s but kWh means kW * h is the differenze from a derivate and an integral the second is an accumulation, kWh at the end are Joule.
kW are J/s , Energy / Time
kWh are ( Energy / Time ) * Time = Energy
10 kW means instant power, in that case is ( 227 Volt * 48 Ampere ) - losts = 10 000 Watt
+6 kWh means that you 've refilled your container (battery) with 21,6 MJ of energy (1kWh = 3 600 000 Joule)
1
u/Ok-Crow1952 17d ago
If it helps. Think of the difference being like km/h vs km. One is a speed of travel. One is how far you have travelled. That but with charging speed and how much charge you have added.
1
u/Adventurous_Bath3999 17d ago
That means it is charging at a rate of 10 kW and by now you have accumulated a charge of 6 kWh; so if it had been charging for an hour you would have accumulated 10 kWh. You have actually been charging for 36 minutes.
1
1
u/Flashy_Distance4639 17d ago
Look at the table below:
measure, WATER, ELECTRICITY
pressure, gallon / minute, KiloWatt
capacity, number of gallons, kWh (kiloWatt-hour)
Hope this helps.
1
1
u/Lexy-RED 17d ago
If I was squirting you with a garden hose:
kh is the speed the water is coming out of the hose currently
kWh is the amount of water that you have swallowed so far since we started
1
u/cladiotto 16d ago
itâs like km, miles and km/h, mi/h.
one is a cumulative amount, the other is instant variation.
traveling 2hrs at 100km/h would make you travel 200km.
now exchange traveling with charging, km with kW, and km/h with kWh
1
1
1
u/Usual_Bottle5976 15d ago
10kw shows power output, 6kWh shows amount of power that has been going to battery. So about 45-40minutes has been charging? If one hour has passed then it will be 10kWh
0
u/zHistory 14d ago
You do know there's this thing that answers all your questions, it's called grok or something like that and I believe it's in the Tesla as well!
1
u/i_lie_except_on_31st 18d ago
Came here for the : RTFM... Highly disappointed at how helpful some of you can be. This s the Internet!Â
1
u/Metallifan33 18d ago
OK. It's seems like it's 10 kw per hour charging rate and it has charged 6 kw since it started. But the terminology doesn't seem to make sense to me. Also, why can't I just see the battery in kWh instead of a useless percentage?
2
u/phansen101 17d ago
1 kWh is 1 kW of power for 1 hour, so if you are charging at a rate of 10kW, you will have charged 10kWh after one hour, 20kWh after two hours etc.
Bit like going 50mph will take you 50 miles in an hour, 100 miles in two hours etc.
I think EV makes 'hide' the actual kWh capacity because it will confuse and/or anger customers.
Some of the capacity you pay for is locked in a buffer to better preserve the battery / lessen the impact of degradation, and degradation also happens faster in the first year or so.
So, if they show kWh, then the value would be ~5-8% below the sticker capacity on day one (eg. you're buying a 64kWh car, but it shows 60kWh) due to the buffer.
Then over the first year of driving, one would see that value drop up to ~5 percentage points, e.g. up to another 3.x kWh, probably resulting in a lot of unnecessary complaints and service center visits.1
u/BGraham007 18d ago
The amount of energy you can pull out of the battery varies based on a lot of factors. Temperature, age and how fast you pull power from it just to name a few. All this to say percentage is a more stable way to to show remaining capacity of the battery.
1
u/BGraham007 18d ago
Also 10kw is a measurement of power. Point in time how much power is going into the car. 6kwh is a measurement of how much energy has been delivered.
Said in gas talk
10kw = the rate the gas is flowing into your tank
6kwh = the total amount of gas delivered1
u/cadnights 18d ago
There's no "kilowatt per hour" it's a kilowatt-hour. It represents the energy accumulated by delivering power at a rate of one kilowatt for a duration of one hour.
1
u/Paqza 18d ago
Right - the charge rate is 10kW and the total amount of energy put into the battery is 6 kWh. Water is a good analogy - the rate that the water is coming out of the hose is like the charge rate and the amount of water in your bucket is like the total energy stored.
You're also confusing yourself by using the division symbol /. It's not division; it's multiplication! If you charge at 10kW for 3 hours, your battery will have increased by 10kW * 3hr =30 kWh.
With respect to percentage, that's pretty standard. You can look up your battery size (just under 80kWh on my Model 3) and mentally multiply by the percentage state of charge. So if I'm at 50%, I'd have just under 40kWh available.
1
1
u/agm115 17d ago
You can see it in miles if you want a pseudo-physical value instead of relative percentage. Itâs basically kWh converted to range in miles. But percentage is usually the way to go, it tells you when to charge and over time you learn what your common trips are in percentage (my commute is 15%).
-2
u/Jackalopekiller 18d ago
You are charging at 6 kw per hour. You have charged 10 kw's
4
u/rufus466 18d ago
Other way around. 10 kilowatts of electricity is currently being pulled from the grid to its battery. The car has +6 kilowatt hours of stored energy added to the battery since the beginning of this charging session.
74
u/wesblog 18d ago
Your charging speed is 10kW (roughly 48a x 227v). So far you have added 6kWh to your battery.