Charging efficiency.

[MY-user]

I was wondering if anyone knows how how efficiently you can charge Tesla battery. Charging is not a 100% efficient process. In other words to add 1kwh charge you need to consume more than 1kwh.

 

[dogmodes]

Depends on how you‘re charging, if it’s off 110 expect about 80% efficiency, and 96-97% from 240v

 

[MY-user]

Depends on how you‘re charging, if it’s off 110 expect about 80% efficiency, and 96-97% from 240v

Thank you! I didn't realize 240v is so efficient that we can round it to 100%.

 

[jcanoe]

Studies have shown that Level 1 (120V) charging efficiency can vary from 74% to ~84% depending on the battery temperature; Level 2 (240V) charging can be as high as 90%. I assume 90% charging efficiency when estimating Level 2 cost and charging time.

Public Level 2 charging is usually based on 208V commercial power (193V to 195V observed); the available power for charging is at best 13% lower than when charging at home where 240V is the standard.

 

[MY-user]

Studies have shown that Level 1 (120V) charging efficiency can vary from 70% to ~84% depending on the battery temperature; Level 2 (240V) charging can be as high as 90%. I assume 90% charging efficiency when estimating Level 2 cost and charging time.

Public Level 2 charging is usually based on 208V commercial power (193V to 195V observed); the available power for charging is at best 13% lower than when charging at home where 240V is the standard

Studies have shown that Level 1 (120V) charging efficiency can vary from 70% to ~84% depending on the battery temperature; Level 2 (240V) charging can be as high as 90%. I assume 90% charging efficiency when estimating Level 2 cost and charging time.

Public Level 2 charging is usually based on 208V commercial power (193V to 195V observed); the available power for charging is at best 13% lower than when charging at home where 240V is the standard.

Well, 70% is unacceptable. Would you happen to have a link where we could learn more about it?

 

[jcanoe]

Level 1charging with a low of 74% efficiency: A comparison of electric vehicle Level 1 and Level 2 charging efficiency

Low temperatures can be a major factor in extending time to charge in cold weather using Level 1 charging. The Tesla vehicle won't charge the battery unless, until the battery temperature is 10C (50F.) If Level 1 charging is your only option then plug in, start to charge immediately as soon as you arrive at home so the battery is already warm from driving.

 

[Rocky_H]

Depends on how you‘re charging, if it’s off 110 expect about 80% efficiency, and 96-97% from 240v

Thank you! I didn't realize 240v is so efficient that we can round it to 100%.

Well, people say it that way, which is a little misleading, because then people think it's because of the voltage. It's not specifically that. It's just more efficient with higher power. There is a certain amount of power loss that's just overhead to having the car awake running the charging process. If you have a very low power input, you are losing a high % of that. If you can get a much higher power input, then that same amount of overhead loss becomes a smaller %, and the efficiency is better.

As an example, let's say someone was charging at 120V and 24A. A TT-30 outlet does this. That is 2,880 Watts. What about if it were 240V at 12A? A 6-15 outlet would do that. That is also the same power, at 2,880 Watts. It's the same power, so the efficiency should be pretty close to the same, even though one is 120V while the other is 240V.

 

[WattsappMTL]

If you want to keep track of charging efficiency, get the (free) TezLab app and link it to your car. It estimates charging efficiency based on real-time data from the onboard charger. I'm getting 95% at Level 2 public chargers (6/6 kW), 97% at home (8kw). I no longer have access to data from my last 115V charging session but it's much lower (especially in cold weather).

 

[MY-user]

If you want to keep track of charging efficiency, get the (free) TezLab app and link it to your car. It estimates charging efficiency based on real-time data from the onboard charger. I'm getting 95% at Level 2 public chargers (6/6 kW), 97% at home (8kw). I no longer have access to data from my last 115V charging session but it's much lower (especially in cold weather).

Thank you for the info!

 

[MY1stEV]

The OptiWatt app will also show you charging efficiency and is free as well.

If I recall, I think I saw about 86%-87% charging efficiency on 5-15 (120v) and now get 95%-96% on 14-50 (240v).

 

[rejedejo]

I was wondering if anyone knows how how efficiently you can charge Tesla battery. Charging is not a 100% efficient process. In other words to add 1kwh charge you need to consume more than 1kwh.

Why is this even an issue? How come can't we just read off how much energy went into the car? Why are we all trying to calculate what our fancy cars tell us versus what we suspect may be the truth? Gasoline is sold by the .001 gallons and there's a stamp at the pump saying that some agency is verifying this data, so you can know exactly how much energy goes into a gasoline car.

I think there be a requirement to report the actual kilo Watt hours into the car, just like there's a requirement to log the actual miles.

By the way, the numbers your car reports to you are significantly lower than the kWh you put into it.

 

[rejedejo]

Well, people say it that way, which is a little misleading, because then people think it's because of the voltage. It's not specifically that. It's just more efficient with higher power. There is a certain amount of power loss that's just overhead to having the car awake running the charging process. If you have a very low power input, you are losing a high % of that. If you can get a much higher power input, then that same amount of overhead loss becomes a smaller %, and the efficiency is better.

As an example, let's say someone was charging at 120V and 24A. A TT-30 outlet does this. That is 2,880 Watts. What about if it were 240V at 12A? A 6-15 outlet would do that. That is also the same power, at 2,880 Watts. It's the same power, so the efficiency should be pretty close to the same, even though one is 120V while the other is 240V.

And then there's the difference between what your car tells you your usage is versus what it actually uses. I ran a 2013 S from february to august and averaged 667 kWh/mile over 2,000 miles. Input kWh.

 

[MY-user]

Why is this even an issue? How come can't we just read off how much energy went into the car?

By the way, the numbers your car reports to you are significantly lower than the kWh you put into it.

You answered your own question. I only wanted to see the difference between power in vs. power available.

 

[rejedejo]

Studies have shown that Level 1 (120V) charging efficiency can vary from 74% to ~84% depending on the battery temperature; Level 2 (240V) charging can be as high as 90%. I assume 90% charging efficiency when estimating Level 2 cost and charging time.

Public Level 2 charging is usually based on 208V commercial power (193V to 195V observed); the available power for charging is at best 13% lower than when charging at home where 240V is the standard.

208 3Ø power, but only 2 legs used. sigh.

 

[rejedejo]

I was wondering if anyone knows how how efficiently you can charge Tesla battery. Charging is not a 100% efficient process. In other words to add 1kwh charge you need to consume more than 1kwh.

Yeah, that's true. There should be an honest accounting of the energy into the car. Reported like the miles are. Kilo Watt hours into the car, then if you charge at your friend's house you can honestly pay him the difference, instead of doing stated charge change * efficiency and who know what.

 

[rejedejo]

You answered your own question. I only wanted to see the difference between power in vs. power available.

You answered your own question. I only wanted to see the difference between power in vs. power available.

What? the difference between what goes into your car and what the car reports having gone into it is not clear, certainly it's not the same, that difference is hard to measure.

 

[MY-user]

What? the difference between what goes into your car and what the car reports having gone into it is not clear, certainly it's not the same, that difference is hard to measure.

I didn't mean what the car reports went in. I was referring to what your electric meter shows vs. what tesla battery has available. By the way. I am still waiting for the car and didn't know that Tesla can show what went in.

 

[rejedejo]

I have an OBD CAN bus reader and use the "Scan My Tesla" app to read that CAN data. In that data Tesla reports AC charge kWh, DC charge kWh, Regen charge kWh and also Drive kWh. I also have a kWh meter between my outlet and charger. The energy issues are manifold: 1 is charge efficiency, that to me means the efficiency of the car reported AC charge kWh per input kWh from my meter, these are the losses while charging and likely a result of the AC to DC and then up-voltage converters. I charge at 240V and 32A, and the difference between the car's reported AC charge kWh efficiency and input kWh is averaging about 92%. The other issue is how many total input kWh am I using per mile traveled, and that number varies enormously with temperature and length of trips etc. The average long term usage for me has been around 420 watt hours per mile, that includes the charging inefficiency and all the other uses like radio, and security mode etc. I wish I could trust the car to tell me how many kWh it used by reporting it honestly like it reports miles. Input kWh. Not just drive kWh neglecting all other things that are essential to me and my car.

 

[MY-user]

The average long term usage for me has been around 420 watt hours per mile, that includes the charging inefficiency and all the other uses like radio, and security mode etc.

420wh/m is a lot. LR MY will go less than 180 miles on a full charge. I'm planning to take advantage of everything the car has to offer and not try to save the energy. Are sure it's not 320?

By the way, cool drone shot of your ride and the solar roof.

 

[boulder.dude]

I have an OBD CAN bus reader and use the "Scan My Tesla" app to read that CAN data. In that data Tesla reports AC charge kWh, DC charge kWh, Regen charge kWh and also Drive kWh. I also have a kWh meter between my outlet and charger. The energy issues are manifold: 1 is charge efficiency, that to me means the efficiency of the car reported AC charge kWh per input kWh from my meter, these are the losses while charging and likely a result of the AC to DC and then up-voltage converters. I charge at 240V and 32A, and the difference between the car's reported AC charge kWh efficiency and input kWh is averaging about 92%. The other issue is how many total input kWh am I using per mile traveled, and that number varies enormously with temperature and length of trips etc. The average long term usage for me has been around 420 watt hours per mile, that includes the charging inefficiency and all the other uses like radio, and security mode etc. I wish I could trust the car to tell me how many kWh it used by reporting it honestly like it reports miles. Input kWh. Not just drive kWh neglecting all other things that are essential to me and my car.

Have you done any testing to see how charging efficiency varies with current (A)? I suspect the lower current (while keeping voltage to 240V) the better.