Charging table - time to charge at 120/240V considering efficiency+

[dhiltonp]

Tesla's official charging rates are estimates, but I think they make NEMA 5-15 charging seem really bad (3 miles/hour for a model 3?).

I've plugged some data into a spreadsheet to calculate charging times for various volts and amps.

volts	amps (continuous)	kW	efficiency	kW actual	hours to charge 75kWh	hours to charge 70%	% added in 10h	miles/hr at 300Wh/mile	cost to charge 75kWh at 12 cents/kWh
120	12	1.44	85.40%	1.22976	60.0h	42.5h	16%	4.392	$10.54
120	15	1.8	87%	1.566	47.8h	33.7h	21%	5.22	$10.34
120	24	2.88	89%	2.5632	29.1h	20.0h	34%	8.544	$10.11
240	12	2.88	93.60%	2.69568	27.3h	19.2h	36%	8.9856	$9.62
240	15	3.6	94%	3.3732	22.2h	15.1h	45%	11.28	$9.57
240	24	5.76	93.90%	5.40864	13.1h	9.1h	72%	18.0288	$9.58
240	32	7.68	95.60%	7.34208	10.3h	7.0h	98%	24.4736	$9.41
240	40	9.6	94%	9.024	8.2h	5.1h	120%	30.08	$9.57
240	48	11.52	93%	10.7136	7.6h	4.1h	143%	35.712	$9.68

Bold efficiencies are from the tesla forums; the other values are guesses.

Charge rate can of course vary based on ambient; it can even be too cold to charge at all with a lower-powered charger.

Here are my values compared to tesla's posted numbers:

Adapter	Amps (continuous)	max mileage gained per hour	326/max mileage	my calculation	excess time
5-15	12	3	103.0h	60.0h	42.0h
5-20	15	4	81.0h	47.8h	33.2h
6-15	12	10	32.0h	27.3h	4.7h
6-20	15	14	23.6h	22.2h	1.3h
10-30	24	21	15.7h	13.1h	1.6h
14-30	24	21	15.7h	13.1h	1.6h
14-50 (MC)	32	29	11.0h	10.3h	1.6h
6-50 (MC)	32	29	11.0h	10.3h	1.6h
wall/6-50/14-50	40	36	9.0h	8.2h	0.8h
wall	50	42	7.9h	7.6h	0.2h

The times I've calculated differ drastically from the official times, particularly over 5-15 and 5-20.

What sort of charging times are you all seeing in practice?

 

[Rocky_H]

but I think they make NEMA 5-15 charging seem really bad (3 miles/hour for a model 3?).

That has been blatantly wrong ever since the Model 3 came out. You know what was in the chart for the old energy hog Model S in 2012? 3 mph. That's just ridiculously wrong that they copied over that same number exactly to the new MUCH more efficient Model 3, which has about 50% better efficiency. The Model 3 is more like 5 to 5 and a half or so, not 3 mph.

 

[jcanoe]

Why are the 5-20 and 6-20 limited to 15A? On a 20A circuit applying the 80% rule when charging an EV would be 16A. I actually had a ClipperCreek (CC) LCS-20P EVSE with a NEMA 14-50 power plug (the LCS-20 is rated at 20A, enables charging at 240V/16A (3.8kW)) and the Tesla Model Y would display 16A while charging at 4kW rate. I sold the CC LCS-20P and now I use an Amazing-E Fast EVSE that enables charging at 240V and 32A, the Tesla Model Y charging screen displays 32A and 8kW while charging.

When charging my Model Y using the LCS-20 EVSE I was able to add slightly more than 12 miles of range per hour. This is the same as I would expect using the Tesla Gen2 Mobile Connector with the 6-20 plug adapter. I would expect that the Gen2 Mobile Connector with the 5-20 plug adapter would enable charging at ~6 miles of range added per hour.

 

[dhiltonp]

Thanks for your input @jcanoe, I really appreciate your finding an issue and providing solid data points:

• 120V/16A: ~6miles
• 240V/16A: 12.x miles
• 240V/32A: 25.5 miles

I'm a little surprised - your 120V data matches what I had found but not your 240V data. I get your 240V values if I set efficiency to 90%. I wonder why your efficiency differs from the efficiency numbers I linked above.

I expect the onboard charger efficiency would be the same. I guess your 240V a little lower than usual, maybe from your power company, a voltage drop due to the 240v wire gauge/run length, or maybe a drop from your EVSE? As in yours is specifically designed for 16A, while the linked data points come from tesla's MC which can handle 32A. I guess it could be due to a difference in ambient temperature too...

I don't want to throw out your data. I know that the linked numbers he was comparing values from the distribution panel and the car. Assuming his device measures voltage directly and uses a clamp style ammeter (I don't actually know), I don't think it would under read values - and your 120V values match :/

I can't edit my post so here are the updated tables:

volts	amps (continuous)	kW	efficiency	kW actual	hours to charge 75kWh	hours to charge 70%	% added in 10h	miles/hr at 270Wh/mile (2021 LR EPA)	miles/hr at 304Wh/mile (2021 P EPA)	cost to charge 75kWh at 12 cents/kWh
120	12	1.44	85.40%	1.22976	60.0h	42.5h	16%	4.55	4.05	$10.54
120	16	1.92	87%	1.6704	44.9h	31.6h	22%	6.19	5.49	$10.34
120	24	2.88	89%	2.5632	29.1h	20.0h	34%	9.49	8.43	$10.11
240	12	2.88	93.60%	2.69568	27.3h	19.2h	36%	9.98	8.87	$9.62
240	16	3.84	94%	3.6096	20.5h	14.4h	48%	13.37	11.87	$9.57
240	24	5.76	93.90%	5.40864	13.1h	9.1h	72%	20.03	17.79	$9.58
240	32	7.68	95.60%	7.34208	10.3h	7.0h	98%	27.19	24.15	$9.41
240	40	9.6	94%	9.024	8.2h	5.1h	120%	33.42	29.68	$9.57
240	48	11.52	93%	10.7136	7.6h	4.1h	143%	39.68	35.24	$9.68

Adapter	Amps (continuous)	max mileage gained per hour	my calculation	326/max mileage	my calculation	excess time
5-15	12	3	4.55	103.0h	60.0h	42.0h
5-20	16	4	6.19	81.0h	44.9h	36.1h
6-15	12	10	9.98	32.0h	27.3h	4.7h
6-20	16	14	13.37	23.6h	20.5h	2.0h
10-30/14-30	24	21	20.03	15.7h	13.1h	1.6h
14-50/6-50 (MC)	32	29	27.19	11.0h	10.3h	1.6h
wall/6-50/14-50	40	36	33.42	9.0h	8.2h	0.8h
wall	50	42	39.68	7.9h	7.6h	0.2h

 

[jcanoe]

When charging at home my Tesla Model Y's charging screen rarely shows 240V or if it does then the voltage drops a bit once charging begins, ~233V to 235V is typically what I see while charging. The Amazing-E Fast EVSE is capable of 240V/32A. Sometimes the Tesla shows 31A. I contacted ClipperCreek and they told me that this was normal, that the vehicle and the EVSE negotiate the maximum amperage for each charging session. My lifetime Wh/mi number is 268Wh/mi. I used that value or 270Wh/mi, I can't recall which one. I frequently precondition my Model Y, this impacts the time to charge, i.e. from 70% to 80% SOC but does not show in my lifetime Wh/mi. If I was not preconditioning I would need less time to charge each day. I use 74kWh as the capacity of the battery in my Model Y (Tesla provided me with documentation with the vehicle for a Maryland state tax rebate program that was still in effect when I purchased my Model Y in June, 2020.) So I convert a 10% charge to ~7.4kWh.

 

[Rocky_H]

When charging at home my Tesla Model Y's charging screen rarely shows 240V or if it does then the voltage drops a bit once charging begins, ~233V to 235V is typically what I see while charging. The Amazing-E Fast EVSE is capable of 240V/32A. Sometimes the Tesla shows 31A. I contacted ClipperCreek and they told me that this was normal, that the vehicle and the EVSE negotiate the maximum amperage for each charging session.

Huh--that is kind of interesting. 233V is kind of low, and I wonder if the Amazing-E internally monitors the voltage level, and if it is getting pretty low if it backs off the amp signal. That would make sense then why you sometimes get 31A instead of 32A, if it is sensibly lowering that a little to keep the voltage up.

 

[dhiltonp]

When charging at home my Tesla Model Y's charging screen rarely shows 240V or if it does then the voltage drops a bit once charging begins, ~233V to 235V is typically what I see while charging. The Amazing-E Fast EVSE is capable of 240V/32A. Sometimes the Tesla shows 31A. I contacted ClipperCreek and they told me that this was normal, that the vehicle and the EVSE negotiate the maximum amperage for each charging session. My lifetime Wh/mi number is 268Wh/mi. I used that value or 270Wh/mi, I can't recall which one. I frequently precondition my Model Y, this impacts the time to charge, i.e. from 70% to 80% SOC but does not show in my lifetime Wh/mi. If I was not preconditioning I would need less time to charge each day. I use 74kWh as the capacity of the battery in my Model Y (Tesla provided me with documentation with the vehicle for a Maryland state tax rebate program that was still in effect when I purchased my Model Y in June, 2020.) So I convert a 10% charge to ~7.4kWh.

If I plug in 233V*31A*95.6% efficiency, I get 6.9kW. 6.9kW/.27kWh/mi = 25.5 miles/hour.

I messed up something else - the 270Wh/mile EPA number actually already includes a charge efficiency of ~88%. I should have used 238Wh/mile for full equivalence - although I know they aren't the most useful values.

 

[RidgeRunner]

I would like to see a table or spreadsheet of the different superchargers 300, 250, and 150 etc and the time to charge from different states of charge percents to different higher states of charge. Ex. 20% to 80% or 30% to 90%. In addition the range degradation effect of higher speeds (MPH). Here is why: the Tesla salesman when asked about time to charge he said it would only take 20 minutes to charge. Maybe that is for an optimal V3 300 KW charger. I don't know if that is right? but what I see on a trip to Dallas is some 150KW chargers and one 300KW. I'd like to drive from south end of Houston to north side of Dallas( 300 miles) with out making three 45 minute stops and having to drive at 65 MPH? (I know that is an exaggeration) I also realize that the info is available on Tesla's trip planner. I don't have a Tesla but would like to predict what the trip would be like before making the purchase.

 

[jcanoe]

I would like to see a table or spreadsheet of the different superchargers 300, 250, and 150 etc and the time to charge from different states of charge percents to different higher states of charge. Ex. 20% to 80% or 30% to 90%. In addition the range degradation effect of higher speeds (MPH). Here is why: the Tesla salesman when asked about time to charge he said it would only take 20 minutes to charge. Maybe that is for an optimal V3 300 KW charger. I don't know if that is right? but what I see on a trip to Dallas is some 150KW chargers and one 300KW. I'd like to drive from south end of Houston to north side of Dallas( 300 miles) with out making three 45 minute stops and having to drive at 65 MPH? (I know that is an exaggeration) I also realize that the info is available on Tesla's trip planner. I don't have a Tesla but would like to predict what the trip would be like before making the purchase.

The Tesla salesperson is technically correct. Most Supercharger charging sessions are ~20 minutes (by choice.) The Tesla owner/operator makes a choice, decides that their time is better spent driving than waiting for the Tesla vehicle to charge to more than 70% (80% maximum.) That is the preferred way to use the Supercharger network. You spend less time charging if you stop every 2 to 2.5 hours and charge for ~20 minutes. You'll arrive at your destination having made one or two more charging stops but you'll probably be less fatigued.

A great way to plan road trips in a Tesla or any EV is to use A Better Route Planner (ABRP). ABRP is available as a web-based application and as a phone app. Once you plan a few trips using ABRP you really appreciate the convenience of having the Tesla Supercharger network. Currently the Tesla Supercharger network can only be used by Tesla vehicles. Tesla has stated that in the future non-Tesla vehicle will be able to use the Supercharger network. In most places today in the US you can stop and charge at a Tesla Supercharger every 120 to 140 miles.

A Better Routeplanner

 

[dhiltonp]

Here are the results of a recent Tesla model 3 charging test.

Conveniently some of their results are really easy to remember. From the first infographic:

• 0-60% in 21 minutes
• 60-90% in 21 minutes
• 90-100% in 21 minutes

Also from the article:

In 10 minutes I had reached 32% state of charge and added back 24 kWh. That's enough to power the Model 3 for 100 miles of 70-mph highway driving range. It took a total of 23 minutes to reach 65% SOC, at which point I added back 200 miles of range.

For now, the difference between V2 and V3 superchargers is minimal (maybe 5 minutes) unless power is being shared between stalls (over 50% in use). The difference is minimal because the model 3 and model Y don't spend much time at peak charging rates (see the graph in the linked article).

 

[threeputts]

Here are the results of a recent Tesla model 3 charging test.

My takeaway from that video is aim to arrive at a supercharger at 9% with a pre-conditioned battery. You can get from there to 60% in less than 17 minutes.

 

[UncleCreepy]

You can drain the battery as low as you are comfortable with a preconditioned battery, if necessary.
During a trip from Eastern Ontario to BC I frequently drained the battery to 4-6% and then enjoyed the high supercharging power (250 kW or 1666 kph or about 17 miles/minute).
Never had enough time for a thorough number 2 while supercharging .
Even if the extra 66% power (V3 vs. V2 SuC) only last for a limited time, it makes a considerable difference to charge at an additional 100 kW.

 

[Wolfpacker83]

I use the standard wall outlet and can only charge at 8A due to my circuit. My efficiency (according to optiwatt) is always between 70-80%. Is this normal?
Does the charging cost that optiwatt displays take into account the efficiency or does the cost assume a 100% efficiency? (I searched the optiwatt site but couldn't find the answer)

 

[RidgeRunner]

Here are the results of a recent Tesla model 3 charging test.

Conveniently some of their results are really easy to remember. From the first infographic:

• 0-60% in 21 minutes
• 60-90% in 21 minutes
• 90-100% in 21 minutes

Also from the article:


For now, the difference between V2 and V3 superchargers is minimal (maybe 5 minutes) unless power is being shared between stalls (over 50% in use). The difference is minimal because the model 3 and model Y don't spend much time at peak charging rates (see the graph in the linked article).

thank you, I'm not seeing a large and significant reason to be concerned. chargers may get more crowded in the coming months. 6 months ago I never saw a Tesla around my neck of Houston. now I'm seeing two and three while out and about.

 

[dhiltonp]

I use the standard wall outlet and can only charge at 8A due to my circuit. My efficiency (according to optiwatt) is always between 70-80%. Is this normal?
Does the charging cost that optiwatt displays take into account the efficiency or does the cost assume a 100% efficiency? (I searched the optiwatt site but couldn't find the answer)

Unfortunately, that efficiency is likely accurate, in which case you are spending an extra 15% on electricity vs. the optimum.

When charging, not all power is used for charging; some constant overhead is used to operate the computer and BMS; let's say 200W.

At 120V, this would be about 1.5A. Charging at 2A would be ~25% efficient, 3A ~50% efficient, 6A 75% efficient, 12A ~87% efficient.

This calculated efficiency is actually higher than the actual efficiency would be; I'm ignoring AC-DC converter losses etc.

 

[Trip McNealy]

A great way to plan road trips in a Tesla or any EV is to use A Better Route Planner (ABRP). ABRP is available as a web-based application and as a phone app. Once you plan a few trips using ABRP you really appreciate the convenience of having the Tesla Supercharger network. Currently the Tesla Supercharger network can only be used by Tesla vehicles. Tesla has stated that in the future non-Tesla vehicle will be able to use the Supercharger network. In most places today in the US you can stop and charge at a Tesla Supercharger every 120 to 140 miles.

A Better Routeplanner

Silly question but what is the difference/advantage of using ABRP vs. the maps/navigation functionality in car which also brings up the recommended Supercharger stops along the route?

 

[boulder.dude]

Silly question but what is the difference/advantage of using ABRP vs. the maps/navigation functionality in car which also brings up the recommended Supercharger stops along the route?

Main advantage of ABRP is you don’t need to be in the car to use it when you want to figure out some stuff & plan a trip.

Also, you can specify start location, and start/end SOC % which also helps with planning.

When you’re actually driving, use the car nav over ABRP — it’s more accurate.

 

[Rocky_H]

Silly question but what is the difference/advantage of using ABRP vs. the maps/navigation functionality in car which also brings up the recommended Supercharger stops along the route?

Main advantage of ABRP is you don’t need to be in the car to use it when you want to figure out some stuff & plan a trip.

That, and also the Nav in the car can only do anything from where the car currently is at the starting point. If you want to check some options for return trip, or a hypothetical from some other city to somewhere else, the car's Nav won't let you pick somewhere else as your starting point.