Real World 5-15 Charging Speeds

[uberfunk]

I'm currently charging my 2022 Model 3 RWD with a regular 110v 12a NEMA 5-15 outlet. I get 8km/hr (5miles/hr), which is much more than what Tesla advertises on their website (they say 4.8km/hr).

I live in a townhouse and I had an electrician take a look at my panel - he said it looks pretty full. This is just based on what he saw without doing an inspection. He said I won't be able to install anything over 20amps without an inspection. Since I'm already "pretty maxed", I probably won't be able to install a 30amp anyway so the inspection seems like a bit of a waste of money. 20amps would be nice...but again, not sure if it's worth the cost of the inspection, especially since he could do the inspection and then find out that I can't even do 20amps.

However, he said he would be able to install a 2-pole 15amp breaker and NEMA 6-15 outlet without an inspection.

I'm curious, anyone here charging with 6-15? If so, what are your real world charging speeds like? Should I expect more than the Tesla figure of 17.7km/hr?

Thank you.

 

[jjrandorin]

I'm currently charging my 2022 Model 3 RWD with a regular 110v 12a NEMA 5-15 outlet. I get 8km/hr (5miles/hr), which is much more than what Tesla advertises on their website (they say 4.8km/hr).

I live in a townhouse and I had an electrician take a look at my panel - he said it looks pretty full. This is just based on what he saw without doing an inspection. He said I won't be able to install anything over 20amps without an inspection. Since I'm already "pretty maxed", I probably won't be able to install a 30amp anyway so the inspection seems like a bit of a waste of money. 20amps would be nice...but again, not sure if it's worth the cost of the inspection, especially since he could do the inspection and then find out that I can't even do 20amps.

However, he said he would be able to install a 2-pole 15amp breaker and NEMA 6-15 outlet without an inspection.

I'm curious, anyone here charging with 6-15? If so, what are your real world charging speeds like? Should I expect more than the Tesla figure of 17.7km/hr?

Thank you.

The only one that isnt accurate from teslas charts is the 120v 5-15. That one is about 5 miles per hour like you mention, at least on a model 3. The rest of them charge pretty much exactly what tesla says, or very close, given your voltage.

 

[Jeremy3292]

You said you couldn't install anything over 20 amps, so why can't you do a 6-20 outlet? That would be a 20 amp 2 pole breaker and would give you 15-16 mph which is very adequate for most people.

If not a 6-15 is definitely the best option and the Tesla charts are accurate. The 5-15 and 5-20 are not accurate and are understated a few mph.

 

[uberfunk]

You said you couldn't install anything over 20 amps, so why can't you do a 6-20 outlet? That would be a 20 amp 2 pole breaker and would give you 15-16 mph which is very adequate for most people.

If not a 6-15 is definitely the best option and the Tesla charts are accurate. The 5-15 and 5-20 are not accurate and are understated a few mph.

If I wanted 30amps, I would for sure need an inspection but the electrician said he doesn't think I would have the capacity for it anyway so it might be a bit of a waste. But he thinks I could do 20amps but it would need an inspection to confirm. I was hoping to get some real-world numbers of 6-15 charging since that wouldn't need an inspection and if it was more than the 17.7km/hr that Tesla reports (like if it hit 20km/hr), I might go that route since it would be "good enough" for our needs. But it looks like the Tesla figures are actually accurate, for anything other than 5-15 and 5-20.

As a bare minimum Level 2, 17.7km/hr is still pretty good for our needs but 6-20 would be amazing to have. Is $150 for the inspection for an additional 8-9 km/hr worth it?

 

[wws]

You'd get a bit over 2x a 5-15. Reason is there is some fixed overhead when the charging circuit is active. This fixed overhead does not change when using higher voltage and/or current. So a higher percentage of the power goes to charging vs overhead. Worth doing. Especially where it gets cold - like in Canada.

 

[Jeremy3292]

As a bare minimum Level 2, 17.7km/hr is still pretty good for our needs but 6-20 would be amazing to have. Is $150 for the inspection for an additional 8-9 km/hr worth it?

Nothing ventured, nothing gained

I can't imagine having a 6-15 would be "ok" but having a 6-20 would be where the line is drawn and is "too much" from an inspection standpoint. We are talking 4 amps difference...12 amps vs 16 amps (constant draw 15 amp vs 20 amp breaker). Whereas 24 amps is literally double 12 amps (constant draw 15 amp vs 30 amp breaker) and it would make sense that could be "too much."

To put the charging speeds in perspective, you said you have M3 RWD which has an EPA rating of 272 miles (you can convert to km).

6-15 charging (11 mph) would take 24.73 hours 0 to 100%
6-20 charging (15 mph) would take 18.13 hours 0 to 100%.

So the 6-15 is 36.4% slower than the 6-20. I personally installed a 6-20 outlet at my parents house as it is the most bang for your buck IMO (12 gauge wire rated up to 20 amps).

 

[Cyberm3]

Technically any electrical changes would require a permit along with strata approval, at least here in BC. I'm also in a townhouse and doing any electrical work has larger implications then if it was just your house. In BC if you are in a strata unit you can't do your own electrical work. Home owner electrical permits are not applicable, only a licensed electrician can pull a permit for work in strata units.

That said, converting to a 6-15 is easy to do. Change to a 2 pole 15a breaker and switch the wall plug. Also check the wiring, if the builder used 12g wire your good to up the circuit to 20a (Nema 16-20).

- Nema 5-15 = 120v x 12a = 1,440w
- Nema 6-15 = 240v x 12a = 2,880w (double the power)
- Nema 6-20 = 240v x 16a = 3,840w (2.66 times the power of a 5-15)

 

[romaclea]

We've been using a 6-15 outlet since we got our Model 3 LR last December. I've been logging everything for the last two a half months and it's typically 18-20kph. Or if you prefer percentages, last night we charged the battery from 38-80% in 12:20.

Our plan was to use the 6-15 (since it was in the house when we bought it) and upgrade to something higher power if that seemed insufficient. Based on our experience so far I'm in no rush to change (and this is based on the assumption of only charging during off-peak times). It probably depends on how you use your car. If you're driving long distances every day it might prove insufficient. In our case I figure any day where the battery gets low enough to not be able to be fully charge it will be followed by a day where we don't need it fully charged. We've only had the car three months but so far it has worked out.

We're in Ottawa so it gets chilly. We do however have the car in a garage which helps keep it warmer. Depending on where you are you might get different results. My last experience charging using a 5-15 was our last trip to Toronto when we got only 5kph (but it was -14C), we got from 47-80% in over 35 hours, rather slower speeds than you're getting.

 

[davewill]

Technically any electrical changes would require a permit along with strata approval, at least here in BC. I'm also in a townhouse and doing any electrical work has larger implications then if it was just your house. In BC if you are in a strata unit you can't do your own electrical work. Home owner electrical permits are not applicable, only a licensed electrician can pull a permit for work in strata units.

That said, converting to a 6-15 is easy to do. Change to a 2 pole 15a breaker and switch the wall plug. Also check the wiring, if the builder used 12g wire your good to up the circuit to 20a (Nema 16-20).

- Nema 5-15 = 120v x 12a = 1,440w
- Nema 6-15 = 240v x 12a = 2,880w (double the power)
- Nema 6-20 = 240v x 16a = 3,840w (2.66 times the power of a 5-15)

That doesn't really tell the story. You should subtract a 3-400w overhead from each of those numbers:

- Nema 5-15 = 120v x 12a = 1,440w - 400w = 1040w
- Nema 6-15 = 240v x 12a = 2,880w - 400w = 2480w (charges 2.3 times as fast as a 5-15)
- Nema 6-20 = 240v x 16a = 3,840w - 400w = 3440w (charges 3.3 times as fast as a 5-15)

That overhead really makes a difference when charging at 120v. In my mind, that makes either of the 240v choices well worth doing. Personally, I'd choose the 20a outlet, especially if it's only an extra $150. With 120v charging, you pretty much have to have the car plugged in every moment possible. Assuming 12 hrs of charge time available each night, that means you can only keep up with 60 miles (96.5 km) per day of use before you start falling behind.

 

[Jeremy3292]

That doesn't really tell the story. You should subtract a 3-400w overhead from each of those numbers:

- Nema 5-15 = 120v x 12a = 1,440w - 400w = 1040w
- Nema 6-15 = 240v x 12a = 2,880w - 400w = 2480w (charges 2.3 times as fast as a 5-15)
- Nema 6-20 = 240v x 16a = 3,840w - 400w = 3440w (charges 3.3 times as fast as a 5-15)

That overhead really makes a difference when charging at 120v. In my mind, that makes either of the 240v choices well worth doing. Personally, I'd choose the 20a outlet, especially if it's only an extra $150. With 120v charging, you pretty much have to have the car plugged in every moment possible. Assuming 12 hrs of charge time available each night, that means you can only keep up with 60 miles (96.5 km) per day of use before you start falling behind.

While I agree with the overhead losses on the 5-15 120v circuit, I don't believe those losses translate to the 240v outlets. There would be much less overhead when operating on a 240v circuit.

 

[Frank99]

There would be much less overhead when operating on a 240v circuit.

I hate to be disagreeable, but I think davewill has it right. I don’t know if the 400W overhead number is correct, but it will be more or less constant regardless of voltage. His point was that the impact of the overhead is smaller at higher voltage and higher current-it’s a smaller percentage of the charging power at 240v/20A than at 120v/15A.

 

[Cyberm3]

It was meant to give a general idea of the differences...

If you really wanted to tell the whole story we could start discussing losses for battery conditioning, not everyone's voltage is exactly 120/240v, etc.

Point being is that it's quite easy to upgrade to a 6-15 or even a 6-20 if the builder already put in 12g wire. He would see a nice bump in charging speed.

 

[Frank99]

I’ll certainly agree with you there. BTW, I ran some tests a long time ago to check charging efficiency v. Voltage/current. You can find the write up at: https://forums.tesla.com/discussion/168051/120v-240v-charging-efficiency-answers

Final answer:
V/Amps Efficiency
120/12 85.4%
240/06 90.5%
240/12 93.6%
240/24 93.9%
240/32 95.6%
With some question as to whether the 240/12A result is correct (it should probably be 91.6%).

 

[Jeremy3292]

I hate to be disagreeable, but I think davewill has it right. I don’t know if the 400W overhead number is correct, but it will be more or less constant regardless of voltage. His point was that the impact of the overhead is smaller at higher voltage and higher current-it’s a smaller percentage of the charging power at 240v/20A than at 120v/15A.

I’ll certainly agree with you there. BTW, I ran some tests a long time ago to check charging efficiency v. Voltage/current. You can find the write up at: https://forums.tesla.com/discussion/168051/120v-240v-charging-efficiency-answers

Final answer:
V/Amps Efficiency
120/12 85.4%
240/06 90.5%
240/12 93.6%
240/24 93.9%
240/32 95.6%
With some question as to whether the 240/12A result is correct (it should probably be 91.6%).

Yes, I was thinking more in line with your second post that I quoted above. Makes sense that the overhead would be constant; I read the post differently. Cheers

 

[Braumin]

If I wanted 30amps, I would for sure need an inspection but the electrician said he doesn't think I would have the capacity for it anyway so it might be a bit of a waste. But he thinks I could do 20amps but it would need an inspection to confirm.

I don't want to be a jerk here but an electrician should be able to do a load calculation. I am not sure why he's just guessing. It's not difficult.

Maybe this is just a friend of yours doing you a favor though.

 

[uberfunk]

I don't want to be a jerk here but an electrician should be able to do a load calculation. I am not sure why he's just guessing. It's not difficult.

Maybe this is just a friend of yours doing you a favor though.

Oh no no, not a friend. He came to do a free on-site estimate. We chatted and he had a look at the panel, placement of the outlet, etc. The load calculation is the $150 extra to determine if he can put 20 or 30 amps.

I don't know if the load calculation is typically an extra charge or if it's generally part of the scope of work. $775 ($625 for permit, parts, labour + $150 for the load calculation) seems high to me to just install an outlet and some breakers. The outlet will literally go beside the panel so running a new cable will be less than a foot long.

 

[Jeremy3292]

Oh no no, not a friend. He came to do a free on-site estimate. We chatted and he had a look at the panel, placement of the outlet, etc. The load calculation is the $150 extra to determine if he can put 20 or 30 amps.

I don't know if the load calculation is typically an extra charge or if it's generally part of the scope of work. $775 ($625 for permit, parts, labour + $150 for the load calculation) seems high to me to just install an outlet and some breakers. The outlet will literally go beside the panel so running a new cable will be less than a foot long.

You have to pull a permit for that? Really? Wow that's ridiculous.

 

[Frank99]

The load calculation is about a half hours worth of work, wandering around to all your major appliances to write down the power requirements off the manufacturer label, then plugging the data into an app that does the calculations ( There are several online calculators available). $150 seems a bit steep for that.

 

[terranx]

Oh no no, not a friend. He came to do a free on-site estimate. We chatted and he had a look at the panel, placement of the outlet, etc. The load calculation is the $150 extra to determine if he can put 20 or 30 amps.

I don't know if the load calculation is typically an extra charge or if it's generally part of the scope of work. $775 ($625 for permit, parts, labour + $150 for the load calculation) seems high to me to just install an outlet and some breakers. The outlet will literally go beside the panel so running a new cable will be less than a foot long.

If you’re handy, this sounds like the perfect DIY scenario honestly.

 

[Locoloco]

The only one that isnt accurate from teslas charts is the 120v 5-15. That one is about 5 miles per hour like you mention, at least on a model 3. The rest of them charge pretty much exactly what tesla says, or very close, given your voltage.

My brand new model 3 gets 8 km/hr at 12 amps on a NEMA 5-15. I was worried for a little while because I thought I was only supposed to get 4 km/hr.