15% Charge Loss

[Jon Chow]

I charged my new Model 3 using a 110v outlet for 15 hours last night from midnight to 3pm (which qualified for the lowest rate of $0.27/kwh) and got 80 miles or 18 kwh in the car. Can I expect this 5 miles per hour charge rate when the weather gets colder?

I noticed that the electricity used for just charging the car was about 21kwh--3kwh more than the car received? Would I experience similar percentage loss using a 220v outlet?

 

[RayK]

I don't think that being in SF will affect your charging rate all that much when it gets cold. I don't do home charging here in San Jose so you may want to wait around for a more informed opinion. The coldest it's been this year down here was 29.8F.

The car consumes a couple of hundred watts when it's "on" (i.e., not sleeping). When you use a 120V outlet (Level 1) to charge, a portion of that power goes to keeping the car awake. If you used a 240V outlet (Level 2), then a smaller percentage of that charging power is required to keep the computers and what not running. Thus, in terms of efficiency, and if you can, it's better to use Level 2 charging than Level 1.

 

[AZAV8R]

I charged my new Model 3 using a 110v outlet for 15 hours last night from midnight to 3pm (which qualified for the lowest rate of $0.27/kwh) and got 80 miles or 18 kwh in the car. Can I expect this 5 miles per hour charge rate when the weather gets colder?

I noticed that the electricity used for just charging the car was about 21kwh--3kwh more than the car received? Would I experience similar percentage loss using a 220v outlet?

Sorry, I don't have a good answer for you, but is $.27/kwh a typo? I'm in Phoenix and pay $.08/kwh off peak. If it's accurate, HOLY CRAP!

 

[LoudMusic]

Sorry, I don't have a good answer for you, but is $.27/kwh a typo? I'm in Phoenix and pay $.08/kwh off peak. If it's accurate, HOLY CRAP!

Yeah - electricity rates in California are bonkers. The state average is $0.30/kwh.

 

[RayK]

Currently, (Summer rates, E1 rate schedule) my Tier 1 cost from PG&E is $0.35271 / kWh. Tier 2, after using up my Tier 1 allotment (9.8kWh/day) is $0.43999. That's the major reason why I haven't installed my Wall Connector and rely almost exclusively on a ChargePoint CHAdeMO station near my home at $0.19/kWh. I have solar on the roof but it's a small system (~3.7kW) and the running of the A/C every day for the last couple of weeks cancels out that power:

Time Of Use EV2-A rate schedule is $0.27 off peak 12M to 3PM, then $0.47 until 4PM, $0.58 between 4PM and 9PM, then back to $0.47 until 12M.

 

[stopcrazypp]

I charged my new Model 3 using a 110v outlet for 15 hours last night from midnight to 3pm (which qualified for the lowest rate of $0.27/kwh) and got 80 miles or 18 kwh in the car. Can I expect this 5 miles per hour charge rate when the weather gets colder?

If the temps are cold enough, a larger portion of the energy gets used for heating the battery. However if you are in SF, generally the temps don't really get as cold as the worst cases (in extreme cases, the car does not even charge, all the energy goes to heating the battery).

I noticed that the electricity used for just charging the car was about 21kwh--3kwh more than the car received? Would I experience similar percentage loss using a 220v outlet?

No, you would not experience the same percentage loss with a 220V outlet. The amount of heat in kW required generally is fixed per given temperature, so given a 220V outlet delivers more power, that means the heating load becomes a smaller proportion of the overall power delivered and more power in proportion goes to actually charging the battery.

 

[E90alex]

The “miles charged” is based on ideal EPA rated range so the amount will not change based on weather or other conditions.

Charging at 120V is very inefficient. The lost energy is from keeping the car electronics on while the car is charging. 240V will not lose as much power because charging will complete sooner and the car can go to sleep.

 

[dafish]

I charged my new Model 3 using a 110v outlet for 15 hours last night from midnight to 3pm (which qualified for the lowest rate of $0.27/kwh) and got 80 miles or 18 kwh in the car. Can I expect this 5 miles per hour charge rate when the weather gets colder?

I noticed that the electricity used for just charging the car was about 21kwh--3kwh more than the car received? Would I experience similar percentage loss using a 220v outlet?

maybe. In theory yes. In practice? I see 11-15% loss using a WC at 48a. roughly what you state. I lose 5-11% from breaker to WC, and 3-6% from WC to battery. I use emporia for the energy transfer at the breaker and tessie for the rest. I suppose it comes down to what you measured to get your loss data.

i’m going to drop to 40a charge rate and see if i have less loss.

 

[brianbcc]

Yeah - electricity rates in California are bonkers. The state average is $0.30/kwh.

Here in Santa Clara (South Bay Area), it's $0.12/, for reference

 

[ucmndd]

Here in Santa Clara (South Bay Area), it's $0.12/, for reference

More like $0.15 average, but yes, I’m extremely envious of those that live in areas with non-profit municipal owned utilities as opposed to the rest of us that get completely screwed by the big 3 IOUs.

Rates and Fees | Silicon Valley Power

 

[father_of_6]

You'll be happy to have a 240v hardwired EVSE (like the one Tesla sells).

 

[brianbcc]

More like $0.15 average, but yes, I’m extremely envious of those that live in areas with non-profit municipal owned utilities as opposed to the rest of us that get completely screwed by the big 3 IOUs.

Rates and Fees | Silicon Valley Power

Actually $0.1299, to be perfectly accurate, but what's a few cents among friends?
And yes, loved getting away from PG&E electricity prices

 

[shyboy]

maybe. In theory yes. In practice? I see 11-15% loss using a WC at 48a. roughly what you state. I lose 5-11% from breaker to WC, and 3-6% from WC to battery. I use emporia for the energy transfer at the breaker and tessie for the rest. I suppose it comes down to what you measured to get your loss data.

i’m going to drop to 40a charge rate and see if i have less loss.

I experienced the same. I do not have emporia to measure, but the WC app always shows 2Kw more than what tesla report back on every charge.
And I mostly charge at 40a for some unrelated issue and sometime 48a when I am in rush and charge during the day.

WC is always approx. 2Kw higher.

 

[dafish]

I experienced the same. I do not have emporia to measure, but the WC app always shows 2Kw more than what tesla report back on every charge.
And I mostly charge at 40a for some unrelated issue and sometime 48a when I am in rush and charge during the day.

WC is always approx. 2Kw higher.

My supposition is that heat is the primary component to loss in the WC, and that this offsets the relatively small amount of energy the car is saving by being awake less. If so there should be a "sweet spot" of charging amps that's most effective.

 

[GtiMart]

There is a charging loss in converting the energy from AC to DC but I don't know what that number is or whether it's better at 240V or not but there are people that have measured charging efficiency elsewhere.
What I want to add is that the car consumes 200-250w when it is awake, and it must be awake to charge. On a 120V 12A connection (thus providing 1.4kW), 250w represents 17%. On a 240V 48A connection (providing 11.5kW) that 250w draw only represents 2%. Charging for a shorter period will have less total overhead.

 

[dafish]

Lots of posts on this topic over the years, not lots of good data (that I’ve seen). It all seems to come down to what folks use as the “total current used”. Some get this from the car, some from the WC. I look at current from the breaker as I see circuit loss as part of the total.

 

[johnny_cakes]

I noticed that the electricity used for just charging the car was about 21kwh--3kwh more than the car received? Would I experience similar percentage loss using a 220v outlet?

I recently had an opportunity to charge with 110v, 220v, and Supercharger all in one week and here are the efficiency comparisons:

 

[AZAV8R]

Currently, (Summer rates, E1 rate schedule) my Tier 1 cost from PG&E is $0.35271 / kWh. Tier 2, after using up my Tier 1 allotment (9.8kWh/day) is $0.43999. That's the major reason why I haven't installed my Wall Connector and rely almost exclusively on a ChargePoint CHAdeMO station near my home at $0.19/kWh. I have solar on the roof but it's a small system (~3.7kW) and the running of the A/C every day for the last couple of weeks cancels out that power:
View attachment 961513

Time Of Use EV2-A rate schedule is $0.27 off peak 12M to 3PM, then $0.47 until 4PM, $0.58 between 4PM and 9PM, then back to $0.47 until 12M.

Yikes! I will never again bitch about $.43/kWh at a Supercharger. TIme to go solar!

 

[RayK]

Yikes! I will never again bitch about $.43/kWh at a Supercharger. TIme to go solar!

This is why I am happy to spend an hour or so once every couple of weeks sitting in my car at the local ChargePoint station using my CHAdeMO adapter. As long as I have access to this public charging station, subsidized by the Santa Clara Valley Water District, I will be charging there. Currently, the off-peak rate at a nearby (Urban) Supercharger is $0.30. Peak rate is $0.38. 250kW stations, also nearby, is $0.36/$0.43. Tesla has adjusted costs several times over the last year or two. I remember when off-peak was about 1/2 the cost of peak.

 

[dafish]

Guess we'll see: