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Efficiency of Charging at 220v versus 120v?
- Thread starter Rags
- Start date
Yes, and not much.
120V charging is around 80% efficient, while 240 is a bit over 90%. The difference is that the car is kept awake for the duration of the charge event, and takes like 250W or somesuch. That's a decent amount of overhead on a charge session that's got maybe 1440 watts. Its less of an overhead on 240, and the duration of the charge is half or less, depending on the current of the 240V circuit.
If you don't need it, don't get it. Even the cheapest electrician-installed outlet will be $200 or much more, depending on the distance to the panel. Heck, even the GFCI for a 14-50 will run you $100-$150.
120V charging is around 80% efficient, while 240 is a bit over 90%. The difference is that the car is kept awake for the duration of the charge event, and takes like 250W or somesuch. That's a decent amount of overhead on a charge session that's got maybe 1440 watts. Its less of an overhead on 240, and the duration of the charge is half or less, depending on the current of the 240V circuit.
If you don't need it, don't get it. Even the cheapest electrician-installed outlet will be $200 or much more, depending on the distance to the panel. Heck, even the GFCI for a 14-50 will run you $100-$150.
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AlanSubie4Life
Efficiency Obsessed Member
Note that the charging efficiencies in this table are too high (as you mentioned in your first email, they range from upper 70%s not including battery heating, to maximum 90%).
Tesla publishes charging efficiency for the public (Basic Search | Document Index System | US EPA) and the highest they claim is about 89% (as of a year ago - I haven’t checked the very modern vehicles to ensure it is the same). When using the tables there is always a confusing 4.5% discrepancy due to displayed rated miles vs. rated miles energy content when looking at the displayed rates in the car. But the published data on energy consumed vs. measured charging event energy is rock solid. (The only question is whether it uses 32A or 48A charging, but there is some circumstantial evidence to suggest what they are doing there.)
For the OP, he should note that if his car is not in an insulated garage, in Indiana the charging efficiency and rates will be far worse in cold weather with the 120V outlet due to limited available energy to heat the battery (and if in extreme cases it cannot keep up with heat losses from the battery, the car won’t charge at all).
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FastEddieB
Member
If a 120v outlet can be easily upgraded from 15A to 20A, with the appropriate 6-20 adapter there’s a nice 25% or so increase in charge speed right there. But if pulling heavier gauge wires is necessary to accomplish that, might as well go ahead and wire in a 240V outlet.
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CDennis100
Member
Fwiw, I was quoted $606 for my installation, which was about four feet from my panel and didn’t include necessary drywall repair work. I’m comfy working with electricity and after a few confidence boosting YouTube videos I did it myself. I only had capacity for 30A breaker so I’m getting between 23-26 MPH but that’s def good enough and way better than 3 per hour @110V. Total cost was just over $100 plus satisfaction of doing it myself!
Go for the 220 for sure…
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roblab
Active Member
Definitely! Kudos for doing it yourself and finding the satisfaction of a job well done. I have found that every new job I undertake boosts my knowledge and my confidence level for the next challenge, and I somehow don't feel sorry for taking a job away from some high priced electrician. Way to go!
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FastEddieB
Member
As mentioned in another thread, I conveniently had a 240v 30A service to a hangar door, quite convenient to where we normally park. I just piggybacked a second L14-30 receptacle off the hangar door receptacle. All we have to be careful of is not to raise/lower the hangar door while charging is in progress. I know there’s some small risk, but so far so good, and the 30A breaker is there to prevent disaster if one of us forgets.
Like you, we get 23+ mph, which invariably gets us back up to the 75% we‘ve set for daily driving in just a few hours. As another option, we have a 14-50 240v receptacle in an RV pedestal 100’ or so from the house that we could use if necessary. In 4 months and 12,000+ miles it has not ever been needed.
Like you, we get 23+ mph, which invariably gets us back up to the 75% we‘ve set for daily driving in just a few hours. As another option, we have a 14-50 240v receptacle in an RV pedestal 100’ or so from the house that we could use if necessary. In 4 months and 12,000+ miles it has not ever been needed.
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