220V vs 240V - need advice on new home build

Kickaha

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Hello folks - I am building a new home and I have requested a 60A/240V circuit for my R1S. My builder keeps telling specifying a 60A/220V circuit. From an electrical perspective, I often see 220/240V called out. Should I insist on 240V or is it a distinction without a difference?

Thanks!





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Yes they are the same. I installed a 20 amp 240 volt outlet in the garage for my power tools. I'm going to use it for the R1S(assuming I buy it) so I measured the voltage at the outlet just to see what it actually is. It is 235 volts.
 

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The voltage will vary by neighborhood. If yours is 240v you will max charge about 10% faster than 220v. Some commercial property is as low as 200v. Not much you can do about it.
 

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Yes they are the same. I installed a 20 amp 240 volt outlet in the garage for my power tools. I'm going to use it for the R1S(assuming I buy it) so I measured the voltage at the outlet just to see what it actually is. It is 235 volts.
Just curious if there was a reason you installed a 20 amp outlet versus a 50 amp outlet? I installed a 30amp in my garage when I purchased my Volt, a decision I have come to regret. I am not sure if I will make the change or just charge my R1S at
 

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The voltage will vary by neighborhood. If yours is 240v you will max charge about 10% faster than 220v. Some commercial property is as low as 200v. Not much you can do about it.
I read somewhere (I think it was an interview with RJ) where he said basic electrical engineering / battery laws dictate battery life..... something along the lines of "sure, you can pour a whole bunch of energy into a battery really, really fast. But you can only do that probably 10 or 20 times before the battery is completely shot."

So, does that imply that if you push the charging speed, you're proportionally diminishing the life of one's battery? If my car spends 12 hours per night in the garage, do I need max capable charger (60a / 240v) or am I better off (for the battery life) to go with something a bit smaller (and slower)?

sheydon
- who's new to all this EV stuff
 

n8dgr8

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I read somewhere (I think it was an interview with RJ) where he said basic electrical engineering / battery laws dictate battery life..... something along the lines of "sure, you can pour a whole bunch of energy into a battery really, really fast. But you can only do that probably 10 or 20 times before the battery is completely shot."

So, does that imply that if you push the charging speed, you're proportionally diminishing the life of one's battery? If my car spends 12 hours per night in the garage, do I need max capable charger (60a / 240v) or am I better off (for the battery life) to go with something a bit smaller (and slower)?

sheydon
- who's new to all this EV stuff
It is using the DC Fast charging at much faster rates or always charging to 100% that slightly diminish battery capacity. On our Tesla I dial it down to extend the life of the mobile charging cable not to protect the battery.
 

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I read somewhere (I think it was an interview with RJ) where he said basic electrical engineering / battery laws dictate battery life..... something along the lines of "sure, you can pour a whole bunch of energy into a battery really, really fast. But you can only do that probably 10 or 20 times before the battery is completely shot."

So, does that imply that if you push the charging speed, you're proportionally diminishing the life of one's battery? If my car spends 12 hours per night in the garage, do I need max capable charger (60a / 240v) or am I better off (for the battery life) to go with something a bit smaller (and slower)?

sheydon
- who's new to all this EV stuff
If you were talking DCFC, where you charge at HIGH power levels (maybe 200-350kW), then yes.

However, at Level 2 charging levels (Rivian caps out at ~11kW), no. So for charging at your home, don't worry about it.
 

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I read somewhere (I think it was an interview with RJ) where he said basic electrical engineering / battery laws dictate battery life..... something along the lines of "sure, you can pour a whole bunch of energy into a battery really, really fast. But you can only do that probably 10 or 20 times before the battery is completely shot."

So, does that imply that if you push the charging speed, you're proportionally diminishing the life of one's battery? If my car spends 12 hours per night in the garage, do I need max capable charger (60a / 240v) or am I better off (for the battery life) to go with something a bit smaller (and slower)?

sheydon
- who's new to all this EV stuff
I think he was referring to charging without some sort of battery management system. They have done a lot of testing for charging and have a pretty decent battery warranty so you can be certain that the battery management system will protect the battery.
 

sheydon

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Thanks everyone!
 

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Hello folks - I am building a new home and I have requested a 60A/240V circuit for my R1S. My builder keeps telling specifying a 60A/220V circuit. From an electrical perspective, I often see 220/240V called out. Should I insist on 240V or is it a distinction without a difference?

Thanks!
They are wired exactly the same, the voltage difference depends on your power company and the requirements in your area.

For a real deep dive into why this is the case, I recommend this video by Technology Connections, but in case you don’t have 25 minutes, here’s a TL;DW.

The reasons for this difference in specification is 2-fold. The video I linked to discusses this reason starting around 17:56. First, some people just like referring to standard mains voltage in the USA as 110V. I’m not sure why. In reality, the voltage in your house can vary anywhere between 110V and 125V, and everything that plugs in will deal with it. This variability occurs as part of load management on the power grid, as frequency is the most important variable in the grid, and sometimes utility companies let the voltage sag or surge a bit to maintain the correct frequency. 220V is double 110V, so he says that. He’s not necessarily wrong, but it’s weird.

The second reason is because of split-phase power. The video discusses this at 18:45. In apartment buildings and most commercial buildings, the power supply is 3-phase 240V power. The lower voltage 120V circuits are just one phase of the 3-phase power, with a ground wire, providing 120V. If you take 2 phases of this power, you get 2 120V phases that are only 120º out of phase with each other, instead of the 180º you’d get from a residential split-phase transformer. Because of this, high-voltage circuits in commercial and apartment buildings run at ~208V instead of the higher 240V. That’s why anything with a high-voltage plug in the USA is rated for 208/240V, and can really handle anything between about 205V and 250V.

As long as you have the higher-gauge wire and 2 phases available in your garage, you will likely have 240V available for charging, since you probably have split-phase residential power.
 

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