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Wall Charger - Idle 240v Consumption

rnh415M3

Member
Nov 12, 2018
18
4
San Francisco
I was wondering if anyone had the answer to this. I had my electrician install a 240 outlet so I am using the wall charger that came with the car and the appropriate adapter. The light on the charger maintains a lit green light regardless of whether its sitting there or is plugged into my car. I was curious if anyone know the consumption of the following:

  1. How much energy does the charger NOT plugged into the car sonsume if the green light is lit?
  2. How much energy does the charger consume when it is plugged in to the car but the car is at full capactity (or whatever you set max charging to, in my case 90%)
 

voip-ninja

Give me some sugar baby
Mar 15, 2012
4,121
4,691
Colorado
I was wondering if anyone had the answer to this. I had my electrician install a 240 outlet so I am using the wall charger that came with the car and the appropriate adapter. The light on the charger maintains a lit green light regardless of whether its sitting there or is plugged into my car. I was curious if anyone know the consumption of the following:

  1. How much energy does the charger NOT plugged into the car sonsume if the green light is lit?
  2. How much energy does the charger consume when it is plugged in to the car but the car is at full capactity (or whatever you set max charging to, in my case 90%)

You'll get more feedback on this question if you ask a moderator to move it to the appropriate sub-forum.

I can't provide the exact #s for you but the power draw in both circumstances you describe;

1. Power connector not connected to car.
2. Car fully charged.

Is negligible. The power connector (the charger is actually inside of your car) doesn't allow any large amperage to flow until it negotiates a connection with the car and opens a contactor or relay. It might use perhaps 1-5 watts at most to light the LED and "listen" for a car getting plugged into it.

Similarly when the car is done charging the relay is closed and the connector isn't consuming power. The car knows it's connected though and if you do something like turn on climate control while it's still connected, or if slow battery drain of the car gets below a certain % it will start pulling power again.

If you truly must know how much power it is using in this standby state it would be pretty easy to find out by safely connecting an ammeter to the terminals at the circuit breaker and measuring the current flow.

TL DR - don't worry about it, it's negligible.
 
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Jedi2155

Model 3 has Arrived.
Jul 6, 2018
1,669
1,397
Upland, CA
I was wondering if anyone had the answer to this. I had my electrician install a 240 outlet so I am using the wall charger that came with the car and the appropriate adapter. The light on the charger maintains a lit green light regardless of whether its sitting there or is plugged into my car. I was curious if anyone know the consumption of the following:

  1. How much energy does the charger NOT plugged into the car sonsume if the green light is lit?
  2. How much energy does the charger consume when it is plugged in to the car but the car is at full capactity (or whatever you set max charging to, in my case 90%)

1.
While I don't know the real numbers without directly measuring the input, I suspect it to be relatively low because there aren't many electronics in the EVSE. Technically the HPWC is not a "charger" by traditional electrical terms. The charger (AC-DC converter) is built into the car, while the HPWC is a glorified GFCI (ground fault current interrupter). It probably draws a few watts at most unless its poorly designed. The high power draw ones are the "smart" EVSEs with all the fancy communication ones.

2. Not much more than when its unplugged. However if the car door gets opened, the car will draw power from the EVSE instead of the battery even if set a scheduled charged.
 

FlyNavy01

Member
Apr 30, 2017
425
894
Jacksonville, FL
It uses about 10 watts. 88 KWh / year.

Kind of wasteful. That would charge my car 2.5 times (2.5 weeks).
The Model 3 has a ~76kWh battery pack, which means after charging losses, that would barely charge your car once.

Regardless, that seems high compared to mine, which is always been between 3.2-3.7W. Doesn't matter if it's plugged in or not.

IMG_6239.JPG
 

FlyNavy01

Member
Apr 30, 2017
425
894
Jacksonville, FL
He (your Electrician) might have asked you if you wanted the receptacle mounted inverted so your plug wouldn't be contorted...
Are you referring to mine? True, the receptacle he used wouldn't work any other way based on it's internal design. I have the cable mounted as such that most of the strain has been relieved outside of the frame of the photo. I'll probably change it myself eventually but my job is very busy and demanding currently so it's low on my priority list.
 

ac_power

Member
Jan 23, 2019
139
41
Arizona
So it seems Gen2 has idle current quadrupled.
BTW FlyNavy01, does your meter show zero with UMC unplugged ? Dependent on your connection, there's a trick, to run power meter phase wire through the ring so it subtracts its own current from overall line load, otherwise it may never show zero.
 

mswlogo

Well-Known Member
Aug 27, 2018
5,965
4,572
MA, NH
It uses about 10 watts. 88 KWh / year.

Kind of wasteful. That would charge my car 2.5 times (2.5 weeks).

Sorry, I measured incorrectly. I measured with an amp meter and calculated VA not watts.

It’s 2.5 watts. But that is based on the 120v adapter. I’d assume 240 adapter would not be much different.
 

Xebec

Member
Mar 20, 2019
40
38
PA
Is there anyone with a Gen 3 wall connector that has the ability to test the idle power consumption for that model?
 

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