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Power usage when charger is not charging

Power usage when charger is not charging

Hello: Brand new Tesla S owner here. The most fun I have had since I brought my first car (67 GTO convertible) in 1968. I have a question about the charger. In my case, I am using the travel charger with a 6-50 adapter (there are superchargers within 4 miles if I choose to use them). I noticed that when the charger is plugged in but not in use, the lights are on and the charger is warm denoting some "vampire" power usage. I assume the wall charger acts the same. The question is, how much power is being used in the idle state, and why not have an internal shut off switch to completely cut off power use when not charging? Seems like a good idea as Tesla is all about overall energy savings. I don't want to keep plugging/unplugging the charger or flipping off the circuit breaker if the idle current is significant.

rob | 02. oktober 2019

The car uses power even when sitting. How much depends on what's going on. If sentry is on it will use more power. Other things going on too. So, you wouldn't be saving any energy because the car would pull it from the battery.

My first car was a 66 GTO. My model 3 reminds me of it in a lot of ways. Both torquey as heck.

steve2q | 02. oktober 2019

Rob..I am referring to power used by the charger when it is NOT connected to the car.

jimglas | 03. oktober 2019

lighting a coule of LEDs and monitoring dormant solid state stuff doesnt draw much power

nukequazar | 03. oktober 2019

@steve2q

This is a great question with no answer here yet. Chargers all use power when they're plugged in, even little cell phone chargers, but who knows how much? As you said, if it's warm then it's wasting energy. Chargers are always warm even when they're not charging anything. I assume it's that there is always energy lost crossing the transformer coils.

There was a PSA a few years ago about energy wasted leaving chargers plugged in 24/7:

Save Electricity PSA - YouTube
https://www.youtube.com/watch?v=bzehqEXjKw4

sschaem | 03. oktober 2019

For the mobile version its easy to control. Unplug it.
For the wall connector, I dont have numbers but I would expect it to be well under <5w at idle.
My guess is that the thing doesnt even use $2 worth of electricity a year in 24/h/365 of idle service.

Tesla-David | 03. oktober 2019

The power usage is de minius. We have two Tesla HPWC’s to charge our MS and M3, and always leave the cars plugged in, and closely track our electric use with solar panels, Powerwall. batteries with our Tesla app. The power draws from our HPWC’s are very small when cars are not charging.

TeslaTap.com | 03. oktober 2019

@nukequazar - On the mobile connector, I measured less than 1W when idle. Really not worth unplugging. Cost at 1 W (and it's less) at $.30/kW would be $2.62 year. My guess is the wear and tear on the connector of unplugging and plugging it in (730 times/year) would require replacement of the receptacle perhaps in less than a year at far more costly than saving $2.62.

rob | 03. oktober 2019

I plugged the charger into a Killawat metert. For me, it draws:
2.2 Watts.
In Austin TX that's $2.02 /yr.

The Tesla charger is at 92F

For reference, my USB Wyze video camera is 127F

DanFoster1 | 04. oktober 2019

As measured at the panel, my HPWC draws less than 2 Watts when idle for approximately $1.72 of electricity per year which approximately 1/4 of a latte LOL. One can save many times that by drying just a few loads of clothes (especially towels) on a clothesline instead of using the electric (or gas) clothes dryer! In favorable weather, we’ve saved up to $30 a month drying everything on the line.