Trickle charge question

[Tes-londa]

So I know the adage “a plugged in Tesla is a happy Tesla”.


My wife and I are trying to figure out the logistics of our bill. I keep the car charged pretty much 24/7 regardless of weather.


App says I used 150 KWH in the last 31 days for a rate of about 35$ according to the app. However my utility bill is saying I’m using about 300 KWH more on average a month from before I bought the car.


Does the trickle charge run expensive in long term owners here on the forum? I mean the car has about 1500 miles if that. We barely drive it. Would it be better to just not plug it in unless it’s near dead?

 

[andaconda]

I ignore charging until it needs it. I plug it in at about 40% regardless of the weather.

 

[Tes-londa]

I ignore charging until it needs it. I plug it in at about 40% regardless of the weather.

Bah. I wanna find the stats, like if it’s dirt cheap to leave trickle charging at full charge and we’re not gonna drive it for a couple days if it’s $$$

 

[Mateo83]

No data, just bro science. I have a 50 amp 220v plug for my welder, I doubt the charger will cost more than running a welding machine.

Also its winter, my utilities rise to keep the house warm.

 

[jcanoe]

I suggest that you leave the Tesla Model Y plugged in with the charging limit set to 70% to 80% since you don't drive the Model Y very much right now. If you leave Sentry mode and/or Summon mode active at your home location the Tesla Model Y will consume ~7% of the battery per 24 hours, (about 5.5kWh per day). 5kWh X 30 days and there are your missing 150kWh. I can't explain why the Tesla stats are off by half (except the feature is new, probably considered to be a beta release like almost everything else about Tesla.) I suggest that you set Sentry Mode to be off at your home location, the same for Summon if your Model Y has the Full Self Driving.

 

[SSonnentag]

240V charging is roughly 92% efficient, so you'll draw a little more power than the car can store, but this is true whether you're plugged in always or only when you need a charge. My S loses about 0.5 to 1 kWh of power per day just sitting. Again, this will happen whether plugged in or not. Simply having the charger plugged into the car isn't going to affect your power usage. I would look elsewhere for the additional power draw you're experiencing.

 

[John in LB]

So I know the adage “a plugged in Tesla is a happy Tesla”.


My wife and I are trying to figure out the logistics of our bill. I keep the car charged pretty much 24/7 regardless of weather.


App says I used 150 KWH in the last 31 days for a rate of about 35$ according to the app. However my utility bill is saying I’m using about 300 KWH more on average a month from before I bought the car.


Does the trickle charge run expensive in long term owners here on the forum? I mean the car has about 1500 miles if that. We barely drive it. Would it be better to just not plug it in unless it’s near dead?

I have an X plugged in in MA at a house that no one is at. I have external metering that I can see remotely as well as the new Tesla APP charging stats. Both are completely consistent and show usage of 107 kWh over a 31 day period. That averages 3.5 kWh per day. That usage will continue to happen whether you leave the car plugged in or only charge it once in a while.

Definitely turn off Sentry Mode, Summons and other features that make it easier to remotely communicate with the car. Finally, you can try POWER OFF the unit through the service screen. Also, remember that every time you look at the APP, it is waking up the car... (it's like looking in your refrigerator to see if the light is on... )

I would keep the car plugged in all the time and set it for 70 or 80%... (I keep mine at 50% only because it is not being driven.). That is best for the health of the big battery.

 

[NeverGoingBack]

Make sure your settings in the app reflect your actual per kwh cost. Most recent bill, total kwh consumed divided by total $ (to pick up all the dopey taxes and fees).

 

[LibertyEV]

I’m having my Tesla wall connector installed tomorrow. Just want to clarify. Does the Tesla wall charger trickle charge once it reaches the set percentage of charge? Or does it shut off and kick back on once it gets low enough?

 

[Rocky_H]

I’m having my Tesla wall connector installed tomorrow. Just want to clarify. Does the Tesla wall charger trickle charge once it reaches the set percentage of charge? Or does it shut off and kick back on once it gets low enough?

First off, that is not controlled by the wall connector or mobile charge cable. It's controlled by the car. The car will not constantly trickle. It's just a general safety thing that they do not want the cord energized all the time. It will fill until it reaches the limit and then shut off. If you have a start time set, then it will wait until that next start time comes around. If you don't have a scheduled start, then it will let it go down some amount (used to be about 3%) below the limit before it wakes up and recharges back up.

 

[STS-134]

App says I used 150 KWH in the last 31 days for a rate of about 35$ according to the app. However my utility bill is saying I’m using about 300 KWH more on average a month from before I bought the car.


Does the trickle charge run expensive in long term owners here on the forum? I mean the car has about 1500 miles if that. We barely drive it. Would it be better to just not plug it in unless it’s near dead?

The car doesn't ever "trickle" charge. It draws power until it reaches the set battery charge level, then it stops drawing. Unless by "trickle" you mean charging on 120V, which is VERY inefficient. The car has a ~300-400W hotel load from the computer, which runs whenever the car is charging. You can probably guess that the lower the charge rate, the more inefficient this is. A 120V/15A socket can only provide 12A of continuous load or 1440W; about 25% of this goes to run the computer, and if the batteries need to be heated in order to be charged, some of that energy will be diverted for that purpose too. Contrast this with charging at 240V/48A or 11520W: much lower overhead and a higher percentage of the energy can be put into the battery, and then the computers can be shut down much quicker.

I’m having my Tesla wall connector installed tomorrow. Just want to clarify. Does the Tesla wall charger trickle charge once it reaches the set percentage of charge? Or does it shut off and kick back on once it gets low enough?

First off, that is not controlled by the wall connector or mobile charge cable. It's controlled by the car. The car will not constantly trickle. It's just a general safety thing that they do not want the cord energized all the time. It will fill until it reaches the limit and then shut off. If you have a start time set, then it will wait until that next start time comes around. If you don't have a scheduled start, then it will let it go down some amount (used to be about 3%) below the limit before it wakes up and recharges back up.

Yep, and with the WC, it's very easy to see when the vehicle is pulling energy and when it's not:
1. Solid green light: not connected
2. Solid blue light: connected, not charging
3. Scrolling green lights: vehicle is charging

When you connect your car, you'll see it pull energy from the WC whenever the HVAC system is running. It will also pull energy according to the charging schedule, then it will stop and go back to solid blue. The batteries do slowly self discharge, and so if you don't drive the car, it will pull energy again according to the charging schedule, or if no schedule is set, according to a hysteresis cycle that keeps the battery near the set point.