Is there any advantage of leaving the X plugged in even when charge is completed?

[djillusion]

I tend to unplug the charger as soon as I get the notification via the Tesla app.

I’m curious to know if there is any issue with leaving the charger plugged in? Does it help the batteries, degrade them or provide any pro’s / con’s?

 

[AppleSam]

I’ve often wondered the same thing but after doing a bit of research I’ve learned a happy Tesla is a plugged in Tesla. System is smart enough to stop the charge when complete but will “trickle” charge when needed...say for software updates / communications with Tesla / etc.

 

[aja2460]

I tend to unplug the charger as soon as I get the notification via the Tesla app.

I’m curious to know if there is any issue with leaving the charger plugged in? Does it help the batteries, degrade them or provide any pro’s / con’s?

I still do as I was told in 2013... 'A plugged in Tesla is as a happy Tesla'

 

[ElectricSteve]

It‘s very beneficial. Power for the computers, heating and cooling etc. comes from external power instead of it‘s own battery. Saves charge/discharge cycles thus helps battery life.

A happy EV is a plugged in EV. Just don‘t do it at public chargers when other people want to charge. Leave when done. But at home, where you should be charging anyway if possible, keep it plugged in, especially when it’s colder.

 

[djillusion]

Excellent feedback - thx!

ill leave it plugged it when at home - this is good to get confirmed & know moving forward.

 

[animorph]

The car draws no current if it is sitting idle and doesn't need to charge.
The car will draw from the plug if climate is on (like when you open a door, precondition the car, or just sit in the car)
The car will charge as needed, on schedule if you have set one. Looks like a bug in recent software has it charging more often, but usually it will wait for about 3% below the set charge limit before starting a charge.
If you are unexpectedly away, or the car unexpectedly starts draining the battery, you're covered if the car is plugged in.
You can save the effort of going out to the car to unplug it.

 

[Fiver]

Just a reminder that nothing "draws from the plug". Everything goes through the battery, there is no bypass around it. So yes, it will recharge the battery as it's using power for onboard systems, but don't go thinking some relay gets flipped and suddenly the battery is bypassed and the car is drawing directly from the wall to power it's internal systems.

 

[Tam]

...I’m curious to know if there is any issue with leaving the charger plugged in? Does it help the batteries, degrade them or provide any pro’s / con’s?

Since the owner's manual advice to plug in when not driving, so I would plug in.

A shallow discharge is better than a deep discharge so the plug in advantage is it would top off often.

If you keep your car plugged in and when your car needs HVAC either in very cold weather to warm the main battery or to keep your cabin cool, the HVAC would use the shore power instead of your battery so it reduces wears and tears for your battery.

 

[ElectricSteve]

Just a reminder that nothing "draws from the plug". Everything goes through the battery, there is no bypass around it. So yes, it will recharge the battery as it's using power for onboard systems, but don't go thinking some relay gets flipped and suddenly the battery is bypassed and the car is drawing directly from the wall to power it's internal systems.

According to my information, bypassing the battery is exactly what happens when a lot of power is drawn from the wall AND the external source can deliver all of that power.

When the battery and/or the cabin are heated up/cooled down at max. speed, this can take up to 6kW which is drawn directly from wall-power (through a controller of course). The main battery is not used (bypassed) during that time. Logically, 6kW wall-power (or whatever is required at that time, could be 4kW or anything else) must be available. A simple 120 or 230V single phase 10A or 13A connection can not deliver 6kW. When connected that way, we DO see the battery being consumed because wall-power alone is not enough. If the full 6kW is available externally though, the battery is not losing range at all and it is not recharged, all the while the fans are sounding like jet engines and the car is cooled down, or heated up quickly.
My two Tesla's have been behaving like that for the past 6 years.

 

[Fiver]

The wiring schematics of S/X show everything goes through the charge controller from the battery. I haven't seen the wiring schematics for 3/Y, but based on the Sandy Monroe tear downs it looks to be the same, but I acknowledge I can't confirm it 100% for those cars.

For S/X though, everything inside the car is powered through the battery. That battery is recharged at the same pace it's discharging to run its systems when on "shore power" so to the end user it looks like it's bypassing the HV system.

Link: Imgur

 

[djillusion]

does the X hold full charge if/when always plugged in?

or do the batteries have its typical idle drain and the charger will always "top off" when it sees/sense a drop? i noticed i plugged in my charger last night and got the full notification of 251 miles in typical fashion.

the charger is still plugged in, but this morning the X is now at 246 miles and the Tesla app says "charging complete". more or less curious to know the logic when the plugged-in charger continues to charge the batteries (ie, is there a threshold). hope that made some sense.

 

[mxnym]

The wiring schematics of S/X show everything goes through the charge controller from the battery. I haven't seen the wiring schematics for 3/Y, but based on the Sandy Monroe tear downs it looks to be the same, but I acknowledge I can't confirm it 100% for those cars.

For S/X though, everything inside the car is powered through the battery. That battery is recharged at the same pace it's discharging to run its systems when on "shore power" so to the end user it looks like it's bypassing the HV system.

Link: Imgur

Assuming you're implying that both of those pictures are from the S/X diagrams, can you tell me where you found an S/X that only has a 10 or 20 kW A/C charging system? AFAIK, the oldest ones would do 40 or 80 kW, the next generation would do 48 or 72 kW, and the current generation does 48 kW. Also, since you know so much about electricity, can you explain to me why it's impossible for the electricity from those chargers to turn left in that diagram at the T junction where battery and drive inverter are connected instead of right? Finally, for some super-fun bonus points, can you explain to me why Teslas connected to large enough supplies only draw power after the battery drops 3% when you're not running the A/C but start drawing power immediately when you are running the A/C?

 

[mxnym]

does the X hold full charge if/when always plugged in?

or do the batteries have its typical idle drain and the charger will always "top off" when it sees/sense a drop? i noticed i plugged in my charger last night and got the full notification of 251 miles in typical fashion.

the charger is still plugged in, but this morning the X is now at 246 miles and the Tesla app says "charging complete". more or less curious to know the logic when the plugged-in charger continues to charge the batteries (ie, is there a threshold). hope that made some sense.

That is normal. I don't know the cutoff, but even beyond the cutoff, behavior will vary. For instance, when you have scheduled charging set up, it won't start charging from idle drain until the scheduled time in spite of the cutoff. Moreover, there will be some confusion as there is a version floating around out there right now that charges very frequently, and we can only assume that new behavior is a bug.

 

[ElectricSteve]

The wiring schematics of S/X show everything goes through the charge controller from the battery. I haven't seen the wiring schematics for 3/Y, but based on the Sandy Monroe tear downs it looks to be the same, but I acknowledge I can't confirm it 100% for those cars.

For S/X though, everything inside the car is powered through the battery. That battery is recharged at the same pace it's discharging to run its systems when on "shore power" so to the end user it looks like it's bypassing the HV system.

Link: Imgur

That diagram is ancient. It shows the dual-AC Charger from the earliest Model S. The setup is different since 2016 when they introduced a new AC charger.
Besides that, the diagram does not show that onboard devices cannot be charged from wall-power alone. The HV battery is merely an endpoint, like the drive inverter.

 

[Fiver]

Assuming you're implying that both of those pictures are from the S/X diagrams, can you tell me where you found an S/X that only has a 10 or 20 kW A/C charging system? AFAIK, the oldest ones would do 40 or 80 kW, the next generation would do 48 or 72 kW, and the current generation does 48 kW. Also, since you know so much about electricity, can you explain to me why it's impossible for the electricity from those chargers to turn left in that diagram at the T junction where battery and drive inverter are connected instead of right? Finally, for some super-fun bonus points, can you explain to me why Teslas connected to large enough supplies only draw power after the battery drops 3% when you're not running the A/C but start drawing power immediately when you are running the A/C?

OK, there's never been any Tesla that can do the charging you describe in kW, I believe you meant to say amps. The original S/X had either a 40amp single or 80amp dual charging setup, which (in the US) provided at max, 22.16kW. (80amps@277v). Most charged with 40amps @ 240v for 9.6kW. Skip ahead a few generations, and currently all shipping Tesla's come with either a 32 or 48amp onboard charger.

Everything inside the car is DC powered. That DC current is pulled from the battery (350v to 400v depending on car model), and is stepped down through the DC/DC converter en-route to the various sub-systems inside the car. The majority of which are 12v, but some systems (cabin heat, air conditioning, battery coolant, drivetrain) run at different voltages, but are still DC.

I relate exactly what the repair manual says: "The vehicle recognizes when the AC charge source is connected using CAN communication with the BMS. When charging from an alternating current (AC) source, current flows from the source through the connector to the charge port. From the charge port, it passes through the HVJB (High voltage junction box) and then is routed by bus bars to the on board charger(s). The charger(s) convert AC to DC and supply current to the battery.
The purpose of the HV battery is to provide power to drive the car and run all the accessory systems. It is the primary energy source for the vehicle. The DC-DC converter also functions as a high voltage junction block, distributing current from the HV battery to the A/C compressor, coolant heater, and cabin heater.

Everything there is DC, and is pulled through the DC battery. AC charges said battery. Yes you may run all these systems through the battery while charging, but they are not AC powered, they are DC powered and there is no DC conversion prior to the main pack. None of the subsystems inside the car run on AC power.

 

[Fiver]

Model X with the more recent charger. The battery is the heart of it all. I haven't bothered to dig through the model 3 wiring diagrams as I don't own one.

I'm not saying you should leave your car unplugged, Tesla themselves tells owners a happy car is a plugged in car. I'm just saying you should understand that power draw is always routed through the pack. It's up to you to decide if you think that added wear means anything to pack life. I personally don't think it does any meaningful long term damage, but there is a tiny bit of wear.

 

[dmurphy]

I'm not saying you should leave your car unplugged, Tesla themselves tells owners a happy car is a plugged in car. I'm just saying you should understand that power draw is always routed through the pack. It's up to you to decide if you think that added wear means anything to pack life. I personally don't think it does any meaningful long term damage, but there is a tiny bit of wear.

It's actually fairly simple. The AC-DC converter puts current on the bus. When there's a draw (i.e. the heater running), it draws down the current from the bus. The current is coming from the battery and the AC-DC converter.

Now, if the current from the AC-DC converter is enough to run the accessory, great. If it needs more than is available on the bus, the battery will supply it.

True whether the vehicle is plugged in or not. You're right - there's no contactor that opens to isolate the battery and use shore power exclusively. But that said - if the battery's topped off and there's still enough current on the bus because the charger is plugged in, it's not going to draw down the battery any.

So yeah, the rule is as always: ABC. Always be chargin'. I set my Model 3 to 90% and forget about it. When it's home, it's plugged in. Going to do the same when the X arrives next week.

 

[wreighven]

...

So yeah, the rule is as always: ABC. Always be chargin'. I set my Model 3 to 90% and forget about it. When it's home, it's plugged in. Going to do the same when the X arrives next week.

Congrats on your new X!

 

[dmurphy]

Congrats on your new X!

Thanks! Excited to get it home. Now I've got to decide whether to daisy-chain the two wall connectors, or put them on their own circuits... Was leaning towards daisy-chaining until I realized a full charge on the X takes an extra 25% longer than the 3. (Well, it's a 25% larger battery ....)

 

[Tam]

...power draw is always routed through the pack....

This Youtube disproves that. When your pack completed its charge and it draws 0 amps / 40 amps or whatever your charger amp limit is, then you turn on your HVAC, the ampere drawn would move up to as much as 10 amps / 40 amps. That's 10 amps from shore power without using the 10 amps from the battery.