Thermal management system temp-thresholds when plugged in

[jedwin]

We are told that one of the main reasons to keep the car plugged in at home is to assure that the battery thermal management system can activate when ambient temps are too high or low, to keep the batteries healthy for the long term. My question is: at what temperatures does the battery cooling or heating kick in? I know I've read posts where folks were reporting some significant noise from the cooling system in summer.

Since this recommendation (the good ol' "a plugged in EV is a happy EV") is not about plugging in when charging, but keeping it plugged in, I've been surprised to have never heard the thermal management kick on in winter, with garage temps usually in the 20s, sometimes in the teens or perhaps a tad lower. And for the past two days my car was sitting in 95 degrees (97 when I put the thermometer on the hood), with again no system kicking in.

I'm wondering if it needs to be quite close to the Manual's stated storage range to activate? (below -4F, above 113F)

I definitely DO nearly always get the "charging limited while the battery warms" notice in winter, though the rate is only moderately lower than normal (as I recall, 7kW, while the typical rate on my charger is 9kW) for the 30-45min that the warming system is on. But again, this is thermal conditioning for charging; I'm curious about ongoing thermal management.

Other than for protective thermal management, what other purposes does leaving the car plugged in serve? Topping off the 12V battery, I suppose. Anything else?

 

[alee]

Interesting question. My garage in AZ is pretty toasty now and I just stepped outside and the fans in my car were running at a moderate RPM. My car wasn’t plugged in however.

I’m using a Tesla Gen 3 wall charger ( from my previous Model S), and a Lectron 80 Amp adapter. I’m on a 60A circuit and charge at 48A but I recall lectron stating to disconnect the adapter when not in use.
I’m wondering if thermal management would command fans on even if not plugged in, hence my fans being on earlier.

 

[EVCar]

Interesting question. My garage in AZ is pretty toasty now and I just stepped outside and the fans in my car were running at a moderate RPM. My car wasn’t plugged in however.

I’m using a Tesla Gen 3 wall charger ( from my previous Model S), and a Lectron 80 Amp adapter. I’m on a 60A circuit and charge at 48A but I recall lectron stating to disconnect the adapter when not in use.
I’m wondering if thermal management would command fans on even if not plugged in, hence my fans being on earlier.

I think it does, except when the SOC is really low.
Someone can correct me on the SOC if not true.

 

[Adnillien]

Interesting question. My garage in AZ is pretty toasty now and I just stepped outside and the fans in my car were running at a moderate RPM. My car wasn’t plugged in however.

I’m using a Tesla Gen 3 wall charger ( from my previous Model S), and a Lectron 80 Amp adapter. I’m on a 60A circuit and charge at 48A but I recall lectron stating to disconnect the adapter when not in use.
I’m wondering if thermal management would command fans on even if not plugged in, hence my fans being on earlier.

I have not noticed the fans coming on in my hot AZ garage unless I wake up the car by walking past with a key or waking it with the app.

 

[alee]

I have not noticed the fans coming on in my hot AZ garage unless I wake up the car by walking past with a key or waking it with the app.

Good to know. The odd thing is the car didn’t appear to be awake - no lights on and mirrors folded. Once I hit the lock button on the fob the fans switched off.

Now that I think about it, my Model S has done a similar thing before. It’s as if it didn’t “shutdown” properly.

 

[jedwin]

Once I hit the lock button on the fob the fans switched off.

And per https://lucidowners.com/members/adnillien.520/
“I have not noticed the fans coming on in my hot AZ garage unless I wake up the car by walking past with a key or waking it with the app.”

Both of these reports only compound my confusion about the purpose of leaving the car plugged in. If these fans are indeed the batteries’ thermal management system, and they only are activated when the car is awake/unlocked, as Adnillien notes, how does keeping it plugged in support thermal management?

 

[ColonelBadger]

I had my car plugged in at home all winter here in NH, and the Garage got pretty damn cold, never seemed to provide any benefit. I always got the cold battery indicator and low region indicator when I got in.

 

[alee]

And per https://lucidowners.com/members/adnillien.520/
“I have not noticed the fans coming on in my hot AZ garage unless I wake up the car by walking past with a key or waking it with the app.”

Both of these reports only compound my confusion about the purpose of leaving the car plugged in. If these fans are indeed the batteries’ thermal management system, and they only are activated when the car is awake/unlocked, as Adnillien notes, how does keeping it plugged in support thermal management?

Right. And I can only relate to similar directions from my previous Tesla - keep it plugged in. Now with that vehicle, when the parasitic drain took my SOC about 3-4 % below my set level, the vehicle would wake up the charger and charge back to my set level.
I’m not sure if Lucid does this but I have crazy low losses from sitting off the charger. Left car at airport for 4 days last week and SOC was the same as when I left it.

Leaving anything plugged in is also creating some risk and exposure to surges and other line-related issues I presume.

But Lectron confirmed it’s just fine to keep their adapter plugged into the car from the Tesla Wall Charger so I’ll be keeping mine plugged in.

 

[jedwin]

The Lucid definitely keeps it topped off; I’m not sure if it kicks on at 79% or 78% when it’s set at 80.…

But that’s not the stated reason that they tell us to leave it plugged in; and as you note, the SOC when unplugged is remarkably stable. I’m really just trying to find out what the benefit is. WHY is a plugged in EV a “happy EV“?

 

[alee]

The Lucid definitely keeps it topped off; I’m not sure if it kicks on at 79% or 78% when it’s set at 80.…

But that’s not the stated reason that they tell us to leave it plugged in; and as you note, the SOC when unplugged is remarkably stable. I’m really just trying to find out what the benefit is. WHY is a plugged in EV a “happy EV“?

Just for kicks, I asked Copilot. Nothing more than what we probably already knew but It seems the same basic reasons:

• BMS for optimal SOC and 12v charging as needed
• Temperature regulation - especially in extremes (It mentioned Arizona as an extreme heat example and cooling requirements)
• Software updates and vehicle access

This recommendation seems consistent across the major brands like Tesla, GM, Ford domestically. Nissan is an outlier going against this strategy for long-term storage.

 

[jedwin]

That all makes sense, though of course, the first and third bullet points are not things we need all the time (especially those who rarely use more than a tiny fraction of available range).

It’s the second one where I was looking for a little more definitive info about how hot or cold the battery needs to get before it needs to activate the thermal regulation system (when just sitting, not the conditioning for optimum charging).

I’m not sure why I’m so adamantly curious about this! It’s generally not that hard to leave it plugged in—though not stepping over the cord in the garage might be nice. I’ve toggled off the automatic-unlock setting, so that it doesn’t wake up and unnecessarily initiate charging for a couple of minutes when I walk by the garage to get the mail or take a walk…. I think I’m just stubbornly wishing that Lucid would share a little more about the concrete thresholds and various kinds of data that they have, which would feed the info geek in many of us!

 

[alee]

I'm like you and certainly geek out over the technical details. Perhaps a great topic for a future forum "Ask me anything" session with the engineering team

 

[Wassy2]

We are told that one of the main reasons to keep the car plugged in at home is to assure that the battery thermal management system can activate when ambient temps are too high or low, to keep the batteries healthy for the long term. My question is: at what temperatures does the battery cooling or heating kick in? I know I've read posts where folks were reporting some significant noise from the cooling system in summer.

Since this recommendation (the good ol' "a plugged in EV is a happy EV") is not about plugging in when charging, but keeping it plugged in, I've been surprised to have never heard the thermal management kick on in winter, with garage temps usually in the 20s, sometimes in the teens or perhaps a tad lower. And for the past two days my car was sitting in 95 degrees (97 when I put the thermometer on the hood), with again no system kicking in.

I'm wondering if it needs to be quite close to the Manual's stated storage range to activate? (below -4F, above 113F)

I definitely DO nearly always get the "charging limited while the battery warms" notice in winter, though the rate is only moderately lower than normal (as I recall, 7kW, while the typical rate on my charger is 9kW) for the 30-45min that the warming system is on. But again, this is thermal conditioning for charging; I'm curious about ongoing thermal management.

Other than for protective thermal management, what other purposes does leaving the car plugged in serve? Topping off the 12V battery, I suppose. Anything else?

Yes! Thats why U want to keep it plugged in when not in use even if the battery is charged, so that the thermal management gear wont drain ur battery when the fans kick in, because it will! Trust!

 

[Adnillien]

Yes! Thats why U want to keep it plugged in when not in use even if the battery is charged, so that the thermal management gear wont drain ur battery when the fans kick in, because it will! Trust!

I don't think that you are understanding @jedwin real question and point. The Lucid Air, even when plugged in, does not seem to run battery thermal management system, either in very hot or very cold situations, unless the you wake the car up. Maybe you have observed something different with the BMS?

 

[GearHead]

I don't think that you are understanding @jedwin real question and point. The Lucid Air, even when plugged in, does not seem to run battery thermal management system, either in very hot or very cold situations, unless the you wake the car up. Maybe you have observed something different with the BMS?

I agree. I never see any charging or electrical activity unless the SOC is less than 80% and it is scheduled to charge or awakened. My Wallbox charger does not record any additional draw as well.

Pete