Buzzing when remote-started

[Kmp14]

I am sure this will fall under the "that is normal" category, but I just wanted to come out here and ask, maybe get hazed for asking an already answered question. I did search for "buzzing" and didn't find anything related to remote start.

I have noticed that when I remote start my new MME, I hear a loud buzzing, it is not the HVAC blower fan. So far, it seems I have only heard it when plugged in. Is it the process that warms up the battery? I have also noticed it during a scheduled departure operation, so BOTH remote start and scheduled departure. Hopefully this is normal?

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[devmach-e]

You pretty much nailed it: pre-conditioning/departure time is causing a system or three to start running. Mostly likely the heating system that warms the "coolant", plus the pumps to get the warming liquid to the places it needs to be, and fans for the cabin.

 

[Kmp14]

You pretty much nailed it: pre-conditioning/departure time is causing a system or three to start running. Mostly likely the heating system that warms the "coolant", plus the pumps to get the warming liquid to the places it needs to be, and fans for the cabin.

Next question, I swear I read that battery warming only happened when pre-conditioning with a set departure time and not during remote start, even when plugged in. Not only do I hear the buzzing when remote starting, but I even heard it today when plugged into 120v! I thought I had read 2 things about "pre-conditioning", maybe I am wrong, but I thought:

1: Battery pre-conditioning only happens with a scheduled departure time and plugged into 240v, and
2: That it doesn't happen if plugged into 120v.

If the sound I am hearing when remote starting is battery pre-conditioning then it appears to be happening when remote starting (and plugged in, of course).

I have a house energy monitor system, and sure enough, even when plugged into 120v, when I remote start the car, I can see amp draw on the circuit the EVSE is plugged into jump to 11 amps. This has me thinking that even plugged into 120v, battery pre-conditioning is happening?

 

[devmach-e]

There is a single heater/cooler in the car that provides warm/cold liquid to the cabin's HVAC system and the battery's thermal management system. Whether you pre-condition the battery & cabin via a set departure time, or you just do a remote start to warm up the car, that same system runs no matter what. The difference between a planned departure and just a remote start/warming of the cabin basically comes down to which of the subsystems gets priority.

I don't know if battery conditioning can operate on 120V. I have a 240V L2 EVSE at home, so I've never had the opportunity to test things. Also, I don't live where it gets much below 38 overnight. I'm only relaying what others on here have experienced. @Mach-Lee has been doing some interesting experiments on cold-weather preconditioning that might interest you.

 

[Mach-Lee]

Next question, I swear I read that battery warming only happened when pre-conditioning with a set departure time and not during remote start, even when plugged in. Not only do I hear the buzzing when remote starting, but I even heard it today when plugged into 120v! I thought I had read 2 things about "pre-conditioning", maybe I am wrong, but I thought:

1: Battery pre-conditioning only happens with a scheduled departure time and plugged into 240v, and
2: That it doesn't happen if plugged into 120v.

If the sound I am hearing when remote starting is battery pre-conditioning then it appears to be happening when remote starting (and plugged in, of course).

I have a house energy monitor system, and sure enough, even when plugged into 120v, when I remote start the car, I can see amp draw on the circuit the EVSE is plugged into jump to 11 amps. This has me thinking that even plugged into 120v, battery pre-conditioning is happening?

You're probably hearing the coolant pump. So it's either heating the cabin or the battery. A departure time will heat the cabin BTW.

2023's may have different battery heating behavior so I'm interested. If you leave it plugged in at your charge target, do you see periodic heating? Maybe 1-3 times in a 24 hour period when parked in an area below freezing.

I'm also interested if you set a departure time with the cabin temp to OFF if you see current draw before the departure time. When I tried this unplugged, it heated the cabin after the set time even when I told it not to.

 

[Kmp14]

You're probably hearing the coolant pump. So it's either heating the cabin or the battery. A departure time will heat the cabin BTW.

2023's may have different battery heating behavior so I'm interested. If you leave it plugged in at your charge target, do you see periodic heating? Maybe 1-3 times in a 24 hour period when parked in an area below freezing.

I'm also interested if you set a departure time with the cabin temp to OFF if you see current draw before the departure time. When I tried this unplugged, it heated the cabin after the set time even when I told it not to.

I don't think the car has ever started pulling juice once it reached the set charge target. I will keep an eye on it and let you know. Chicago getting down to below zero F tonight, so my garage should be getting below freezing for sure.

I will also try a departure time with the heat set to off and see what happens.

 

[AKgrampy]

My understanding is the car will still heat the cabin when plugged into 120V but it may also drain energy from the HVB to provide heat. I do not believe it will precondition the batteries when plugged into 120V though. My thought on this is preconditioning is to provide added range so why would they drain the the HVB (lose range) in order to condition battery and gain range.

 

[Kmp14]

My understanding is the car will still heat the cabin when plugged into 120V but it may also drain energy from the HVB to provide heat. I do not believe it will precondition the batteries when plugged into 120V though. My thought on this is preconditioning is to provide added range so why would they drain the the HVB (lose range) in order to condition battery and gain range.

Yes, that all makes sense, and consistent with what I have read here on the forums and I think I've seen in YouTube videos. The reason it's even a question again is because while plugged into a 120 volt EVSE, I heard that loud buzzing noise during remote start, which we are thinking is the noise that's made when the battery warming part of the remote start is happening? I don't hear that noise when remote starting and not plugged in. So something different is happening during remote start, even when plugged in to 120v.

 

[AKgrampy]

Yes, that all makes sense, and consistent with what I have read here on the forums and I think I've seen in YouTube videos. The reason it's even a question again is because while plugged into a 120 volt EVSE, I heard that loud buzzing noise during remote start, which we are thinking is the noise that's made when the battery warming part of the remote start is happening? I don't hear that noise when remote starting and not plugged in. So something different is happening during remote start, even when plugged in to 120v.

Once again I am no expert. When you are plugged in at 120V and remote start then the plug and the HVB (my understanding) share the role of providing energy so there is the conversion from AC to DC taking place along with use of the HVB for climate. Remote start does not warm the battery as far as I know but will heat the cabin and obviously no AC/DC conversion. I may be wrong minded here but only preconditioning and driving the car will provide any battery warming.

 

[Kmp14]

You're probably hearing the coolant pump. So it's either heating the cabin or the battery. A departure time will heat the cabin BTW.

2023's may have different battery heating behavior so I'm interested. If you leave it plugged in at your charge target, do you see periodic heating? Maybe 1-3 times in a 24 hour period when parked in an area below freezing.

I'm also interested if you set a departure time with the cabin temp to OFF if you see current draw before the departure time. When I tried this unplugged, it heated the cabin after the set time even when I told it not to.

I checked the logs for last night and my MME did start pulling kW from my juicebox this morning for about 15 minutes. I guess that is hvb being kept warm?

 

[Mach-Lee]

I checked the logs for last night and my MME did start pulling kW from my juicebox this morning for about 15 minutes. I guess that is hvb being kept warm?

Were you plugged into 120V or 240V when it did this?

 

[Kmp14]

Were you plugged into 120V or 240V when it did this?

240v

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