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Anyway to reduce vampire drain - MCU 2 - Q2 2015 70D

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David_Cary

Active Member
Dec 17, 2012
1,544
1,330
Cary, NC
I just did the MCU2 upgrade.
I was on full energy saving mode before and not always connected - range mode. I had forgot about the increased vampire drain but also wasn't sure mine would be as effected since they talk about pre Q2/2015 being the issue.
My early 5/2015 - last week before LTE - has noticeably increased vampire drain. It seems to be at 3-4 kWh per day. I don't have it on an energy monitor but just based on mileage lost and this was in a 70 degree garage. No background apps.
I have been working remote and don't drive much so the vampire really hurts. And I am one of those energy nerds where it isn't the money that I care about. I have a large solar array and am inching closer to net zero energy despite 2 EVs. So the 1000 kwh a year really hurts.

I was thinking is there anyway to induce deep sleep or is that still a thing with older cars and MCU2? I have to think there is some way to do it especially for long stretches without driving. Is there an anti-brick mode. My wife prefers we drive in her Model 3 if we go somewhere together so I frequently go days without driving my car.

If the used market wasn't so crazy right now, I would probably get an EV without vampire drain....
 
I have a mid-2016 MS90D. I just upgraded mine to MCU2 within the past month. With MCU1 I had energy saving turned on, but also had always connected on. I also do not have cabin overheat protection turned on and do not use pre-conditioning scheduled. I keep the app shut down on my phone unless I'm actively using it, but I do run my own datalogger program to ping the car at a low frequency via the API. With this setup I would see about 0.5-0.6 kWh a day vampire drain on average.

With MCU2 there is no longer a energy saving or always connected mode, but I still have cabin overheat protection turned off. With this setup I'm seeing similar, if not maybe slighly lower vampire drain. It's a little hard to do a true apples-to-apples comparison yet as I've been driving my car a lot more since doing the MCU2 upgrade, so do not have data from letting it set 1-2 weeks at a time unused.

I would suggest you first quick check to make sure you've not accidentally have cabin overheat protection or preconditioning turned on. Those are the couple quick things which I could think might be driving 3-4 kWh a day parasitic drain. My experience would say you have something else going on and this is not just an MCU1 to MCU2 change.
 
Unfortunately it's a hardware issue. @wk057 has a great explanation of what's going on with the higher vampire drain with some Model S':
MCU2 was designed with the standby supply in mind and thus doesn't have the same hardware abilities for power saving. For example, the modem, gateway, and CPU are able to be powered directly from the standby supply in the pack. In older S', this has to happen from the normal 12V system without hardware for any intermediate modes. Based on my understanding of the hardware, a retrofit capability wasn't planned so no need for hardware capable of significant power saving was required. The savings of not requiring closed contactors and DCDC enabled outweighed any potential benefit by an order of magnitude.

Then when these units get installed in older no-standby supply cars, they're wasteful since they use more power AND the contactors need to be on and cycle.

MCU1 was designed without the standby supply in mind, so it was designed to not require continuous power for a lot of functions to keep portions in lower power modes. Tesla has been trying to optimize this through software with a bit of crude predictive day to day driver's routines trying to determine when to be at the ready and when not to be, but there's just not a lot they can do on earlier models that lack the in-battery standby power supply.
 
Unfortunately it's a hardware issue. @wk057 has a great explanation of what's going on with the higher vampire drain with some Model S':

It's too bad they can't just have a home mode where when you're parked at home, there's a setting that turns virtually everything off with a setting so that you basically can't see the car on the app or do anything remotely until you open the door.
 
My experience would say you have something else going on
@David_Cary You could check if the 12v battery is running low, as the car wakes up more frequently to recharge it when the 12v battery is about to die.

I was thinking is there anyway to induce deep sleep
It's too bad they can't just have a home mode where when you're parked at home, there's a setting that turns virtually everything off

Yes, especially considering this setting already exists, but Tesla doesn't make it accesible to the driver/owner:


20220104_095426.jpg
 
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@Art VandeIay sorry for off-topic question, but what are the ESP and TC settings in the above screenshot?

Being a Finn, it sometimes annoys me that I have a powerful RWD car in winter and there is no way to turn ESP off.. TC can be disabled but it doesn't disable ESP. Go even slightly sideways and car destroys the fun with brakes.
 
what are the ESP and TC settings in the above screenshot

Here's the options you get on each drop-down menu.

ESP:

20220105_171215.jpg


Traction Control:

20220105_171050.jpg


there is no way to turn ESP off...

The original Dyno Mode turned off ESP and TC, but after people started crashing their cars 😒, Tesla implemented the "Reduced Power" mode when the steering wheel sensor detected any input and placed the car in turtle mode with Dyno Mode active.

That's the perfect example of why we just can't have nice things... :rolleyes:
 
I have a pretty new 12V battery and nothing is checked (like cabin overheat etc). There definitely seemed like a change with MCU2 but I wasn't tracking it really closely. I used to see 4 or 5 miles gone a day and now it is 8 to 10. I have read wk057's explanation. I was hopeful that it wouldn't effect my car being not "pre-Q2 2015".
Is there not a fuse to force deep sleep? Or hit the brakes 5 times while in park with the driver's window 1/2 down?
 
I have a pretty new 12V battery and nothing is checked (like cabin overheat etc). There definitely seemed like a change with MCU2 but I wasn't tracking it really closely. I used to see 4 or 5 miles gone a day and now it is 8 to 10. I have read wk057's explanation. I was hopeful that it wouldn't effect my car being not "pre-Q2 2015".
Is there not a fuse to force deep sleep? Or hit the brakes 5 times while in park with the driver's window 1/2 down?
Did you have a special application on you phone like teslafi, teslaapp or ....
Did you add the tesla widgets in front of you main screen mopbile phone ?
In driving menu you have the "ECONOMY" mode
 
My car info is in my signature below. No 3rd party API app and no energy wasting settings on the car.

Just upgraded from MCU1 to MCU2. Also, have a brand new HV battery installed. Per the service center check, my 12V is healthy. My vampire drain has gone up and it's now @2% minimum in a 24 hours window, constantly parked in the garage. With my old MCU1, the drain was averaging ~1% in the same conditions.
 
My car info is in my signature below. No 3rd party API app and no energy wasting settings on the car.

Just upgraded from MCU1 to MCU2. Also, have a brand new HV battery installed. Per the service center check, my 12V is healthy. My vampire drain has gone up and it's now @2% minimum in a 24 hours window, constantly parked in the garage. With my old MCU1, the drain was averaging ~1% in the same conditions.
I have a mid-2016 'refresh' AP1 MS90D. I upgraded to MCU2 last December. I spend most of my time oversees on assignment and my car will sit for 2-3 months at a time. I manage my SOC by charging car up to 70 or 80% SOC, lower the setpoint to 50%. Battery SOC will slowly drop and then I'll trigger to recharge back up to 70 or 80% and to reset the cycle. All that means I have lots of experience with my car sitting in my garage for extended times and watching my vampire drain. A couple thoughts.

I know you said not energy draining settings, but I saw I got quite a few software updates in the first few weeks after MCU2 upgrade. I'd go in and double/triple check nothing got changed on you during an update. I just know I've seen on a few occasions I've had a setting changed for now obvious reason during an update.

Don't know what SOC you're charging to, but some MS85 owners have experience much more aggressive battery temp management when SOC is above 70 or 80%, causing the battery cooling system to run and promoting excessive drain. If you're normally charging up to above 70%, try dropping it down to 60% and let it sit for a couple days to see if this acts differently. I know you stated you have a new HV battery, but unclear to me what the triggers are for this behavior as seems to be different experience between different owners.

I also know that I've seen a strange behavior show up on my car beginning last fall where the SOC loss per day behave very non-linear in the 60-70% SOC region. My car can typically go about 6 weeks between 80% SOC and 51 or 52% SOC. That's an average over that 6 week period of about 2% every 3 days, or less than 1% a day. However, this is not linear with time. In the range from about 70% SOC to maybe around 62-63% the vampire drain will "appear" about 1.5-2 time higher than that. Once it gets below 62ish, then vampire drain flattens back out. I've seen this since before my MCU2 upgrade, so unrelated. It's also very consistent, have observed this over many cycle and over 6 months. I cannot believe that the parasitic power loss is actually different, but this is a learned non-linearity in the BMS system over the range when it sits for long times. I've done several long trips during this period, never see any funny in how SOC/RM behaves through that range, but consistent behavior when stored. Where I'm headed with all this, is maybe you're sitting in a range like this and watching the car in a different SOC range might show you a different behavior.

Here's snapshot of what this looks like for me. The dates are the start date or 'day 0' on the x axis. The most recent trace shows a really sharp drop, but found that car was not going to sleep for some reason. I was able finally to get a family member to check the car, found the center screen black, so did a scroll wheel reset behavior for me, resulting in it behaving again. Also, regarding influence of week vs new 12V battery, I just had the 12V battery replaced right before start of the current cycle, so on Jun 30th. The prior 12V battery was 4.5 years old. I don't see any appreciable influence of the aged vs. new 12V battery in this data. You do see a little difference between the colder months, Jan 26-Mar10 stretch from the warmer months, potentially tied to batterh thermal management consuming a little more energy when my garage was colder than it's been running the past few months.

1659584979980.png
 
I have a mid-2016 'refresh' AP1 MS90D. I upgraded to MCU2 last December. I spend most of my time oversees on assignment and my car will sit for 2-3 months at a time. I manage my SOC by charging car up to 70 or 80% SOC, lower the setpoint to 50%. Battery SOC will slowly drop and then I'll trigger to recharge back up to 70 or 80% and to reset the cycle. All that means I have lots of experience with my car sitting in my garage for extended times and watching my vampire drain. A couple thoughts.

I know you said not energy draining settings, but I saw I got quite a few software updates in the first few weeks after MCU2 upgrade. I'd go in and double/triple check nothing got changed on you during an update. I just know I've seen on a few occasions I've had a setting changed for now obvious reason during an update.

Don't know what SOC you're charging to, but some MS85 owners have experience much more aggressive battery temp management when SOC is above 70 or 80%, causing the battery cooling system to run and promoting excessive drain. If you're normally charging up to above 70%, try dropping it down to 60% and let it sit for a couple days to see if this acts differently. I know you stated you have a new HV battery, but unclear to me what the triggers are for this behavior as seems to be different experience between different owners.

I also know that I've seen a strange behavior show up on my car beginning last fall where the SOC loss per day behave very non-linear in the 60-70% SOC region. My car can typically go about 6 weeks between 80% SOC and 51 or 52% SOC. That's an average over that 6 week period of about 2% every 3 days, or less than 1% a day. However, this is not linear with time. In the range from about 70% SOC to maybe around 62-63% the vampire drain will "appear" about 1.5-2 time higher than that. Once it gets below 62ish, then vampire drain flattens back out. I've seen this since before my MCU2 upgrade, so unrelated. It's also very consistent, have observed this over many cycle and over 6 months. I cannot believe that the parasitic power loss is actually different, but this is a learned non-linearity in the BMS system over the range when it sits for long times. I've done several long trips during this period, never see any funny in how SOC/RM behaves through that range, but consistent behavior when stored. Where I'm headed with all this, is maybe you're sitting in a range like this and watching the car in a different SOC range might show you a different behavior.

Here's snapshot of what this looks like for me. The dates are the start date or 'day 0' on the x axis. The most recent trace shows a really sharp drop, but found that car was not going to sleep for some reason. I was able finally to get a family member to check the car, found the center screen black, so did a scroll wheel reset behavior for me, resulting in it behaving again. Also, regarding influence of week vs new 12V battery, I just had the 12V battery replaced right before start of the current cycle, so on Jun 30th. The prior 12V battery was 4.5 years old. I don't see any appreciable influence of the aged vs. new 12V battery in this data. You do see a little difference between the colder months, Jan 26-Mar10 stretch from the warmer months, potentially tied to batterh thermal management consuming a little more energy when my garage was colder than it's been running the past few months.

View attachment 836452

Thanks for sharing your experience and data.

I know you said not energy draining settings, but I saw I got quite a few software updates in the first few weeks after MCU2 upgrade. I'd go in and double/triple check nothing got changed on you during an update. I just know I've seen on a few occasions I've had a setting changed for now obvious reason during an update.

The software update which the service center installed has been the latest (it's in my signature).

Don't know what SOC you're charging to, but some MS85 owners have experience much more aggressive battery temp management when SOC is above 70 or 80%, causing the battery cooling system to run and promoting excessive drain. If you're normally charging up to above 70%, try dropping it down to 60% and let it sit for a couple days to see if this acts differently. I know you stated you have a new HV battery, but unclear to me what the triggers are for this behavior as seems to be different experience between different owners.

The car was set to charge at 90% by the SC (I personally prefer 50% based on my usage), has been unused, unplugged since I brought it back and parked in the garage, specifically to observe the daily drain after the MCU upgrade and a brand new pack. Also, I'm well familiar with the "pump-gate" (cooling pumps running on some cars beyond 7~70% SOC), something I was experiencing prior to the new HV battery installed (but not any more).

Where I'm headed with all this, is maybe you're sitting in a range like this and watching the car in a different SOC range might show you a different behavior.

I leave the car undisturbed, and only connect via app daily at 10:00 am to measure the RM and SOC. See my thread titled "High Vampire Drain" which I started when I was still on MCU1 and the original battery.

This is what I'm thinking:
My 2% daily loss is due to my particular car (it's Q1-2015 build) with MCU2, which lacks the necessary wiring requirements to leverage the "Stand-by" power supply in my new pack. What that means is that my new MCU2 is powered by the HV battery instead of the 12V, leaving the contactor open (at least most of the time). And, for now, I'm going to stick to my hypothesis.
 
Thanks for sharing your experience and data.



The software update which the service center installed has been the latest (it's in my signature).



The car was set to charge at 90% by the SC (I personally prefer 50% based on my usage), has been unused, unplugged since I brought it back and parked in the garage, specifically to observe the daily drain after the MCU upgrade and a brand new pack. Also, I'm well familiar with the "pump-gate" (cooling pumps running on some cars beyond 7~70% SOC), something I was experiencing prior to the new HV battery installed (but not any more).



I leave the car undisturbed, and only connect via app daily at 10:00 am to measure the RM and SOC. See my thread titled "High Vampire Drain" which I started when I was still on MCU1 and the original battery.

This is what I'm thinking:
My 2% daily loss is due to my particular car (it's Q1-2015 build) with MCU2, which lacks the necessary wiring requirements to leverage the "Stand-by" power supply in my new pack. What that means is that my new MCU2 is powered by the HV battery instead of the 12V, leaving the contactor open (at least most of the time). And, for now, I'm going to stick to my hypothesis.

This is what’s going with the new MCU2 ... Looks like the car never sleeps (daily occurrence since July 31):

1659645979880.png
 
This is what’s going with the new MCU2 ... Looks like the car never sleeps (daily occurrence since July 31):

View attachment 836747
@Droschke - I had a problem with 2022.20.6 where my car suddenly would not go to sleep. That didn't start immediately after installing that update, but about 3 days later. That's where you can see a really sudden, steep drop in the RM/SOC in my plot above. Rebooting the MCU fixed that. If you're still seeing indications of the car not sleeping and haven't driven it, you might try a reboot to see if that helps any. I'm actually running 2022.20.7 now, installed it on July 28th. It was only about 10 days between getting 2022.20.6 and getting 2022.20.7, so not sure if that short interval indicates they found a problem or not.

I do see that MCU2 has a different sleep behavior than MCU1. I actually had to make some revisions to how my data collection program works after the MCU2 upgrade to still get occasional data without keeping it awake all the time. I figured out a way that I can passively 'watch' the car without waking it up if I want. What I will see is it wakes up (responds to requests for data) maybe every 4-7 hours during the day, says awake for about 20 minutes, then goes back asleep/offline. I think that represents when car periodically energizes the contactors to supply power from HVB to recharge the 12V battery. I do intentionally wake my car every 6 hours for about 20 minutes. That's to ensure I get at least 4 groups of data samples a day to allow me to keep an eye on my SOC and tracking statistics. Even doing that I see what's equivalent of about a continuous 30W draw averaged over a 24 hr period. I might be able to reduce that a little, but honestly it's lower than I was averaging with MCU1 and the way I was pulling data, and given that's about 10 cents a day average cost for me, I figure if I'm worried about lowering my home electric usage/bill further, I have much bigger opportunities!

I'm not disputing there may be a difference with your car, being an older model than mine, but just sharing more of what I'm seeing in case it might help spark some ideas for you.
 
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@Droschke - I had a problem with 2022.20.6 where my car suddenly would not go to sleep. That didn't start immediately after installing that update, but about 3 days later. That's where you can see a really sudden, steep drop in the RM/SOC in my plot above. Rebooting the MCU fixed that. If you're still seeing indications of the car not sleeping and haven't driven it, you might try a reboot to see if that helps any. I'm actually running 2022.20.7 now, installed it on July 28th. It was only about 10 days between getting 2022.20.6 and getting 2022.20.7, so not sure if that short interval indicates they found a problem or not.

I do see that MCU2 has a different sleep behavior than MCU1. I actually had to make some revisions to how my data collection program works after the MCU2 upgrade to still get occasional data without keeping it awake all the time. I figured out a way that I can passively 'watch' the car without waking it up if I want. What I will see is it wakes up (responds to requests for data) maybe every 4-7 hours during the day, says awake for about 20 minutes, then goes back asleep/offline. I think that represents when car periodically energizes the contactors to supply power from HVB to recharge the 12V battery. I do intentionally wake my car every 6 hours for about 20 minutes. That's to ensure I get at least 4 groups of data samples a day to allow me to keep an eye on my SOC and tracking statistics. Even doing that I see what's equivalent of about a continuous 30W draw averaged over a 24 hr period. I might be able to reduce that a little, but honestly it's lower than I was averaging with MCU1 and the way I was pulling data, and given that's about 10 cents a day average cost for me, I figure if I'm worried about lowering my home electric usage/bill further, I have much bigger opportunities!

I'm not disputing there may be a difference with your car, being an older model than mine, but just sharing more of what I'm seeing in case it might help spark some ideas for you.

Thanks for the feedback.

The graph I posted is from my router. To take the measurements, I've been leaving the car totally undisturbed in a 24-hour window, except at 10:00 AM every day to get the data, when I either connect via the app or physically go to the car to read the RM and SOC.

Also, keep in mind the other factor, as it relates to how your car sleep pattern is different from mine, is the MCU2 in your 2016 refresh car uses the standby power supply in your pack, whereas my car does not have the wiring capability to do so. My MCU2 power source appears to be the HVB itself.