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What happens when your SOC is above your set limit?

spokey

Active Member
Aug 8, 2020
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From various post here and elsewhere one reason to recommend keeping the car plugged in is that instead of drawing on the battery while the car is sitting there, it will use your charger / home juice.

But what if the SOC is higher than the limit? Say I normally charge to 80% at home. At some point I stop and super charge on the way home. When I get home my SOC is 85%. If I plug in will I draw from my house? Or will the battery drain until I'm at my normal 80% limit and then start using house current?
 
My daily commute is only about 20 miles. Overnight I'll charge my car to 80% and then set the limit to 50%. I'll get back home with like 70% and plug in at night, but no charging occurs. Though I assume the car is pulling power from the house rather than the battery to condition the batteries and heat/cool the car as needed for the following day's commute. After a few days when the battery gets close to or below 50%, I'll reset the limit back to 80% and let the car charge back up over night. Most weeks I only have 1 or 2 cycles.

On weekends if we have some sort of driving trip planned, and will set the limit to 90% or 100% depending on what we are doing. Last weekend started in the morning at 100% and made it back home with 3%. :)

I'm probably over thinking it, but don't mind. I figure eliminating a couple battery cycles each week can't hurt and might help preserve the life of the battery a smidge.
 

spokey

Active Member
Aug 8, 2020
1,327
804
Flagtown
My daily commute is only about 20 miles. Overnight I'll charge my car to 80% and then set the limit to 50%. I'll get back home with like 70% and plug in at night, but no charging occurs. Though I assume the car is pulling power from the house rather than the battery to condition the batteries and heat/cool the car as needed for the following day's commute. After a few days when the battery gets close to or below 50%, I'll reset the limit back to 80% and let the car charge back up over night. Most weeks I only have 1 or 2 cycles.

On weekends if we have some sort of driving trip planned, and will set the limit to 90% or 100% depending on what we are doing. Last weekend started in the morning at 100% and made it back home with 3%. :)

I'm probably over thinking it, but don't mind. I figure eliminating a couple battery cycles each week can't hurt and might help preserve the life of the battery a smidge.
If I'm understanding, you're not noticing any battery drain overnight when the SOC is higher than the set.
 
The battery will continue to drop until it reaches about 3% lower then the SOC is set to for recharging. Then the car will bring it up to the SOC.
While I agree with your comment, my interpretation of the OP's question is different. I thought he was asking if the car will still use the wall charger to maintain the car even if the SOC is higher? My MX does exactly that... The battery doesn't drop due to idle electronics use while plugged in. In the past I have seen it still drain with earlier software versions.
 
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LoudMusic

Active Member
Jul 21, 2020
1,714
2,166
Arkansas
My daily commute is only about 20 miles. Overnight I'll charge my car to 80% and then set the limit to 50%. I'll get back home with like 70% and plug in at night, but no charging occurs. Though I assume the car is pulling power from the house rather than the battery to condition the batteries and heat/cool the car as needed for the following day's commute. After a few days when the battery gets close to or below 50%, I'll reset the limit back to 80% and let the car charge back up over night. Most weeks I only have 1 or 2 cycles.

On weekends if we have some sort of driving trip planned, and will set the limit to 90% or 100% depending on what we are doing. Last weekend started in the morning at 100% and made it back home with 3%. :)

I'm probably over thinking it, but don't mind. I figure eliminating a couple battery cycles each week can't hurt and might help preserve the life of the battery a smidge.

I think that is very odd charging behavior but it certainly doesn't hurt it.

What you're referring to as a cycle isn't a cycle. You'd just be squirting in a little bit of electrons each day. This is precisely what Tesla recommends. A cycle is typically referred to as the complete capacity of the battery being removed from the battery and put back into the battery. It doesn't have to happen all at once. It can be cumulative over multiple sessions.


What I do, and is my recommendation for people who attempt to charge like you do, is simply don't plug in every day. Only plug in when it's down to 50%. Quit fiddling with the settings. Save yourself many steps. Let the EV life wash over you.

However, Tesla say to set it to 90% and plug in every day. This is the behavior I intend to begin when I return to driving on a regular basis. Right now the car just sits for days at a time :D
 
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spokey

Active Member
Aug 8, 2020
1,327
804
Flagtown
While I agree with your comment, my interpretation of the OP's question is different. I thought he was asking if the car will still use the wall charger to maintain the car even if the SOC is higher? My MX does exactly that... The battery doesn't drop due to idle electronics use while plugged in. In the past I have seen it still drain with earlier software versions.
Not sure I understand your answer. You say you agree with @Mensra but you continue to say (I think) that it doesn't drop but uses the charger.

I think you are understanding my question. Yes if I have the limit set at 80% and am at an SOC of 82 and plugged in (I use the mobile with a 14-50) will I stay at 82. I think @Mensra is saying I will not. That misc electronics will use the battery until it drops below 80 and then the charger will bring it back up.
 
Not sure I understand your answer. You say you agree with @Mensra but you continue to say (I think) that it doesn't drop but uses the charger.

I think you are understanding my question. Yes if I have the limit set at 80% and am at an SOC of 82 and plugged in (I use the mobile with a 14-50) will I stay at 82. I think @Mensra is saying I will not. That misc electronics will use the battery until it drops below 80 and then the charger will bring it back up.
well don't mind me. Maybe I'm having a brain dead day :) Just not good at explaining what I experience.

Let me try again. Yes, misc electronics use the battery until it drops to the charging point set by the user, HOWEVER, if my car is plugged into the charger, I see the battery holding its level for a MUCH longer time.

If my car is plugged into the charger and the soc is 2% above the set charge level, I see it can take as much as two weeks to drop that 2%. If not plugged in, it will drop this amount within a few days. This tells me the charger is supplying some juice to the car that is not being used to charge the battery and the current monitor in my electrical panel verifies that. Hope this makes sense. Or perhaps I should just go to bed.
 

LoudMusic

Active Member
Jul 21, 2020
1,714
2,166
Arkansas
I can tell you all as a matter of fact if your SoC is above your charge level the battery will drain while plugged in.

My car was at 75% SoC when I plugged it in with charge level set to 50%. This was several days ago. It is now at 74%. It is in my garage with all systems disabled. Today is the first day in more than a week that I've checked it in the app. The app shows "Charging Complete".
 

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spokey

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Aug 8, 2020
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well don't mind me. Maybe I'm having a brain dead day :) Just not good at explaining what I experience.

Let me try again. Yes, misc electronics use the battery until it drops to the charging point set by the user, HOWEVER, if my car is plugged into the charger, I see the battery holding its level for a MUCH longer time.

If my car is plugged into the charger and the soc is 2% above the set charge level, I see it can take as much as two weeks to drop that 2%. If not plugged in, it will drop this amount within a few days. This tells me the charger is supplying some juice to the car that is not being used to charge the battery and the current monitor in my electrical panel verifies that. Hope this makes sense. Or perhaps I should just go to bed.
no I think I understand you now. It drains back to the limit but slower than you would expect.
 
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LoudMusic

Active Member
Jul 21, 2020
1,714
2,166
Arkansas
well don't mind me. Maybe I'm having a brain dead day :) Just not good at explaining what I experience.

Let me try again. Yes, misc electronics use the battery until it drops to the charging point set by the user, HOWEVER, if my car is plugged into the charger, I see the battery holding its level for a MUCH longer time.

If my car is plugged into the charger and the soc is 2% above the set charge level, I see it can take as much as two weeks to drop that 2%. If not plugged in, it will drop this amount within a few days. This tells me the charger is supplying some juice to the car that is not being used to charge the battery and the current monitor in my electrical panel verifies that. Hope this makes sense. Or perhaps I should just go to bed.

I believe that is all correct but the battery does still drain when plugged in. Just seems much slower. Likely a combination of the charger trickling in some "maintenance" current, and also the car being at its home where we have all the additional services disabled causing it to use less.
 
I believe that is all correct but the battery does still drain when plugged in. Just seems much slower. Likely a combination of the charger trickling in some "maintenance" current, and also the car being at its home where we have all the additional services disabled causing it to use less.
yes, my experience exactly that the drain is slower. However, no the charger is not trickle charging the HV battery. It is either charges or it is doesn't. no in-between.
 
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qdeathstar

Completely Serious
May 17, 2019
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I can tell you all as a matter of fact if your SoC is above your charge level the battery will drain while plugged in.

My car was at 75% SoC when I plugged it in with charge level set to 50%. This was several days ago. It is now at 74%. It is in my garage with all systems disabled. Today is the first day in more than a week that I've checked it in the app. The app shows "Charging Complete".
I feel like the fantom drain would be more that 1 percent over 4-5 days…
 
I can tell you all as a matter of fact if your SoC is above your charge level the battery will drain while plugged in.

My car was at 75% SoC when I plugged it in with charge level set to 50%. This was several days ago. It is now at 74%. It is in my garage with all systems disabled. Today is the first day in more than a week that I've checked it in the app. The app shows "Charging Complete".
I don't think 1% really proves anything either way. For example, you might have been at 74.6% (rounded to 75) at 80 degrees, and now after sitting a few days the car is registering 74.4% (rounded to 74) at 60 degrees. Would be curious to see what happens after a longer period of time?
 

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