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What Percent is Your Tesla Charged to While at Home?
- Thread starter Resist
- Start date
BigNick
Infamous Fat Sweaty Guy
31% sounds like a pretty close average SoC when the car is sitting in the garage. Coincidentally that is the SoC right now.
I just checked SMT and it is reporting 79.3 kWh and 310 miles range of the original rated 315.
I really need to drive more.
Have to add:
There’s nothing wrong doing that, and not bad for the battery. It will be fine.
(I had a text about this in my answer yesterday, that i cut to paste on another place in the post, but it was never pasted so lost in space.)
stopcrazypp
Well-Known Member
There is zero empirical evidence or theoretical mechanism to support this assumption. It's a complete myth that unlike the "avoid 100%" has literally nothing to support it.
BigNick
Infamous Fat Sweaty Guy
I'd say it was dead-on, considering the SMT value can and does fluctuate by about 0.5 kWh in either direction.
As already stated, its a myth.
Here’s the real world:
Researchers have tested what happens if you leave the battery for months at different SOC.
(There are literally hundreds of research reports supporting this, so it can be thrusted as a fact.)
Is there any negative side effects of the battery being heavily discharged at a low SoC (like a full throttle burst at 20%)?
I just picked up a new inventory M3 RWD on Monday and stumbled on this thread trying to figure out how to set up my car for charging since I knew that my car had an LFP battery and may benefit from a different approach compared to my 9 month old MY which I just set to 80% unless I know I’ll need more.
I read most of this thread but am curious what people think of the following approach. I’ve set up the Tessie app to charge according to my TOU plan which has off-peak 12a-6a M-F and 12a-2p on the weekends. Then I set up two recurring automations to set the charge limit to 100% on Friday at noon so the car would be fully charged on the weekend when I am most likely to need it and then switch to 70% on Sunday at 2pm for my weekly commute. I might adjust that 70% level down a bit but part of the reason we bit the bullet on the M3 was that I was running into “turtle mode” a bit too frequently on my 65 mile Leaf. This approach gets me to 100% at least weekly to calibrate the BMS and keeps the SOC at 70% or lower for most of the week.
The only thing I don’t seem to be able to take advantage of is charging with a departure time on the weekends when it is set to 100% so it might be sitting at full SOC for a while, especially if we are using the MY for errands. I just don’t know when I’ll be leaving and don’t actually think I can set it up to that with the Tessie schedule taking advantage of my TOU plan.
Any thoughts on this approach?
Thanks!
I read most of this thread but am curious what people think of the following approach. I’ve set up the Tessie app to charge according to my TOU plan which has off-peak 12a-6a M-F and 12a-2p on the weekends. Then I set up two recurring automations to set the charge limit to 100% on Friday at noon so the car would be fully charged on the weekend when I am most likely to need it and then switch to 70% on Sunday at 2pm for my weekly commute. I might adjust that 70% level down a bit but part of the reason we bit the bullet on the M3 was that I was running into “turtle mode” a bit too frequently on my 65 mile Leaf. This approach gets me to 100% at least weekly to calibrate the BMS and keeps the SOC at 70% or lower for most of the week.
The only thing I don’t seem to be able to take advantage of is charging with a departure time on the weekends when it is set to 100% so it might be sitting at full SOC for a while, especially if we are using the MY for errands. I just don’t know when I’ll be leaving and don’t actually think I can set it up to that with the Tessie schedule taking advantage of my TOU plan.
Any thoughts on this approach?
Thanks!
I think a lot of people make the wrong assumptions about SOC when it comes to when a car is not in use. Yes it is not advisable to keep the Tesla at a really low SOC for an extended period of time like if you were to go on a vacation in case it goes to zero. But if you are just leaving it uncharged for like 2 days if you are not using the car is not going to damage the battery. But if you ever drain it to zero a few times it is not going to damage the pack permanently. Its just best not to make it a habit.
Imagine if you are just coming home from work and you had to make some trips to Walmart/Target/grocery store to pick up something you don't have to freak out if your SOC while parked to do these errands is at 20% or under as long as you are heading home and plan to charge the car in the near future. The only advice which makes sense to me is to not drain the battery to zero and don't charge to 100% often unless you are going on a road trip.
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The car limits the power at low SOC so, no not a problem.
I still drive carefully at low SOC, probably not needed but I do in anyway.
Lithium batteries are happy at low SOC. Even down to 0% real SOC which is well below 0% on the screen.
The low voltage battery is unhappy if being discharged, so we should not let the car drain the HV battery until it shuts down and then leave it without charging. But this is not dangerous to the HV battery but to the LV battery.
Leaving the car at SOC that we know is not going to reach 0% on the screen during the time is safe.
The pictures show the degradation from time.
High SOC is worse, low SOc is better. As we can see, its better for the lithium cells down to 0%, for both NCA, NMC ans LFP.
High temp is worse, low temp is better.
No, he cannot.
The manual is clear that we should not leave the car so it gets completely ”dry” and shuts down. The main reason is that the LV battery will take damage. It will not damage the HV batt though.
The manual states to use 1% per day as a margin, so 14 days would be 14%. The manual doesnt say to aim at 20% or anything as the lowest, just to not go below 0%.
It is quite clear from research that lithium batteries is happier the lower the SOC is, for calendar aging purposes.
king.cong.1119
Member
would this theory still apply to LFP batteries? Assuming LFP can be charged at 100% and naturally has much higher life cycle?
However, most publicly known Bolt fires where the state of charge was publicly known occurred at close to 100% state of charge. History of deep discharging was also implicated in increasing for risk in defective batteries.
Regarding Tesla battery fires, there do appear to be a few that do not seem to be crash or damage related. But the rate is very low.
stopcrazypp
Well-Known Member
That is a very small subset of cases and even in that table many are unknown. I think the reason most are at 100% or close is because most people charge it to that percentage, so when it's done charging it will set there and that is the most prevalent SOC most of the time. It's not necessarily that it has to do with 100% specifically (like for example all if all of those people let the battery sit at 50% that the fire would be avoided).However, most publicly known Bolt fires where the state of charge was publicly known occurred at close to 100% state of charge. History of deep discharging was also implicated in increasing for risk in defective batteries.
When GM initially announced the first fire recall, it advised customers not to charge to 100% and offered an interim software that limited charging to 94%, since GM believed that being at 100% increased the risk of fire. Through various updates to the recalls, GM seems to consistently believe that 100% state-of-charge had the highest risk of catching fire, but also later noted that a history of deep discharging also increased the risk.
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