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Tesla Home Charge Warm When Left Plugged IN
- Thread starter hbv2020
- Start date
bwilson4web
hit the spot
There is an AC-to-DC power supply that drives the electronics including the LED. Perhaps someone might measure the parasitic load with a kill-a-Watt device?
Bob Wilson
Bob Wilson
Eno Deb
Active Member
This doesn't sound normal. The UMC only uses approximately 1-2W when idle according to the inductive power meter in my switch box. The case is cool on mine (except for a warm spot where the green LEDs are). It does get slightly warm (but not hot) when charging. I'm also using a 10-30 outlet.
You're supposed to leave the car plugged in whenever you can, even if you're not charging.
Warm is normal. Large amount of current through the contactors and wires is what is causing it and is expected. Hot is not normal.
Warm is when you can hold it for long (hours) periods of time.
Hot is when you can hold if for maybe 10+ seconds
Warm cords are common on hair dryers and space heaters which pull 12A @ 120V. The car is pulling 30A @240V, about 5 times the amount of power.
Warm is when you can hold it for long (hours) periods of time.
Hot is when you can hold if for maybe 10+ seconds
Warm cords are common on hair dryers and space heaters which pull 12A @ 120V. The car is pulling 30A @240V, about 5 times the amount of power.
Kleenerth3
Member
This is true on trip driving. Getting close to 20% then supercharge to 80% . This is why I'm learning to plot almost all of my longer drives so the computer can figure out when to stop.
My cars limit was set at 90% when we bought it and I left it plugged in when garaged. I did get a warning from the car not to continually charge to 90% , lower to 80%. Now that I did that, babies happy. The computer system in these things is incredible. It will figure out your driving pattern and charge itself in a careful pattern. Go back into the owners manual, around pg. 120 and reread the charging section. It took me a few reads through to get it along with some of these threads.
But please plug that puppy in when not in use. A plugged in car is a happy one.
AlanSubie4Life
Efficiency Obsessed Member
No, that is not correct. Tesla says to leave the car plugged in whenever you are not using it, when possible. Furthermore, they do not allow you to do this and charge to any less than 50%, or over 90% (routinely).
So you want to be maintaining state of charge in the region of 50-90% as much as possible, especially when the car is being left in that state for significant periods of time (i.e. not on trips, when excursions are much less of an issue since they don't last long). That is to say, you don't need to worry at all about state of charge going outside of this range, but just get it back in this range as soon as possible.
Generally, for generic Li-ion chemistries (which may not match to Tesla's), all of the above 50-90% recommendations with shallower discharges are supported by the known data on battery longevity. Whether they apply to Tesla's Model 3 chemistry specifically can be debated - but in general it is supported by the charging limits that the car enforces, in conjunction with Tesla's recommendation to leave the car plugged in.
There are quite a few threads about this and one particular one about Li-ion battery degradation, explained, if you search for it. They are quite informative and you can draw your own conclusions.
In the end, leave the car plugged in as Tesla says, set the charge level to whatever you want, and as long as the car doesn't bug you about what you're doing (setting charge limit to over 90% too often), you'll be doing the best you can.
As far as your original issue, it sounds like it was warm while the car was charging, which is perfectly normal. If it was quite warm to the touch when the car was NOT charging (and had not been charging recently), then that would be cause for concern.
Because Tesla advises owners to do so. It’s in the owner’s manual and, in fact, Tesla used to include placards in the car that advised this, as well.
I understand but I am looking for a more technical reason. Now, if my car was going to sit for a month without driving it I would think it should be plugged in so it would not eventually discharge as a result of vampire drain to zero and degrade the battery. Makes sense.
However, I don’t understand the value of plugging it every moment I am not driving it. I guess if I wanted to be sure I always have a bunch of range available in case of an emergency there is a benefit. The confusing part about these battery charging discussions is that we hear that lithium ion batteries prefer to sit at around 50% charge but we are basically instructed to stay plugged in at 80-90% charge all the time. What is wrong with charging to 80% drive around for a few days without charging get to about say 40% and then charge back to 80% as long as I know my range limitations? Why is charging from say 70% to 80% everyday better than just charging from 50-80% every 2-3 days?
Tesla is a bit tight lipped on this regard. I assume they don’t want to stir the pot and have the average consumer think about these things. They want a general recommendation so it’s easy to adopt an EV. But they’re not using some sort of whiz bang cell tech, so there’s no reason to suspect that degradation is decreased from having the pack sit at a higher SOC longer. The magic to the design is the total system, not the cell itself. Generally lowest degradation occurs basically ice cold and practically dead. But this poses other issues of course. For long term storage the most sensible method would be plugged in and set to 50% SOC. It’s a bit telling they still allow you to charge to 50% SOC. They wouldn’t leave that there if it offered no benefit. And every similar chemistry cell on the market suffers from higher degradation as the SOC increases. However, cell balance and customer experience appear to be significant driving factors for Tesla’s recommendation. I presume the benefits are small enough over the practical service life they’re comfortable recommending just charging daily to 90%. High temperature tends to be a more significant factor, and they manage cell temperature very well. In addition to this, the car keeps very even cell temps, even when driven hard and then parked. This leads to even degradation which allows for more useful range and a longer practical life. In many designs, cell temperatures can vary a fair amount due to internal pack design. This tends to lead to some cells wearing a bit faster and limiting the whole packs ability notably. This is especially problematic on deigns with no active cooling and staggered layout. This can considerably limit the packs ability to rapid charge at higher SOC as the battery degrades, as well as limit output power particularly at low SOC.
In general it’s probably not a huge concern. I don’t have the data Tesla has on their packs. But it’s unlikely you’d have significant balance issues storing the car a few months at 50% SOC. Maybe avoid relying on the last 10-20% of the pack for a few charge cycles afterwards.
In general it’s probably not a huge concern. I don’t have the data Tesla has on their packs. But it’s unlikely you’d have significant balance issues storing the car a few months at 50% SOC. Maybe avoid relying on the last 10-20% of the pack for a few charge cycles afterwards.
AlanSubie4Life
Efficiency Obsessed Member
No, anywhere between 50-90% is fine. Tesla is totally cool with anything in that range. Basically want to maximize your time there, according to Tesla (implicitly). They force that range.
There may be slightly more or less optimum spots in that range, but the exact optimum will likely depend on the particular use scenario.
Stresses apparently increase near zero SoC for some chemistries, so this may not be true.
Just follow Tesla’s instructions and you’ll likely be fine. And don’t stress about the infrequent times when you have to leave it for extended periods at low SoC. There are few situations where that would ever occur.
I would consider ~15% true SOC to be ‘practically dead’. Suppose that bears explaining. And this would be at the cell level, assuming trivial self discharge and no external load. In practice this wouldn’t work that well.
Tesla has a significant interest in ensuring their vehicles perform well for a long time. They wouldn’t tell you something that they thought was likely to notably impact the life of the vehicle. So if they say daily charging to 90% is OK, I’d say that’s probably true. Even if you did store the car long term, it’s not really like your car would have notably higher degradation sitting parked at 90% compared to the other cars on the road getting miles on them. So don’t worry about the battery falling apart sitting at a higher SOC. The difference between ideal and 90% probably isn’t that huge over the expected life of the car. Personally, I’d be more concerned about the stresses on the PCS from the cycling. But apparently they have good confidence in the design.
Tesla has a significant interest in ensuring their vehicles perform well for a long time. They wouldn’t tell you something that they thought was likely to notably impact the life of the vehicle. So if they say daily charging to 90% is OK, I’d say that’s probably true. Even if you did store the car long term, it’s not really like your car would have notably higher degradation sitting parked at 90% compared to the other cars on the road getting miles on them. So don’t worry about the battery falling apart sitting at a higher SOC. The difference between ideal and 90% probably isn’t that huge over the expected life of the car. Personally, I’d be more concerned about the stresses on the PCS from the cycling. But apparently they have good confidence in the design.
If you are not asking a rhetorical question on charging and want opinions other than the manufacturers, some variation of this discussion about charging happens on this board at least 1-2 times a week and has since I joined in novmember of last year, so you can read hundreds (likely thousands), of posts around this topic by searching TMC for charging.
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