Battery Leak

[Diehard]

In comparison an ICE car needs to warm up before you can really defrost. Lots of pollution in the first couple minutes and that energy is mostly wasted.

The CT in your driveway will have a core temp of 50F. It would be interesting to see what defrost faster, your Oldmobile or the CT. Stick around and tell us.

I am pumped for the low guilt precondition function. I am going to drive you in 5 minutes. Get ready.

Olds is long gone. I loved that car. It may have been inefficient starting but it was much more efficient sitting and keeping me warm on the road was a free side effect that didn’t need extra energy. All that said, I can’t wait for my first EV. Even driving a first gen Soul EV in a parking lot got me hooked.

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[Ogre]

I hope you are right. That might also be an efficiency gain with smaller wires etc. What do you think the odds of the whole vehicle going to 800V. That many batteries in series makes me nervous, one bad 4680 would be worse at 800V than 400V correct?

Others know batteries more than I do.

I was listening to an interview with Munro (below) and he seemed to think higher voltage was largely beneficial and mostly a matter of sourcing the parts. Of course he‘d had a few strong drinks before the interview. It’s a good interview.

 

[Ogre]

In comparison an ICE car needs to warm up before you can really defrost. Lots of pollution in the first couple minutes and that energy is mostly wasted.

The CT in your driveway will have a core temp of 50F. It would be interesting to see what defrost faster, your Oldmobile or the CT. Stick around and tell us.

I am pumped for the low guilt precondition function. I am going to drive you in 5 minutes. Get ready.

Our Model Y is defrosted before my wife wakes up half the time, it’s on a schedule based on when she goes to work. Olds can’t beat “Defrosted before you get out of bed”. Though I suppose you could install a remote starter.

 

[Bill906]

Our Model Y is defrosted before my wife wakes up half the time, it’s on a schedule based on when she goes to work. Olds can’t beat “Defrosted before you get out of bed”. Though I suppose you could install a remote starter.

16 of the last 20 years my main vehicle had remote start.

Remote start sure does screw up the mpg calculations on the car. Burning gas but not moving any miles for 15 minutes at a time really pulls down the average.

I am looking forward to preheating WHILE it's plugged in, as well as being able to schedule the preheating.

 

[tidmutt]

Olds is long gone. I loved that car. It may have been inefficient starting but it was much more efficient sitting and keeping me warm on the road was a free side effect that didn’t need extra energy. All that said, I can’t wait for my first EV. Even driving a first gen Soul EV in a parking lot got me hooked.

Well that side effect was because it's inefficient to begin with so it's actually not free, it's much worse, it's permanently less efficient every moment it's in operation.

 

[Diehard]

Well that side effect was because it's inefficient to begin with so it's actually not free, it's much worse, it's permanently less efficient every moment it's in operation.

That is cherry picking. Which one is worse, being more inefficient when you are in operation (doing something) or being inefficient when you are not in operation? My car is sitting in the driveway a whole lot longer than it is moving. Granted my 18 year old ICE battery looses charge when it is sitting too but a whole lot less.

If BEV battery just need to be heated only before moving, it is fine but if it has to continually consume energy to keep it at a minimum temperature like 50 F during a long winter, I don’t call it efficient. It would be like my ICE gas tank leaking.

 

[Crissa]

The problem with giving great info is that I want more.

1 - I don’t have a garage. Does keeping CT outside in winter vs in a garage means only using more energy to warm up the battery when I want to use the vehicle? Or it has to constantly use energy to keep a minimum temp while sitting? Do you keep your bike outside in winter?

2 - If for some reason the System can not take care of the battery in the cold, does that mean permanent damage or capacity loss? Or heat is the only enemy?

1. Plug it in when cold. Tesla has active battery temperature management so will always be the right temperature - as long as it knows to be ready.
2. No, cold doesn't harm lithium batteries. My bike has no heating or cooling and has been operated down to thirty below. Tesla will not allow the battery to come to harm from charging and will yell at you if it's near taking damage from heat.

Cold just makes the battery work slower. Less efficiently. It uses up heat (in battery resistance) to make the electrolyte conduct. At extreme cold, the electrolyte can freeze, and then it can't charge. A Tesla has active temperature management and will avoid this fate by heating the battery and blocking you from charging above the rate that would damage the battery. Or discharging past a point that would damage the battery.

My bike does it in a ham-fisted way: Since it can't heat itself, if it's too cold it says nope to charging and cuts the charger off (32F). And then when it gets too cold or low power to operate, it also says nope and cuts the load (-30F). But it has sensors in the battery... if you put like a heated blanket on the bike, it's perfectly happy. Tesla does all that for you.

-Crissa

PS: One of the magic tricks a modern lithum battery has is that it literally doesn't care about being frozen. It just needs to heat back up before it can discharge or charge properly.

 

[android04]

Warning: I almost wrote a book in my responses to you, and you might be afflicted by a case of TL;DR. I don't blame you if that's the case ?. I'm not an authority on the subject, but I did stay at a Holiday Inn last night. J/K. I've done a lot of research and have an engineering degree, as well as measured and monitored things in my Model 3 over the last 3.75 years and 70,500 miles.

The problem with giving great info is that I want more.

1 - I don’t have a garage. Does keeping CT outside in winter vs in a garage means only using more energy to warm up the battery when I want to use the vehicle? Or it has to constantly use energy to keep a minimum temp while sitting? Do you keep your bike outside in winter?

2 - If for some reason the System can not take care of the battery in the cold, does that mean permanent damage or capacity loss? Or heat is the only enemy?

Lithium ion batteries are damaged by experiencing high heat, or by charging them below 32°F (0°C). The battery isn't harmed by just being out or being used in the cold. Tesla's owners manual states not to expose the car for more than 24 hours to temperatures above 140°F (60°C) and below -22°F (-30°C). The car will run the coolant pumps and fans to cool the battery pack even when it is parked. I don't believe the car will heat the battery pack when it is cold and parked. The problem with charging at cold temperatures below 32°F (0°C) is that the electrolyte is affected and physical damage is done due to lithium plating. It's still fine to drive the car, and is one way to warm up the battery (a battery warms up from being discharged). Another way that Tesla warms the battery in Model 3 is to run the electric drive motor's inverter in an inefficient way to generate heat. That heat is absorbed by the coolant that also pumps through the battery pack and is used to warm it. This method of generating heat can be used while driving and while parked. I'm not sure if Tesla uses the drive inverter to warm the battery pack if it's cold and parked unless you are preconditioning the car through the app or are navigating to a Supercharger. The drive inverter method of heating the battery pack is also used to condition the battery pack when navigating to a Supercharger in order to charge faster (somewhere around 120°F (around 47°C) is the target in order to allow the battery pack to more readily accept a faster charge rate).

Are you saying if I leave it unplugged, the battery gets cold and when I plug it in, the system wouldn’t heat up the battery first before starting to charge? And if I leave it plugged in, it always uses power to keep the battery warm? That sounds like such a waste and like I should either get a garage or an ICE. Did I misunderstand how it works?

Even though a lithium ion battery will be damaged if charged only (not stored, not used) below 32°F (0°C), you can still plug in and charge a Tesla below that temperature. The car will warm up the battery first using the drive inverter method (you can help it get there by accelerating aggressively before charging ?). When the battery is warm enough to accept a lower charge rate, the charger will start with a lower rate and ramp up appropriately. Most lithium ion battery manufacturers state in their spec sheets that a charge rate of 0.1C is allowed for temps between 32 to 14°F (0 to -10°C), and 0.05C for temps between 14 to -4°F (-10 to -20°C). The 0.1C and 0.05C are ways to state current as a fraction of the battery's total capacity. A 100Ah battery would be charged (or discharged, but usually that's written a little differently) at 10A if we were trying to keep it at 0.1C. Last winter during that deep freeze that affected a lot of the US, my area experienced -40°F (-40°C) overnight as the ambient temperature with no wind chill. I work at night and my car sat outside the whole time. In the morning when I went to drive home, the car worked fine except for not having a lot of power when I stepped on the accelerator. Since the battery was very cold, it temporarily lost some of its capacity. After driving part of the way home it warmed enough to have better acceleration. This temporary loss in capacity with cold temperatures also affects batteries of other chemistries. A lithium ion battery has 85% of its capacity at -4°F (-20°C), while a lead acid battery (non-starting battery used for energy storage applications) will have 30% of its capacity at the same temps. When I plugged in my car after that very cold drive last winter, it was still reading -38°F (about -39°C) ambient temperature. The charging started at 0 amps because my drive home was not enough to warm the battery yet. It slowly ramped up the charge rate as the battery warmed. The reason that Tesla reduces or eliminates regenerative braking at colder temperatures is due to regen braking being like charging the battery pack. On Model 3, regen braking can generate power in the 70kW range. That's in the same range as DC fast charging and Supercharging. Tesla Urban Superchargers are 72kW, Gen 2 Superchargers are 150kW, and Gen 3 Superchargers are 250kW.

I really appreciate the super helpful info shared in quite digestible fashion. That brings another question: This probably wouldn't apply to CT but on current Teslas, would replacing the 12V battery with a lithium ion battery require any software adjustment so that main pack does not over charge it? or these batteries are responsible to protect themselves with their own circuits? and simply replacing the old battery with 12V lithium ion is safe?

Most lithium ion batteries that are marketed as replacements for car lead acid batteries are lithium iron phosphate (LiFePO4) because their charging voltage range is extremely similar to lead acid batteries. Especially if the battery to be replaced is an AGM battery (AGM batteries charge at a slightly lower voltage than flooded lead acid batteries, and have different charge levels at a reference voltage), the LiFePO4 is a good match for replacement. An issue once again can be charging the LiFePO4 at cold temps. If the vehicle charges at higher rates than those listed as safe for cold temps (see above) the battery capacity is being reduced permanently over time. Many people have used replacement LiFePO4 12v batteries in their Teslas for years with no issues, even in cold places like Canada. But they are doing slow damage to its capacity over time because I know for a fact that the Tesla will charge it at rates higher than the safe ones at below freezing temps (see above). I installed a shunt on my Model 3's battery to monitor the charging voltage and current, and the highest I ever see it when the 12V battery is somewhat discharged (from a few days of not being used) is in the 7 A range. The OEM battery lists its capacity as 45Ah, so a charge rate of 7.7 A is 0.17C. That is higher than the recommended 0.1C or 0.05C, depending on the cold temperature range. So far I haven't measured in temperatures below 32°F (0°C) because I installed the shunt this summer and the temps in my area haven't yet dipped below freezing. So if the Tesla actually reduces the charge rate of the 12V lead acid battery in the colder temps there is a possibility that the replacement 12V LiFePO4 battery will be charged in a manner that does not reduce its lifespan.

You can read interesting info about the Model 3 battery pack here https://www.tesla.com/ownersmanual/model3/en_us/GUID-7FE78D73-0A17-47C4-B21B-54F641FFAEF4.html

More interesting info about some differences between lithium ion and lead acid batteries in energy storage applications https://www.altenergymag.com/content.php?post_type=1884

And a final link about cold weather effects on lithium ion batteries https://www.ufo-battery.com/does-cold-weather-affect-lithium-ion-battery

 

[Bill906]

Another way that Tesla warms the battery in Model 3 is to run the electric drive motor's inverter in an inefficient way to generate heat.

Curious how you know this. I mean that literally. It’s not meant as a passive aggressive way to say I don’t believe you. I believe you. Just wondering if you read something, did some kind of test etc.

 

[android04]

Curious how you know this. I mean that literally. It’s not meant as a passive aggressive way to say I don’t believe you. I believe you. Just wondering if you read something, did some kind of test etc.

It's been common knowledge for Tesla nerds for years. And it can be measured. If you want actual graphs and measurements, I recommend looking up posts by the user Wugz on Reddit. They are a data nerd and use an app to keep track of many, many things. Then they write up very detailed and informative explanations with nice graphs. If you are interested, you can use the app that Wugz uses (can't remember which one it is), but there are others. You can also get your data directly from the car's CAN network by buying a $20 harness to give you an OBD port, and using a wireless OBD scanner supported by the Scan My Tesla app. I use Scan My Tesla, but do not really have info in nice lists or graphs. Just a few random samples in different situations that I'm interested in. And some of my knowledge about the 12v batteries and replacements for the Model 3 come from my planning for the future when my original OEM battery dies. I wanted to get data on all the different types of lead acid batteries and possible replacements of other chemistries. Have done a lot of reading of manufacturer spec sheets as well as many different websites over a few years. There are also a lot of very informative Youtube videos I've watched with tests, measuring, and teardowns. Some lectures from people with advanced degrees. Have some bookmarked as references, and even made my own cheat sheet with info on batteries. Like I said, I'm no expert. But can become obsessed with certain things and research, observe, or measure until I know a little more about them than most people.

Edit to add a link to Wugz's posts on Reddit. I'm sure you will learn a lot from their graphs and write-ups. https://www.reddit.com/user/Wugz/posts/

 

[happy intruder]

What I've seen from others (don't have an EV yet):

1. Sentry mode is a huge drain. Might want to charge up if you're going to leave the car for even a few days. Or, better, have it parked and connected in a charging location.
2. Car parked, but with Sentry mode disengaged you lose perhaps a few % per day, depending on whether you also have it set to maintain cabin temperatures (e.g. don't exceed 120°F / 49°C)
3. Car completely off results in almost no drop in SoC even over a couple of weeks. Maybe 1-2%.

Would love to hear owners' experiences in this thread. This is just the semi-understanding I've gleaned from the YouTubes and Twitters.

my car (Model S 2020) is parked at home and it is always going off line and I get reminded to start the car.....I cannot connect with Teslafi because is if off-line....but I have no loss of battery.....since I am at home, I do not use the electron gobbling sentry mode. but it is annoying that it is off-line so much

 

[android04]

my car (Model S 2020) is parked at home and it is always going off line and I get reminded to start the car.....I cannot connect with Teslafi because is if off-line....but I have no loss of battery.....since I am at home, I do not use the electron gobbling sentry mode. but it is annoying that it is off-line so much

Older Tesla Model S and X have an Energy Saving mode that you can turn on in the settings which lets the computers and electronics go into a deep sleep and disables the ability to connect to it with the Tesla app (Controls > Display > Energy Saving). However, your newer 2020 Model S does not have that Energy Saving mode setting anymore and it works automatically like all other newer Teslas. Make sure you have enabled Mobile Access under Controls > Safety & Security > Mobile Access. Other than that, the issue might be a weak WiFi signal wherever you park.

 

[android04]

Tesla now uses a 12v lithium pack, with its own circuitry and a unique connector.

Those new lithium ion 12v (more like 16v) batteries were only on the newly refreshed Tesla Model S and X, but a Model Y in China recently was delivered with a similar lithium ion 12v battery. The Model 3 and Y made in China tend to get some new features first before they get to the ones made in California, months later. So chances are that Tesla will eventually switch all their models to the new lithium ion 12v batteries and the Cybertruck would also come with one.

I know this isn’t an answer to your question… but even so.

Elon Musk recently described the Cybertruck as “Intentionally An Insane Technology Bandwagon”. This makes me think Tesla is going to cram as much new stuff into it as they can see possible. My assumption is if you’ve heard Musk talk about it… it’ll happen.

That means a 48v lithium ion battery is highly likely.

As for existing owners and their dinosaur cars with “12v so called batteries”… Tesla has hinted a Lithium Ion upgrade part is in the works for those to. Not sure when… but who cares, we’ll have 48 volts before they figure that out.

The only problem I have with the higher 48V system would be that they would likely use very tiny conductors in the wiring. Tiny wires are more difficult to splice into or repair and easy to damage. It's already hard enough to splice into some of the tiny (24 gauge?) wires that Tesla uses in their current 12V system. The PTC cabin heater CAN network communications wires are tiny, and the tail light wires about the same. Switching to 48V would make it near impossible to splice into them if Tesla also took advantage of making the conductors even smaller. I realize that splicing and repairing wires is not something most people will need (or want) to do though. I can imagine a rodent getting in under the frunk area and chomping a whole bundle of wires clean through in one bite. Perhaps the insulation on the wires would get a little thicker, but that probably won't deter the rodents' attraction to the soy-based material that is commonly used on them.

 

[happy intruder]

Older Tesla Model S and X have an Energy Saving mode that you can turn on in the settings which lets the computers and electronics go into a deep sleep and disables the ability to connect to it with the Tesla app (Controls > Display > Energy Saving). However, your newer 2020 Model S does not have that Energy Saving mode setting anymore and it works automatically like all other newer Teslas. Make sure you have enabled Mobile Access under Controls > Safety & Security > Mobile Access. Other than that, the issue might be a weak WiFi signal wherever you park.

thanks, I'll check

 

[CyberGus]

The challenge of 48v is the need to step-down the voltage, since existing accessories are 12v.

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