No, Tesla changed to the slider because otherwise the EPA would have calculated the range as the average of the two settings (93% and 100% charge). Just as it published the Leaf range as the average of its 80% and 100% charge settings. With a slider there wasn't another setting to average in and that kept the advertised range as the 100% charge range, which is as it should be.
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Which way is better for the battery?
- Thread starter freeewilly
- Start date
djp
Model 3 Performance
That's just speculation, there are no statements from Tesla that link the slider to EPA ratings. The release notes from the time the slider was introduced indicate that it was added to let owners improve the longevity of their battery packs:
(bold added)
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I realize it is likely just a change in calculation as I'm not a complete simpleton, but when on a road trip, which number would YOU rather see?
Until the slider I really had no choice, and it appears (assuming I can trust my "new" 100% range numbers) that my degradation in the 29 months of ownership is within expected levels. That's really all I care about. It's a car, I charge it, I drive it. I don't obsess about how I do either.
MrJones390
Space Boat
PeterW
Member
Isn't this an important part of the equation? Charging to a higher SOC is okay if you use it and don't allow the battery to sit for long periods.
Canuck
Well-Known Member
That's wrong. Fine if you need it but all the data tells us that a lithium ion battery will last longest if you kept it cool and at a 50% state of charge. Too high or two low caused the cathode to degrade. Unless you need more range, put the slider at the middle of the daily range (higher if you deplete the battery too much -- that is why the mid range is more than 50%) and plug it in every night since data also tells us that if you can keep the depth of discharge down, your battery will last longer. The best thing you can do for your battery is always plug it in after use since that will keep the cycles to a minimum. You only have so many full cycles (from full to empty -- but Tesla locks out the top and bottom to make your battery last longer than the ones in your phones, laptops, drills, etc.) Always plug in folks and don't charge too high -- or let it get to too low, unless necessary.
djp
Model 3 Performance
No, I'm just pointing out that there's more evidence to support that the slider was added to help manage battery degradation (which is the stated purpose in the release notes) than there is evidence to support the EPA range theory, which is pure TMC speculation.
Tesla's recommendation to "only charge to the level needed" is in full agreement with the science behind Li-Ion batteries.
stopcrazypp
Well-Known Member
It is possible both played a factor. It is obviously useful for many people to have the slider available, while it conveniently let Tesla get around EPA's stupid rule without giving up adjustable max charge (the Leaf had to give that up).
For the record, we know that rule existed as both the Leaf and RAV4 EV were affected.
For the record, we know that rule existed as both the Leaf and RAV4 EV were affected.
ok dumb question, i thought i knew the answer to this, but im confused now...what does 90% mean?
1. is this mean to charge most of the time to 90% of my total charge capacity (i have a 70D, so 90% of 260 miles, which is 234miles)?
2. or does this have something to do with my daily driving needs (around 40 miles a day)? because i also read somewhere that you should charge only a bit more than your usual day habits...so if i drive 40 miles a day, someone suggested before i charge up to maybe 80 miles each day.
im confused.
1. is this mean to charge most of the time to 90% of my total charge capacity (i have a 70D, so 90% of 260 miles, which is 234miles)?
2. or does this have something to do with my daily driving needs (around 40 miles a day)? because i also read somewhere that you should charge only a bit more than your usual day habits...so if i drive 40 miles a day, someone suggested before i charge up to maybe 80 miles each day.
im confused.
You are confused. 70D doesn't go to 260 miles.
What you want is majority of time at 50%. In hot climates, you want to avoid spending time at higher SOCs. Perhaps the battery will outlast the car even if you have it sit at 90% all the time but this discussion is about what is "better".
To spend the majority of the time at 50%, you would typically charge to your daily need + 120miles (70D). If you have a 20 mile commute and charge upon returning home, I might turn that down to 140 total so that you are at 50% in the heat of the day at work. Particularly in the summer.
Charging to 90% regularly is good to balance the pack which is great for making the displayed range more accurate but does nothing to help with battery longevity (majority view but not necessarily fact). Probably makes sense to charge to 90% every once in while and 100% also. Most people probably do this when they roadtrip.
My car is sitting at 120 right now and I have a 12 mile commute. I should charge but I have free charging at work.... Now that is another issue altogether.
What you want is majority of time at 50%. In hot climates, you want to avoid spending time at higher SOCs. Perhaps the battery will outlast the car even if you have it sit at 90% all the time but this discussion is about what is "better".
To spend the majority of the time at 50%, you would typically charge to your daily need + 120miles (70D). If you have a 20 mile commute and charge upon returning home, I might turn that down to 140 total so that you are at 50% in the heat of the day at work. Particularly in the summer.
Charging to 90% regularly is good to balance the pack which is great for making the displayed range more accurate but does nothing to help with battery longevity (majority view but not necessarily fact). Probably makes sense to charge to 90% every once in while and 100% also. Most people probably do this when they roadtrip.
My car is sitting at 120 right now and I have a 12 mile commute. I should charge but I have free charging at work.... Now that is another issue altogether.
I thought i'd tag onto this thread.
Having just received my p85d i'm pleased i can charge it from solar. I work from home some days and when i do i scale back the amp's to between 6 - 8 amps depending on the weather and other usage. I can charge completely from solar and add 20 miles a day which covers my local journeys.
1) Is this very low power charging bad for the battery or does it not matter ?
2) My daily requirements are fairly low, 5 to 50 miles typically (weekend is different), i can charge for free at work to 90%, but i then go for days not needing to charge as i set the charge limit to 50-70%. Despite plugging in, it won't charge for a few days until the charge drops below the limit i set, is this ok?
As mentioned i may trickle charge of solar in between 90% free charge and the capacity dropping low enough to kick in again. Providing i'm doing no harm i will carry on, but if longevity is improved by sticking with between 50 and 70% with the odd boost to 90% for longer trips i will do that.
Having just received my p85d i'm pleased i can charge it from solar. I work from home some days and when i do i scale back the amp's to between 6 - 8 amps depending on the weather and other usage. I can charge completely from solar and add 20 miles a day which covers my local journeys.
1) Is this very low power charging bad for the battery or does it not matter ?
2) My daily requirements are fairly low, 5 to 50 miles typically (weekend is different), i can charge for free at work to 90%, but i then go for days not needing to charge as i set the charge limit to 50-70%. Despite plugging in, it won't charge for a few days until the charge drops below the limit i set, is this ok?
As mentioned i may trickle charge of solar in between 90% free charge and the capacity dropping low enough to kick in again. Providing i'm doing no harm i will carry on, but if longevity is improved by sticking with between 50 and 70% with the odd boost to 90% for longer trips i will do that.
Slow charging is not bad per se, but it is inefficient. The car has a fixed overhead to run the internal systems such as cooling pumps, control modules, etc. So when you charge at low rates, the overhead is a much greater percentage, meaning less of your solar kWh makes it in to the pack.
First - same Ingineer of Nissan Leaf fame? If so, hello and thanks for your contributions there!
Second - that's not what I had read regarding the Tesla battery, I read last year that it's actually healthier for the battery to use faster charging for some reason. It wasn't just about not wasting watts, but I could be wrong it was just what I read.
Yes, I'm the same Ingineer. Thanks for the compliments!
Please show your source for this information, I don't agree. Everything I know about all forms of Lithium Ion chemistry says slower is better. For one, it's widely accepted that higher cell temperatures accelerates degradation, and charging faster means higher I2R losses, and thus heat build-up in the cell. Obviously at relatively slow rates it's going to not matter much, but still it's a negative life coefficient. Slower allows the chemistry to do it's thing without more loss or as thus as much heat build up. This is also why as a cell gets to higher SoC that charging current must be tapered.
Canuck
Well-Known Member
He probably read that faster charging isn't as hard on a Tesla battery as is it on other lithium batteries because of its TMS. Not better, but not as bad as most.
Not bad at all, it is actually good for the battery. Although charging at 40 Amp is already a pretty slow rate. It's about 1/10 C meaning it's definitely low enough not having to worry about it being bad for the battery.
Tests have shown that the chargers are more efficient at full load (40 Amp for a single charger, 80 Amp for a dual charger). If you charge at only 20 Amp, you end up needing more energy from the grid to recharge the same amount of energy in the battery. The difference is not big, though.
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