1 year service

[garygid]

Then, Helium would be a huge atom, and not leak through anything?

Dry air would be essentially the same, I believe.
It's just harder to find and verify that a place has DRY air.

But, it's not easy to verify that the "nitrogen" in the tires does not have some oxygen in it.

In fact, if the O2 leaks out so easily, it would also "leak" INTO a pure Nitrogen-filled tire, I believe.

 

[ttweed]

In fact, if the O2 leaks out so easily, it would also "leak" INTO a pure Nitrogen-filled tire, I believe.

Gary-
That would depend on the pressure inside the nitrogen-filled tire, wouldn't it? Perhaps the O2 could pass into the tire if it was inflated only to atmospheric pressure, but that is not the case in normal tire usage--pressures inside the tire are much higher than atmospheric. It seems to me that there would be a certain "osmotic pressure" within the tire above which no O2 molecules would be able to migrate across the "membrane" of the tire wall and into the tire from the outside--the tendency would be only for the nitrogen to migrate out. The gas under higher pressure (inside the tire) has greater kinetic energy, and under the laws of entropy, molecules tend to diffuse to a place of lower free energy in order to equalize free energy, until that point when equilibrium (maximum entropy) is reached. I have no idea what pressure differential would be required for this equilibrium to take place, but I'm sure it could be calculated by someone smarter than I am using Morse's equation. This is the same situation that allows reverse osmosis to purify seawater, for instance.

TT

 

[rborba]

Then, Helium would be a huge atom, and not leak through anything?

Helium is way smaller for two reasons. It only has two electrons and both electrons orbit at the same energy level. N and O have more electrons and two energy levels, so their electron clouds are bigger. Second, Helium atoms do not normally bond to each other. A Helium molecule is just one atom, not two like N2 or O2.

But perhaps the biggest problem with filling up the tires with helium is how to keep the car from floating in the air upside down... :lol:

 

[TEG]

...I happened to score the same way on my Leaf. When I asked for more information, the technician said "Every Leaf has shown the same, so no need to worry about it."...

I just did my 1 year checkup at nearly 10K miles, and got 5 stars in all categories...

 

[TEG]

Nitrogen in tires is legit-- Costco uses it. It is more dense than regular air and therefore the tire loses pressure more slowly.

The Straight Dope: Is it better to fill your tires with nitrogen instead of air?

Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

 

[rborba]

I just did my 1 year checkup at nearly 10K miles, and got 5 stars in all categories...

Excellent. Would you mind sharing your charging profile? To 80%, 100%, or mix? Any other factor that might help getting such a perfect score?

 

[Stoaty]

Excellent. Would you mind sharing your charging profile? To 80%, 100%, or mix? Any other factor that might help getting such a perfect score?

Almost all of the scores are perfect, because battery capacity doesn't show as decreased until you hit 85% of original capacity. If you want to get a perfect score, though:

1) Don't use Quick Charging too frequently
2) Charge to 80% when possible, 100% only when you need it
3) Don't lead foot it all the time
4) Don't leave car at 100% charge for any longer than necessary, especially if ambient temperature is high; charge to 100% shortly before you need to go on a longer drive

 

[TEG]

Excellent. Would you mind sharing your charging profile? To 80%, 100%, or mix? Any other factor that might help getting such a perfect score?

Almost all of the scores are perfect, because battery capacity doesn't show as decreased until you hit 85% of original capacity. If you want to get a perfect score, though:

1) Don't use Quick Charging too frequently
2) Charge to 80% when possible, 100% only when you need it
3) Don't lead foot it all the time
4) Don't leave car at 100% charge for any longer than necessary, especially if ambient temperature is high; charge to 100% shortly before you need to go on a longer drive

1) I have never used quick charging.
2) Charge to 80% at least 90% of the time. Rarely go to 100%
3) I "lead foot" it all the time... Doesn't seem to have hurt anything so far.
4) Yes, only use 100% just before I head out on a rare longer drive.
(Don't leave it at 100% for very long.)

My charge timer is set for 80% between Noon and 11:50AM (so basically it never tries to go over 80% unless I hit the override button.)

 

[TomT]

The criteria is so coarse and forgiving it is hard NOT to get 5 stars in all...

I just did my 1 year checkup at nearly 10K miles, and got 5 stars in all categories...

 

[garygid]

I got four stars for quick charging, since I QC'd about 6 or 8 times in a year.

 

[Herm]

Maybe not so forgiving after all then.

 

[planet4ever]

Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

I'm sorry, but I have never given any credence to Popular Mechanics as a scientific journal. By the way, I read Gary's post as meaning just the opposite of the way Tom took it. If the O2 leaks out faster than the N2, then a tire which starts out filled 80% with N2 (i.e. ordinary air) will become filled with almost all N2 over time.

Ray

 

[lkkms2]

Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

I'm sorry, but I have never given any credence to Popular Mechanics as a scientific journal. By the way, I read Gary's post as meaning just the opposite of the way Tom took it. If the O2 leaks out faster than the N2, then a tire which starts out filled 80% with N2 (i.e. ordinary air) will become filled with almost all N2 over time.

Ray

And up to 5% moisture per some of the articles.

 

[lkkms2]

I got four stars for quick charging, since I QC'd about 6 or 8 times in a year.

Were any of those QCs back to back? During a very hot day?

Did you notice how many bars increased on the battery temperature gauge when you QCd?

 

[garygid]

No, at least 2 week spacing.
Some only 5 to 15 minutes long.
Temperate to warm days.
Rarely any change in the Pack Temp Bars, since the center bars are 24 degrees wide. Never above 6 P-Temp Bars, I believe.
So, not frequent use.

One time, several short (2 to 5 minute) QC sessions in one day, to help test a QC unit being manufactured locally. Perhaps that is the criteria: lose a star for mulitple QC sessions (even very short) in one day?

If someone who knows would tell us where the Pack Temp(s) are located in the CAN data, I would include it in the next firmware update of the SOC/GID-Meter.

 

[JPVLeaf]

I got four stars for quick charging, since I QC'd about 6 or 8 times in a year.

Hmmm. I'm going in for my 15k battery check today. I have QC'd only 4-5 times in the past 10.5 mos., 2 of those being in the same day. We'll see if that's enough to get dinged a star for 'frequent use of quick charging".

 

[DaveEV]

One time, several short (2 to 5 minute) QC sessions in one day, to help test a QC unit being manufactured locally. Perhaps that is the criteria: lose a star for mulitple QC sessions (even very short) in one day?

I'm guessing that's what triggered it...

 

[Nekota]

Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

I'm sorry, but I have never given any credence to Popular Mechanics as a scientific journal. By the way, I read Gary's post as meaning just the opposite of the way Tom took it. If the O2 leaks out faster than the N2, then a tire which starts out filled 80% with N2 (i.e. ordinary air) will become filled with almost all N2 over time.

Ray

Here is some data along with test cases that consider the role of water partial pressures. I remember draining the water from air compressors that have a large storage tank as a kid and finally learned why in my thermodynamics (steam tables) classes. The partial pressure of water as a function of temperature determines how much water is present. At 70F it's 0.4 psi, at 40F it's 0.1 psi at 100% relative humidity. So on a warm day at 70% RH you adding water vapor to your tires at 0.7 times 0.4 psi and at 40F and 70% RH you would be adding water vapor at the 0.7 x 0.1 psi rate. Now if you fill your tires from a air compressor that is always on, the RH at 150 psi and 70F drops to 8% so it's pretty dry air.

http://home.comcast.net/~prestondrake/N2_FAQ_Q01.htm" onclick="window.open(this.href);return false;

My conclusion is use the tank style air compressors and ask for several air purge cycles to remove most of the water vapor from inside the tire.


The diffusion of N2 and O2 may differ by 3 or 4 times but the loss of pressure due to diffusion through a rubber tire is going to take a bit of time. I'll run some numbers if someone can give me the sidewall thickness of the tire.

 

[ttweed]

By the way, I read Gary's post as meaning just the opposite of the way Tom took it. If the O2 leaks out faster than the N2, then a tire which starts out filled 80% with N2 (i.e. ordinary air) will become filled with almost all N2 over time.

Not sure how you could interpret what Gary wrote that way, Ray, since he clearly said "...if the O2 leaks out so easily, it would also "leak" INTO a pure Nitrogen-filled tire."

BTW, the dealer did our 1-year battery test while the car was in for the last software update, even though it was a few weeks short of one year in service. It got 5 stars in all categories. We normally charge to 80% every day, with only occasional 100% charges when more range is needed. It has only been on a DC charger once for about 5 minutes, just to see if the L3 port worked correctly.

TT

 

[ttweed]

The diffusion of N2 and O2 may differ by 3 or 4 times but the loss of pressure due to diffusion through a rubber tire is going to take a bit of time. I'll run some numbers if someone can give me the sidewall thickness of the tire.

The sidewall thickness on a non-runflat tire like the Leaf's vary from 6mm at the thinnest point to about 15mm thick at the bead, or about 1/4- to 5/8-inch thick. A runflat tire has a thicker wall section throughout in order to provide more support when under-inflated. The image below shows the comparable section profile of the two types (runflat tire is on the bottom).

How would you propose to calculate the diffusion or migration rate?

Thx,
TT