Best Practice for battery preservation

GoGoGadgetMachE

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Why do you think that is idiotic? If you charge the battery to 100%, then the battery is probably charged at 95% (assuming the buffer is split between top and bottom).

95% is still unpleasant to Lithium batteries.
1602118338299.png


Clearly the more you stay in the middle the slower the degradation.
We don't know how the buffer is split. Even if you're right, "80%" is actually 76%. If the magic number is 80% then they should be telling us "84%" or so. ("85%" would be easier to remember and be close enough.)

but even better would be just to program the damn thing to not make this my problem. Making it my problem is idiotic for previously stated reasons. You never go to a gas station and fill up to only 80%. And normal people charge phones to 100%. If you're trying to be a car for normal people, you don't start with "here's your range oh just kidding you only should use 80% of the range most of the time because [blah blah science]."
 

dbsb3233

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Not sure I'm following you.
The yellow line is only 10% charges (65-75), while the black line is 75% charges (25-100). That's 7.5x more kWh. So the 8400 charges on the yellow line is really the same miles as 1120 charges on the black line. That's roughly 275k miles. Degradation is about 90% on one and 92% on the other. A little worse but fairly minor.
 

zhackwyatt

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We don't know how the buffer is split. Even if you're right, "80%" is actually 76%. If the magic number is 80% then they should be telling us "84%" or so. ("85%" would be easier to remember and be close enough.)

but even better would be just to program the damn thing to not make this my problem. Making it my problem is idiotic for previously stated reasons. You never go to a gas station and fill up to only 80%. And normal people charge phones to 100%. If you're trying to be a car for normal people, you don't start with "here's your range oh just kidding you only should use 80% of the range most of the time because [blah blah science]."
They can't though. If they "program" it so you don't have to worry about it, your not ever going to have that 300 mile range for when you need it on a road trip.
 

dbsb3233

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but even better would be just to program the damn thing to not make this my problem.
They could hold back such a large buffer to make it totally irrelevant (like say 20-80%), but then range would be like 195 or something.
 

zhackwyatt

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The yellow line is only 10% charges (65-75), while the black line is 75% charges (25-100). That's 7.5x more kWh. So the 8400 charges on the yellow line is really the same miles as 1120 charges on the black line. That's roughly 275k miles. Degradation is about 90% on one and 92% on the other. A little worse but fairly minor.
The paper uses a lot more advanced math than I know. I also admin I didn't read the whole thing, but my understanding is a "cycle" has a special meaning. Charging from 25-100 and charging from 65-75 does not mean both are one cycle.
 


dbsb3233

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The paper uses a lot more advanced math than I know. I also admin I didn't read the whole thing, but my understanding is a "cycle" has a special meaning. Charging from 25-100 and charging from 65-75 does not mean both are one cycle.
I'm a little fuzzy as to whether they mean a "cycle" is a charge of the %SOC they show, or if they mean 100% of the battery. I'm guessing the former, but if it is the latter, I think that reiforces it even more.
 

ajmartineau

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A "charging cycle" is 100% of the battery capacity. This has been stated here before. So you do the 75-65% 10 times to equal 75-25% 2 times.
 

zhackwyatt

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I'm a little fuzzy as to whether they mean a "cycle" is a charge of the %SOC they show, or if they mean 100% of the battery. I'm guessing the former, but if it is the latter, I think that reiforces it even more.
A "charging cycle" is 100% of the battery capacity. This has been stated here before. So you do the 75-65% 10 times to equal 75-25% 2 times.
So then the graph is accurate and doesn't need to be normalized right?
 

ajmartineau

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yes, every verticle line is the same number of kWh and miles for each plotted line.
 

GoGoGadgetMachE

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They can't though. If they "program" it so you don't have to worry about it, your not ever going to have that 300 mile range for when you need it on a road trip.
Normal people will never have it anyway if you tell them "80% or else your battery is screwed."

"oh crap I forgot to change the magic setting from the 'don't break things because science blah blah' setting to the 'okay this one time because it's a special case and I pinky swear it is a special case I can do 100%' setting, so now I don't have the range when I am pulling out of the garage and smack my head and say 'DOH!'"

Normal people just don't and won't think about this kind of messing around.

"wait it has that range but I can't use it all because science blah blah? Stupid Ford lied to me about the real range!"

And now we are back to the normal person doing 100% all the time because MOAR RANGE or 80% all the time because they won't think to change it.

But this is an opinion about how people think. Let's see what happens when it's in normal people's hands.
 

ajmartineau

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I like the way Tesla dumbs it down for its users. Daily drive setting, and road trip setting.
 

zhackwyatt

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Normal people will never have it anyway if you tell them "80% or else your battery is screwed."

"oh crap I forgot to change the magic setting from the 'don't break things because science blah blah' setting to the 'okay this one time because it's a special case and I pinky swear it is a special case I can do 100%' setting, so now I don't have the range when I am pulling out of the garage and smack my head and say 'DOH!'"

Normal people just don't and won't think about this kind of messing around.

"wait it has that range but I can't use it all because science blah blah? Stupid Ford lied to me about the real range!"

And now we are back to the normal person doing 100% all the time because MOAR RANGE or 80% all the time because they won't think to change it.

But this is an opinion about how people think. Let's see what happens when it's in normal people's hands.
I don't disagree with your sentiment of normal people. Thankfully I'm not so I have more options and flexibility.
 

kdryden99

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With the buffers already present though doesnt that mean 100% charge is 80% battery capacity.
 

ajmartineau

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no!
If you assume the buffer is split evenly... your 100% is 89%.
 
 




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