Why do Li-ion Batteries die? And how to improve the situation?

[stopcrazypp]

So, charging fast, up to C/2 is better than slow. I currently have dual chargers but only use a 50A 240V (14-50) setup at home charging at 40A. It sounds like I would be extending the life if I installed a HPWC and charged at 80A. Is that correct and would it be worth the $1,200 for the wall unit and another $500 for installation? Would it really make any difference?

I don't see anywhere in the thread that says that charging fast is better for the battery. Charging up faster might be more efficient up to some point (because of overhead), but I think 40A is already past that point. I doubt you would get $1.7k worth of difference from it.

 

[lolachampcar]

The impression I got was the ability to charge quickly thus limiting the time at higher temperatures. It would seem as though Tesla's temperature control would mitigate this concern somewhat.

 

[pilotSteve]

After watching the video I moved my charge time 2 hours forward and kicked my HPWC back up to 80amps.

Thanks everyone for the research. That is exactly what I was asking. My new protocol too.

 

[Vger]

Thanks everyone for the research. That is exactly what I was asking. My new protocol too.

Yes, take home message to me is:

1) Keep the battery as cold as possible for as much of its life as possible. Life in BC is good!
2) Keep that battery at moderate SOC for as much of its duty cycle as possible. so, charge fast to high SOC, but do not stay there long.

BTW, I remind everyone to log your own data in Tomsax's Plug-In America survey: Plug In America
Let's get a lot more data before Tesla Connect! I just updated mine today. Even if you have done it once; make sure your data is current!

 

[nwdiver]

Yes, take home message to me is:

1) Keep the battery as cold as possible for as much of its life as possible. Life in BC is good!

Well... as close to ~40F... colder temps can cause damage during charge cycles. Though I think storing the battery at lower temps is ok.

 

[delanman]

Five or six years ago, I attended a presentation by several professors at George Washington University in D.C. on using a solution of broken buckyballs as an additive to Li-Ion batteries to extend battery life to an extraordinary degree. At the time, they couldn't explain what exactly was happening and were looking for investment by large multi-nationals to commercialize the technology. Our company was making buckyball nano-materials for research labs so it would have been a good match... but it didn't happen - out of my control. I was only the tech scout.

After watching Professor Dahn's presentation, the plating of electrodes and electrode porosity may explain why. The buckyball debris solution could be maintaining porosity over time keeping the plating from blocking electrolyte contact. If I can find the prospectus from the GWU presentation, I'll post it.

 

[jpgrolle]

I have installed an 80A (20 kWh) charger so that I can quickly add charge to the Tesla S, allowing me to minimize the inconveniences associated with leaving the pack at a low state of charge and thus increasing the amount of time the battery stays at a mid/low SOC.

Sorry if this has already been discussed, but: have you considered how the degrading effect of faster charging compares versus the preserving effect of staying between 30-70kWh, rather than 50-90kWh? This coming from someone who charges at 4kWh (single phase 230V). Do you know the relative degradation effect of consistently charging at 4 vs 10 vs 20kW respectively?

 

[AndY1]

There should be no difference. Charging at 22kW AC (type2 Mennekes) is still only C/4 and that's nothing for the Li batteries.

 

[gavine]

How about if the battery spends a lot of time at a low state-of-charge? I know sitting at high SOC is bad (especially at high temperatures), but how about low SOC?

 

[wiztecy]

How about if the battery spends a lot of time at a low state-of-charge? I know sitting at high SOC is bad (especially at high temperatures), but how about low SOC?

Low SOC is bad too. They like 50-60% SOC. Low SOC is really bad if you're pulling from the pack hard such as flooring it, puts lots of stress on the individual cells plus heats them up faster than at a higher SOC.

Looking at the Leaf they're doing all the bad things, no cooling management of the pack, always charging to 100% SOC, always drain to 5-10% SOC, Fast charging with no way to manage the heat build up on a small KW pack.

 

[JZtheHW]

I spent an hour watching the Youtube topic "Why do Li-ion Batteries die? and how to improve the situation?" The professor actually built a through, complex, and precision test system to acquire all kind data to quantify the difference of all kind batteries and the conditions leading to battery degradation.

My conclusion: Tesla did their homework to pick the best technology to build and operate the battery, so take easy, the leading cause of battery degradation is fully charged cell in a high-temperature situation. Keep following principle in mind will prolong your Tesla battery:

1) Avoid fully charge situation as much as possible, especially in the high-temperature situation like summer in Nevada, keep the maximum level as low as practical for your usage at anywhere between 50 to 90%. e.g. for me, a southern California resident, 70% in summer and 80% in winter. As long you keep this principle in mind, pick the maximum level of charge between 50 to 90% suites for your need, and your Tesla battery is in good hand.

2) Keep the charger plugin whenever, why? the Tesla battery has thermal management to maintain the optimal interior temperature, you want to use the electricity from the grid to cool/warm your battery, not the energy from the battery itself. Make sense?

Hopefully this help to ease your concern. Enjoy your Tesla!