Superchargers shorten life of battery?

[jerry33]

OK, I'm confused. I've been driving a 2012 Chevy Volt while I wait for my 3. I bought it used, and I've had it two years. In that time, I plug in all the time, and I charge and discharge fully almost every single day. I haven't noticed any problems with degradation. Is the Volt's battery that much different than a fully electric car battery?

1. There isn't any actual problem with degradation in Tesla's battery. Tesla is being very conservative in how they approach charging--this is probably too conservative for some and probably doesn't cover edge cases such as the 45 kW CHAdeMO charger mentioned above.
2. I'm pretty sure the Volt hides a bit so that it looks full for longer because all LiIon batteries degrade over time, it goes with the chemistry.
3. At 108K miles and over five years, it appears that there has been less than 4% degradation. (I live in one of the hotter states and the car is parked outside.) That's pretty much as good as it's possible to get.
4. The 2015 Leaf battery (this is the one improved for heat) that Denise drives has lost over 17% of it's initial capacity. ASAP, the Leaf goes to Model 3.

 

[Cirrus MS100D]

Disclaimer: not a Volt expert - but my friend who has one explains to me that GM has a pretty large buffer on both ends of the Volt battery.

You can do some searching and find out on the various Tesla battery packs, while the packs may be close to their rated range, they purposefully prevent you from charging or discharging into a certain “protected zone” to make sure you don’t brick the battery.

On the Tesla 100s, you don’t actually get access to about 3kWh.

I think the Volt is around 18 kWh total, but you only get access to about 14 kWh. On a percentage basis, you charging to 100% is much less than a 100 kWh user charging to 100% of the packs total storage.

Thus you can charge to 100% and suffer little to no degradation.

 

[Hank42]

Speaking about HEAT. And my apologies for slightly hijacking this thread ...
I charge my 75,000 miles car on my HPWC weekly or more.
How hot should the handle get?
I can barely touch mine when it is in the middle of a charge. 60 mile per hour draw.
I moved last year and seem to recall at my last location not having this issue?

Could this be because my electrician here didn't install it correctly? Could the connections behind the HPWC cover be loose?

At superchargers where the rate is far higher I would expect it to be hotter than at my house.

Nothing the electrician did would cause your handle to get hot. Some older HPWC's had conductors in the handls that would not fully mate with the cars charge port - causing heat build up in the handle. This will not damage your battery(just your hand). However, talk to Tesla about a replacement cable or HPWC if it's under warranty. Failing that, look down the barrel of the connector and look for any obvious dirt - same for the charge port.

 

[GreenT]

I am using an original HPWC not the HPC.
I have been charging my S for the past hour, reducing the charge rate from 80A to 40A.
The handle is now easy to touch.
See no dirt.

 

[Glamisduner]

OK, I'm confused. I've been driving a 2012 Chevy Volt while I wait for my 3. I bought it used, and I've had it two years. In that time, I plug in all the time, and I charge and discharge fully almost every single day. I haven't noticed any problems with degradation. Is the Volt's battery that much different than a fully electric car battery?

The volt does not allow 100% usage of it's battery like a tesla. It's likely capped at around 75%-80% (I read somewhere volt batteries top at at about 4v (no load), 18650's fully charged are at about 4.2v. at full charge. The Volt won't allow too low of a discharge either, partially due to the way it may need to pull reserve capacity when in ICE mode. GM made this idiot proof and did a really good job at it. It makes it much harder for consumers to abuse the batteries, which is why volts don't have many battery issues compared to some other EVs. It also tends to make people happy when they see 100% instead of 70% etc. There may also be some other battery tricks employed to ensure the customer gets repeatable results. It's nice to have the degradation hidden from a consumer point of view IMO.

Essentially, volts are easy on the battery and have a large reserve capacity. (Did they do this to the bolt too? My guess is yes they did, although maybe not to the same extent?)

Tesla allows you more control of the battery, but I wonder if they may not allow real 100% charging either because they tend to show only small degradation over time?

 

[hacer]

Speaking about HEAT. And my apologies for slightly hijacking this thread ...
I charge my 75,000 miles car on my HPWC weekly or more.
How hot should the handle get?
I can barely touch mine when it is in the middle of a charge. 60 mile per hour draw.
I moved last year and seem to recall at my last location not having this issue?

Could this be because my electrician here didn't install it correctly? Could the connections behind the HPWC cover be loose?

At superchargers where the rate is far higher I would expect it to be hotter than at my house.

In all likelihood you can charge your car overnight at a far lower than 80A rate. So why do you max it out?

 

[David99]

Tesla allows you more control of the battery, but I wonder if they may not allow real 100% charging either because they tend to show only small degradation over time?

100% on a Tesla is true 100%. 0% on a Tesla is about true 5%.

 

[dhanson865]

Thanks for the advice. I have a fairly short commute to work each day. Let’s say I charge it to 70% the first night with my HPWC and it takes me 3 or 4 days to get to 30%. Am I best not to charge it again until I get to 30% or am I fine topping it up to 70% each night just as a matter of routine without shortening the battery life at all?

Doesn't really matter much if you charge it every day or every 2 days or every 3 days as long as you don't have an unexpected need for a longer trip. So I plug it in every night just for the what if factor.

I'd charge higher if it's below freezing out and lower if it is hot enough to use air conditioning for any reason.

So think like this if range isn't an issue:

100% for unusual circumstances (like right before a trip, but very shortly before)
90% in the winter
80% spring and fall
70% summer
60% if its the hottest day of the summer and you can handle the range limitation
50% if you are going to leave it sitting for a day or two, charge it back up if needed later before you use it.

If you are lazy or don't want to hassle pick a number from the above that fits an average and lit it use that most of the time.

But me I change my charging behavior based on use and temperature.

 

[GreenT]

In all likelihood you can charge your car overnight at a far lower than 80A rate. So why do you max it out?

I SHOULD be able to do 80A whenever I feel like it and not be concerned about it heating up so much.

 

[Glamisduner]

I SHOULD be able to do 80A whenever I feel like it and not be concerned about it heating up so much.

You can it's just harder on the battery.

 

[mal_tsla]

100% on a Tesla is true 100%. 0% on a Tesla is about true 5%.

Tesla previously stated that their 100% is 4.15 volts, or 95%:

"Tesla Motors has decided to limit the maximum charge of its cells to 4.15 volts, taking an initial 5 percent range hit to maximize lifetime of the pack. We also limit discharge of our battery pack to 3.0V/cell and will shut down the car when the batteries reach this level."

Do you have evidence to share that shows they've (silently) changed their practices?

A Bit About Batteries

 

[David99]

Tesla previously stated that their 100% is 4.15 volts, or 95%:

"Tesla Motors has decided to limit the maximum charge of its cells to 4.15 volts, taking an initial 5 percent range hit to maximize lifetime of the pack. We also limit discharge of our battery pack to 3.0V/cell and will shut down the car when the batteries reach this level."

Do you have evidence to share that shows they've (silently) changed their practices?

A Bit About Batteries

That post is from 2006 and was for the old Roadster. The Model S/X is different. According to Jason Hughes, who took one of the first Tesla packs apart and built his own battery storage said the cells are getting charged to 100%.

 

[mal_tsla]

That post is from 2006 and was for the old Roadster. The Model S/X is different. According to Jason Hughes, who took one of the first Tesla packs apart and built his own battery storage said the cells are getting charged to 100%.

Interesting! These are 18650 cells just like the S and X, and Tesla makes a compelling case for why limiting voltage is a good idea. Only to turn around and charge them fully in the next cars that use the same type of battery? Would love to know the rest of the story there. Did they modify the chemistry such that 4.2 is no longer the upper voltage limit?

@wk057 -- any details u can point us to?

 

[kmcdds]

Doesn't really matter much if you charge it every day or every 2 days or every 3 days as long as you don't have an unexpected need for a longer trip. So I plug it in every night just for the what if factor.

I'd charge higher if it's below freezing out and lower if it is hot enough to use air conditioning for any reason.

So think like this if range isn't an issue:

100% for unusual circumstances (like right before a trip, but very shortly before)
90% in the winter
80% spring and fall
70% summer
60% if its the hottest day of the summer and you can handle the range limitation
50% if you are going to leave it sitting for a day or two, charge it back up if needed later before you use it.

If you are lazy or don't want to hassle pick a number from the above that fits an average and lit it use that most of the time.

But me I change my charging behavior based on use and temperature.

What's the rationale behind the difference in % charge for the various temperatures?

 

[dhanson865]

What's the rationale behind the difference in % charge for the various temperatures?

Heat degrades batteries. Extremly High State of Charge degrades batteries (as does extremely low state of Charge). Charge cycles degrade batteries. Time degrades batteries.

You can't avoid time unless you live in a different universe than I do. You pretty much can't avoid charge cycles if you plan to drive the car so that leaves heat and state of charge.

Turns out heat and state of charge interact very much. High heat at low state of charge causes less damage than high heat at high state of charge (by a lot).

You can only control heat if you keep your car stowed away in an air conditioned garage. So if you park your car outside and drive it on the road (as I do) your last and only controllable factor out of all 4 we started with is ... you guessed it State of Charge.

I can't control how hot my parking lot at work is or how hot the highway is. I can park under a tree and move the car between morning shade and afternoon shade but that doesn't change much.

I can charge my car less when it will be hot out. That is my only major control on how my cars battery pack ages. Everything else is minor.

OK I could move to Canada or Norway or somewhere else near the arctic circle but given my current home zip code all I can really do is control State of Charge.

Now Tesla does have a cooling loop for the main pack and that makes it much less of an issue. But extra heat at high state of charge is such an issue you'll spend more energy cooling the pack if SOC% is high so a higher SOC% in hot weather equals less range and higher cost per mile driven. Also note Tesla is likely choosing to optimize temperature for performance more than longevity. You can tilt that back a little towards balanced if you change your max SOC% based on outside temp.

It's no absolute deal breaker, you can ignore it if you want. I'm just used to thinking this way coming from a cheaper EV that has no cooling for the main pack. Just like I check my tire pressure and adjust when the temperature increases or decreases, I do similar for my battery pack by adjusting my max SOC% when the temperature increases or decreases.

 

[mal_tsla]

Teslas will cool (or warm) the battery pack as-needed, including while charging. You can safely request a full, fast charge in hot weather. You might not get what you asked for, if that would lead to too much heat. But the car will try, including running the AC full blast. Happens every summer down here in TX.

 

[GreenT]

You can it's just harder on the battery.

Huh?
If 80A is harder on the battery, what does Supercharging do to it?

 

[GreenT]

Interesting! These are 18650 cells just like the S and X, and Tesla makes a compelling case for why limiting voltage is a good idea. Only to turn around and charge them fully in the next cars that use the same type of battery? Would love to know the rest of the story there. Did they modify the chemistry such that 4.2 is no longer the upper voltage limit?

@wk057 -- any details u can point us to?

Don't think wk057 has been around here in ages.
"Senior tinkerer is tinkering elsewhere Mar 17, 2016" from his profile.

 

[dhanson865]

Don't think wk057 has been around here in ages.
"Senior tinkerer is tinkering elsewhere Mar 17, 2016" from his profile.

His last post on here was May 14, 2018

That's just over two weeks ago. And he had dozens of posts in May 2018.

 

[David99]

Interesting! These are 18650 cells just like the S and X, and Tesla makes a compelling case for why limiting voltage is a good idea. Only to turn around and charge them fully in the next cars that use the same type of battery? Would love to know the rest of the story there. Did they modify the chemistry such that 4.2 is no longer the upper voltage limit?

The Model S and X and 3 all recommend charging to only 90% which is also the default setting.