Range shorter than EPA (if you want to protect battery)

[theaveng]

I'm an electrical engineer who has discovered that Lithium-ion batteries don't like to be charged below 20% or above 80% so that limits the useful battery range to 60% of the EPA rating:

0.6 times EPA == 45 miles

 

[EVDRIVER]

You mean discharge below 20%. and charge above 80% although this is a generalization. With all the posts on this topic already you just came to this conclusion? The post almost sounds like your account has been hacked by a spammer.

 

[DaveEV]

The post almost sounds like your account has been hacked by a spammer.

Must be hijacked since the same post appeared on TMC, but there t says he lives in Boston instead of California.

 

[smkettner]

I would expect an electrical engineer to provide a link to some independent testing including quantifying the effect.
Anyone here could easily come to the same conclusion with a quick search and no electrical background.

 

[theaveng]

Not possible to link to physical books that don't exist online (that I'm aware of), but here's a semi-useful site
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries" onclick="window.open(this.href);return false;

 

[Stoaty]

No relationship between charging pattern and battery degradation has been seen in practical usage over the last 2.5 years. The Battery Aging Model (link in my signature) is doing a pretty good job predicting capacity loss based on only 3 parameters, which in order of importance are generally:

Climate
How many full charge discharge cycles or equivalent
Solar Loading

I have driven my Leaf extremely conservatively (lowest SOC ever around 20%), and only charge to 100% maximum once a week right before a long drive, so I should expect to be beating the average. However, the Battery Aging Model is currently predicting my capacity loss to within 0.1%.

Conclusion: If you don't leave your Leaf sitting at 100% charge for long periods of time, a full charge will make very little or no difference in battery longevity.

PS I suggest reading the Wiki (link in my signature) before jumping in with amazing new discoveries.

 

[ydnas7]

FWIW

Regarding Nissan LEAF, for end timer charging, it generally doesn't matter if its to 80% or 100%, as long as recharge doesn't start until SOC is less than 80%.

Ie the 80% or 100% isn't there because one is better than the other, but because cycling only between 80% to 100% is needlessly hard on the battery.

There is a reason why 100% SOC always was considered OK for warranty and LEASING. If you need it, use it.



In extreme, the news just in (10 years ago), a 3% cycle around the midpoint allows for 10x throughput of an NCA battery.

Stoaty's model is good, just follow it.

 

[CMYK4Life]

HEERRRPPPAAA DEEERRRPPP

THANKS!

 

[EVDRIVER]

Not possible to link to physical books that don't exist online (that I'm aware of), but here's a semi-useful site
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries" onclick="window.open(this.href);return false;

If you post is suspected of being spam you should actually clarify. If not we will simply lock or delete the thread.

 

[johnrhansen]

I'm not an electrical engineer and I can tell you to buy the car and use it. I really don't sweat everyday about battery life anymore. I think the thing to do is try to keep it between 20 and 80, but if you have further to go that day, venture into the forbidden zone and use your car for what you bought it for. And if it's cold, turn on the heat.

 

[surfingslovak]

Ie the 80% or 100% isn't there because one is better than the other, but because cycling only between 80% to 100% is needlessly hard on the battery.

Please note that we have not observed any material difference in the field between habitual 80% and 100% chargers. Most of the capacity loss appears to stem from calendar aging, and not from cycling the battery. Consequently, 80% and 100% do not matter as much as some might have thought initially. This is well documented on the forum, and does not require a new thread, especially not one written in an alarmist or inflammatory tone.

Stoaty's model is good, just follow it.

Yes. Please lock this thread, if you can. You certainly have my vote. The OP has history of disruption and unruly behavior on the forum.

 

[XeonPony]

Not a very good engineer if you're just figuring this out! Next you'll "just" discover lead acid wet cells don't like being cycled below 50% SOC!

or that electrons chase holes! (Or holes chase electrons! erf lets not get going on that head ache!)

very few batteries like to be cycled 100%, Nicads needed to be fully drained or ells you'd get memory but they gaind life by not going above to full soc

I take it you dealt with AC systems mostly? Just becuase your an electrical engineer doesn't mean you'd know squat on batteries, it isn't a magical know every thing field, so you stating it was rather pointless IMO as it gives no credibility that you know to what you speak.

I live off batteries so I need to know allot about them, and I am not an engineer on paper, but that vast and indepth experiance on wet cell batteries doesn't make me very use full on Li-Ion batteries these cars use.

 

[theaveng]

Nothing in my original post was inflammatory.

Please don't be hypersensitive..... the post was meant to be advisory. Heck even on my iPhone and laptop I never charge higher than 80% (or discharge below 20%). It's simply good practice to extend battery life.

 

[surfingslovak]

Please don't be hypersensitive..... the post was meant to be advisory. Heck even on my iPhone and laptop I never charge higher than 80% (or discharge below 20%). It's simply good practice to extend battery life.

I'm sorry, but why would you chose to liberally dispense advice on something that you claim to have just discovered? And not only on this board but also on the Tesla forum? This topic has been covered here multiple times, in long and winding threads, no less. It's documented in the Wiki and by Stoaty's aging model. As someone who has frequented this forum for over a year, I'm sure that you are aware of this. And yet you chose to post the following:

so that limits the useful battery range to 60% of the EPA rating:

0.6 times EPA == 45 miles

You claim that the total useful range of the LEAF is 45 miles with a new battery. How is this not inflammatory? How much driving experience do you have with either the LEAF or the Model S, and what exactly do you know about lithium-ion batteries in general, and the battery pack the LEAF uses in particular? These are pertinent questions, I believe, since you felt compelled to write "advisory" posts on multiple EV forums. Here is what some qualified posters had to say about your insightful memo on the Tesla forum:

In one message you say you are an electrical engineer and in the above you disprove the claim. Armchair Engineers think voltage is The Unit of Everything Electrical. The first thing one has to beat out of EE freshmen is the notion that everything is volts.

Capacity of a battery is far from a linear function of voltage. I do not know how Tesla calculates battery SOC for display but if was only a voltmeter then Tesla would be a laughingstock. Temperature greatly affects cell voltage no matter the charge on the cell remains the same. Temperature also affects how much of a charge one can get out of the cell. Then for much of the cell's charge its output voltage is almost constant.

The most reliable way to display a battery's voltage is to put a power meter on its output and count everything that goes in and everything that comes out. Know the capacity is 85 kWh and you've seen 8.5 kWh come out, so that's 10%.

I'll reiterate what others are telling you that you are not hearing: Tesla says its an 85 kWh battery. What Tesla is not telling us is what the sum total "industry rated" kWh of cells is used. Is very probably Tesla's 85 kWh is in the very same "industry" 20% to 80% bracket just exactly the same as a Prius 100% charge is only 80% of "industry standard NiMH capacity rating."

You're linking a COMMENT on a tech blog site? Wow, that's going straight to the source.

In any case, I don't disagree with the comment. For "regular use", i.e. daily driving, I charge to 80%. It's plenty of range for driving to work, extra errands, driving out of town and back again...

For road trips I charge to 100% for maximum range. That's the only time I need maximum range. And being at that higher voltage for a few hours has negligible effect on battery lifetime and range. That is why they have the control!

Also Tesla is conservative about what they call "100%".

In short, this is completely a non-issue.

Indeed.

Using batteries AT ALL degrades them, just like using an ICE wears it out. Charging batteries to "full" (which, as has been pointed out, is not really 100%) degrades them slightly more. But not measurably so. If you're going on a trip and you need it, use it. No big deal at all; and it's been discussed many times on these forums.

Tesla has been building batteries for years, and they are doing just fine in real life.

By the way, Tesla already is putting Superchargers in roughly every 90 - 150 miles (they stated 120 was about ideal). So you can easily keep the batteries in the sweet spot if you are really concerned about unmeasurable bits of degradation when you get near the edges.

 

[Wennfred]

The post was meant to be advisory. Heck even on my iPhone and laptop I never charge higher than 80% (or discharge below 20%). It's simply good practice to extend battery life.

The Leaf has been out since 2010 and delivered in 2011. The info you posted is common knowledge, I was hoping to read something new. That's pretty much what most are saying.

Fred

 

[theaveng]

..... the post was meant to be advisory. Heck even on my iPhone and laptop I never charge higher than 80% (or discharge below 20%). It's simply good practice to extend battery life.

I'm sorry, but why would you chose to liberally dispense advice on something that you claim to have just discovered?

I never used the word "just" in my posting. YOU inserted that word yourself. I have known about this rule-of-thumb (keep Li-Ion battery between 20-80%) since 2012.

I've also known the same rule for NiMH batteries since the Insight & Prius came out (so I learned it circa 2000-2001). I didn't "just" discover this..... you inserted a word which I never uttered. You set-up a Strawman. LOL. :-D

BTW I put very little stock in what Tesla says.
They were caught twisting the truth when they said "safest" car ever tested.
Over the years several luxury cars have scored 5.3, 5.4, 5.5 stars (higher than the Model S). Tesla likes to "spin" things. But even they admit their Roadsters dropped to 70% capacity after 5 years. Perhaps that could have been avoided if the battery had been charged to just 80% instead of 90% (the standard charge according to Tesla's blog). In other words extend battery life.

 

[surfingslovak]

But even they admit their Roadsters dropped to 70% capacity after 5 years. Perhaps that could have been avoided if the battery had been charged to just 80% instead of 90% (the standard charge according to Tesla's blog). In other words extend battery life.

No, this is incorrect, and you clearly don't know what you are talking about. While cycling the battery between 20% and 80% is beneficial in terms of reducing the cycling losses, depending on how the batteries are cooled, most of the degradation can be attributed to calender life loss. In that case, charging practices and habits take a backseat to things like the average long-term battery temperature and the average state of charge. Focusing strictly on a conservative cycling pattern will have very limited benefit, which is exactly what the field data reflects.

The Roadster battery study Tom Saxton has compiled shows that an aggressive and robust cooling system very effectively minimizes calender life loss. This is unfortunately not the case with the LEAF, as this post, and several others show. Moreover, if you really want to maximize cycle life, you would restrict the SOC range further. The Prius uses 40% to 60%, for example. Although it's a Ni-MH battery pack, a similar benefit in terms of extending the useful life of the battery applies to lithium-ion and is often used in satellites, where the batteries must last a decade or longer.

Does this mean that you are going to start another thread claiming that EVs should only use 20% of their stated range for maximum life? I'm very disappointed that the moderators on this forum allow such egregious abuse of this resource by posters like yourself, which have a history of disrespectful behavior, and post self-serving and misleading information in a trollish manner.

 

[theaveng]

Maybe they embrace Open and Honest Speech, instead of censorship of ideas (even if unpopular)?

 

[Nubo]

Maybe they embrace Open and Honest Speech, instead of censorship of ideas (even if unpopular)?

Some have a greater tolerance for foolishness than others. Honestly I find most of your posts tiresome. You take isolated technical facts and conflate them into grandiose claims. Certainly you must have read some of the threads here and realize that the full understanding of the issues has matured and evolved over the last 3 years, while you take one basic and well-known isolated factor and march onto the stage as an Expert who has made a Grand Discovery.

You've read page 1 of Batteries 101, and you want to lecture the graduate students. I'm not sure if you're trolling or is this simply normal behavior in "Shangri-La"?

Do you understand why people are objecting? It's not about censorship.

 

[DaveinOlyWA]

I'm an electrical engineer who has discovered that Lithium-ion batteries don't like to be charged below 20% or above 80% so that limits the useful battery range to 60% of the EPA rating:

0.6 times EPA == 45 miles

43,700 miles and ahr at 57.06 this morning and have charged to 100% 100% of the time since ohhh Summer 2012 also I am below 20% nearly every day. (in fact below 10% about 50% of the time) so not seeing it...