too much rapid charging damages Li-Ion batteries

[psquare]

Interesting results from an analysis conducted on Li-Ion batteries and potential effects of rapid charging (general on Li-Ion batteries, not just for cars)). I remember reading warnings by VW, advising not to use rapid charging (such as CCS) too often on the eGolf. I guess we will all be wiser in 8-10 years time!

Article is in german, below is the Google Translate link to english.

German link: https://idw-online.de/de/news629144

English Google translation: https://translate.google.co.uk/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=https%3A%2F%2Fidw-online.de%2Fde%2Fnews629144&edit-text=

 

[cove3]

This is the #1 issue, especially with Tesla's charging network encouraging high speed charging as routine. I feel the results aren't in until more data and testing is done.

This recent link was promoted by Tesla owners as not to worry, but I'm still on the fence

http://chargedevs.com/newswire/new-study-rapid-charging-doesnt-damage-lithium-ion-batteries-as-much-as-thought/

 

[Jeffj]

Not really a problem for those of us living outside of the UK, California or maybe Atlanta, as we really don't have the option of fast charging...

 

[jadnashuanh]

A lot of this comes down to temperature management. One has to hope that BMW did their homework on the i3. They have NO restriction on how often you use a CCS unit WRT the battery warranty. There is a reason why they only quote the CCS speed at up to 80%...once you get there, the rate of charge tapers off significantly. And, they do have a reasonable buffer at the top where you can't reach the cell's real full charge potential. Personally, I don't worry about it.

Most devices using Li-On batteries don't cost as much as an i3, have internal cooling and temperature management, or the logic the vehicle has to protect the batteries. They spent a number of year optimizing things...I don't try to second guess them.

 

[elptex]

Like all new science, there are reports supporting both sides. Science also acknowledges that lab results (as is the case with the study linked here) are always the same as real world. Thus practical science sits better with me. To that end, Nissan released their internal study data on L3 charging versus L2 and noted that there was a negligible difference in degradation of the two. Tesla has said the same. BMW has said the same will apply to the i3 battery. I love and respect science, but lab results aren't always practical.

 

[cove3]

<<<<BMW has said the same will apply to the i3 battery.>>>

But the VW e-golf users manual page 251 says:
"Frequent and consecutive high voltage charging can permanently decrease the capacity of the high voltage battery"
(However, this might be the recommendation because the egolf does not have a battery cooling system)

http://www.bmwblog.com/2013/04/25/understanding-battery-capacity-loss/

Avoid excessive fast charging. The BMW i3 will have the capability of charging on a DC quick charger which will charge the battery to 80% in about a half hour. While the batteries are not damaged by quick charging process, they can be damaged by the heat created by fast charging. Unlike the Nissan LEAF, the i3 will have a complex thermal management system that is liquid based and its sole purpose is to keep the battery at safe operating temperatures to prolong the battery life and extend the cars range. This system will definitely allow you to fast charge more often without damage then if the car didn’t have it, but most industry experts still warn against consistent use of fast chargers. The science hasn’t really proven this one way or the other just yet, as DC quick charge is just beginning to be available to EV’s, but I would prefer to err on the side of caution and only use DC quick charge when I really needed to.
Ron.

 

[WoodlandHills]

Or you could lease your car and charge anywhere and anytime you want as often as you like, since it's just a rental.....

 

[cove3]

You could but it's best if we try our best to conserve scarce resources for future generations. Someone, perhaps a less fortunate person wanting to help the environment but not being able to afford a new i3, may be buying your car coming off lease and would want to get 60 or 70 miles.

Ron

 

[WoodlandHills]

And when EV batteries get too weak to be usable in a car they will be recycled as solar power storage in somebody's garage, so no matter what condition they are in they will not get scrapped for a long time..... So beat on it like a rented mule, that's what the warranty is for!

 

[jadnashuanh]

I tend to believe BMW did their homework on the ground-up design of the i3. They spent a huge amount of time and money developing the whole car, and if they say it isn't an issue, and their warranty is backing you up, why would you question it?

As stated...it is excessive heat that is the main culprit...and, with the active, smart, liquid cooling system in the i3, I do not believe it is an issue.

Your i3 is NOT a laptop computer or a smartphone. At least in the laptop, the only cooling is for the CPU (and maybe the video processor if you have a gaming machine), but there is no cooling in a smartphone. Those were not designed for rapid charging in the same manner as the i3. Their batteries may not last as long if you don't coddle them.

 

[elptex]

I tend to believe BMW did their homework on the ground-up design of the i3. They spent a huge amount of time and money developing the whole car, and if they say it isn't an issue, and their warranty is backing you up, why would you question it?

Agreed. I think it always good to "question" things with the mindset of understanding why something is being done. In that regard, what you say is exactly how I feel: BMW did their research and they implemented the best that any manufacturer currently offers.

As stated...it is excessive heat that is the main culprit...and, with the active, smart, liquid cooling system in the i3, I do not believe it is an issue.

I recall someone posting a picture on the Facebook group of the battery temperature readout (available in the diagnostic screens) while L3/quick charging and it was nominal. Their point was essentially that the active cooling/heating system was doing its job and doing it well. Tried to find the picture but the Facebook group is not the best format for finding historic content like that.

 

[mjk]

Maybe using the REx with the HSOC patch in the U.S. isn't such a bad decision after all. Just sayin'.

 

[I33t]

So if Nissan, Tesla and BMW are saying it isn't a significant issue, what's VW complaining about? Perhaps they have specified the charge system, battery or battery management systems incorrectly, or maybe they are just opening a warranty bail-out hole for themselves?

 

[WoodlandHills]

Or maybe VW know that their batteries are not up to snuff? After all, VW are the experts on THEIR batteries, perhaps there is something about their tech that is different than the others.

 

[cove3]

It's likely due to the VW egolf batteries not being cooled, probably to save weight. Just passive cooling. VW said their studies showed it didn't need it, so maybe it's conservative to recommend not to consecutive charge CCS. From the reading I've done, the battery chemistry is very similar to the i3

Ron

 

[I33t]

The Leaf batteries are passively cooled as well, although I think I heard they are heading to active temp management?

No active temperature management is the main reason I cancelled my Leaf order. Surprised VW has gone down that route. :shock: Might explain why they are not releasing the car everywhere, hope you live in a reliably cool area cove3...

 

[jadnashuanh]

The LEAF had issues in places like Arizona in the summer even using an EVSE. Active cooling, and never rapidly charging to maximum capacity, I think, are the main reasons the i3 can handle the CCS inputs. There's good reason they claim rapid only to 80%. If you keep it connected, it will take a fair amount of time to fully top off compared to getting to that 80%. This is controlled by the car and it's logic. My guess is that it uses the battery temperature as a major part of the equation on how fast and how much charge it will accept with any charging method.

 

[stumbledotcom]

I've been able to use various CCS units multiple times. Both the dual CHAdeMO/CCS 50 kW and BMW i's standalone 24 kW units will get the i3 to 80% in less than 20 minutes then estimate about an hour for the remaining 20%. I've never had the patience to stick around until it reaches 100% so I can't say how accurate that estimate is. Weather conditions have always been in the mid to high 60's F.

I see this discussion akin to debating when to change the oil in an ICE. Some people swear by oil changes every 3000 miles while others accept the longer intervals now recommended by manufacturers and oil life monitoring systems. It doesn't matter what kind of argument you make to a 3000 mile believer, they do what they've always done.

Personally I plan to recharge on Level 3 every chance I get since BMW doesn't counsel against repeated CCS charging, provides a robust warranty, and (at least in California) offers free CCS charges through June 2016.

 

[psquare]

Although I did a lot of preparation, I have to be honest and admit that I never researched charging or cooling systems when I compared the eGolf, Leaf and i3 before signing on the dotted line last year.

I've had a conversation with a neighbour recently, who is a pilot and when we talked about the i3 (which he liked and was very interested in), and one of his first questions was about the batteries and dangers of overheating. He said that fires caused by Li-Ion battery sets in a 787 Dreamliner which were in the press last year and asked whether I had looked into anything in the i3 that would prevent it. Truth be told, I hadn't, but reading the Wiki pages around the 787 issues, there are not too many indications that it is purely a temperature problem which caused the fire (if this is anything to go by). The fact that BMW seems to have done its homework on the i3 battery and charging systems is a big plus for this car, I'd say.

 

[JPWhite]

A lot of this comes down to temperature management. One has to hope that BMW did their homework on the i3. They have NO restriction on how often you use a CCS unit WRT the battery warranty. There is a reason why they only quote the CCS speed at up to 80%...once you get there, the rate of charge tapers off significantly. And, they do have a reasonable buffer at the top where you can't reach the cell's real full charge potential. Personally, I don't worry about it.

Most devices using Li-On batteries don't cost as much as an i3, have internal cooling and temperature management, or the logic the vehicle has to protect the batteries. They spent a number of year optimizing things...I don't try to second guess them.

Agree that Rapid Charging is not the issue, temperature is. In mild climates Rapid Charging has no detectable impact on battery durability/life

A UK LEAF with 120,000 miles and 1700 Rapid Charging sessions still has excellent battery health.

http://www.electric-vehiclenews.com/2015/05/nissan-leaf-taxi-passes-160000-km-and.html