Why Lithium Ion Batteries Prematurely Fail

[Punx0r]

For the first year I charged the bike (RC lico) immediately after use so it was ready to use again next time. Good practice, right? Not after reading about electrolyte stability and gassing at higher voltages... Now I put the bike away "discharged" and charge up before use. It just takes a little forward-planning.

 

[Joseph C.]

Canabilised from Tesla Motors Club:

Jeff Dahn, FRSC
Professor of Physics and Atmospheric Science
NSERC/3M Canada Industrial Research Chair
Canada Research Chair

Subject: Re: Question RE: "Why do Li-ion Batteries die ? and how to improve the situation? "

Professor Dahn, if you have a chance, I have a few more follow up questions. I do very much appreciate your time answering my questions!

Since they are both cobalt based would the consumer care recommendations (store at lowish SOC, Lowish temperatures, tending to mid voltage cycling) for LiCo02 cells be the same as a LiNiCoAi02 or a LiCoAi02 cell?

YES

Also, does the rate of charge (0.5C vs. 1C vs 1.5C etc.) have any impact on the cell life?

YES - I WOULD AVOID CHARGING AT GREATER THAN C-RATE AND WOULD RECOMMEND C/2, ESPECIALLY FOR "ENERGY CELLS". POWER CELLS (E.G. IN TOOLS) WILL HAVE LITTLE PROBLEM WITH C-RATE CHARGING AND WOULD BE FINE. THE CELLS IN THE TESLA S ARE MORE AT THE ENERGY CELL END OF THE SPECTRUM.


have you tested NCA cells like the Panasonic NCR18650A and NCR18650B and would their care characteristics be the same.

WE HAVE LOOKED AT THE "A" AN IT IS VERY SIMILAR TO LCO CELLS

Nicad is less and less common in consumer electronics but is still used and I have several gadgets that have them. I have been treating these pretty much the same (store at lowish SOC, Lowish temperatures, tending to mid voltage cycling) accept every so often I do a complete discharge and full charge to reduce the tendency toward memory effect. In your opinion, is this on track? anything to add?

THIS IS GOOD. MEMORY EFFECT COMES WHEN CELLS ARE LEFT FULLY CHARGED OR FLOATED AT FULL CHARGE FOR LONF PERIOS OF TIME.

In general, I am amazed at how few of devices/chargers have any sort of BMS other than avoiding runaway combustion. It would make so much sense for every one of these devices to have a long life mode, where they could be left plugged in but only charge to about 50%. so many of these devices end up plugged in all the time, and it dramatically cuts down their shelf life. please consider explicitly recommending this in your research if appropriate. To many phones, computers etc are thrown away because the battery only lasted a year or two, when, if treated better, could have lasted 5-10 years. by applying this care regimen, peak performance of many products can be vastly extended. I've gotten 5 years out of an iphone, 5+ years out of a cordless shaver and long life out of many other products. This has required a lot of careful charging... it would be so much easier if I could set the SOC limit on each device based on my needs, such as at home near a charger vs traveling where I need max charge. we need someone like you to push the industry to make this kind of thing a standard! (no pressure :~). Tesla with it's slider option has nailed this. some way to adjust the end charge limit should be on all consumer products. a SOC meter that showed red at both ends, with green in the middle, would help this be more intuitive for consumers, who now simply think fully charged is the best, which simply leads to killing the battery prematurely.

THIS WOULD BE A GOOD THING. MOST HUMANS TREAT BATTERIES A BLACK BOXES AND DO NOT THINK OR CARE. YOU ARE A RARE SOUL!

OH and as an aside, the Tesla S is aluminum, so no need to worry about rusting :~) and the AC induction motor is brushless with the only contacts points being two bearing sets... potentially, this car should last a very long time!

I KNEW ALL OF THIS AND BRIEFLY FORGOT! "

http://www.teslamotorsclub.com/showthread.php/27109-Why-do-Li-ion-Batteries-die-And-how-to-improve-the-situation/page5?p=574103&viewfull=1#post574103

 

[Joseph C.]

http://www.embedded-world.eu/fileadmin/user_upload/pdf/batterie2011/Sonnemann_Panasonic.pdf

Interesting breakdown of NCA cells. Apparently, Manganese increases safety, Nickel increases capacity, Cobalt increases stability and Aluminium increases safety - not to mention reduces cost.

 

[wineboyrider]

I like the idea of a faster charger too use just before I use my lipo packs? Plug in about an hour before takeoff rather than trickle charge all night.....

 

[TheBeastie]

http://www.embedded-world.eu/fileadmin/user_upload/pdf/batterie2011/Sonnemann_Panasonic.pdf

Interesting breakdown of NCA cells. Apparently, Manganese increases safety, Nickel increases capacity, Cobalt increases stability and Aluminium increases safety - not to mention reduces cost.

I see with the 4.1 vs 4.2 charge rule on page 42 that they got a lot more recharge cycles by charing only up to 4.1.
4.1 about 1300 cycles vs 4.2 charge only got about 900 cycles.

 

[madin88]

Anyone know what chemistry Sony Konion VTC4 or the Samsung 25R do have? Nothing mentioned in the spec sheet..
these are currently the most powerfull 18650 cells on the market.

It would be very interesting how much short regen cycles do weaken the battery. I think this will be a few thousand or more over whole battery life. Any infos about this?

 

[friendly1uk]

I think many people wanting electric cars have a short commute in mind. They buy thinking about range and battery life, then do short trips leaving it fully charged a lot of the time. If you could tell your car you intended to do 10 miles tomorrow, It could charge to 50% plus 5 miles. With such vehicle usage, much longer pack life's could be talked about. Then, should you need a bit more range, you do still have half a charge. Which could be a full charge on Saturdays for shopping. Even my alarm clock could work that out.


No lvc protection leads to a few early demises

 

[Joseph C.]

I think many people wanting electric cars have a short commute in mind. They buy thinking about range and battery life, then do short trips leaving it fully charged a lot of the time. If you could tell your car you intended to do 10 miles tomorrow, It could charge to 50% plus 5 miles. With such vehicle usage, much longer pack life's could be talked about. Then, should you need a bit more range, you do still have half a charge. Which could be a full charge on Saturdays for shopping. Even my alarm clock could work that out.


No lvc protection leads to a few early demises

Yes, but on most EV packs a 50 per cent SOC means an increase in the discharge c-rate. On a large pack like a Model S it would probably be a good strategy.

 

[dogman dan]

He mentioned in the lecture that a typical car pack is never charged 100%. So 100% of what they let you charge, is not a 100% charge. They picked that easy to reach fruit already.

But at any level of charge, hot is the problem with the leaf. So even at the less than full, "full charge" you got a problem in Palm Springs, Phoenix, etc.

 

[gogo]

He mentioned in the lecture that a typical car pack is never charged 100%. So 100% of what they let you charge, is not a 100% charge. They picked that easy to reach fruit already.

But at any level of charge, hot is the problem with the leaf. So even at the less than full, "full charge" you got a problem in Palm Springs, Phoenix, etc.

That's an important distinction that is worth emphasizing on this forum, that Tesla's control regime stays away from the upper and lower potentials already.

Evaporative battery cooling in PHX, FTW?

 

[e-beach]

.....But at any level of charge, hot is the problem with the leaf. So even at the less than full, "full charge" you got a problem in Palm Springs, Phoenix, etc.

Yep gota charge 'em in the refrigerator! And only drive them on cool days/nights :lol:

Air conditioned garages anyone?

On the other hand I have had a temperature controller attached to my beer brewing refrigerator for years. It gives me a constant temperature at what I set it at....60℉ might be a good place to charge my e-bike batteries......hummm.

Evaporative cooling.....a bit too much moisture me thinks.....but with a solar power setup might be a way to cool a hot garage at low cost...to keep the batteries cooler while charging anyway.

As for riding on a hot day....How about a battery box with a chunk of dry-ice at the bottom and a fan blowing the cool air around.



OK..ok...ok, not practical. But wind does do a lot to cool my electric parts when they get hot. A battery box with air flow would probably do a lot, fan or otherwise.

 

[Matt Gruber]

i can park my bike in the foyer. good AC.
how many here have cars? (electric)
only applies to the Leaf, who has the Leaf?

 

[999zip999]

Lowering charge voltage to 3.5v from 3.59v.on my A123 20 ah cells. With a 1420 on balance charge.

 

[e-beach]

.........how many here have cars?

I don't have a car. Sold my car and van when I built my e-bike. I have felt liberated ever since!

 

[alsmith]

i can park my bike in the foyer. good AC.
how many here have cars?

I had a car when I first got my (UK spec 250W) ebike, I wanted to see if it could replace the car. It couldn't manage what I needed, especially hills. Advice from Ed Lyen and lots of reading here led to parts capable of doing the job (Crytalyte 5300, Lyen 18 FET controller), when I knew it could do the job the car went. Bike only now.

 

[circuit]

The video explains that there is not much impact on calendar life by cycling current. All is important is voltage, temperature and time. Soooo.. one would ask if charging "energy optimized" cell at 1C and 2C in temperature-controlled environment (preventing 2C from getting hotter) leads to same outcome?
Also, what happens when charging in low temperatures? Why low current charging is OK? How low should we go?

 

[dogman dan]

I got a slightly different take on it. I thought it was not just charging temp, but any sitting around hot. And worst of all, sitting around hot and fully charged.

In their testing of course, it was never just sitting. But whatever gets your battery above 40 f has got to be bad for it's calendar life right? So yeah, you'd want to be careful about charging so fast it heats the pack as well as discharging so fast it heats the pack above ambient. Or parking where it's 50f.

But I just can't see wanting to chill a bike battery to 40F, like regular refrigerator temps since they perform so much worse by that temp. I can see rich folks in Palm Springs or Phoenix having air conditioned garages. In fact, at a certain price range, they already are.

What happens when you keep a discharged battery in the fridge and charge it is a good question. I suspect it would be harmless unless it was frozen. But I'd want to let it warm some while it charged, so you don't spend your wh on the discharge heating the pack in the first few miles.

 

[circuit]

I got a slightly different take on it. I thought it was not just charging temp, but any sitting around hot. And worst of all, sitting around hot and fully charged.

My take is the same.The longer you charge it, the longer it is subjected to high voltage. And temperature...
so my question is... If you manage to keep temperature the same and charge it twice as fast (and discharge right away), is it better for calendar life? Let's say cycle count is the same.

 

[madin88]

chemistry comparison between the most powerful 18650 cells:

sony konion VTC4: NiMnCo = NMC
samsung 25R: NiCoAl = NCA

aside from the higher capacity, is samsung the winner?

 

[docnjoj]

Lowering charge voltage to 3.5v from 3.59v.on my A123 20 ah cells. With a 1420 on balance charge.

Hey zip. I to am only charging to 3.55 and tend to end rides after 20 miles. This is about 3.00 and my Thunder 1220 puts back about 10.5-11 amp/hrs. This amounts to about 60% assuming about 17 amp/hrs total capacity from the year old amp20 cells. There is some sag at the ind of the 20 miles going up our big 1.5 mile 4% hill, but it keeps n ticking. The battery meter n my S12S shows abut half full and drops down below when I accelerate on the hill. I don't really notice any loss of distance since we rid fixed, known mileage routs.
otherDoc

 

[999zip999]

Doc I do take out 16- 17ah out on long rides and cells read 2.8v at the lowest I know this is close to the cliff. But the veriance in the cells can just be the 1420 as I jiggle the wires and it gets better. Funcky 1420. Still at 3.59v but know 3.45v is pretty much full as needed. I think a bms at 3.8v bleed off is usless for long pack health. But these cells don't stay long at that voltage so small damage. But every bms charge ? Can you set a bms to 3.5v ?

 

[docnjoj]

I'm not using a BMS but use Cellogs on the ride and now the new S12S meter also. The Thunder Charger is my charge BMS and the Cellog alarms for lvc. I never go anywhere near the 17 ah d/c. I use only 10-11 a/h for 20 miles.
otherDoc

 

[dnmun]

Doc I do take out 16- 17ah out on long rides and cells read 2.8v at the lowest I know this is close to the cliff. But the veriance in the cells can just be the 1420 as I jiggle the wires and it gets better. Funcky 1420. Still at 3.59v but know 3.45v is pretty much full as needed. I think a bms at 3.8v bleed off is usless for long pack health. But these cells don't stay long at that voltage so small damage. But every bms charge ? Can you set a bms to 3.5v ?

i don't know how you interpret this but it should be sending a huge WARNING sign to you.

if you have to jiggle the sense wire plug to get the hyperion to display the cell voltage, then it is making a bad connection to the cell so you have no control over the final cell voltage while charging. this may be how the fire started when that guy in the RC group thread was using the hyperion to balance charge his pack.

you may be headed for this same situation if the sense wires are now so worn out from plugging in and unplugging that they no longer make electrical contact.

why would you charge to 3.5V anyway? what is the point of not charging it up fully?

 

[docnjoj]

Hopefully not charging fully could increase cell life a bit. It is what the electric car folks do. It aso may work with LiCo hobby batts by only charging to 4.1 or 4.15. I don't know for sure but it does make sense and is still well within my riding range. I don't use my Hyperion now as it caused a lot of "fussy" trouble. The Thunder is much more robust and not problematic at all during balance charging, which is the only type I do.
otherDoc

 

[999zip999]

I just jiggle the wires to make the 1420 wire the wires just a little and walk away hoping it don't go beep beep beep. Right Doc. 420 cycles.