A123 "Shelf Life"?

RD Blakeslee · Nov 20, 2006, 10:13 AM

Apparently, A123's developers have data showing 6000 cycles in conservative applications. Well, that's more than EIGHT YEARS of subdued flying, 2 flights per day, every day of the year. Will they last that long?

While it's wouldn't be conclusive IMO, tests designed to simulate aging might be helpful.

Are there any?

- RD

everydayflyer · Nov 20, 2006, 10:27 AM

Very good question RD.
The most cycles I have read of to date in an RC application was just over 400 but no time frame, average loads ,DOD charge rates etc. details were provided.

http://www.rcgroups.com/forums/showp...2&postcount=46

I have also not seen any recomended storage state of charge or temperatures listed for these cells other than the fact that 3.3 volts per cell seems to be the normal shipped voltage.

Charles

gulio · Nov 21, 2006, 02:00 AM

They said they had a 10 year "shelf life".

I jokingly asked to buy some "ten year old" ones. How does one know the shelf life of new batt technology?

Kraeuterbutter · Nov 21, 2006, 03:46 AM

yes, someone of A123-racing
told me in a car-forum where i asked the same question, that
the cells have a shelf-lifetime of 10years..

same thing i could read on an Prius-hyprid webpage, where guys put bigger batts (meanwhile also A123-batteries) into there hyprids to get more electric-only-range and to be able to charge it from the net

RD Blakeslee · Nov 21, 2006, 09:23 AM

Well, if it's ten years, I probably won't have to buy any more batteries for my sailplane or some other small appliances I've converted to M1s.

My LiPos have been lasting about three years.

everydayflyer · Nov 21, 2006, 10:03 AM

And if indeed the shel life is 10 years then the mystery of the low voltage cells showing up in some DeWalt packs deepens.

Perhaps the next serious question(?) to ask would be,
What is the normal screening time / number of cyles given these cells before being sold / placed in distrubition chain?

What is the nonimale failure rate of cells before and aftyer being placed in service?

Way back when Sanyo use to cycle their NiCad cells 50 times before releasing them or so I have been told.

Thunder Power holds cells for several weeks before using them in pack assembly.

IMO brand new ,freshly manufactured cells can not be graded very accurately with a token sampling and a few short accelerated test.

Charles

bjpaul · Nov 21, 2006, 10:51 AM

Lots of questions there Charles...... some have been touched on in other threads.

From a previous thread we learned some Lipo's (perhaps all) are shipped from the manufacturer in an "unactivated state". It takes some undetermined number of cycles to fully activate them. Do all assemblers cycle cells? If they don't there is no way to accurately match for IR and capacity.

Do A123's need activation?

With Nicads I believe we called this "formatting"

In another thread there was speculation that the design of the DeWalt balancer could lead to a very slow self discharge of a cell in the pack. The rate would be so low that it would be many months before a cell was fully discharged. Which cell that was discharged may be random and that if true that would explain why some have seen no imbalance, others (myself included) have seen one cell partially discharged, and some have received a pack with a dead cell. It appears to be related to the age of the pack.

If true this is a DeWalt problem and not a A123 cell problem.

time and more experience will hopefully tell.

Brad

Gene Bond · Nov 21, 2006, 11:41 PM

Well said, Brad.

We have a lot to learn... More info being shared all the time will help!

fly_boy99 · Nov 22, 2006, 12:43 AM

Isn't it funny how we come full circle on almost everything in life.

First it was nicads, nimhs then the big move to lipos and now back
to round cells.

What's next, a 10000mah chip?

bjpaul · Nov 22, 2006, 08:20 AM

Quote:

Originally Posted by fly_boy99

Isn't it funny how we come full circle on almost everything in life.

First it was nicads, nimhs then the big move to lipos and now back
to round cells.

What's next, a 10000mah chip?

Remember "what goes around comes around"

Brad

fly_boy99 · Nov 22, 2006, 08:11 PM

Sorry for going off topic but what's going around Brad?

Nov 20, 2006, 10:13 AM	#1
RD Blakeslee Registered User Join Date: Jan 2002 Posts: 6,548	A123 "Shelf Life"? Apparently, A123's developers have data showing 6000 cycles in conservative applications. Well, that's more than EIGHT YEARS of subdued flying, 2 flights per day, every day of the year. Will they last that long? While it's wouldn't be conclusive IMO, tests designed to simulate aging might be helpful. Are there any? - RD

Nov 21, 2006, 10:03 AM	#6
everydayflyer Southern Pride Join Date: Oct 2004 Location: Haralson County GA. USA Posts: 24,223	And if indeed the shel life is 10 years then the mystery of the low voltage cells showing up in some DeWalt packs deepens. Perhaps the next serious question(?) to ask would be, What is the normal screening time / number of cyles given these cells before being sold / placed in distrubition chain? What is the nonimale failure rate of cells before and aftyer being placed in service? Way back when Sanyo use to cycle their NiCad cells 50 times before releasing them or so I have been told. Thunder Power holds cells for several weeks before using them in pack assembly. IMO brand new ,freshly manufactured cells can not be graded very accurately with a token sampling and a few short accelerated test. Charles Last edited by everydayflyer; Nov 21, 2006 at 10:39 AM.

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Nov 20, 2006, 10:27 AM	#2
everydayflyer Southern Pride Join Date: Oct 2004 Location: Haralson County GA. USA Posts: 24,223	Very good question RD. The most cycles I have read of to date in an RC application was just over 400 but no time frame, average loads ,DOD charge rates etc. details were provided. http://www.rcgroups.com/forums/showp...2&postcount=46 I have also not seen any recomended storage state of charge or temperatures listed for these cells other than the fact that 3.3 volts per cell seems to be the normal shipped voltage. Charles

Nov 21, 2006, 02:00 AM	#3
gulio That's a funny word Join Date: Apr 2003 Location: NE Ohio Posts: 2,208	They said they had a 10 year "shelf life". I jokingly asked to buy some "ten year old" ones. How does one know the shelf life of new batt technology?

Nov 21, 2006, 03:46 AM	#4
Kraeuterbutter Registered User Join Date: Mar 2002 Location: Europe, Austria, Burgenland Posts: 1,774	yes, someone of A123-racing told me in a car-forum where i asked the same question, that the cells have a shelf-lifetime of 10years.. same thing i could read on an Prius-hyprid webpage, where guys put bigger batts (meanwhile also A123-batteries) into there hyprids to get more electric-only-range and to be able to charge it from the net

Nov 21, 2006, 09:23 AM	#5
RD Blakeslee Registered User Join Date: Jan 2002 Posts: 6,548	Well, if it's ten years, I probably won't have to buy any more batteries for my sailplane or some other small appliances I've converted to M1s. My LiPos have been lasting about three years.

Nov 21, 2006, 10:51 AM	#7
bjpaul It must be a glitch Join Date: Dec 2000 Location: Sanford Centrl Reg, Florida, United States Posts: 3,139	Lots of questions there Charles...... some have been touched on in other threads. From a previous thread we learned some Lipo's (perhaps all) are shipped from the manufacturer in an "unactivated state". It takes some undetermined number of cycles to fully activate them. Do all assemblers cycle cells? If they don't there is no way to accurately match for IR and capacity. Do A123's need activation? With Nicads I believe we called this "formatting" In another thread there was speculation that the design of the DeWalt balancer could lead to a very slow self discharge of a cell in the pack. The rate would be so low that it would be many months before a cell was fully discharged. Which cell that was discharged may be random and that if true that would explain why some have seen no imbalance, others (myself included) have seen one cell partially discharged, and some have received a pack with a dead cell. It appears to be related to the age of the pack. If true this is a DeWalt problem and not a A123 cell problem. time and more experience will hopefully tell. Brad

Nov 21, 2006, 11:41 PM	#8
Gene Bond Crash Master Join Date: Sep 2001 Location: Indianapolis, IN Posts: 16,207	Well said, Brad. We have a lot to learn... More info being shared all the time will help!

Nov 22, 2006, 12:43 AM	#9
fly_boy99 Flying motor mount master Join Date: Oct 2004 Location: San Jose, California, United States Posts: 8,457	Isn't it funny how we come full circle on almost everything in life. First it was nicads, nimhs then the big move to lipos and now back to round cells. What's next, a 10000mah chip?

Nov 22, 2006, 08:11 PM	#11
fly_boy99 Flying motor mount master Join Date: Oct 2004 Location: San Jose, California, United States Posts: 8,457	Sorry for going off topic but what's going around Brad?