Real-World Pack Capability/Capacity for Li-Mn Pack
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gudy
Well-known member
this is LiFePO4 ... isn't that different from Lithium Manganese ?
gudy
Well-known member
mmmm "LiFePO4 based LiFe(1-x)Mg(x)PO4" ... has Lithium Manganese always been using Phosphate as well ? (no idea why but in my mind LifePO4 was iron phosphate ...)
garygid
Well-known member
Yes, it is different.
Coffee_Slurry
Well-known member
gudy said:
Sortof. Valence is big on lithium iron magnesium phosphate (LiFeMgPO4). Segway uses these ("Saphion" branded). They're not likely to explode on overcharge or short circuit. Valence has some impressive safety videos:
http://www.valence.com/
A123 has a similar deal.. replacing electrodes with "nano" iron-phosphate.
Nissan/AESC is all about nickel+manganese+cobalt (spinel) design:
http://www.greencarcongress.com/2009/11/nissan-nmc-20091129.html
(Common bulk cells today use LiCoO2, cobalt-oxide cathodes.)
Lots of good info in The Wiki:
http://en.wikipedia.org/wiki/Lithium-ion_battery
AndyH
Well-known member
Yes - these are all slightly different - but this info is very very good for the later lithium variations - especially those intended for EV use as cycle life and thermal control are the two central targets for the chemists to improve.
The Valence cells are fairly low performance in the overall lithium world - not much better than some of the Chinese large format cells - and they still gave a good 10 year/80% life. Considering that the older tech LiFePO4 cells that I work with could do that about 8 years ago, I feel very good indeed about these newer cells!
Andy
The Valence cells are fairly low performance in the overall lithium world - not much better than some of the Chinese large format cells - and they still gave a good 10 year/80% life. Considering that the older tech LiFePO4 cells that I work with could do that about 8 years ago, I feel very good indeed about these newer cells!
Andy
LTLFTcomposite
Well-known member
Something interesting to note in that article...
Lithium-ion batteries containing more than 25 grams (0.88 oz) equivalent lithium content (ELC) are exempt from the rule and are forbidden in air travel.
I wonder if it is permissible to ship a Leaf (or Leaf battery packs/modules) as air freight?
Lithium-ion batteries containing more than 25 grams (0.88 oz) equivalent lithium content (ELC) are exempt from the rule and are forbidden in air travel.
I wonder if it is permissible to ship a Leaf (or Leaf battery packs/modules) as air freight?
LTLFTcomposite
Well-known member
JasonT said:
That literature shows a lot of consumer electronics and doesn't appear to contemplate super-sized EV batteries. Interesting question whether the standard for safety should be lower just because there are only three people on the plane instead of 150. If a problem does arise, hopefully at least one package on the plane will contain a satellite phone and not just a volleyball.
smkettner
Well-known member
These reports are encouraging for when the eventual battery replacement time comes
Although in eight + years there may well be even more improvements
Although in eight + years there may well be even more improvements
smkettner said:
There seems to be a lot of people who think you will necessarily be replacing the battery after 8-10 years. There are 14-year-old RAV4EVs still on the road out there with their original NiMH packs. How often (or even if) you'll be replacing the battery depends entirely on how much or how little you abuse it.
If you drag race your Leaf with quick charging between runs every weekend you can expect to need a new battery fairly quick. If you drive it more humanely then you might not even own the car long enough to need a new battery.
=Smidge=
AndyH
Well-known member
Nice job, Smidge! It appears that there are two primary questions when it comes to pack replacement (or return on investment) - how long will the current pack last and how much range do I need?
Folks have been running lead-acid and NiMh for many years and their performance and lifespans are pretty comfortably known. And NiMh has proven to work very well for the long term. On paper, lithium-based cells should do significantly better and last longer than NiMh - and they're more energy efficient to boot - but the relative lack of real-world experience (testimonials?!) leaves many with a nagging doubt. Now we're getting the real-world numbers from some of the earlier lithium variants that show that the paper estimates might actually be correct! And lithium performance and capability has improved over the past 10 years much faster than books and web sites can keep up!
The point about battery replacement is spot on -- some may fear that they'll have to replace the pack every 8 to 10 years, but the pack doesn't die - it just loses some capacity. So in 10 years our 100 mile per change car is a 70 or 80 mile per change car. If we only drive 35 miles per day on average there's absolutely no reason to replace the pack.
I love it when 'facts' get in the way of 'fear'. :lol:
Folks have been running lead-acid and NiMh for many years and their performance and lifespans are pretty comfortably known. And NiMh has proven to work very well for the long term. On paper, lithium-based cells should do significantly better and last longer than NiMh - and they're more energy efficient to boot - but the relative lack of real-world experience (testimonials?!) leaves many with a nagging doubt. Now we're getting the real-world numbers from some of the earlier lithium variants that show that the paper estimates might actually be correct! And lithium performance and capability has improved over the past 10 years much faster than books and web sites can keep up!
The point about battery replacement is spot on -- some may fear that they'll have to replace the pack every 8 to 10 years, but the pack doesn't die - it just loses some capacity. So in 10 years our 100 mile per change car is a 70 or 80 mile per change car. If we only drive 35 miles per day on average there's absolutely no reason to replace the pack.
I love it when 'facts' get in the way of 'fear'. :lol:
DarkStar
Well-known member
It's really because they don't go looking for it, or they discount the results based on the source.AndyH said:
Radio-control hobbyists have been experimenting with batteries for as long as batteries have existed. 5 or 6 years ago it was decided that LiPo batteries would be the way to go (based on all the reasons you've given) and everyone has been upgrading to them. Even the folks that used to only operate glow-fuel engines (frequently called "nitro" by R/C car owners) are now switching over as the performance is much better with LiPo batteries.
Don't take my word for it (enjoy many years worth or reading): http://www.rcgroups.com/batteries-and-chargers-129/
AndyH
Well-known member
I agree, Chris - but it's not limited to RC folks. Many in the electric bicycle community have more than 10 years' experience with lithium as well. Unfortunately, folks in the more traditional EV community resist learning from the RC and e-bike folks.
Hit up Endless-Sphere if you're feeling geeky some time - there's nothing like learning the finer points of pack balancing from chemists and particle physicists.
As for so-called "range anxiety" - don't tell that to Justin Le from ebikes.ca. He ran an ebike from Vancouver to the Atlantic Ocean in the summer of 2008 after building his own battery packs and designing his own regenerative motor controller and other kit. Grab some popcorn and follow along to learn the finer points of things like "energy management" and "opportunity charging": :lol:
http://www.endless-sphere.com/forums/viewtopic.php?f=29&t=7134
Yes - LiFePO4, LiPo, and NiCad at journey's start...
Andy
Hit up Endless-Sphere if you're feeling geeky some time - there's nothing like learning the finer points of pack balancing from chemists and particle physicists.
As for so-called "range anxiety" - don't tell that to Justin Le from ebikes.ca. He ran an ebike from Vancouver to the Atlantic Ocean in the summer of 2008 after building his own battery packs and designing his own regenerative motor controller and other kit. Grab some popcorn and follow along to learn the finer points of things like "energy management" and "opportunity charging": :lol:
http://www.endless-sphere.com/forums/viewtopic.php?f=29&t=7134
Yes - LiFePO4, LiPo, and NiCad at journey's start...
Andy
I just thought of a different angle to rebut the "range anxiety" non-issue: 100 miles is roughly 1/4 to 1/3 tank of gas for many vehicles. So if you're driving normally, do you start to freak out when you're down to your last 1/4 tank?
Probably not very often. You'll probably think "I should stop for gas on my way home tomorrow" or similar. If you're like me you might even wait for the "low gas" light to come on before saying that :lol: So now imagine if every morning you leave the house with 1/4 tank of gas, regardless of how much was in the tank when you parked the previous day. How often would you stop at the gas station?
Added bonus: For some people, it's also refilled every afternoon when you leave from work.
If you think EVs don't have adequate range for your needs, or you're not sure either way, just ask yourself the "quarter tank" question.
=Smidge=
Probably not very often. You'll probably think "I should stop for gas on my way home tomorrow" or similar. If you're like me you might even wait for the "low gas" light to come on before saying that :lol: So now imagine if every morning you leave the house with 1/4 tank of gas, regardless of how much was in the tank when you parked the previous day. How often would you stop at the gas station?
Added bonus: For some people, it's also refilled every afternoon when you leave from work.
If you think EVs don't have adequate range for your needs, or you're not sure either way, just ask yourself the "quarter tank" question.
=Smidge=
DaveinOlyWA
Well-known member
still say that Nissan is not providing a battery warranty that is approaching what they have discovered thru their own testing process. if the are saying 80% after 100,000 miles, i say they have tested and found the batteries to be lasting AT LEAST twice that long.
otherwise they would not be doing it. of course, like all warranties, i am sure it will be riddled with exceptions, use, etc. Telematics will track all usage so abuse will be easy to spot and Nissan will see it coming long before you pull into the dealers lot to complain.
so they are either pushing the tech early, knowing its not ready, but is close to developing tech that is. (so an in warranty upgrade in 12-18 months is already planned and budgeted for)
or we are simply wasting a lot of brain power on nothing.
either way, i am good.
quoted from Telematics Terms of Service
nformation Collected. We collect information about you and your Nissan LEAF™ several different ways: (i) from what you and your Nissan LEAF™ dealer provide to us when you accept this Agreement or buy or lease your Nissan LEAF™; (ii) from your use of the Telematics Services; (iii) from calls or emails between us; (iv) from our wireless carrier; and (v) from your Nissan LEAF™ itself. The information we may obtain from your Nissan LEAF™ includes, without limitation, (x) information about the Nissan LEAF™ and its operation, including without limitation, Vehicle Identification Number, GPS and navigation information, speed and distance information, driving habit and style, battery use management information, battery charging history, battery deterioration information, electrical system functions, software version information, and other spot data to assist in identifying and analyzing the performance of your Nissan LEAF™; information about your use of the Telematics Services and the corresponding website and smartphone application; and (z) data about accidents involving your Nissan LEAF™ (for example, the direction from which your Nissan LEAF™ was hit and which air bags have deployed). Because your Telematics Services are provided through wireless and satellite networks, we cannot promise or guarantee that your communications will not be intercepted by others. You agree Nissan will not be liable for any damages for any loss of privacy occurring in communication over such networks. If you do not notify us of a sale or transfer of your Nissan LEAF™, we may continue to send reports or other information about the Nissan LEAF™ or the account to the address currently on file with us. In such case, we are not responsible for any privacy related damages you may suffer.
otherwise they would not be doing it. of course, like all warranties, i am sure it will be riddled with exceptions, use, etc. Telematics will track all usage so abuse will be easy to spot and Nissan will see it coming long before you pull into the dealers lot to complain.
so they are either pushing the tech early, knowing its not ready, but is close to developing tech that is. (so an in warranty upgrade in 12-18 months is already planned and budgeted for)
or we are simply wasting a lot of brain power on nothing.
either way, i am good.
quoted from Telematics Terms of Service
nformation Collected. We collect information about you and your Nissan LEAF™ several different ways: (i) from what you and your Nissan LEAF™ dealer provide to us when you accept this Agreement or buy or lease your Nissan LEAF™; (ii) from your use of the Telematics Services; (iii) from calls or emails between us; (iv) from our wireless carrier; and (v) from your Nissan LEAF™ itself. The information we may obtain from your Nissan LEAF™ includes, without limitation, (x) information about the Nissan LEAF™ and its operation, including without limitation, Vehicle Identification Number, GPS and navigation information, speed and distance information, driving habit and style, battery use management information, battery charging history, battery deterioration information, electrical system functions, software version information, and other spot data to assist in identifying and analyzing the performance of your Nissan LEAF™;
information about your use of the Telematics Services and the corresponding website and smartphone application; and (z) data about accidents involving your Nissan LEAF™ (for example, the direction from which your Nissan LEAF™ was hit and which air bags have deployed). Because your Telematics Services are provided through wireless and satellite networks, we cannot promise or guarantee that your communications will not be intercepted by others. You agree Nissan will not be liable for any damages for any loss of privacy occurring in communication over such networks. If you do not notify us of a sale or transfer of your Nissan LEAF™, we may continue to send reports or other information about the Nissan LEAF™ or the account to the address currently on file with us. In such case, we are not responsible for any privacy related damages you may suffer.AndyH
Well-known member
Let's dig into the warranty fear for a minute. I absolutely think that no company is going to define a warranty they expect to lose money on - or even break-even on. So I think Nissan has a very good idea how the pack will perform. From the warranty side of things, I'm not at all concerned.
From the geek side, coming from someone that builds small lithium packs and management systems for customers, I can absolutely understand why one would want to get some annual pack status checks and real-time info from the packs in the field.
Here's a look at the LiFePO4 pack in my motorcycle. This bike was shipped with no management system - just a bunch of series cells, a motor controller, and motor. It's been my experimental test bed for different management systems, and not all of them worked as planned. (In other words, I knowingly damaged cells 'on purpose' while evaluating different management systems.)
Thunder Sky cells are pretty low in the 'performance food chain' so the voltage and internal resistance variation between cells isn't unexpected, but it's pretty easy to see that one cell is not performing like the rest of the pack. This cell (one of 21 60Ah cells in series) was the limiting factor for the pack. Its failure resulted in max speed loss of just over 10mph (60mph to 48mph) and took a big bite out of range. I was able to identify the failed cell because my pack is wired for data logging.
Pulling the cells for bench testing confirmed the cell failure (cell 12).
(A modern computerized management system can get this type of info while we drive - so Nissan can likely diagnose cell degradation without dropping the pack.) Full performance was regained after a cell swap. There are three other cells in the pack that are lower than average, but they haven't hit my personal 'warranty threshold' yet.
I don't know the details of the Leaf computer systems and/or management system, but I think it's safe to bet that they've improved on the systems fielded by GM, Hughes, and Ford in the 1990s. Here's a look at pack monitoring used in the 1998 GM S10 EV:
The vehicle "knows" a fair amount just by monitoring voltages inside the pack. For example, the S10's computer keeps track of the following malfunctions, sets a 'check engine light,' and stores trouble codes for each of these:
This info is derived solely from monitoring and comparing cell and total pack voltage. In addition, the S10EV monitors current into and out of the pack (driving, charging, and regeneration), and pack and module temperature. Any/all of these problems are stored in the computer system and communicated to the technician via the OBDII port just like any other vehicle.
One of the basic quality control steps a lithium cell manufacturer uses is to leave the cell on the shelf for a period of time - usually a full year. This allows the manufacturer to detect leaks and also to evaluate self discharge. It's very unlikely that AESC (Nissan/NEC) would put marginal cells in the field.
Cell and pack monitoring is a good thing. It's highly unlikely that an entire Leaf pack of 192 cells will fail or weaken at the same time. Identifying the failed cell and/or module of 4 cells restores range and performance - there's no need to swap an entire pack if/when a cell dies.
Let's pretend that my cell data is for part of a Leaf pack. We can see four total weak cells out of the 21 charted. Using the S10 data collection info above, we'd have a 'wrench' symbol on the dash and would likely get the following error codes:
- Cell Performance (voltage lower than average) for cells 5, 12, 20, 21
- Circuit Low (cell low under load) for cells 5, 12, 20, 21
- Circuit very low for cell 12
As a tech, assuming I have the other drive style, charge data, and environmental data, I can see that the entire pack has not been abused because most of the pack is in reasonable shape for its age. It's clear though that we likely have three weak cells and one that has failed (or that we have a wiring problem between the cells and the management system...) and that these are outside the owner's span of control. Warranty time!
From the geek side, coming from someone that builds small lithium packs and management systems for customers, I can absolutely understand why one would want to get some annual pack status checks and real-time info from the packs in the field.
Here's a look at the LiFePO4 pack in my motorcycle. This bike was shipped with no management system - just a bunch of series cells, a motor controller, and motor. It's been my experimental test bed for different management systems, and not all of them worked as planned. (In other words, I knowingly damaged cells 'on purpose' while evaluating different management systems.)
Thunder Sky cells are pretty low in the 'performance food chain' so the voltage and internal resistance variation between cells isn't unexpected, but it's pretty easy to see that one cell is not performing like the rest of the pack. This cell (one of 21 60Ah cells in series) was the limiting factor for the pack. Its failure resulted in max speed loss of just over 10mph (60mph to 48mph) and took a big bite out of range. I was able to identify the failed cell because my pack is wired for data logging.
Pulling the cells for bench testing confirmed the cell failure (cell 12).
(A modern computerized management system can get this type of info while we drive - so Nissan can likely diagnose cell degradation without dropping the pack.) Full performance was regained after a cell swap. There are three other cells in the pack that are lower than average, but they haven't hit my personal 'warranty threshold' yet.
I don't know the details of the Leaf computer systems and/or management system, but I think it's safe to bet that they've improved on the systems fielded by GM, Hughes, and Ford in the 1990s. Here's a look at pack monitoring used in the 1998 GM S10 EV:
The vehicle "knows" a fair amount just by monitoring voltages inside the pack. For example, the S10's computer keeps track of the following malfunctions, sets a 'check engine light,' and stores trouble codes for each of these:
This info is derived solely from monitoring and comparing cell and total pack voltage. In addition, the S10EV monitors current into and out of the pack (driving, charging, and regeneration), and pack and module temperature. Any/all of these problems are stored in the computer system and communicated to the technician via the OBDII port just like any other vehicle.
One of the basic quality control steps a lithium cell manufacturer uses is to leave the cell on the shelf for a period of time - usually a full year. This allows the manufacturer to detect leaks and also to evaluate self discharge. It's very unlikely that AESC (Nissan/NEC) would put marginal cells in the field.
Cell and pack monitoring is a good thing. It's highly unlikely that an entire Leaf pack of 192 cells will fail or weaken at the same time. Identifying the failed cell and/or module of 4 cells restores range and performance - there's no need to swap an entire pack if/when a cell dies.
Let's pretend that my cell data is for part of a Leaf pack. We can see four total weak cells out of the 21 charted. Using the S10 data collection info above, we'd have a 'wrench' symbol on the dash and would likely get the following error codes:
- Cell Performance (voltage lower than average) for cells 5, 12, 20, 21
- Circuit Low (cell low under load) for cells 5, 12, 20, 21
- Circuit very low for cell 12
As a tech, assuming I have the other drive style, charge data, and environmental data, I can see that the entire pack has not been abused because most of the pack is in reasonable shape for its age. It's clear though that we likely have three weak cells and one that has failed (or that we have a wiring problem between the cells and the management system...) and that these are outside the owner's span of control. Warranty time!
Mmmm graph porn. Outstanding analysis - I learned a few things!AndyH said:
How long do you think it'll take before the average Leaf owner can get that data any time they want? If the Leaf uses OBD-II for it then we're already half way there. I want a website where people can upload their EV's data for comparison and bragging rights
=Smidge=
TomT
Well-known member
I'm not even sure that the Leaf HAS an OBDII port. Since it is not a ICE vehicle, it may not be required to have one...
One other thought: Honda has had some major battery loss of capacity problems with their hybrids that are not all they old... Enough in fact, the the CARB is getting involved.
One other thought: Honda has had some major battery loss of capacity problems with their hybrids that are not all they old... Enough in fact, the the CARB is getting involved.
AndyH said:How long do you think it'll take before the average Leaf owner can get that data any time they want? If the Leaf uses OBD-II for it then we're already half way there. I want a website where people can upload their EV's data for comparison and bragging rights
=Smidge=
DarkStar
Well-known member
http://en.wikipedia.org/wiki/On-board_diagnosticsSmidge204 said:Mmmm graph porn. Outstanding analysis - I learned a few things!AndyH said:
How long do you think it'll take before the average Leaf owner can get that data any time they want? If the Leaf uses OBD-II for it then we're already half way there. I want a website where people can upload their EV's data for comparison and bragging rights
=Smidge=
Emphasis mine.
