Lithium Battery Reports & Tests' 9/08

[miro13car]

John
Are you sure Sony Konions are LiMnCo?
I think they are just Lithium Manganise, no Co content.
Can anybody save me search and respond?
Andy,
I agree we should be careful in showing bicycle fires unless they really show emotor on bike, but small ebike pack cannot rather ignite any parts on bike, so ebike fire is for sure caused by chemistry of batt.
Ecar fire is another thing with kilowatts of energy such pack can easly ignite car interor just by short caused by fat metal object.
So really many of such fires if not all of them are results of shorts or simply charger fires.
Based on what I read on RC many forums REGULAR LPolymer is really dangerous and nobody at his right mind would try to use it on ecar WITHOUT double or triple redudancy/safety futures built into pack, Tesla is example of it.
Andy,
safety futures which Tesla uses are unrealistic on bicycle if only for cost and simply lack of room - just imagine this computerized system on average bike.
I would scared to death to have 10Ah reg. LPolymer on my bike.
LiMnCo is really rare and cost a lot and NOT available for hobbysts if used by Kokam as lifeforphysics wrote.
So it is rather exotic chemistry I WOULD SAY.
MC

 

[BMI]

RC hobby is the biggest user of Lithium Polymer cells for sure which comes to my mind.
Few ebikes use LPolymer cells, correct me it I am wrong and post a link for me to see LPolymer powered bike factory-made...

Why limit yourself to ebike packs? Guess what chemistry they're using in the Tesla Roadster? 6831 18650 LiCo cells. The linked paper outlines the steps they took to keep the pack safe.

I was only reading somewhere a couple of days ago that Tesla is looking to use LiFePO4 cells from PHET in new car models. Still tiny 18650 cells but LiFePO4 instead of LiCo so they must have some long term concerns with the chemistry?

 

[liveforphysics]

LiMn2O4 (aka, LiMn) has a higher no damage peak resting voltage (4.3-4.35v), and a nominal of 3.8-3.85v.

LiMnCo has a no damage peak resting voltage of 4.1-4.15v, and a nominal of 3.7-3.65v.

The voltage discharge curve profiles from the green Kinion cells would indicate nominal points in the range of 3.65v.


Roughrider- From testing I've seen, the 500cycle point shows a 1.1% increase in cell capacity. 500 cycles is more like break-in completed rather than end of life.

From testing of Kokam cells sharing chemistry with the green Kinions.

1400 1C cycles of 100% DOD drops LiMnCo to the 80% useful capacity point.

5500 1c cycles of 80% DOD to drop LiMnCo to the 80% useful capacity point.





BUT, it should be said that I've never taken a Kinion cell apart and performed qualitative chemical analysis to figure out exactly what type of chemistry is being used. From observing the behavior of the cell, my money is on LiMnCo.

They are extremely safe, and pretty impressive little cells when you consider it's easy to get them for <$0.30/Whr. They definitely take more time to build a pack from though!

 

[miro13car]

liveforphysics,
so what company manufacture LiMnCo, what brand, because I would say they are pretty rare chemistry?
MC

 

[bobmcree]

we are losing part of the big picture. the original green lifebatt cells were a huge leap forward in what we can buy for our own bikes. the first lifebatt cells we purchased had to be removed from packs that had no bms, because there was no working system as yet. many of us today are using a123 cells scavenged from dewalt packs purchased on ebay, because they have ignored our market segment. if we take a look at the impedance of 4 or 5 of the a123 cells compared with a single bmi cell of the same capacity, we find they are roughly comparable when we account for the increased resistance of the intercell connections in the a123 case. I paid an average of $10 for my a123 cells so for $40-$50 i get a bunch of cells with no warranty at all and a wiring nightmare. For similar cost i can get a bmi cell with similar capacity and impedance, AND a warranty of at least that the cell will work before i start abusing it. We get nothing like that from DeWalt or A123.

producing the high current test data is being delayed by the demise of a large chinese elm tree in my yard. I wil be out with the chain saw for the rest of the day and will try to get some 50 amp discharge data this evening. the guy offering the ping cells has not come through yet, but i expect the headway cell i purchased from the bulk buy to be here soon, and i will provide the comparative data on several of the lifebatt green cells and the one grey bmi cell i do have.

 

[miro13car]

Green cell was great progress because it offers 10Ah in one cylinder, there is no way around it , you have to use 4 * A123
to sabstitue for one green cell. If you think about all that interconnections, with just 4mOhms of cell impedance for max performance every inch of even thickest wire counts. After moving my HPS LBatt from rear rack to under frame I shorted AWG 10 wires by less than 1meter which had dramatic effect on peformance motor/controller.
Current from standing start max increased from 47A to 53A.
Acceleration time to 20m/h shortened from 12sec to 9 sec.
Simple one 10Ah cell simplifies pack construction a lot.
MC

 

[Lapwing]

Green cell was great progress because it offers 10Ah in one cylinder, there is no way around it , you have to use 4 * A123
to sabstitue for one green cell. If you think about all that interconnections, with just 4mOhms of cell impedance for max performance every inch of even thickest wire counts. After moving my HPS LBatt from rear rack to under frame I shorted AWG 10 wires by less than 1meter which had dramatic effect on peformance motor/controller.
Current from standing start max increased from 47A to 53A.
Acceleration time to 20m/h shortened from 12sec to 9 sec.
Simple one 10Ah cell simplifies pack construction a lot.
MC

Absolutely correct. Short wiring runs, with minimal terminations - that's the way to go. Team Agni proved this also with their race bike build. Motors and controler right adjacent to each other, with the batteries but inches away. Large single 70Ah cells with the minimum number and large surface area clamp teminations.

Pointless spending mucho denero on low resistance batteries and then throwing in a bunch of cable.

 

[AndyH]

Bob and Armin -- I'm disappointed that you continue to ignore the 'entire picture' with respect to these cells by referring to green cells only as old LiFeBatt cells.

Yes - there are old LiFeBatt cells. And there are old BMI cells. There are also old PSI cells. There are also NEW PSI cells and they are green. While a green cell with 'LiFeBatt' ink-jet printed on it is old, green cells are and will continue to be current production from PSI.

While it's apparent that LiFeBatt and BMI produce good quality cells, it's also apparent that PSI continues to produce good quality and consistent cells. And they provide the supporting documentation for that performance. They're also fully transparent with regard to manufacturing location, quality and environmental certifications, pricing, warranty, and support.

Case in point - here are factory numbers for PSI's standard cells - that contain ZERO material from Phostech.

View attachment PSI_1208_Analysis.jpg

Please note that PSI's standard cell has 1kHz impedance in the same ball-park as Bob's BMI testing. Please also note that the CAPACITY of these standard cells relative to Bob's testing.

Per PSI - these cells can be put to work immediately - they do not require partial discharges or conditioning to achieve long life. Yes - the cell will show changes in performance over the initial cycles - but it does not need to be babied for it's early life.

(caution - sales data follows)

E-S members can acquire these cells with service and support from the U.S. The most they'll pay is $35 per cell in single-cell quantities. Warranty for single cells is 2 years unlimited cycles. Warranty for assembled packs (assembled by us or the customer) when used with the Goodrum/Fechter BMS or other approved BMS solution and an approved charger is three years unlimited cycles. And yes - the warranty has been exercised!

(end sales data)

As I've already said, Armin - I hope you sell a LOT of cells. I hope you sell so many BMI cells that you can retire to the South of France if you choose! Same for Bob - I hope your business/no business :wink: works just as you envision and brings you everything you want from it. But let's keep it real?

 

[TylerDurden]

As per Don Harmon, PSI and BMI and LifeButt are identical. Armin may be sourcing from PSI anyway:

You buy cells through PSI now under BMI's permission and the cells that we were diccussing in this post are identical to the ones that you sell.

You can play games with everyone here if you like but ultimately they will see that the LiFeBATT cells in Miro Car's pack are identical to your "so called superior" Gray cells.

In fact Miro's are Gray too- just with a LifeBATT lable on them instead of a BMI lable. Don't let him fool you Miro - you got the same thing in the pack you bought from LiFeBATT.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=9864&p=168426&#p168426

Notice in his rant that Harmon made no mention of Phostech being a distinguishing LifeBatt feature. If MiroCar's cells are identical to PSI and PSI have no Phostech...

 

[Lapwing]

John
Are you sure Sony Konions are LiMnCo?
I think they are just Lithium Manganise, no Co content.
Can anybody save me search and respond?
..................... LiMnCo is really rare and cost a lot and NOT available for hobbysts if used by Kokam as lifeforphysics wrote.
So it is rather exotic chemistry I WOULD SAY.
MC

MSDS here for http://www.swe.com/MSDS/KOKAM/KOKAM_MSDS.pdf

a touch of nickel also

 

[RoughRider]

@Lapwing

thats the MSDS for KOKAM not for the KONIONs from SONY...

the post was about SONY, not kokam....


@BMI and Co
its getting absurd here...

 

[BMI]

Bob and Armin -- I'm disappointed that you continue to ignore the 'entire picture' with respect to these cells by referring to green cells only as old LiFeBatt cells.

Yes - there are old LiFeBatt cells. And there are old BMI cells. There are also old PSI cells. There are also NEW PSI cells and they are green. While a green cell with 'LiFeBatt' ink-jet printed on it is old, green cells are and will continue to be current production from PSI.

While it's apparent that LiFeBatt and BMI produce good quality cells, it's also apparent that PSI continues to produce good quality and consistent cells. And they provide the supporting documentation for that performance. They're also fully transparent with regard to manufacturing location, quality and environmental certifications, pricing, warranty, and support.

Case in point - here are factory numbers for PSI's standard cells - that contain ZERO material from Phostech.

Please note that PSI's standard cell has 1kHz impedance in the same ball-park as Bob's BMI testing. Please also note that the CAPACITY of these standard cells relative to Bob's testing.

Per PSI - these cells can be put to work immediately - they do not require partial discharges or conditioning to achieve long life. Yes - the cell will show changes in performance over the initial cycles - but it does not need to be babied for it's early life.

(caution - sales data follows)

E-S members can acquire these cells with service and support from the U.S. The most they'll pay is $35 per cell in single-cell quantities. Warranty for single cells is 2 years unlimited cycles. Warranty for assembled packs (assembled by us or the customer) when used with the Goodrum/Fechter BMS or other approved BMS solution and an approved charger is three years unlimited cycles. And yes - the warranty has been exercised!

(end sales data)

As I've already said, Armin - I hope you sell a LOT of cells. I hope you sell so many BMI cells that you can retire to the South of France if you choose! Same for Bob - I hope your business/no business :wink: works just as you envision and brings you everything you want from it. But let's keep it real?

.....But I am keeping it real Andy. I am trying to bring reality and the truth to the situation when for so long it has not been real.
Too many people have thought for too long that the green cells and the grey cells are the same and are made from the same materials in the same factory. Well I am just trying to clear the air here and show that green cells and grey cells are NOT the same cell and have different performance characteristics since they use a different mixture in each of these cells.

I understand your situation Andy having been made aware that you have perhaps several thousand of the older green cells left in stock so you don't want it to look like the cells which you are offering are now obsolete. There is no need to be defensive because the green cells are still fantastic and provide superior performance compared to all the guys who are using Ping and Headway packs.
If the grey cells and green cells are the same then why don't they all come in the same color wrapper? The answer is simple. It is to differentiate between the cells because they ARE different. And if an even later version cell is released in a red/white/black/pink or polka dot wrapper that too could be expected to be different to the current grey cells.

Yes, all the current PSI cells may be "new" and will continue to be the current production cell because PSI is not able to make a new/better cell than the green cell they are making now.
How can they make a better improved cell since all their top cell design engineers,PhD's and scientists left PSI and are now employed at BMI and are busy working on the next generation cells? This includes almost (f not all) of the original cell design team who invented the original green PSI cell (which you supply) when they were employed by PSI.
You may be aware that PSI never used to supply their cells to end users directly and then for a while Raymond King started supplying cells directly from PSI (after the key engineering staff left to work at BMI). Then this abruptly stopped and people lost all contact with Raymond King as well. The reason is Raymond King left PSI to work for BMI also (in the role of technical/sales manager).

Bottom line is that BMI grey cells are a higher discharge rate cell when compared to first generation (current production) PSI green cells. We will leave it Bob Mcree to prove or disprove this so people can decide for themselves if both cells are the same or not (Bob's curves don't lie).

.....I can tell you Andy that there is no way I will be retiring to the south of France from selling loose cells. There is such a small margin in the price of the cells from manufacturing cost to be able to make a good income from it. In fact there is no price break from the factory until I order at least 1000 cells so I certainly can't afford to retire any time soon.
Maybe I can go and work for PSI. I hear they have plenty of vacancies! :wink:

 

[AndyH]

.....But I am keeping it real Andy. I am trying to bring reality and the truth to the situation when for so long it has not been real.

Truly from the heart - 'trying' is not 'doing'. That's important.

Too many people have thought for too long that the green cells and the grey cells are the same and are made from the same materials in the same factory.

Who thinks that? PSI's standard cells don't use Phostech material. That's a confirmed ratio of zero percent. You and Don both say your cells use Phostech material. If true, that makes at least some of the materials different. Myth busted. Moving on...

What people really want to know is NOT that Phostech is patented, or even how much is in the cell. What they want to know is what it's going to do for them. You've heard of using Features and Benefits to sell? Most people spout features - PHOSTECH! Super Grey Shrink Wrap! But the consumer spends all their time listening to WIIFM - what's in it for me? They want the benefit. How much farther will your pack take them over a 1C or 2C duct tape pack? How much better performance or lifespan? How about blue cells? How about green?! Why should they pay the extra for your product? That's your job to communicate!

Well I am just trying to clear the air here and show that green cells and grey cells are NOT the same cell and have different performance characteristics since they use a different mixture in each of these cells.

You're certainly saying they're different, Armin, I'll give you that. When will your new factory have it's QA division running so you can talk to us about testing and performance? How, exactly, are you showing the difference?

I understand your situation Andy having been made aware that you have perhaps several thousand of the older green cells left in stock so you don't want it to look like the cells which you are offering are now obsolete. There is no need to be defensive because the green cells are still fantastic and provide superior performance compared to all the guys who are using Ping and Headway packs.

Sorry, Mate. You might want to get another source of information. :lol: You don't have to make stuff up - just ask - I'll tell you! What do you want to know? (Feel free to pause at 'LEAN manufacturing' on the way to looking up 'transparency'.) Inventory on the shelf is like having employees in jail. And since cells lose capacity sitting on the shelf...

If the grey cells and green cells are the same then why don't they all come in the same color wrapper? The answer is simple. It is to differentiate between the cells because they ARE different. And if an even later version cell is released in a red/white/black/pink or polka dot wrapper that too could be expected to be different to the current grey cells.

That's one answer, I guess. Another is that different colors are used because companies want to create their own identity. Take oil filters, for example. Do you think that Mobil 1 or K&N would go out of their way to advertize that their filters are made in the same factory? Do you think that either would put in their TV spots "made by the company that brings you the $1.25 filters like the mighty and service champ used by the quick lubes"? Champion Labs makes all four. Paint color - like shrink wrap - is cheap. Along with changing the shrink color, you might want to use a different barcode and serial number structure. That would allow you distance yourselves a bit farther from PSI and strengthen your plausible deniability. Real test results would be better. Take another play from Don's book - they have different colored shrink, they have a rodent, they have a market focus/area of specialization, and they have a range of test results from a U.S. lab working on a Department of Energy contract.

Yes, all the current PSI cells may be "new" and will continue to be the current production cell because PSI is not able to make a new/better cell than the green cell they are making now.

Man, I'm sorry to hear that. I wonder who they contracted with to make the new cells they've been testing since last fall?

How can they make a better improved cell since all their top cell design engineers,PhD's and scientists left PSI and are now employed at BMI and are busy working on the next generation cells? This includes almost (f not all) of the original cell design team who invented the original green PSI cell (which you supply) when they were employed by PSI.
You may be aware that PSI never used to supply their cells to end users directly and then for a while Raymond King started supplying cells directly from PSI (after the key engineering staff left to work at BMI). Then this abruptly stopped and people lost all contact with Raymond King as well. The reason is Raymond King left PSI to work for BMI also (in the role of technical/sales manager).

This is interesting. I was told that Raymond worked for LiFeBatt.

Bottom line is that BMI grey cells are a higher discharge rate cell when compared to first generation (current production) PSI green cells. We will leave it Bob Mcree to prove or disprove this so people can decide for themselves if both cells are the same or not (Bob's curves don't lie).

Again - you SAY they have a higher rate. How much higher? I'm still at a loss as to why a company with such an experienced staff doesn't have test results of their own to use for marketing and support.

.....I can tell you Andy that there is no way I will be retiring to the south of France from selling loose cells. There is such a small margin in the price of the cells from manufacturing cost to be able to make a good income from it. In fact there is no price break from the factory until I order at least 1000 cells so I certainly can't afford to retire any time soon.

You forget that the price of the cells is known to the membership. :wink:

I didn't say from selling loose cells, did I? This is the place to use your creativity! I would think that, if your product is as good as you say, and your staff is as capable, you'd be in the running for EV and PHEV contracts. Leverage your experience in boats - most need starting and house batteries. Thunder Sky has batteries for submarines - does Australia and/or New Zealand have a tourist sub market? How about lithium in scuba tows? Twice the endurance allows higher rental rates, fewer pack replacements... Don't listen to me, though - I'm retired. How could I possibly help you get here? :wink:

 

[BMI]

I am not here to argue with Andy or anyone else but to just provide as much information as I am permitted to do so and help to answer some questions. Of course there will always be the "knockers" out there, and there is nothing I can do about that. In the end it comes down to if people want to listen to what I have to say then fine, and if they don't then equally fine.
Contrary to your popular belief Andy, I don't need rodents or any other means of sales hype to sell BMI cells and battery products. I am an electrical engineer, technician and licenced electrical contrator so I don't live in the world of sales spin as many others do.
The products sell themselves when people try them the first time and see how much better they perform compared to most of the similar products on the market.
Many of BMI sales are generated through existing customers telling others and showing their friends and colleagues how well the BMI products work so essentially they are doing all the "selling" for me. I would much rather lend my technical expertise to working on actual electric vehicle projects and helping customers achieve their electric vehicle goals rather than being merely a "battery salesman".

 

[GGoodrum]

I was going to try and stay out of this, as I respect both of you, but this back and forth bantering needs to stop. I think there is more than enough room in the marketplace for both of these cells. If the newer versions of the cells coming off of BMI's production line show a big improvement, great. Armin can sell them at a premium, and then maybe at least take a trip to the south of France.

I do, however, think it is not accurate to say categorically say that BMI has cornered the market on all the battery engineers in Taiwan, and as such only BMI will be able to make continuous improvements. I've been to Taiwan on business about 75-80 times, over the years, and I am here to tell you there is no shortage on talent, in pretty much any field. So to imply that the green PSI cells are "old", and will stay that way is just not accurate.

One other point I'd like to make is that even the original "green" cells are more than strong enough to be used in single string/10Ah configurations many want to use for higher performing ebike setups (i.e. -- 80-100A peaks..). With even the latest version of the Ping packs, you'd need a 30Ah configuration to handle that much current. You'd also need a 2p configuration for Headway cells to supply 80-100A peaks. I know from personnal experience that my original 24-cell setup of "1st generation" green PSI cells can handle these kinds of loads with no problem, as these two 12-cell packs are still in use on my wife's Townie, which has a 5304 and a Bob-Mcree-modded Clyte V2 controller. I'm ot sure exactly how many cycles they've been through, but it is well into the hundreds, and they seem just as strong.

I don't care if no improvements are made to these cells, they work fine in a single-string, high performance ebike setup. Making, let's say, a 20-25% improvement in the C rating isn't going to make a hell of a lot of difference, in my opinion. If anything, I'd like to keep the performance where it is, and see the capacity go up 20-25%, especially if Andy's reasonable prices can remain the same.

Where a higher C-rated 10Ah cell will do better is for higher performance motorcycle conversions. In that case, being able to hit 250-300A peaks, in a 2P/20Ah configuration would be desirable, I think.

In any case, I think there are lots of "niches" for many different cell perofrmance levels. For the low-to-midlevel commuter setups, the Pings are still very good value. The Headways work for many midlevel performers, and in 2-3p configurations, they offer "affordable" options for motorcycles and scooters, but with decent performance. The PSIs are great for higher performance ebike setups, and building packs out of these is a snap, especially with the "Lego" blocks. Finally, assuming the newer BMI cells really do have a significant boost in performance, they will be great in high performance motorcycle conversions and for the more extreme ebike setups, those that blur the lines with motorcycles.

Anyway, that's my $.02.

-- Gary

 

[bobmcree]

thanks gary for your insight. certainly the very first green lifebatt cells continue to perform well on a 20A Ezee powered Cruzbike. You and i like to ride bikes that use 50A and more, and at these currents these original cells have a lot of voltage sag. The newer lifebatt and bmi cells are much better. I have just not felt well enough to set up the next high current tests; kicking the narcotics after about 6 years is not fun but i am very happy to be doing it. I will try to get the 50 and 100A testing of the green lifebatt cells and newer grey bmi cells done this weekend.

We have both had our own experiences with lifebatt and i can only say that i wish anyone trying to work with don the best. i could not do it. I have given up for now on finding some capital to import a batch of bmi cells, but that may change. At least armin will sell us the cells, where don will only sell a complete system that we could harvest cells from with no warranty, the same way i obtained the original lifebatt cells.

 

[liveforphysics]

Bob-

Have you ever thought about making packs from Kokam pouch cells? They use the least exciting most safe lithium chemistry. They can even self balance like NiCd. They don't offer quite the specific Ri of these grey BMI cells, but they also enable very simple pack construction methods, and offer cell capacity suitable to not need the extra connections of running multiple cells in P.

The 20Ah, 40Ah, and 70Ah cells all seem like great choices for powering E-bikes. I've been quoted $114 shipped per 70Ah cell in single cell quanities. I assume it would drop if you ordered a large lot of them. You could offer the worlds lightest and most compact saftey chemistry e-bike batteries at a cost of $0.44/w-hr. I think it would be a pretty hot selling item. I would buy a pack from you if you made one!

 

[bobmcree]

randy draper, famous for losing a race up a hawaiian volcano to a bunch of handicapped folks but still being the fastest e-bike, has been touting the kokam cells as an option for ebikes for years. if you really want me to build you a pack just buy the cells and contact me privately to build it. I have not looked at them lately but i am dubious of the safety of any pouch cells.

i had the best evening i have had in years, raking and mowing until dark with my back pain easily controlled with ibuprofen the same as any other old guy, I just cannot tell any of you how good it feels not to be dependent on narcotics for pain control. i strongly advise anyone with chronic back pain to look into rf ablation where they cook the nerves with microwaves and after a few weeks it just STOPS hurting.

 

[BMI]

I was going to try and stay out of this, as I respect both of you, but this back and forth bantering needs to stop. I think there is more than enough room in the marketplace for both of these cells. If the newer versions of the cells coming off of BMI's production line show a big improvement, great. Armin can sell them at a premium, and then maybe at least take a trip to the south of France.

I do, however, think it is not accurate to say categorically say that BMI has cornered the market on all the battery engineers in Taiwan, and as such only BMI will be able to make continuous improvements. I've been to Taiwan on business about 75-80 times, over the years, and I am here to tell you there is no shortage on talent, in pretty much any field. So to imply that the green PSI cells are "old", and will stay that way is just not accurate.

One other point I'd like to make is that even the original "green" cells are more than strong enough to be used in single string/10Ah configurations many want to use for higher performing ebike setups (i.e. -- 80-100A peaks..). With even the latest version of the Ping packs, you'd need a 30Ah configuration to handle that much current. You'd also need a 2p configuration for Headway cells to supply 80-100A peaks. I know from personnal experience that my original 24-cell setup of "1st generation" green PSI cells can handle these kinds of loads with no problem, as these two 12-cell packs are still in use on my wife's Townie, which has a 5304 and a Bob-Mcree-modded Clyte V2 controller. I'm ot sure exactly how many cycles they've been through, but it is well into the hundreds, and they seem just as strong.

I don't care if no improvements are made to these cells, they work fine in a single-string, high performance ebike setup. Making, let's say, a 20-25% improvement in the C rating isn't going to make a hell of a lot of difference, in my opinion. If anything, I'd like to keep the performance where it is, and see the capacity go up 20-25%, especially if Andy's reasonable prices can remain the same.

Where a higher C-rated 10Ah cell will do better is for higher performance motorcycle conversions. In that case, being able to hit 250-300A peaks, in a 2P/20Ah configuration would be desirable, I think.

In any case, I think there are lots of "niches" for many different cell perofrmance levels. For the low-to-midlevel commuter setups, the Pings are still very good value. The Headways work for many midlevel performers, and in 2-3p configurations, they offer "affordable" options for motorcycles and scooters, but with decent performance. The PSIs are great for higher performance ebike setups, and building packs out of these is a snap, especially with the "Lego" blocks. Finally, assuming the newer BMI cells really do have a significant boost in performance, they will be great in high performance motorcycle conversions and for the more extreme ebike setups, those that blur the lines with motorcycles.

Anyway, that's my $.02.

-- Gary

I agree with everything you have to say Gary. Both the green PSI cells and grey BMI cells provide higher discharge power compared to the lower C rated Ping and Headway cells so are deinitely the best choice for high performance e-bikes.
I will stick my head out and say it is my belief also that Ping and Headway cells will start failing much quicker due to their cheaper method of construction. Perhaps we are starting to see early signs of this already? It may take another 12 to 24 months before we really start to see more failures in these cheaper cells. So in the end if I am correct it may in fact work out to be cheaper to pay the higher price initially for a better quality pack which lasts longer and all the while be able to take advantage of the higher discharge power these cells offer.

I also agree there is plenty of talent and experienced cell desiners in Taiwan. PHET is another Taiwanese company which makes very good cells. I do believe that the majority of the "talent" in the LiFePO4 battery world is in Taiwan rather than China so the Taiwanese made batteries will continue to be overall better quality than batteries made in China.

 

[BMI]

Where a higher C-rated 10Ah cell will do better is for higher performance motorcycle conversions. In that case, being able to hit 250-300A peaks, in a 2P/20Ah configuration would be desirable, I think.

-- Gary

The BMI cells are connected in a 2P configuration in the BMI car start batteries. As you can see in this actual discharge curve during starting the two cells in parallel provide a peak discharge current of around 450 amps. This peak current occurs the instant the ignition key is turned and the starter motor is basically just a short circuit before it starts to rotate at which time back EMF is produced and as a result the current drops back rapidly.
I use this battery to start my 6 cylinder (3300cc engine) Toyota Camry work car and even though the battery is much smaller than the original lead acid battery and weighs less than 10 pounds it cranks the engine over far more powerfully than any lead acid battery I have ever previously owned.

View attachment BMI SB1220 Engine Start battery discharge.doc

 

[TylerDurden]

Both the green PSI cells and grey BMI cells provide higher discharge power compared to the lower C rated Ping and Headway cells so are deinitely the best choice for high performance e-bikes.

"I do like the Kokam cells for racing because of their excellent energy density at high discharge rates and their very low internal resistance.

For applications where the highest energy density is not crucial I would still tend to prefer ThunderSky because (1) they are cheaper (2) they are much easier to install and (3) in the case of cells made after about 2005 they have longer life, which is very important to the economics of running an electric vehicle."

-Cedric Lynch

 

[AndyH]

... As you can see in this actual discharge curve during starting the two cells in parallel provide a peak discharge current of around 450 amps...

What size fuse do you use inside the pack? The All New Energy VMS docs say to use a 100A fast blow between cells two and three in each 4S string. Miro reported that his LB pack had a 160A fuse installed though, so maybe the 100A is just a suggestion.

Thanks!

 

[miro13car]

defintely my HPS pack from LB had 160A fuse for each 4 cells = 3 in total.
MC

 

[BMI]

... As you can see in this actual discharge curve during starting the two cells in parallel provide a peak discharge current of around 450 amps...

What size fuse do you use inside the pack? The All New Energy VMS docs say to use a 100A fast blow between cells two and three in each 4S string. Miro reported that his LB pack had a 160A fuse installed though, so maybe the 100A is just a suggestion.

Thanks!

The HPS packs usually have a 150amp slow blow fuseable link. This is what it looks like (sorry for the blurry image but its shiny and there was a bad reflection from the camera flash). It is embossed 150A.

 

[AndyH]

Thanks!