Lithium Battery Reports & Tests' 9/08

[miro13car]

WE means who?
MC

 

[Battboy]

The Kingston College entry in the Open Class is sponsored by LiFeBATT in case you didn't see that in the picture?

 

[bobmcree]

Yay - We Qualified. Not bad for a College built bike on a small budget! http://www.wired.com/autopia/2009/06/electric-bikes/

No, there are no "Green Cells" in this bike. We haven't made those Cells in over a year. There is a whole new generation of XPS Cells now being offered in our new XPS Series Packs.

that's great. i would be happy to provide the same unbiased testing on one of your new cells, and everyone here knows i will report the results honestly. I never said that the green cells were not a good product. the grey bmi cells are just better. I would be quite interested to see how your newer cells compare with the newer bmi cells in impedance, voltage output under load, and price.

i must apologize to everyone for starting to take the thread in a direction i said i would not go again. thanks don for not taking the bait, and let's just try to go forward.

 

[Battboy]

Bob, We have learned from some past mistakes not to engage in any further battery spec. competitions. When we are satisfied with our real world testing (like this particular TT Challenge) We will publish our Cell Specs on the LiFeBATT website only after internal company testing and new Sandia lab tests that are in progress now. Since LiFeBATT has no interest in selling individual cells and our new generation VMS boards (unlike some of our competitors) we don't need to prove anything to "cell speculators". Our new XPS Series Packs including our second generation of cells and proprietary electronic management system will be available in a modular, scaleable, family of standard products very soon. LiFeBATT no longer publishes it's pricing or other specs. since our dedicated market are OEM manufacturers. I don't forsee this ever changing in the future.

Good luck to you -and I am really glad to see you got some great results with your back surgery. Nice to discuss things rationally without resorting to labels like "liar" for a change, Bob. Also I hope your efforts to promote Health Care for all Americans is a winner. I saw Obama this morning giving a speech in Green Bay on his plan.

Regards,

Don Harmon

 

[AndyH]

... the link you provided does not show a graph i could find of a lifebatt cell at 25A and i did not see any temperature data on a cell discharged at 25A for its full capacity. ...

Bob, with all due respect, I can assure you that 'argue' isn't a factor in my suggestion. My usual view of claims and specs is 'trust but verify', for what it's worth.

I believe the information I posted and the results reported by the Doc are relevant because we know that these early cells were made by PSI. I expect they shared common construction methods, crews, and procedures. Formula may have differed. Performance appears different.

I purchased two lots of cells from Yesa in May and June 2008. They were in the 4BF1K8xx-xxxx serial number range. One of the cells I kept for longer term testing is 4BF1K825-0096. This is the cell that was used to run the break-in charts and other tests I referenced earlier. I also have rI data for a brand new cell - 4BF1K812-0188. I used a non-contact IR thermometer to log temperatures of 0096 during the higher load tests. The highest temperature I saw was 58C - and that was approximately 20 minutes after the conclusion of a 12C/120A constant load discharge.

I used a LaMantia BA402 to run a scripted discharge cycle on the cell. The machine tested DC resistance at numerous points during the discharge. When the test was performed, the device was a couple of months old and within NIST-traceable calibration. 500mA and 2000mA loads were used to generate the resistance number. The temperature data for 0188 was collected with the device's thermocouple attached to the top center of the cell.

The chart below (in the PDF) was the first cycle for 0188. Cell 0096 had more than 35 cycles to 2.1V - it was used for the charts I referenced earlier, including the cell break-in numbers. My intent was to 'survey' the change in resistance thru the state of charge for a fresh and broken-in cell. I found that, for these cells, Ri dropped and capacity increased once the cell had 12-14 cycles on it.

I realize the Ri numbers shown are not directly comparable to your 1KHz numbers, and I also realize that I didn't discharge the cell to 50% capacity, let the cell rest for four hours, then run a single test.

View attachment 4BF1K812-0188.pdf


The info suggests some significant performance differences in the cells that might be worth exploring more deeply.

I think your theory about internal connecting tabs is interesting. I can confirm that cell 4BF1K825-0096 has nine aluminum tabs connecting the jellyroll to the positive terminal inside the cell. I didn't cut 0188 open so cannot confirm its construction. I also haven't cut a current-production PSI cell so cannot directly compare these.

View attachment 0096_tabs.jpg

If this is of use to you - great. If not, you'll not hurt my feelings.

Andy

PS - sorry the 'body shop' comment threw you. I realize not everyone refers to 'surgery' as a 'service visit', and maybe not everyone refers to their Chiropractor as 'Captain Crunch'... :wink:

 

[dnmun]

andy, you have also cut open an old brown sleeve headway cell too as i recall. that had the electrodes welded through the tabs to the underside of a plate with over 30 connections it seemed and i wondered how this, a strap to the center post, compared to that type, in your opinion.

 

[AndyH]

andy, you have also cut open an old brown sleeve headway cell too as i recall. that had the electrodes welded through the tabs to the underside of a plate with over 30 connections it seemed and i wondered how this, a strap to the center post, compared to that type, in your opinion.

It was one of the new blue cells, actually. How do the connections compare? I don't think I know enough to give a meaningful answer. Sorry.

The Headway had the straps from the 'jellyroll' grouped together, the multiple straps and all the spot welds to an aluminum plate, but just four spot welds to the outside of the cell.

View attachment headway_inner.jpg
View attachment headway_spots.jpg
View attachment headway_dome.jpg

It's certainly secure - the spotwelds aren't likely to loosen over time. I don't know how to judge the surface area or equivalent wire size of the spotwelds.

The PSI cell has fewer straps from the jellyroll but they're thicker. The small bolt that 'collects' the straps has a 10mm diameter pad - pretty good surface area. The 3mm diameter collector bolt screws into the terminal about 6mm, and there's an additional contact patch between the 'collector nut' and the inner face of the terminal.

View attachment collector_bolt.jpg

It looks like the PSI cell might have a more direct path to the 'outside world' and fewer junctions/connections enroute. The connecting straps are welded to the jellroll, squeezed into the bolt,then transferred to the terminal.

The Headway construction has the straps from the jellyroll welded to a collector cup, then straps are spot welded to another aluminum plate, then there are the four spot welds to the aluminum outer dome, and this is spotwelded to the steel 'terminal cap'.

 

[dnmun]

thanks, just what i wanted to see, i agree about the surface area and better conductivity. 4 spot welds does seem small if you are pushing 30A through it. wonder how they can tighten the cap nut under the straps. maybe a small socket they put inside and torque on the outside stud to secure it, but all that has to be done inside the glove box too since the jelly roll machine will have applied all the paste and wound the electrodes by then. thanks, dm

 

[bobmcree]

Bob, We have learned from some past mistakes not to engage in any further battery spec. competitions.

i guess what this means is that you are afraid of the results of comparison testing done by impartial users. You have told us you would never respond to this forum again and here you are under a fake name so the few people who do not know don harmon is battboy might think it is someone new.

your answer to the test results showing that the grey bmi cells are superior to the green lifebatt cells was at first "we have not made those cells in a year." i guess that means anyone buying them now is getting old batteries that have been laying around discharging for god only knows how long.

now i understand you are making some new allegations that the cells must be used upright to avoid "cell creep"? i suggest you use cellcreep as your next logon name after everyone learns that battboy is a shill for lifebatt usa. where on your website did it ever tell me i had to use spacers between my cells, and where does it even tell current buyers that they must use your cells in an upright position?

Nice to discuss things rationally without resorting to labels like "liar" for a change, Bob. Don Harmon

the only reason i have stopped calling you a liar is that everyone knows, and that i see no need to repeat the obvious.

 

[TylerDurden]

Nice to discuss things rationally without resorting to labels like "liar" for a change, Bob. Don Harmon

the only reason i have stopped calling you a liar is that everyone knows, and that i see no need to repeat the obvious.

Besides... "liar" would be simply inadequate.

 

[Nimbuzz]

C'mon guys knock it off -- this is an important battery thread and you are diluting it big time.

 

[bobmcree]

C'mon guys knock it off -- this is an important battery thread and you are diluting it big time.

absolutely. i do not want people to avoid the thread to avoid old hostilities. i probably should not have answered the question from don at all, but i did not intend for the thread to be sidetracked. don has contacted me off list several times about this thread, and after i expressly told him that i would not accept any further communication without the understanding it would be posted, he sent the following, which has cleared up the question regarding the green vs. grey cells, which was the only comparison i was making.


"the new bmi cells are lower impedance and otherwise superior, and you have made the decision not to provide any evidence that your new product is any better than the green cells that are clearly inferior in terms of ability to provide the currents needed for electric vehicles.

since LiFeBATT has not made a Green Cell in well over a year and ones we have made since then are Gray Cells - these are identical to the BMI Gray cells. In fact BOTH are made on the same production line! so I clearly agree that the Gray Cells are superior to the old Green Cells and never disputed this. Why would I when BMI & LiFeBATT are the same cell. You only need to test "either /or" since they are identical- probably just a different batch with a different lable pasted on (either LiFeBATT or BMI)." -from don h.


I cannot compare the performance of the BMI grey cell i have with the current production from Lifebatt because Lifebatt will not supply one. Don thinks i am selling a product which he says must be inferior to his, and this is just not true. I represent no products. I am not an expert, just another guy with an ebike, some batteries, and some test equipment who is trying to share his data with his friends. I never claimed my data was better than anybody else's; just in some cases that we had not made the exact same tests. It looks like there is more data now and i will have more of my own to contribute in the next couple of days. I also have a batch of 6 of the original lifebatt cells back in house so i can see how they compare with the one cell i tested previously.

The past Lifebatt sponsored testing i saw from sandia labs was based on performance of the cells when only 10% of capacity was exercised. This probably shows how well they will perform in a hybrid car but may not be the best predictor of performance to be expected when the battery is used to power a plug-in vehicle that discharges the battery more deeply.

 

[BMI]

Bob, since Don Harmon has stated that "Lifebatt does not sell loose cells" what is the point of testing something which e-bike owners can't buy? (It appears however that loose Lifebatt cells are being used to build electric motorcycle packs particularly in the UK so perhaps it is just another lie made by Mr Harmon that Lifebatt don't sell loose cells).
At least BMI makes loose cells freely available for sale in any quantity from a single cell to thousands of cells so you can be confident that they can be ordered at any time should you decide to order some for e-bike packs of your own design.

BMI has a completely different business philosophy to Lifebatt in that BMI believes in giving the customer what they want and providing all the loose materials including cells, joining links, cell holding frames, etc, to e-bike owners who wish to build their own custom battery since we understand that the HPS packs in many cases are not suitable for e-bike use so we don't force people into buying a packaged solution which won't do what the customer wants.

It all comes down to giving the customer what they want rather than telling them what they can have.

 

[RoughRider]

so, here we go again...

WHO is luying again?

DON says that grey bmi and lifebatt cells are the same and they come from the same factory...

BMI says that BMI has their own factory...

what is the truth or will we ever find out the truth?

 

[BMI]

so, here we go again...

WHO is luying again?

DON says that grey bmi and lifebatt cells are the same and they come from the same factory...

BMI says that BMI has their own factory...

what is the truth or will we ever find out the truth?

It is very simple really.
Mr Harmon and myself are both correct here. The grey 40138F1 cells are manufactured in the same factory which makes cells for both BMI as well as Lifebatt. It is a shared production facility. This is distinct from the older (original) green cells with slightly lower performance which come from a different factory. The cells made for Don Harmon are made for the Lifebatt battery packs while cells are manufactured for BMI which go into BMI factory battery packs as well as cells which are sold loose to people such as e-bike owners on this forum who want to assemble their own battery packs. Generally the BMI cells with a white label are used to manufacture the HPS battery packs while some cells are labelled with a black BMI label for individual sale as loose cells.

Photo above shows white BMI cells during assembly of a factory battery pack during QC testing.

I can't explain it any more simply or make it any clearer than that.

 

[RoughRider]

so, there is NO BMI factory for the cells, right?

your BMI "factory" just assambles the cells that come from the manufacturer, right?

this manufacturer produces cells for BMI and lifebatt...correct?

 

[BMI]

so, there is NO BMI factory for the cells, right?

your BMI "factory" just assambles the cells that come from the manufacturer, right?

this manufacturer produces cells for BMI and lifebatt...correct?

We ARE the manufacturer of the cells.
Our (BMI/Lifebatt) factory assembles, puts together, builds, manufacturers, constructs (or what ever word you want to use) the actual cells themselves from the individual materials used which go to make up a cell.

Well if you can't understand that then I am sorry for you and your lack of understanding simple english.

 

[RoughRider]

i dont think it is the reason, that i can not understand it...

but the fact, that you publish several versions of YOUR thruth...

on the first few sides of this thread you told us, that you have your own factory and you have nothing to do with PSI..

and you told this more than once...

BUT...

we found out, that this is not thrue...at that moment your cells were produced by PSI...but you stil negate this...

but we found out, that the ID numers of the cells were identical...

on your website you say, that the green cells are cheap fakes of your cells...but we all know, that PSI-cells are green...

the reason is, that you have been not honest in the past...

 

[RoughRider]

Ok now for the answers to the above questions-
PSI manufacture and sell the original/first generation 40138 cell (the old green ones)
BMI and Lifebatt sell the latest generation grey and red cells which are an improvement on the PSI cells. The BMI and Lifebatt cells use patented Phostech LiFePO4 powder which is manufactured in Germany and shipped to Taiwan for manufacture into 40138 cells.
So to put it simply once and for all BMI and Lifebatt cells are the same and come off the same production line while PSI cells are a different cell and use non Phostech LiFePO4 powder in their manufacture.

Nothing personal to anyone at PSI, BMI, or LiFeBatt. But my data collection and analysis suggests the existence of data inconsistencies...

1. BMI and LiFeBatt have made great use of a mis-representation that green cells are old. BMI continues to do so in their ebay ads, website text, and in written articles. Not only are green cells old, but they could very well be cheap Chinese copies made with inferior components.

Here's the problem: Green cells are current production cells from PSI - the only company that makes 40138 LiFePO4 cells with this terminal construction. Green is their color, as grey and red are used by BMI/LiFeBatt. PSI produces cells with and without Phostech material. Their standard green cells does NOT use Phostech. I know that PSI manufactured LiFeBatt and BMI cells under contract as recently as fall quarter 2008.

One demonstration of that fact is this: Visit Armin's product page, scroll down 1/2 way, and look at the photos of his grey cells. Note the serial number barcode and sequence: 4BF1M305-0593. Compare it to one of the cells I received from PSI in Dec 08:



IF these cells were produced by BMI and/or LiFeBatt in another facility, why did they duplicate the PSI barcode, the PSI serial number sequence, and then choose to begin numbering their 'new' cells 'within' the PSI serial number sequence?

[edit] Could 'old' mean 'first generation'? It's obviously not 'old' with regard to time. Since the cells share the same cannister, manufacturing crew and (presumably) processes, this could leave 'old' to mean that a Phostech forumula, or other formula change, makes 'next generation' cells. Could be. But since it's the same factory, and they would presumably make a run of Urban-Assault black Endless-Sphere cells with a proprietary amount of Phostech if we wrote a check, could we claim all the other colors to be 'old copies' too? [/edit]

2. It's very easy for anyone to say device 'a' is an improvement over device 'b'. The first question this creates in my mind is 'compared to what?' They're an improvement how? They're better how? In regulated industries, confirmation must be performed by independent labs in accordance with established ISO, ANSI, or other specification. I don't know of a performance specification for LiFePO4, so it appears we're in a bit of a 'wild west' situation where anyone can say what they wish. It would be a significant marketing advantage for the folks at LiFeBatt and/or BMI to produce charts to prove the claimed superiority of their products. I cannot understand why they do not - unless they cannot. I've already placed a bet in Doc's testing thread that he will find no significant difference between the BMI cell and a PSI cell once his testing is complete.

3. Armin states that BMI and LiFeBatt cells now come from another manufacturer and are no longer connected with PSI. That could be. It appears that as of at least December 11th 2008 BMI and LiFeBatt purchase cells from the same manufacturer. As already stated, I have it from the source that it was PSI until fall '08.

I understand that PSI holds the patents on the design and manufacturing of these non-standard size cells with their terminals posts and seals. I also suspect that PSI is a larger corporation than BMI and/or LiFeBatt (this could be incorrect - I cannot find any information on BMI. I would expect a larger company to act a bit more 'corporate' though. This seems to favor PSI.). It doesn't make sense to me that a small company would put themselves in a position to be sued out of existence by violating PSI's patents - that's generally not a good long-term business strategy.

In addition, the photos posted on Armin's site, and that he may have supplied to the folks at Electric Echo, do show the manufacturing facility used to make these cells - and it's the PSI production floor with PSI's equipment and people. I don't know where they assemble packs with the completed cells. It would seem that a company with a new production facility might use photos from that facility instead of a facility they go to so much trouble to distance themselves from in print.

4. BMI continues to cling to the '20C' marking on their packs, and uses it in their advertizing. LiFeBatt did as well, but Don Harmon posted on this forum that it was an erroneous discharge rate and would no longer be used by LiFeBatt. Here are two facts that suggest this is marketing-speak only and has no function in the 'real world'. First is that 20C on a 10Ah cell means a 200A discharge rate. Even if the cell could flow that much energy, it would be very dramatic - for about three minutes. Then the cell is empty. Assuming they follow pack building guidelines published by the VMS manufacturer, All New Energy, the packs are built with a 100A fast-blow or a 75A slow blow fuse between two adjacent cells. The pack won't produce more than 10C for very long before the fusible link blows and the pack is off-line.

[edit] This portion about pack construction, though correct, doesn't speak to the capabilities of the cell. There might be differences in performance, but it doesn't appear to be openly available. [/edit]

If any of this is incorrect, I ask anyone to correct my position. If they can prove their point, I will correct my posts. I will provide sources and contact info if an independent party wishes to verify my comments. I don't care who the company is or what they sell - I am interested only in accurate information. I'll take my store down before I'll use bad info or untruth to sell. That dog don't hunt.

Sorry mods...maybe this stuff can be stripped out and moved to fix the severe thread creep.

 

[BMI]

I have never said that the green cells are quote "cheap fakes"?
When I use the term "older" cells I mean original/first generation/earliest and not "old" as in sitting around a long time.
The green cells are the original/oldest cells and there are now the more recent version cells which are grey in colour which are an improvement on the older green cells.
Just as you would expect a later model car to have more advanced features than an older model of the same make. It doesn't take a brain surgeon to understand this. I never said there is anything wrong with the green cells, just that they are different cells from the grey ones since there has been much confusion on this subject with many people thinking they are the same cells with the same performance.

Lets leave it to Bob Mcree's indepenadant testing to provide the final answer if both cells are the same or not so there is no need to believe what I say. People can make up their own minds if they believe I am telling the truth or not.

Also please understand that any information published on other websites might not be up to date. For example the pics of the factory on the Electric Echo website are not of the new factory since those photos were taken over twelve months ago. A lot of changes have taken place in a year.

 

[bobmcree]

i hope we can focus just on batteries and not on personalities. i have said i am not an expert on batteries; though like everyone i am the sum of my experience, and quite a bit of that is in metrology and electrical engineering. i know how to measure physical phenomena with a degree of accuracy i can substantiate quite adequately even to most skeptics. When we compare measurements between two different locations there are many sources of variations, and of course when the test to be performed is not exactly the same, comparing results is a bit more difficult. My last impedance and discharge curves of an early green Lifebatt cell were based on a single cell, so i am pleased that i have a chance to re-test a batch of 6 cells that has been used in the second E-Cruzbike for a few weeks.

My measurements have indicated that the grey BMI cells have about half the internal impedance of the original green Lifebatt cells. Don has verified that indeed the original green Lifebatt cells are inferior in that respect to their current production grey cells. I cannot buy or otherwise obtain a current model Lifebatt cell, so i cannot say how they compare. It is certainly easy for me to believe that battery assembly could be performed to different formulas and standards for two customers in a common factory, so the idea that all grey cells are the same has not been supported by any real data. I cannot speak to the quality of any cells other than the ones i have tested and leave it to others to decide how to apply that data in their own decision process.

Armin has cells that are 2-3 milliohms, and the only alternative in 40138 format seems to be to buy older cells that have been described by the manufacturer as inferior to the present product, which they say is equivalent to the grey bmi cells.

Don is like the Republican party's health care policy. He says his old products are inferior but he will not sell you the new ones. He knocks bmi but offers no alternatives. the old green cells are great. the newer grey cells are better. my next post will have discharge curves at high currents. i WILL NOT RESPOND TO ANY OTHER QUESTIONS IN THIS THREAD EXCEPT AS RELATE TO THE TEST RESULTS.

 

[BMI]

My measurements have indicated that the grey BMI cells have about half the internal impedance of the original green Lifebatt cells. Don has verified that indeed the original green Lifebatt cells are inferior in that respect to their current production grey cells.

Armin has cells that are 2-3 milliohms, and the only alternative in 40138 format seems to be to buy older cells that have been described by the manufacturer as inferior to the present product, which they say is equivalent to the grey bmi cells.

i WILL NOT RESPOND TO ANY OTHER QUESTIONS IN THIS THREAD EXCEPT AS RELATE TO THE TEST RESULTS.

Bob, it is interesting that your test results are very similar to the readings I have taken at random from several shipments of cells. I find that the vast majority of grey BMI cells measure an internal impedance in the region of between 2 and 3 milliohms. This would make up about 90% of all cells I have tested (just a rough estimate). I ocassinally find one or two which measure out under 2 milliohms (1.8-2.0 milliohms) but this is rare. I am yet to see a cell which measures greater than 3.5 milliohms so all cells come in at way under the specification of less than 6 milliohms.

 

[scoot]

Hi BMI...Could you provide me/us with the physical dimensions of the grey cells please? I need to do a fit test for my battery pan.

 

[AndyH]

Will BMI be consulting with A123-Systems anytime soon?

Seems the best they can do for internal impedance is 8 milliohms (1kHz) for their 26550 cells when new and about 15mΩ when cycled (acording to Argonne Labs).

 

[BMI]

Hi BMI...Could you provide me/us with the physical dimensions of the grey cells please? I need to do a fit test for my battery pan.

They are a standard 40138 size cell so are identical in dimensions to the green (first generation) PSI cells and the Lifebatt cells. 40138 means 40mm diameter and the cell body is 138mm long. M6 threaded terminals protrude from each end.
The cell outine is here-
View attachment Cell Outline.doc