Lithium Battery Reports & Tests' 9/08

[magudaman]

I have been using A123 Dewalt packs for almost 3 years now and I purchased them through Ebay retailers.

Cell Specifications:

[pre]Nominal capacity and voltage 2.3 Ah, 3.3 V
Internal impedance (1kHz AC) 8 m1 typical
Internal resistance (10A, 1s DC) 10 m1 typical
Recommended standard charge method 3A to 3.6V CCCV, 45 min
Recommended fast charge current 10A to 3.6V CCCV, 15 min
Maximum continuous discharge 70A
Pulse discharge at 10 sec 120A
Cycle life at 10C discharge, 100% DOD Over 1,000 cycles
Recommended pulse charge/discharge cutoff 3.8V to 1.6V
Operating temperature range -30°C to +60°C
Storage temperature range -50°C to +60°C
Core cell weight 70 grams[/pre]

Dewalt packs contain 10 cells and BMS unit. I currently am running 40 cell or 4 packs in series at 66v

Pack weight about 2.5 lbs

My tests with these cells:
Setup – Cells BMS are bypassed when discharging and charged through the BMS:

These cell were original used on a Schwinn S1000 scooter in parallel at 33v 8.4ah. The peak power they would see is about 150 amps peak.

Today they are run in series at 66v on a Crystalyte 409 with a 35 amp controller. I am running 26” wheels and can see about 30 mph 33 mph uploaded. I only get around 7.5 miles but average about 23 mph on my rides.

I have also owned a CBA since I bought these batteries and did intial controlled capacity tests:
Initial capacity test from 6/25/2006, Similar charts came from the other 3 packs:

Today’s test from 1/15/2009:

I would say there is around 500 cycles on these batteries based on my current riding habits and cycle count on my Cycle Analyst which has only been around for year and half. Almost all my cycles are 100% DOD.
Some of my packs came from tool kits from dewalt and I just ebayed the tools and cases. On one sets, one of the packs was not testing good. I contacted dewalt who promptly sent an entire new kit and a box to mail back the old one. Luckily I was testing the battery through the BMS.

Conclusion:

Overall these batteries have outlasted the vehicles I have put them in and are showing amazing longevity. They have also proved their great current handling and really have a flat discharge curve. As an investment these batteries were well worth the money in contrast to other chemistries and would probably be the brand i would buy again.

 

[Nimbuzz]

Great reports by all on this important thread! Mag, your report and pics are especially awesome = Danka!!

Questions; 1) You say 4 packs in series at 66V -- Wouldn't this be 2P, 2S for 66V? 2) Do you charge these in a regular Dewalt charger? 3) When you say 100% DOD do you mean you go to the BMS' low voltage cutoff? But now I see you are bypassing the BMS. So you are riding until there is NO power left? 4) I, for one, would find it very interesting to see another test graph to see the difference after all these cycles? Oops, Wow -- I just posted and see that you just added a test today -- thanks!!

I'm especially excited by your report because I have 4 Dewalt packs to hook up to my 5304 at 66v!

Again, your report with the test graphs is soooo helpful! This thread and this whole site are the cutting edge!! The Govs and Corps aren't quite doing it but the guys here are piecing it all together to build solutions, as did the Wright Bros!
Fun Stuff!!

 

[magudaman]

Nice finds and good questions.

You say 4 packs in series at 66V -- Wouldn't this be 2P, 2S for 66V?

You are correct I am running 2s2p for 66v around 4.2ah.

Do you charge these in a regular Dewalt charger?

Yes I do. I use the stock BMS only while charging and then bypass while discharging.

When you say 100% DOD do you mean you go to the BMS' low voltage cutoff? But now I see you are bypassing the BMS. So you are riding until there is NO power left?

When I say 100% DOD (depth of discharge) that is based on the capacity of the battery as 100%. If I only drained it half way I would be going to a 50% DOD. I drain my batteries based on Ah and never ever go over 4.4ah. If for some reason I loose my Ah number the lowest voltage I drain to is 58 volts. But those are really worst case scenarios. Usually I keep it at around 4.2ah max.

That 5304 is going to scream! Be sure to post up your setup and let us know how it works out!

 

[biohazardman]

Info/Spec Checklist;

A -- Link to Mfg specs and purchase site and describe warranty
http://www.foxxpower.com/
(3) years from the date of original retail purchase

B -- Brand name and Type of battery or cell
Foxpower
LifePo4

C -- Capacity and Voltage, Rated maximum charge and discharge current.
I have the 36V 10AH pack
Charge rate <20A, 2A balancing charger provided no BMS on the pack itself.
Discharge rate 3C continuously and 5C peak, for up to 30 seconds

D -- Description of tests or riding = motor, rider & cargo weight, hills, speed, distance and meter reports.
Battery ran a 36V GM 500W motor with rider and bike weight including the battery at near 260lbs. Motor slowed significantly on hills. Speed was in general 18-20 MPH. Approximately 20 miles per charge with minimal pedaling on accelerating from a stop.

E -- Estimated number of cycles and depth of cycles actually performed so far and voltage and capacity difference from new.
Estimated 100 cycles with 10% to cutoff no notice of change in voltage or performance.
Batteries at 3.3V after full charge and three weeks of storage.

F -- Feedback on dealer or Mfg accessability and response to any problems or questions”
Product was in my hand within a week of ordering it. Questions answered promptly untill then. After receipt of goods typical Chinese communication wise mostly one to two week in answering e-mails. I did not phone them may have been better if I had.

I ran the pack in series with a couple of 9AH 12 volt batts in parallel for 48V for the last 500+miles. Acceleration and hill climbing abilities were much improved and the miles per charge was maybe at maximum a mile less.

I just purchased a 48V pack as the 36V has done well. It is now in my grubby little hands so will report on it in the near future.

OK the future is here pic of the newest 36V pack I sent in as requested to have converted to 48V cuz my 36v controller fried. Replace the controller with a 48v unit and added a couple of 12 SLAs to get the voltage right. Instant torque junky I am.

Near five weeks to get, it back and was beginning to get concerned when I got an e-mail from Zane with saying it would be on its way. The pack arrived three of four days later as you see it. Not quite the same build quality but figured I was still serviceable. So set about splitting the pack and made boxes to put in the panniers. So when I drop it things will still work. Bent the ABS with a heat gun while clamped between boards. The rewire from what looked like 26 gauge to 20 gauge took a couple of hours.

First charge shows a weak batt. Second charge the weak battery started melting shortly after I hooked up the charger. E-mailed Zane and got an immediate response five more batts in my hand in less than a week. Replaced batt #3 rode 17 miles. Replace batts #7 and #1 as the full charge lights came on as soon as they were hooked to the charger. Replaced batts #1 and #7 again as the new ones got hot as soon as the charger was plugged in. Next try at charging everything seems to be good and the charger shuts itself off about four hours later. Another 17 mile hot Roding it all the way ride 20-23mph flat out with a top of 25 even a couple mph higher on hills I often rode 17mph now going 19mph up them. Expect the same mileage out of this one as the 36v as I ride and accelerate faster. I hate the panniers mounting assembly as they keep nearly falling off the bike so finally got the zip ties out. A couple of ties installed at the bottom and no more problems.
Looks like Foxpower comes through again albeit a bit shaky this time. Excellent support after my first bad battery problem.

Well just had to add that due to unforeseen circumstances I had to pedal home from work some 25 miles in the middle of the night in 32 degree temps. I helped the best I could but had a mile plus long 1000ft uphill grade to deal with so relied on the motor and batteries heavily as I am not well. Batteries did not cut out till I was .25 miles from home at which time I went easy on the throttle and they got me all the way there. My car was covered in a thin sheet of ice when I arrived and a few snowflakes were beginning to fall. Feet got cold due to the steel-toed boots but the ninja mask, clear glasses, and gloves kept me way more comfy than they should have been all things considered. Lets not forget stopping a couple of times to pump up the tire as it had a slow leak. Could have been a very different story if the batteries had not held up. All and all was one of those days I just look back at and and laugh as things just got progressivly worse as the day went on until I found myself alone at near 1AM at a transit station wating for the lightrail that had been cut due to the tight budget.

 

[StevenR]

C'lyte 53030 Torture Test of the Ping v2 48V20aH continues. After taking much abuse for running without BMS to avoid overcurrent cutouts, I soldered together two of the four shunt wires about halfway. I probably ran 25 cycles at 50% DOD without BMS. No cutouts with max throttle for the first 15aH. At that point it would cutout on hills or high throttle. That got me within a couple miles of home and I ran the last bit taking it easy and it didn't cut out. I am not sure if the pack is operating up to spec or not. It was cold - no more than 40F and I bet I could have gotten a bunch of miles/aH on the flats taking it easy - no more than 1kW. My continuous wattage is about 1000W although some hills were more like 1500W. I max out (10 seconds) at 2200W. Peak, indicated by the CA is right around 60A (3000W). This seems to be the same with or without the BMS and with or without the modified shunt. It didn't trip out on full throttle speed runs, just full throttle starts.

When I measure cell voltages a day or so after charging I see several cells that are at 3.3 volts while the rest are at 3.6 volts. I run 0.5 aH out and everything reads 3.3 volts +/-0.01 volt. On the charger, there seem to be a couple cells that only get to 3.35 volts and never go higher. Others are running over 3.9 volts. The charger (Soneil 4808SRF reset to 3.5A and 58.89 V CV) has a green light but is delivering 0.05A and dropping. Cell 1 (the one on the positive end of the chain) is rising to 3.69 volts and when it gets there the charger goes to 0.00 amps on the WattsUp meter.

Is this normal, do I have bad cells or is the BMS not balancing right? Should I try to individually boost the low cells with a single cell charger? How would I do this - just put 3.9 (4.1V?) on the base of the resistors on the BMS? Do I need a chager or can I just use a variable supply?

This has not changed since right from the start - I don't think I damaged it yet, it came this way. And there may be nothing wrong - when it gets to be 70-80F, it may run right out to 20aH. The 5303 seems to be sagging it out on LVC near the end of charge and 18aH (10% more with +30F) may be all I can expect. And that's just fine.

I anticipate three to five 50-100%DOD cycles per week while the weather holds (now until the end of October - 100 cycles). I believe I have about 30 cycles on it so far. If it goes to 18aH before the first LVC, I will consider that baseline and watch for degredation. If all is well (or at least stable at the current conditions) and I really get 80% at 1000 cycles, it will take 10 years! I expect (hope? dream?) the Ping v2 will look like an SLA compared to what will be available then so, for me, it probably is a moot point. I will upgrade every year or two and will probably NEVER see significant loss of capacity...

 

[monster]

i'm really happy with my pings 48v 12ah x2 on an X503. i've only done 400miles on them so far, but i do about 100miles/week so i'll rack up the cycles in no time. haven't reached gone on a ride long enough to exced the range of the pack yet -the longest i did was 35 miles.

 

[rbelisle1]

I dont know, but my agm's ran me for 750 miles, before they were tired... 7.5 miles one way, charge and then back for 15 miles a day.. For the cost (about 100 bucks) to replace them, they were great.. Plus the new agms I got have a 1 year, non prorated waranty. so I am happy,,,

50 amp we contoller
500 watt direct drive front hub
3 12volt 18ah batteries..

daily driver with no issues at all, runs everyday...

 

[miro13car]

swbluto,
in your post second one,
LifeBatt/BMI cell is different than PSI, it should be NOT shown as the same.
PSI is green and it do not contain Phostech powder, same Ah but lower continous Amps which makes it different animal than LifrBatt and BMI which are identical cells with diffrent labels on them.
Miroslaw

 

[AndyH]

swbluto,
in your post second one,
LifeBatt/BMI cell is different than PSI, it should be NOT shown as the same.
PSI is green and it do not contain Phostech powder, same Ah but lower continous Amps which makes it different animal than LifrBatt and BMI which are identical cells with diffrent labels on them.
Miroslaw

How do you know this, Miroslaw?

 

[miro13car]

Andy,
from Armin Pauza , distributor of BMI,
FROM Lithum Batt Australia web site ,
from this forum
MC

 

[AndyH]

Andy,
from Armin Pauza , distributor of BMI,
FROM Lithum Batt Australia web site ,
from this forum
MC

Thanks MC. I ask only because I've been looking for this information as well and so far haven't seen any proof that Phostech is used, how much, and whether it makes any performance difference. Don said a lot of things about LiFeBatt, but in the end he acknowledged that their cells were make by PSI and had a very small amount of Phostech powder in the cell. Armin is a great guy, and very knowledgeable, but the best performance information I could get from him was testimonials. Unfortunately, from my days in sales and as a military analyst, testimonials are useless for science. And - as we've learned in this forum already - anyone can say anything...

I understand that BMI and/or LiFeBatt may be (or have) recently opened a factory to make their own cells. I've been able to cross-reference the facts enough to suggest that PSI made all the cells until at least the summer of '08. While it probably means that PSI is no longer making their cells, doesn't confirm that they're making their own - they may have simply contracted with another manufacturer, or it could mean they have a new shop. Who knows?

Back to performance - I have tested PSI's cells - purchased thru both Yesa and direct from PSI. I have seen the chart published for the early LiFeBatt cells (and the data published in the Sandia Lab report - which is near useless), but I still haven't seen anthing that shows that a cell spiked with a few percent Phostech performs better or worse than a 'plain vanilla' PSI cell with no Phostech material.

Sorry - 21 years as an analyst has left me with a 'need to know' and an absolute hate of bad information. And my time in sales has opened my eyes to too many ways bad data can be packaged and used to sell a product. So - absolutely nothing personal with you, Don, Armin, or anyone else living or dead.

All the best,
Andy

 

[swbluto]

I should make mention of something like "suspicions of" in the post, as I don't have conclusive evidence one way or another. Just some heavy suspicion from JD with his quite excellent reasoning.

Anyways, I don't have the ability to modify the post anymore! I guess at the age of 21, it matured.(It's had 21 edits)

It actually won't allow me to link more than 10 links so it prevents me from editing it, so I suspect knightmb has been making some sweeping "updates"/changes as of late.

 

[miro13car]

well,
our Doctorbass will be testing BMI cell soon when he gets his electronic load up and running.
WILL YOU BELIEVE HIM?
Just read his posts carefully, didn`t he already tested PSI cell, just use SEARCH on this forum.
No doubt in my mind BMI will show better performance.
Jozzer on this forum was using PSI and LifeBatt cells in his bike.
He knows.
PSI is rated at lower continous than grey cell.
MC

 

[AndyH]

well,
our Doctorbass will be testing BMI cell soon when he gets his electronic load up and running.
WILL YOU BELIEVE HIM?
Just read his posts carefully, didn`t he already tested PSI cell, just use SEARCH on this forum.
No doubt in my mind BMI will show better performance.
Jozzer on this forum was using PSI and LifeBatt cells in his bike.
He knows.
PSI is rated at lower continous than grey cell.
MC

It's ok, MC - as I said - it's not personal and it's not about belief. I look forward to the Doc's tests! BMI still claims 20C, yet Don Harmon said that LiFeBatt cells were NOT 20C capable and had the 20C claim removed from their literature. I guess that suggests that BMI and LiFeBatt are not the same?

 

[GGoodrum]

Don also claimed that the original LiFeBatt/PSI cells were 20C as well. I didn't buy it then, and I don't buy it now. I have two 12-cell packs, which are defintely PSI-made, that I still use in series and after a year and a half, they are holding up quite well, but based on my experience with high-end RC LiPos, and with a123-based packs, I'd rate these around 7C continuous, and maybe 10C burst. that's still nothing to sneeze at, even in a single-"p"/10Ah pack, but 20C? No way.

Coincidently, I just took the "covers" off these two 12-cell packs, to check on the cell voltagess and to make sure there were no leaks, etc. I'm happy to report there were no leaks and the cell voltages were all right around 3.325-3.330V. I tightened things up a bit, and replaced the LVC board in one pack. Anyway, I cycled them a couple of times and they still seem like new.

-- Gary

 

[BMI]

Hello to everyone on The Endless-sphere Forum!

This is my first official post here and I have finally decided to come on to the forum (at the prompting of some of the members) and answer as many questions as I can regarding BMI cells and battery products (and the no doubt many re-occuring questions such as differences with Lifebatt, PSI, etc).

I will do my best to clear up all the lies, misconceptions and other untruths propogated by the principals of Lifebatt Inc.
Let me say at the outset that I have nothing against the international distributors of Lifebatt (I was the first/original Australian Lifebatt distributor myself before I got burned by Don Harmon/Michelle Robinson who are the owners of Lifebatt Inc.) The international distributors are indeed decent people. It is just unfortunate that they are representatives of the US parent company and royalties from the sale of Lifebatt products go directly to its unethical owners so they are making money without even having to sell any batteries themselves.

I spend a considerable amount of time clearing up many of the lies which are told to customers relating to technical issues from people who have purchased battery products from Lifebatt Inc. At least on this public forum everone might benefit who reads these pages rather than just the many cell and battery owners who I send detailed replies to individually in an effort to sort out their problems.

So I am not sure where to start and whether to reply to some of the questions raised on this thread or let people ask direct questions of me. I guess I will leave it there and answer questions as they are asked.
I will try to visit the forum as often as possible but often I am very busy with large electric vehicle projects. For example I am in the middle of working on a large electric boat conversion project which will be powered by BMI batteries with a total cell count of 384 BMI/Lifebatt 10Ah 40138F1cells (minimum).

I will finish this, my first ES post, by saying a big thankyou to some of the great guys here whom I greatly respect. These are guys who I have learned a great deal from their advice and opinions offered on this forum (and who are members I don't personally know) while others I do know and who I have had considerable personal/business dealings with. A few names of people who fit into either of these categories are Bob Mcree, Gary Goodrum, Richard Fetcher and of course Doctorbass for all his efforts and time he spends in testing the many cells sent to him from many battery manufacturers.
If I could live up to the reputations of any of those above mentioned gentlemen I would indeed be very happy.

Armin Pauza
General Manager & Principal Electrical Engineer
Battery Manufacturer's International Corporation (BMI/Lifebatt Production Australia)

 

[Ypedal]

Welcome to ES !!!!

The one big question we have pending is this " C Rate ! " .. are LIfebatt, PSI, BMI, etc.. any different in this regard ? or are they all off the same production line ? Phostech powder that LB usa claims in X amount.. etc...

I have PSI cells in use, and imo, 10C max, 7C continuous is about as generous as i would be with them. 20C... ? no way.

 

[jimw1960]

Hello to everyone on The Endless-sphere Forum!

So I am not sure where to start ...

Perhaps a good start would be to post a 10c discharge curve for the BMI battery. The best I've seen is a 3.5c discharge curve that a certain ebay seller of BMI tried to pass off as a 10c curve on this forum. I heard docbass is getting a BMI cell for testing and he'll probably get that information to the forum in the near future, but it would be good to see what BMI says its battery will do at 10c.

 

[Nimbuzz]

This is good stuff. We are getting down to the nitty gritty in defining some of the batteries.

Please remember whenever a battery is discussed that it is very helpful to give the basic specs. It is hard to go back in the thread and find the specs for each of the many Lithium batteries being discussed here.

Spec check list;
-- V
-- ah
-- C rating, claimed or tested
-- weight

As people are actually shopping for batteries here, also helpful are;
-- Price
-- Link to sale site

And of course real world ride results are the bottom line.

 

[fechter]

Hello to everyone on The Endless-sphere Forum!

This is my first official post here and I have finally decided to come on to the forum (at the prompting of some of the members) and answer as many questions as I can regarding BMI cells and battery products (and the no doubt many re-occuring questions such as differences with Lifebatt, PSI, etc).

Welcome! and thanks for joining the discussion.

What are you using for a BMS on that big pack?

 

[BMI]

To answer ypedal's question regarding BMS protection used on the big boat battery, just standard factory BMI HPS batteries with inbuilt VMS boards will be used. An HPS driver module will be fitted to the battery DB9 data port to automatically trip the main battery circuit breaker (vis a shunt trip coil) to provide LVC protection should the battery bank ever become completely discharged (no need for a contactor).

Since as a manufacturer's representative, many here won't believe what I say regarding discharge rates and over all performance so I think it is best if any test results published here are performed by an independant tester (calling Doctorbass).

I think it would be very interesting to see a direct comparision performed between Headway, Ping and BMI.

Tests I would personally like to see results for would include-
1) Internal impedance measurement of each cell
2) Discharge curves at say 3C, 5C and 10C
3) The temperature of the cell recorded at the end of the discharge at the above rates (this will be very interesting)
4) Actual capacity measurement to see how close the cell is to the manufacturer's claimed capacity.

So is Doctorbass up to the task?

 

[bobmcree]

i think doc can handle it, i believe he has a CBA2 with 2 of the amps? i also have all the appropriate equipment and will be happy to duplicate his tests on the same cells; data which i think would be of value to everyone. i have done my own testing on other cells over the years, and i think most people who know me will believe my results are objective. BMI is sending me a couple of test cells; hopefully i can get ahold of some others for comparison.

 

[AndyH]

Since as a manufacturer's representative, many here won't believe what I say regarding discharge rates and over all performance so I think it is best if any test results published here are performed by an independant tester (calling Doctorbass).

Can you share anything about these cells Armin?

I think it would be very interesting to see a direct comparision performed between Headway, Ping and BMI.

Tests I would personally like to see results for would include-
1) Internal impedance measurement of each cell
2) Discharge curves at say 3C, 5C and 10C
3) The temperature of the cell recorded at the end of the discharge at the above rates (this will be very interesting)
4) Actual capacity measurement to see how close the cell is to the manufacturer's claimed capacity.

So is Doctorbass up to the task?

I want to evaluate a pair of cells as well - will the best representative cells come directly from you? Or my neighbor McStar? Or?

 

[Nimbuzz]

Andy & Doc Bass -- For the most impartial test we would buy cells rather than have a mfg send us some that could very well be the cream of the crop. I would chip in $20 to buy cells from each mfg for Doc Bass & goodrum to test.

 

[Lapwing]

One of the key "issues" with this dual stud style of cell is the poor sealing of the studs, and electrolyte loss.

this previously posted by bobmcree

I have read a number if reports where cell damage has resulted from electrolyte loss after less than 6 months use.

Headway have a completely different construction on there screwed cells, and so don't have this issue.

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=8109&p=122950&hilit=+BMI+inside#p122950

Seriously much as I like the electrical performance, this construction issue is a deal breaker for me.

The Headway has a much beter design.

Anyone care to comment?