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  #1  
Old 03-18-2012, 10:03 PM
kerrymann kerrymann is offline
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Lightbulb Standardized PL6 testing for A123 cells and compiling data

I am using A123 20ah pouch cells and I know several other people here are too and I wanted to throw out an idea. I was thinking if we all used the same test program we could compile our data and compare results here on the forum. The goals would be:

#1 A data base of all of our cells from different suppliers would allow the DIY community to compare the different sources of these cells and get build some confidence before sending $5k-10k to some guy in china that says it's good. While it's no guarantee that any of the other DIY'ers will get the same results from a supplier it can help weed out the bad gray market suppliers.

#2 The only way to get good comparable results is through consistency. Using the same hardware (PL6) and software should give us a pretty good apples to apples comparison. We'd need to agree on one test. I get get capacity variances of 10% on a cell by using a 1a discharge as opposed to a 10a or 40a.... I think this will be largely driven buy who has tested the most cells and what did they use?

#3 I am leaving my PL6 running a infinite cycle test on one cell anytime I am not using it for something else. I hope in time to get some life cycle data. I only have one PL6 testing 1 cell, which is hard to draw conclusions from. If others would do the same we make up our own little testing lab by sharing the data (see #2)

#4 I am an engineer, and I like data.

Thoughts?

For any of this to be relevant item #2 is key.
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  #2  
Old 03-18-2012, 10:22 PM
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rwaudio rwaudio is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Some data, capacity and IR for 151 cells. I tested another 60ish with a different method but these are all PL6
38A charge to 3.65v terminate C/20
38A discharge to 2.25v

My pair of PL6's are virtually identical, purchased at different times, but testing a pair of cells then letting them sit, swapping chargers and testing again has given ~0.05Ah maximum variation. I did this test a few times with the same results. If I let the cell sit overnight or for a few days I typically got within 0.02Ah.

Cell Capacity PL6 IR
17.43 0.8
17.57 0.6
17.60 0.7
17.66 0.7
17.66 0.7
17.70 0.7
17.72 0.7
17.73 0.7
17.76 0.7
17.76 0.8
17.78 0.7
17.82 0.7
17.83 0.7
17.84 0.7
17.86 0.7
17.89 0.7
17.91 0.6
17.92 0.8
17.92 0.7
17.95 0.8
17.99 0.7
18.00 0.7
18.06 0.65
18.08 0.7
18.11 0.7
18.13 0.7
18.15 0.7
18.25 0.6
18.26 0.7
18.27 0.7
18.28 0.6
18.31 0.6
18.33 0.65
18.33 0.7
18.33 0.7
18.34 0.7
18.34 0.7
18.35 0.7
18.36 0.6
18.37 0.7
18.39 0.7
18.40 0.7
18.40 0.7
18.41 0.7
18.41 0.7
18.44 0.7
18.44 0.7
18.47 0.65
18.49 0.8
18.50 0.7
18.50 0.8
18.51 0.7
18.51 0.7
18.51 0.7
18.52 0.6
18.52 0.7
18.52 0.7
18.54 0.8
18.55 0.7
18.55 0.7
18.55 0.7
18.55 0.7
18.56 0.6
18.56 0.65
18.56 0.7
18.56 0.7
18.57 0.7
18.59 0.7
18.59 0.7
18.59 0.7
18.59 0.7
18.60 0.65
18.61 0.7
18.61 0.7
18.62 0.6
18.62 0.6
18.62 0.65
18.62 0.7
18.62 0.8
18.63 0.7
18.64 0.7
18.65 0.7
18.65 0.7
18.67 0.7
18.69 0.6
18.69 0.6
18.69 0.7
18.69 0.7
18.70 0.6
18.70 0.7
18.71 0.75
18.72 0.7
18.73 0.7
18.73 0.7
18.74 0.7
18.75 0.75
18.77 0.6
18.77 0.7
18.77 0.7
18.78 0.8
18.79 0.65
18.79 0.7
18.80 0.7
18.80 0.7
18.81 0.7
18.81 0.7
18.83 0.8
18.84 0.7
18.84 0.8
18.85 0.7
18.87 0.8
18.88 0.6
18.88 0.65
18.88 0.7
18.90 0.8
18.91 0.7
18.92 0.65
18.92 0.7
18.92 0.7
18.93 0.7
18.93 0.8
18.94 0.7
18.97 0.7
18.98 0.7
19.00 0.6
19.00 0.6
19.01 0.7
19.02 0.7
19.03 0.7
19.05 0.7
19.12 0.7
19.12 0.7
19.14 0.6
19.15 0.7
19.16 0.6
19.16 0.7
19.16 0.7
19.17 0.7
19.18 0.6
19.19 0.6
19.19 0.7
19.20 0.7
19.21 0.7
19.21 0.7
19.25 0.6
19.26 0.6
19.30 0.6
19.31 0.7
19.39 0.7
19.47 0.6
19.52 0.7
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  #3  
Old 03-19-2012, 06:56 AM
adamj12b adamj12b is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

I like this idea alot as I plan to start testing these cells withing the next month.

I have been planing to use the PL6 as well for its high power discharge.

I plan to test my cells at at least 1C, but might even go to 2C as these are working range of batteries in an EV.

What are you guys using for charge/ discharge cycles?

I was thinking out of the box, top the cells to 3.65V. Then a discharge cycle to either 2.0 or 2.25V measure capacity and another charge to 3.65 for storage while I build the packs. If the charge/discharge rate is 2C, then a cell should be able to be tested about ever hour. Do you think this is testing the cells too hard? The datasheet for these cells say only 10% capacity loss after 3000 cycles with 2.0v being the LVC if I remember correctly.

I plan to test all of my cells and then group them based on capacity and internal resistance, matching the parallel cells as close as I possibly can.

Im thinking about ordering my PowerLab6 today, anybody know a better price then $197.95 for the kit with the output leads and serial adapter?

-Adam
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Last edited by adamj12b; 03-19-2012 at 06:58 AM.
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  #4  
Old 03-22-2012, 02:26 AM
boekel boekel is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Quote:
Originally Posted by adamj12b View Post
Im thinking about ordering my PowerLab6 today, anybody know a better price then $197.95 for the kit with the output leads and serial adapter?
I bought the PL8 because the 6 was out of stock for the 'non usa' store..

I just got this in the mail from Revo, maybe you can save some money (tough not for first time customers):

Now through March 31, 2012, receive 10% OFF normal retail price for any PowerLab 6 or PowerLab 6 Combo! Any orders you place between now and March 31 qualify. This offer is available only through the REVO USA webstore. To obtain this special limited-time pricing, enter coupon code PR032112 in the coupon code field during checkout, then click "Apply". Code is unlimited in that you may use it as many times as you like during the offer period.


Please note: The Revo store does not recognize promotional codes for first time buyers on the site. If you are a first time buyer who qualifies for the promotional code, please call REVO USA sales at (301) 798-2770 and we will assist you with the order and insure you receive the special 10% savings offer.
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  #5  
Old 03-22-2012, 06:25 AM
kerrymann kerrymann is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Quote:
Originally Posted by adamj12b View Post
I like this idea alot as I plan to start testing these cells withing the next month.

I have been planing to use the PL6 as well for its high power discharge.

I plan to test my cells at at least 1C, but might even go to 2C as these are working range of batteries in an EV.

What are you guys using for charge/ discharge cycles?

I was thinking out of the box, top the cells to 3.65V. Then a discharge cycle to either 2.0 or 2.25V measure capacity and another charge to 3.65 for storage while I build the packs. If the charge/discharge rate is 2C, then a cell should be able to be tested about ever hour. Do you think this is testing the cells too hard?
-Adam
I am repeating my cells with rwaudio's settings (see above). It's only 2C which is well within the operating range of these cells. I only have eight now but I will be ordering 220 next week.

Quote:
Originally Posted by rwaudio View Post
Some data, capacity and IR for 151 cells. I tested another 60ish with a different method but these are all PL6
38A charge to 3.65v terminate C/20
38A discharge to 2.25v

My pair of PL6's are virtually identical, purchased at different times, but testing a pair of cells then letting them sit, swapping chargers and testing again has given ~0.05Ah maximum variation. I did this test a few times with the same results. If I let the cell sit overnight or for a few days I typically got within 0.02Ah.
Thanks! I am plugging it into excel and I will post it here along with my limited data.
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1986 GL1200 Trike, 196V, 9"ADC, SLAs = RETIRED
2013 Chevy Volt
Remember that your EV is only as clean as your power grid. Go SOLAR!
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  #6  
Old 03-22-2012, 08:58 AM
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rwaudio rwaudio is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Also just to clarify, mine were some of the earliest A123's available outside of A123RC.com they are the tabless cells.

I have 152 more cells that will be coming soon, some for me some for others.
I will probably be measuring them all. They are cells with 12.1mm tabs not the full length tabs. I will continue testing with my settings and see how these compare to tabless cells.
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Old 04-06-2012, 11:05 PM
kerrymann kerrymann is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Sorry I haven't done anything on this recently. I am dealing with motor adapter issues right now, but that is another thread.....

Actually the big issue I ran into is that after the 2nd cell was retested at 2C my PL6 stoped charging. It act likes it working with a setpoint at 38amps but shows 0 amps of current. I have called and emailed their tech support a couple times but haven't gotten a reply. If anyone else has run into this or a solution, please let me know.

I was thinking about ordering another PL6 to test my 250 cells so I might go ahead and do it now.

Kerry
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1994 Mazda Miata EV Dual Warp 9's, Soliton1, A123s
1986 GL1200 Trike, 196V, 9"ADC, SLAs = RETIRED
2013 Chevy Volt
Remember that your EV is only as clean as your power grid. Go SOLAR!
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  #8  
Old 04-07-2012, 06:45 AM
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rwaudio rwaudio is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Quote:
Originally Posted by kerrymann View Post
Sorry I haven't done anything on this recently. I am dealing with motor adapter issues right now, but that is another thread.....

Actually the big issue I ran into is that after the 2nd cell was retested at 2C my PL6 stoped charging. It act likes it working with a setpoint at 38amps but shows 0 amps of current. I have called and emailed their tech support a couple times but haven't gotten a reply. If anyone else has run into this or a solution, please let me know.

I was thinking about ordering another PL6 to test my 250 cells so I might go ahead and do it now.

Kerry
Once in awhile I get an error message, and it typically seems to be caused by a communication error to the PC, the last few cells I've tested I use the controls on the primary to initiate charging. The firmware has a few bugs, but both of mine typically work well.
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Old 04-07-2012, 08:03 AM
Henkka Henkka is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

This common database of test results sounds very good! We actually tried to do similar database with eCars-Now OS-community before with Thundersky cells but only managed to do few cold-temperature tests (see http://www.sahkoautot.fi/paja:batterytests , you can see our Open Source web-software doing all the logging and gathering a "common database" of test-results). But this database never got very far, only few tests were done - lack of time and too few people doing the actual tests...

But now I have 10 x A123 cells too (for my Porche 944) and have so far tested 4 of them with 1C (20A). I have usually tested with 2 cycles to see if there is any significant rise in capacity. So far difference between first and second cycle has been very small. I could also test with 2C (as I have PL8) after I have completed my 1C & 2 cycles testing.

For my use, I need also data how much temperature affects capacity and how much these cells warm up when discharged. (As it gets rather cold here in Finland during wintertime, -25 C is quite normal. And I have not found actual data about any serious cold temperature "lab" testing available.)

So for that reason my recent test-setup (photos in http://www.flickr.com/photos/yty/set...7629380248814/) includes 20 mm styrofoam on both sides of the acrylic cell-clamping device to thermally isolate the cell from ambient air. For now I log temperatures with just 2 cheap multimeters but it's rather tedious job to combine PL8 logs with temperature logs. So for that reason I have thought of writing simple program just to control PL8 and to use Arduino with LM335 temp-sensors and read those as well. My friend has already done that with Labview and is going to control 5 PL8 units for some serious testing with Turnigy Nano-cells.

In what temperature you guys are testing the cells ? I would think that something like 20 C (68 F) could be a "standard" temperature?

My cells so far have all been under 17Ah, actually between 15.5 - 16.9 Ah. I need to test them all to see actual variation.

You can see the cells in http://www.flickr.com/photos/yty/set...7629495306153/

Henkka
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Old 04-07-2012, 08:18 AM
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rwaudio rwaudio is offline
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Default Re: Standardized PL6 testing for A123 cells and compiling data

Quote:
Originally Posted by Henkka View Post
This common database of test results sounds very good! We actually tried to do similar database with eCars-Now OS-community before with Thundersky cells but only managed to do few cold-temperature tests (see http://www.sahkoautot.fi/paja:batterytests , you can see our Open Source web-software doing all the logging and gathering a "common database" of test-results). But this database never got very far, only few tests were done - lack of time and too few people doing the actual tests...

But now I have 10 x A123 cells too (for my Porche 944) and have so far tested 4 of them with 1C (20A). I have usually tested with 2 cycles to see if there is any significant rise in capacity. So far difference between first and second cycle has been very small. I could also test with 2C (as I have PL8) after I have completed my 1C & 2 cycles testing.

For my use, I need also data how much temperature affects capacity and how much these cells warm up when discharged. (As it gets rather cold here in Finland during wintertime, -25 C is quite normal. And I have not found actual data about any serious cold temperature "lab" testing available.)

So for that reason my recent test-setup (photos in http://www.flickr.com/photos/yty/set...7629380248814/) includes 20 mm styrofoam on both sides of the acrylic cell-clamping device to thermally isolate the cell from ambient air. For now I log temperatures with just 2 cheap multimeters but it's rather tedious job to combine PL8 logs with temperature logs. So for that reason I have thought of writing simple program just to control PL8 and to use Arduino with LM335 temp-sensors and read those as well. My friend has already done that with Labview and is going to control 5 PL8 units for some serious testing with Turnigy Nano-cells.

In what temperature you guys are testing the cells ? I would think that something like 20 C (68 F) could be a "standard" temperature?

My cells so far have all been under 17Ah, actually between 15.5 - 16.9 Ah. I need to test them all to see actual variation.

You can see the cells in http://www.flickr.com/photos/yty/set...7629495306153/

Henkka
--
http://randomev.wordpress.com - Random EV blog, Porche 944, CAN devices etc.
The cells are rated with a discharge to 2.0v so only discharging to 2.8v will explain the significant difference in measured capacity. It doesn't matter what you actually do in the car (I won't discharge below 2.5 or 2.75v) however to get a fairly accurate capacity I'm discharging to 2.25v
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