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Discussion Starter · #1 ·
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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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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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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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.


[FONT=Arial, Arial Black]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.[/FONT]
 

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Discussion Starter · #5 ·
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.

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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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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Discussion Starter · #7 ·
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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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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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/sets/72157629380248814/) 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/sets/72157629495306153/

Henkka
--
http://randomev.wordpress.com - Random EV blog, Porche 944, CAN devices etc.
 

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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/sets/72157629380248814/) 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/sets/72157629495306153/

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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here's my observations after using a PL6 to test cycle my 48 CALB cells (130ah).

1. it was fairly common for the charger to fault for some reason at the bottom of the cycle. It would fully discharge, then have some kind of communication error and not begin the charge cycle. I'd just have to stop the program, and restart it as a single charge cycle instead of a full cycle to finish the cell. It just meant I needed to be quite watchful of the process, not just set it and forget it.

2. The IR readings are all over the place. even on the same cell, the IR would vary from .5-.9 depending on where it is in the charge cycle. I just decided on a consistent part of the charge curve (about 10 minutes into the charge cycle, still at a low SOC) to make the reading for comparisons sake.

3. I charged all the cells up to 3.60v, c/20 current shutoff. I DID NOT put the cells in parallel at any time. I then re-installed in my car, wired them up in series, and drove it. On the next charge cycle, my charger brought them up to an average of 3.50vpc and the voltages on the individual cells ranged from 3.40 to 3.53 volts. This is a much larger variance than I was expecting, I thought they would be much closer top balanced after individually charging them to 3.60v on the PL6. After seeing this variance, I did a little top balancing with a power supply to bring them all a bit closer.
 

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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
Yes, this definitely could be the reason. For comparison, I need to test with same parameters as you have been testing. So I'm going to do some tests with the same current (38A) and voltage between 3.65 - 2.25V.
 

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My 8 sample cells just arrived. They all have a voltage of 3.29V - 3.293V.
I just wanted to start charging them. How can I create a custom (user) preset?
Maybe I overread something in the manual, but i didn't find anything about it.
If I delete a preset and want to edit it, the charger says it can't edit an empty preset or so.

I don't have the PC USB connector yet, because I didn't find it in germany anywhere...
 

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Discussion Starter · #14 ·
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.
I tried that but still nothing. I finally got a hold of tech support and after a 2 minute call he said it was a bad unit and they would replace it (I have to pay return shipping). Meanwhile I still have 256 cells to test.....

BTW, if you do need tech support help I recommend filling a case using their website:
To initiate a case directly :
1. Log on to your account at www.store.revolectrix.com
2. Click the "My Account" tab
3. Under Support, click "Contact Support"
4. On the case form, enter a subject which contains the product name, part number, or description
5. Type a message in the message field
6. The fields on the top right of the form are optional
7. Click Submit
Or calling directly (if you don't get voice mail) (301) 829-5533

In my 3 attempts to request support via email ([email protected]) they never got it or responded.

Also FYI, if you buy direct from them if you do need a replacement the can ship one out as soon as your case is approved. If you buy from another source (like I did) they need to get the old one first.
 
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
RW would you mind attaching your preset to this thread? We can all just use that and be confident in the test set-up.

My 8 sample cells just arrived. They all have a voltage of 3.29V - 3.293V.
I just wanted to start charging them. How can I create a custom (user) preset?
Maybe I overread something in the manual, but i didn't find anything about it.
If I delete a preset and want to edit it, the charger says it can't edit an empty preset or so.

I don't have the PC USB connector yet, because I didn't find it in germany anywhere...
 
I have only done it with USB cable. I have run custom presets without the USB cable and I am pretty sure you can program but I don't think it will report the capacity? The USB connection is what logs the data and where I record my capacities.
 

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I have only done it with USB cable. I have run custom presets without the USB cable and I am pretty sure you can program but I don't think it will report the capacity? The USB connection is what logs the data and where I record my capacities.
Just got my FUIM3 and started to put cycles on the cells.
I setup a discharge current of 20Ah but the PL6 only discharges at 8.0Ah. Why does it do this? Is that the max. discharge current without regenerative discharging?
How do I tell the PL6 to measure the internal resistance? It just says..
Cell 1= -.- mΩ

Btw. my first cell was 19161 mAh but @ 8A & C/10 and the same voltage that you use..

Just to clarify, you use and post the discharge capacity not the charge capacity, right?
 

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Just got my FUIM3 and started to put cycles on the cells.
I setup a discharge current of 20Ah but the PL6 only discharges at 8.0Ah. Why does it do this? Is that the max. discharge current without regenerative discharging?
How do I tell the PL6 to measure the internal resistance? It just says..
Cell 1= -.- mΩ

Btw. my first cell was 19161 mAh but @ 8A & C/10 and the same voltage that you use..

Just to clarify, you use and post the discharge capacity not the charge capacity, right?
I think you have the supply set to power supply an not battery. It has to be connected to a 12 or 24V battery to do regenerative discharge.

IR will only be calculated during charge and can only be calculated on a cell with less then 75% charge.

Yes. You post the Discharge capacity as this is what is actually available in the cell.

-Adam
 

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Discussion Starter · #17 ·
Just got my FUIM3 and started to put cycles on the cells.
I setup a discharge current of 20Ah but the PL6 only discharges at 8.0Ah. Why does it do this? Is that the max. discharge current without regenerative discharging?
How do I tell the PL6 to measure the internal resistance? It just says..
Cell 1= -.- mΩ

Btw. my first cell was 19161 mAh but @ 8A & C/10 and the same voltage that you use..

Just to clarify, you use and post the discharge capacity not the charge capacity, right?
I think that you don't have the balance wires connected. In addition to the charge cables you need to connect pins 1 + 9 (the red and black ones) to the cell to get the highest current. These are also used to measure the resistance.

Yes, you want discharge capacity. (you only worry about charge capacity if it's for a TV show :)
 

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I think that you don't have the balance wires connected. In addition to the charge cables you need to connect pins 1 + 9 (the red and black ones) to the cell to get the highest current. These are also used to measure the resistance.
Thx.. I Had to connect the balance wires. I connected 1 and 9 but when I look at RWAUDIO's blog I can see that he connected the black wire and the white one next to it. What's the correct configuration?
Now it is discharging @ 38A.

Edit:
I tested 2 Cells.. both had a Ir of 4.6mΩ. Could it be because I used 1 and 9 of the balancer cables?
Do your cells get slightly warm when charging or discharging @38A?
 

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Thx.. I Had to connect the balance wires. I connected 1 and 9 but when I look at RWAUDIO's blog I can see that he connected the black wire and the white one next to it. What's the correct configuration?
Now it is discharging @ 38A.

Edit:
I tested 2 Cells.. both had a Ir of 4.6mΩ. Could it be because I used 1 and 9 of the balancer cables?
Do your cells get slightly warm when charging or discharging @38A?
There are two ways to correctly hook it up. However you need the matching software settings to the hardware configuration that you use. If you are using the PC interface go to the options tab and under start settings there is a pull down called "Node Wiring" this basically tells the charger what wires to use. It's in the manual but I believe FMA wiring uses 1 and 9 and XM/EH uses 1 and 2.

The important key to getting consistent Ir readings is to use alligator clips or similar to connect the balance wires to the cell tabs directly and not the current carrying blocks/connectors or whatever you are using to connect the charger to the cells. (Notice in the attached picture I keep the high current connections and balance wires as separated as possible)

My cells get warm to the touch but not hot when charging/discharging at 38A.
 

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