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"New" A123 cells (evaluation to follow)

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"New" A123 cells (evaluation to follow)

Old 05-14-2009, 11:27 AM
  #1  
StoneGod
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Default "New" A123 cells (evaluation to follow)

Hi everyone,

I've just received my new A123 cells from Steven at Robotic Power Solutions (http://www.battlepack.com/A123.asp). These are NOT the DeWalt cardboard wrapped cells that we are all used to. There cells are reported to be (and appear to be) of a higher quality build, and are tightly wrapped in a green plastic sleeve.

In the near term I will be complaring the "old" cells (new cardbaord sleeved cells) with the "new" cells (new green plastic sleeved cells), so we will get an apples-to-apples comparison. These cells have the same specs. from A123 Systems as the "old" cells do; however, I'm hoping/expecting to find lower IR readings and lower substandard cell frequency (i.e., cells that can't be charged, cells that can't be charged to their full voltage of 3.6v, cells that have a complete internal circuit break, etc.) in these "new" cells.

I will be reporting my personal findings as well as informing you of stats that I've been able to gather.

**Disclaimer** My testing may be more limited than some of you, as I don't have an Eagle Tree setup on my heli or the like. That said, I will be reported ALL of my observable and measurable findings in an unbiased fashion. Again, I have no affiliation with Robotic Power Solutions. I'm just an end user, much like the rest of you...and, much the rest of you, I too have encountered ALL of the "defects" I've listed above in A123 cells that I've previously purchased - all of which have been the "old" cardboard sleeve type cells. If those of you equiped with Eagle Tree setups, or other measuring devices, would be interested in adding your measurable data of these "new" A123 cells to my posting, please feel free to do so.
Old 05-14-2009, 12:26 PM
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Red Scholefield
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Default RE: "New" A123 cells (evaluation to follow)

Changing the sleeve on cells from cardboard to heat shrink doesn't indicate that the cells are any different. Not sure what problems you have had with the paper sleeved cells, but from all the input I have had the A123 cells we have been using since they became available have served well. I am still running my original 4S packs that I put in service in June of 06. And I'm flying these two or three times a week, year round here in Florida. Actually a pack made from paper sleeved cells is probably better than plastic shrink wrap as they can withsand much higher temperatures before the sleeving is compromised. We always employed paper sleeves on packs destined for high rate discharge applications.
Old 05-15-2009, 09:14 PM
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everydayflyer
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Default RE: "New" A123 cells (evaluation to follow)

Around 4 years ago some vendors claimed to have a source for A123 cells of better than DeWalt quality. It would appear that Steve do9es in fact have a source for a better grade of A123 cells. Perhaps these better / more consistant cells are the ones now being manufactured in the A123 Systems Enerland Plant which they purchased about a year ago and the DeWalt cells are now two or more years old.
Old 05-16-2009, 08:54 AM
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Red Scholefield
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Default RE:


ORIGINAL: everydayflyer

Around 4 years ago some vendors claimed to have a source for A123 cells of better than DeWalt quality. It would appear that Steve do9es in fact have a source for a better grade of A123 cells. Perhaps these better / more consistant cells are the ones now being manufactured in the A123 Systems Enerland Plant which they purchased about a year ago and the DeWalt cells are now two or more years old.
I would expect improvements to come with time, but my 3 year old A123s from DeWalt are still going strong. You have done some meaningful testing on A123 as a baseline, I hope you can get some of the new ones to verify if they are in fact "new and improved".
Old 05-21-2009, 01:59 AM
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Default RE: RE:

Hi everyone. Here is the "NEW" A123/M1 review I've been promising you, and for those of you that don't really want to read the entire review I've provided a summary.

Summary: The new (green plastic sleeve) A123 cells available at www.battlepack.com/a123.asp are of a much higher quality build than the older (white cardboard sleeve) A123 cells that we're all used to getting. Their IRs all meet spec., as do their nominal and peak voltages; however, (here is the BIG bonus) out of over 2700 cells obtained and sold through battlepack.com, they have reported that NONE have been found to be substandard/defective vs. 4-5% of the old version A123 cells. These new cells also appear to be a little lighter (by about 2.5g/ea) than the old M1 cells, and also seem (in my opinion) to solder more easily than the old style cells. Am I happy with these new cells? You bet...and I'll be buying more of them.


When I received the new cells from Battlepack.com, I opened the box and was surprised at the apparent quality of the cells. The lime-green plastic shrink wrap that covered the cells, as a replacement for the old familiar while cardboard sleeves, was flawless, professional, and made me immediately think that these cells where of a higher quality than the old ones.

First up, I tested each cell for its shipped voltage level. ALL eight(8) cells were at exactly 3.31v! That in itself made me wonder if my volt meter was working correctly, so I tested each cell again using my iCharger 1010B+ with the same results - 3.31v!!

The next thing I did was get setup for building my new 4s1p packs. Two 6" pieces of Deans 12 gauge wire (Black and Red), a female Deans connector, and three(3) shorter pieces of Deans wire for connecting the cells. All soldered onto the cells using Novak 3% silver solder.

Soldering the negative pole of A123s has never been very difficult, as they seem to take the heat well...but, soldering the positive pole has always taken more effort than I would otherwise like. The positive pole really sucks up the heat from the iron, and I've always been concerned about damaging the cells due to too much heat transfer causing them to overheat. This issue seems to be solved (or at least much improved) with these new cells. The negative and positive poles soldered up easily using my 80 Watt soldering iron, and very little excess heat was transferred into the cells themselves.

Once I'd finished installing the Deans leads, and connecting the 4 cells together in series, I installed a balance connector and then wrapped the new pack. I then repeated the process with the second pack.

Next up was testing Internal Resistance (IR) of the cells, so I connected the packs to my charger and ran the test. The IRs of the eight(8) new cells were: 8, 8, 10, 10, 11, 10, 11, 11. What does that tell me? Well, compared to my old style cardboard sleeved cells that I bought (supposedly new) off of ebay, these cells have lower IR readings. My old cells ranged from 12 to 14. That said, from a functional perspective I don't expect that there is much difference that would be seen...So, for all intents and purposes, I consider my new cells to be of equal IRs to my old style cells.

Next up was charging! I charge all my A123 cells to 3.65v (balanced) on my iCharger 1010B+. If a cell won't take a full charge, I write the max. voltage that it was able to charge to and put it aside (so I can later match it with other cells of the same max. voltage, and build a pack - at least that allows me to get some use out of them).

These new cells were all at 3.31v to start with, so balancing them shouldn't be an issue at all, but for the first charge - what the heck. So, I hooked up my packs and charged them. All of my new celled charged up to 3.65v without any issues. How does that compare to my last eight(8) cells of the old cardboard sleeve variety that I bought off of ebay? Well, of those eight(8) cells, only 5 would charge to 3.65v; two(2) charged to 3.35v; and one(1) cell wouldn't take a charge at all. In short, these new cells appeared to be head-and-shoulders above my old cells.

Now, having only a small number of old and new style cells, I decided to look into the rate of defective/substandard cells of both varieties. What I learned is that the old style cells (white cardboard sleeves) that we've been buying off of ebay or obtaining from DeWalt battery packs have a defect rate of about 4-5%. Further, these cells are the ones that A123 Systems has for R/C and tool uses.

In contrast, the new (green plastic shrink wrap sleeved) cells are not designated for R/C and tool use. They have the exact same specs. as any A123/M1 cell out there; however, they undergo a more stringent quality control process. From what I've learned from Battlepack.com, they haven't found a single defective cell in all of the new cells they've obtained from A123 Systems...and they've sold over 2700 of these new cells. So, even if I argue that 1:3000 of these new cells will be defective, that still leaves a huge gap in quality between the "old" and "new" M1 cells.

One last point I'd like to mention is their weight. I forgot about weighing the individual cells before I started building with them, because I just figured they'd be the typical 70g/ea. give or take a gram or two...BUT, when I weighed my two(2) new packs and compared their weights to my old packs, my new packs were a full 10g lighter! Could it be the difference between the cardboard sleeves vs. plastic shrink wrap, or is it that my soldering job has gotten THAT much better? Well, I don't think it's my soldering job.

Cheers and happy flying.
Old 05-22-2009, 12:06 PM
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dirtybird
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I have just received 20 cardboard cells from a seller on ebay. The seller said the cells were used.
Every cell measures 3.355V+,-0.005V. I am going to put them in my holder and check the IR.
It appears the seller has thrown away the bad cells in the process of using them.
I paid $7.75/cell
Old 05-26-2009, 11:24 PM
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I set 14 cells up in a 14s1p pack and charged them They were all in balance at 75% charge at the beginning of the charge and charged to 100% in less than 15 minutes. I think they are very good cells. I can't measure the IR since I seem to have misplaced my Harbor Freight meter.

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