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IMPULSE-ive Marketing

Old 01-26-2006, 10:51 PM
  #1  
Greg Covey
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Default IMPULSE-ive Marketing

Hi,

As the Director of Marketing for FMA Inc., I understand the need to promote your products and put them in the best light to attract customers. At FMA, we have always been more conservative in advertising and shy away from techniques that stretch the truth. We boast the facts and have serious pride in our products and overall integrity.

As an R/Cer, I have seen some of my favorite vendors push the limits of marketing and have held my tongue in 2005. In 2006, I have seen false marketing go too far and feel that I must speak to protect the users, the hobby, and the new Lithium technology that has boosted electric flight to new limits.

A new Lithium pack brand called Impulse is distributed by Ripmax in the UK and sold in the U.S. at Hobby People. Impulse has started a new marketing trend to re-label manufacturers cells in an effort to boost the discharge "C" rating. Although there may be other misrepresented cells, I have uncovered two of them below.

The Impluse 1450mAh (23C) cell is rated at 33.3amps "Maximum Continuous Discharge". This pack is actually made from Saehan 1900mAh (12C) cells rated at 22.5amps by the manufacturer. FMA has tested these same 1900mAh cells as (8C) 15.2amps. The cell starts to puff at 20amps continuous and reaches 166 degrees F.

Impulse also has a 950mAh (25C) pack that boasts a 23.7amp "Maximum Continuous Discharge". This pack uses Saehan 1320mAh (12C) cells rated at 15.8amps by the manufacturer. FMA has tested these same cells and plans to rate them as 8C (10.5amps) at 140 degrees F for continuous discharge when used in the new Cellpro Slimline packs that will be available soon.

When used within proper rating limits, the Saehan (Gen III) cells provide good capacity and performance in a slender, light weight pack.

The misrepresentation of true cell ratings destroys the cycle life of the Lithium pack and costs the customer more money as it needs to be replaced in a few dozen cycles. The absurd ratings promoted by Impulse also put the R/Cer at risk as these packs will puff and possibly blow when used at the promoted current levels for extended periods.
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Old 01-27-2006, 02:38 AM
  #2  
RD Blakeslee
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Originally Posted by Greg Covey View Post
Impulse also has a 950mAh (25C) pack that ... uses Saehan 1320mAh (12C) cells rated at 15.8amps by the manufacturer. FMA has tested these same cells ...
What equipment did FMA use and where is its data?

FMA's assertion that the Impulse 950 pack is, in fact, made from 1320 mAh capacity cells appears to be contradicted by data from another source:

http://www.rcgroups.com/forums/showp...53&postcount=2

- RD
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Old 01-27-2006, 01:12 PM
  #3  
Greg Covey
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RD,

Please review the photos carefully for your answers as the Saehan part numbers are identical on both the Impulse packs (which include capacity) and our evaluation cells directly from Emerging Power. We have data to display but please feel free to purchase packs from Hobby People to calm your own suspicions. Perhaps Rod can also open his packs to see what cells are inside.

As people look for less expensive cells (and they should) the vendors with less integrity will find ways to promote their products to appeaze the customers weakness. Their short-term goals feed on our desire for instant gratification. What they fail to reveal is how many cycles the pack will last at that rating. The latest promotion from Impulse goes beyond even that false claim to a level that may be hazardous to the customer.

For a general understanding of Lithium cell longevity and safety, please read my article on Lithium Power Solutions. Shortly, we will add cycle life data to the Cell Rating Spec so customers can see how temperature and discharge current affect the lifespan of their purchase. If people knew that their application only gave them 40-50 flights instead of 400-500 flights, they may feel empowered to change the setup otherwise the cost per flight can be quite high.
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Old 01-27-2006, 03:10 PM
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Talking about cycle life, check the Hobby Lobby and Tower Kokam descriptions. They say " Packs can deliver up to 13.6 amps continuous which is 15 times their capacity (15C)."

Cycle life is not mentioned. What is the cycle life of those batteries at the maximium continuos discharge rate?
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Old 01-27-2006, 04:31 PM
  #5  
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If I understand you correctly, Greg, the cells in "Impulse" packs are not the same from pack to pack, even though the packs are rated as equal?

So, a pack like Rod tested is accurately advertised, whereas another "Impulse" might not be?

- RD
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Old 01-27-2006, 04:40 PM
  #6  
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Originally Posted by Greg Covey View Post
RD,... We have data to display but please feel free to purchase packs from Hobby People to calm your own suspicions. Perhaps Rod can also open his packs to see what cells are inside...
Kinda condescending, aren't you Greg?

It really isn't a matter of our suspicions, as much as it is a full disclosure on your part of the evidence supporting your accusation.

- RD

Last edited by RD Blakeslee; 01-31-2006 at 03:39 AM.
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Old 01-27-2006, 05:21 PM
  #7  
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Other than someone's hand-written magic marker saying "1320" I don't see anywhere where the cells are indicated as being 1320ma. Did I miss something?
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Old 01-27-2006, 08:31 PM
  #8  
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Greg,

Looking at your Impulse photos, it appears that an inference may have been drawn that cells from the same manufacturer having the same size designations are necessarily the same cells, but that's not true.

For example, compare the two TP cells in the attachments. Note the designations stamped on each cell and their very different performance characteristics.

EDIT, 1/28/06: THE TEMPERATURES ON THE GRAPH WERE ACCIDENTALLY REVERSED, i.e., the temperatures assigned to the red curve should have been assigned to the black, and vice-versa.

Greg, If you'll post your data, we may be able to compare yours with ours and find something helpful.

- RD
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Last edited by RD Blakeslee; 01-28-2006 at 08:14 PM.
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Old 01-27-2006, 09:22 PM
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Greg Covey
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RD,

I wasn't trying to be condescending but feel that you are rarely satisfied with data other than your own. I also know that you have the proper testing equipment. A quick purchase from Hobby People would help add data to this cell. I was not aware that Saehan would create identical looking cells that differ in performance.

There is now some confusing data regarding the Impulse 950mAh pack. At a current drain of 0.5 amps the pack yielded 1.01Ah. This is different than the 1320mAh Saehan sample cells which we received for verification testing in our new line. All numbers, dimensions, weight, and PCB numbers match between the two cells.

I guess there is something new about this cell which we must test further. I am disturbed that the manufacturer has various versions of the same cell using the same identical size and numbering scheme.

We will continue testing at higher currents but will be surprised if it survives a 25C (23.7amp) continuous discharge.

Last edited by Mike Parsons; 02-10-2006 at 01:02 AM.
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Old 01-27-2006, 10:20 PM
  #10  
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RD,

It would be interesting to see if you can duplicate greg's results. If you have the time and inclination please do the same tests and post your findings here.

marc
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Old 01-27-2006, 11:19 PM
  #11  
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Originally Posted by Greg Covey View Post
<SNIP>I was not aware that Saehan would create identical looking cells that differ in performance.

There is now some confusing data regarding the Impulse 950mAh pack. At a current drain of 0.5 amps the pack yielded 1.01Ah. This is different than the 1320mAh Saehan sample cells which we received for verification testing in our new line. All numbers, dimensions, weight, and PCB numbers match between the two cells.

I guess there is something new about this cell which we must test further. I am disturbed that the manufacturer has various versions of the same cell using the same identical size and numbering scheme.
Greg,

I have several observations to make:
1. Your photo of the 1450 pack Saehan cells is identical to the 1450 Kokam counterfeit I posted in this thread. Please see the side by side photo of the cell with the photo you took below.
2. The 950 Impulse delivered 0.99 Ah at 0.95A (see the thread here)
3. I am currently carrying out a 0.264A discharge on the 950 2S Impulse - the voltage knee has been reached at 0.85 Ah (0.2C if 1320 mAh), so it looks like the pack will deliver ~1 Ah at this low current. I'll post this curve when it completes.
4. The 'counterfeit' 1450 Saehan cells do not perform like the 950 Impulse, from your statement above I assume that the Saehan 1450 in the pack does not perform like the Impulse 1450.

It seems to me that the same Saehan designation is being used across vastly different cells.

Rod
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Old 01-28-2006, 12:09 AM
  #12  
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Originally Posted by admin View Post
RD,

It would be interesting to see if you can duplicate greg's results. If you have the time and inclination please do the same tests and post your findings here.

marc
marc, I would be glad to.

Greg would you send me a copy of the cell at issue? That's the only way I know of to be sure we're testing the same cell, since designations on the cells cannot be relied on to establish identity.

I'll PM you my mailing address, if you agree.

- RD
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Old 01-28-2006, 12:24 AM
  #13  
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Default Impulse 950 1.01 Ah at 0.26 A

Discharged at 0.26A gave 1.01 Ah.
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Old 01-29-2006, 12:08 AM
  #14  
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RD,

We should be able to do that. The cells are at FMA in MD and I am back in NY now. Please specify if you want one of each new Impulse cell; 1450mAh and 950mAh. We bought two cells packs so Eric at FMA can keep one each on file also.

I would like to clarify that in my second post, when I said that we have data to show, it was on the Saehan 1900mAh (12C) cell and 1320mAh (12C) cell that we were evaluating for the new Cellpro Slimline series. At the time, I didn't realize that the Impulse cells were different internally. Eric started testing the Impulse 950 cell on Friday and I did not hear any results other than the initial low current test for a capacity check. I am assuming that Eric will continue various current level tests on Monday.

Rod,

Thanks for the data. All these cell counterfeits have me puzzled. On a lighter note, what if the so-called Gen 4 ThunderPower cells turn out to be Kokams?
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Old 01-29-2006, 01:48 AM
  #15  
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Originally Posted by Greg Covey View Post
RD,

We should be able to do that. The cells are at FMA in MD and I am back in NY now. Please specify if you want one of each new Impulse cell; 1450mAh and 950mAh. We bought two cells packs so Eric at FMA can keep one each on file also.

I would like to clarify that in my second post, when I said that we have data to show, it was on the Saehan 1900mAh (12C) cell and 1320mAh (12C) cell that we were evaluating for the new Cellpro Slimline series. At the time, I didn't realize that the Impulse cells were different internally. Eric started testing the Impulse 950 cell on Friday and I did not hear any results other than the initial low current test for a capacity check. I am assuming that Eric will continue various current level tests on Monday.

Rod,

Thanks for the data. All these cell counterfeits have me puzzled. On a lighter note, what if the so-called Gen 4 ThunderPower cells turn out to be Kokams?
Eric reported at end of day Friday that the IMPLULSE pack delivered 1010 mAH at 0.5C. That correlates with the curve Rod posted on a different cell of fhe same make. The 950 and 1450 cells are exactly the same size and weight as the TP/Saehans 1320 and 1950 respectively. The tests just run and examination of the cells pictured lead to the following:

1) The issue that has been highlighted by Rod and others is that the TP packs have excessive heat rise with increasing discharge rate. I have tried to explain that light weight is OK if you keep the discharge rate down to the point that temperature does not go much over 140 deg F.
2) The main strategy for the three generations of TP packs has been that they are much lighter than competing packs. That strategy has been to criticize all other vendor packs as being too heavy, amplified by claimants who report improved flight performance for TP packs. The fact is, wattage delivered is the primary measure of cell performance and cell weight has little effect in todays brushless powered models. Yes, it may be a factor in some of the older generation , small, park flyers with geared brushed motors that are marginal flyers.
4) However, the temperature rise leads to short cycle life and early problems of the kind posted by several, including Qban Flyer.
5) Extensive testing has shown that the heat rise in a pack is related almost exclusively to the mass of the pack. Even air cooling has little effect and having the cells separated or abutted makes little difference.
6) The route taken to a solution by Saehans but not announced is to make a rellatively heavier cell. The capacity of a cell is a direct ratio to the amount of lithium in the cell. UN/DOT specifications for transport use Lithium Equivelant that is 0.3 X capacity in AH.
7) The capacity of a cell that is the same dimensions and weight as the 1320 has enough less lithium in it to reduce capacity to 1010 mAh instead of 1320.
8) The effect is to increase the mass of copper, aluminum, etc in the cell relative to the amount of lithium to a) permit better heat management and b) to be able to claim a higher discharge rate. This is a tacit admission that the TP cells are too light to yield the service life that most modelers want and certainly much less than the claims.
9) Effectively, the discharge rate of the 1320 cell has been reduced to about 14C by this action but without the run time of the 1320 when at lower loads.
10) The web sites with the IMPULSE packs have no dimensions, weight, or discharge curves; just state that the pack is a 25C. On Monday, the sample packs will be run at up to 25C to see what the temperature rise is. At completion, a cell will be dismantled to get a count of plates relative to the 1320 and failure mode and effects will be analyzed.
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Old 01-29-2006, 03:14 AM
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Originally Posted by Fred Marks View Post
10) The web sites with the IMPULSE packs have no dimensions, weight, or discharge curves; just state that the pack is a 25C. On Monday, the sample packs will be run at up to 25C to see what the temperature rise is. At completion, a cell will be dismantled to get a count of plates relative to the 1320 and failure mode and effects will be analyzed.
No discharge curves; however the data sheet that was included does give the weights and their maximum ratings for the cells (attached).

The discharge curves I ran up to 20C suggest that the temperature rise will be to 140F at 20C and ~ 160F at 25C (attached). I feel comfortable in saying it has a strong performance up to 20C, but I wouldn't personally push it to the 25C as stated (which is why I did not).

The rating of the cell by the manufacturers at 25C seems to be on the same basis as some other manufacturers: maximum discharge current where the voltage is above 3V and temperature <= 160F. Personally I dislike temperatures around 160F as several of us have shown that at these temperatures cycle life can be measured in single digits, whereas at 140F similar problems are not encountered. I'm sure that once RD's cyclic rig is in full operation we will have additional quantifiable data across many manufacturers and may be able to confirm this.

..... So I would have rated the performance (based on the tests) as a solid 20C, however the particular vendors have rated at 25C on what seems a simlar basis to many other vendors for different cells.

Rod
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Old 01-29-2006, 05:06 AM
  #17  
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5) Extensive testing has shown that the heat rise in a pack is related almost exclusively to the mass of the pack. Even air cooling has little effect and having the cells separated or abutted makes little difference.


If air cooling has little effect why is it that most testers insist on testing with no forced air flow to insure worse case conditions for the cells and why does a 6MPH breeze typically reduce the maximum temperature by 15-25F?

Charles
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Old 01-29-2006, 05:17 AM
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Originally Posted by everydayflyer View Post


If air cooling has little effect why is it that most testers insist on testing with no forced air flow to insure worse case conditions for the cells and why does a 6MPH breeze typically reduce the maximum temperature by 15-25F?

Charles
If you separate the cells enough and duct air right down the pack, it might. However, packs aren't built that way and most have heat shrink covering that keeps cooling air from the inner cells. The inner cells get little cooling air. No evidence seen except undocumented, untested claim that 6mph airflow drops temp by 15-25 F. The TP packs have the cells glued together so zero cooling air goes over the inner cells.
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Old 01-29-2006, 11:58 AM
  #19  
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Re post #14, Thanks, Greg.

What I would propose to do is apply my standard graphing protocol to any cell(s) marc has in mind (post #10).

- RD
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Old 01-29-2006, 12:56 PM
  #20  
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Regarding the attention concentrated on temperature in LiPo cells as it affects their application in eflight:

In a recent test, one LiPo went 10 cycles @ 15 C with moderate degradation in its capacity, while another did not survive three cycles.
http://www.rcgroups.com/forums/showthread.php?t=467825
The survivor cell reached 176F.

The failed cell reached 169F.
http://www.rcgroups.com/forums/showpost.php?p=4291008&postcount=1

The interaction of cell temperature and weight also seems to get concentrated attention.
The weight per unit capacity of the failed cell is 2.07; 2.19 for the other.

I suspect differences in size and shape and especially, differences in their internal structural and chemistry, acount for much more of the difference in all LiPos’ performance than do temperature and weight differences alone. At my level of expertise, I’ll never figure out all the interactions but, to my way of thinking and for my purposes, it doesn’t matter.

I’m satisfied to subject LiPos to a more severe test than they’re likely to see in eflight applications, determine emprically which ones can take it and which ones can’t, and let it go at that.

The most annoying problem all of us face (it's come up in this thread) is getting a good ID on the LiPos we test. Some manufacturers and vendors deliberately obscure that information.

- RD

Last edited by RD Blakeslee; 01-31-2006 at 03:42 AM.
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Old 01-29-2006, 01:55 PM
  #21  
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Originally Posted by Fred Marks View Post
If you separate the cells enough and duct air right down the pack, it might. However, packs aren't built that way and most have heat shrink covering that keeps cooling air from the inner cells. The inner cells get little cooling air. No evidence seen except undocumented, untested claim that 6mph airflow drops temp by 15-25 F. The TP packs have the cells glued together so zero cooling air goes over the inner cells.
In the case of single cell testing there are no cells to space apart. As to the question of air flow being benefical in limiting / reducind cell / pack temperatures in flight, well like I have posted many times. The highest temperature read by me of any of my Lipolys aftert a flight has been 128F.

Even the airflow off of a CBA II will have a cooling effect on LiPolys being tested at high C levels and it is heated air.



Charles
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Old 01-29-2006, 02:26 PM
  #22  
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Originally Posted by everydayflyer View Post
... Even the airflow off of a CBA II will have a cooling effect on LiPolys being tested at high C levels and it is heated air...
The air around a cell undergoing graphing must be isolated from this, or any other disturbance, if "in still air" is the temperature standard for the protocol.

- RD
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Old 01-29-2006, 04:56 PM
  #23  
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I was referring to Fred's comment in post #15

5) Extensive testing has shown that the heat rise in a pack is related almost exclusively to the mass of the pack. Even air cooling has little effect and having the cells separated or abutted makes little difference
.

I am aware of

The air around a cell undergoing graphing must be isolated from this, or any other disturbance, if "in still air" is the temperature standard for the protocol.

- RD
If the purpose is to provide a worse case Serrano for the cells / pack.

My testing has for the most part always been more inline with actual in flight usage.

Charles
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Old 01-30-2006, 12:08 AM
  #24  
Greg Covey
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Aside from the usual nit-picking that goes on in threads like these, my main concern of user safety with the Impulse pack ratings have been calmed by Rod. It appears that the Impulse 950mAh pack will not be a safety hazzard when run at 25C.

We have also learned that a cell with the same physical characteristics and markings can be different internally and provide different performance. As usual, the buyer must be aware of the integrity of the vendors they choose.

Thanks to everyone for participating in this thread but I am closing it to allow others to post their data appropriately. RD can e-mail his address to me at [email protected] so we can send the cells out to him and then we'll have a minimum of three different testers providing data.

Last edited by Greg Covey; 01-30-2006 at 12:52 PM.
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Old 01-30-2006, 02:31 AM
  #25  
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Thumbs down Impulse Li Po,s

See FMA for answers

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