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Old 12-19-2005, 07:40 AM   #946
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Last edited by cr250; 10-19-2013 at 04:11 PM.
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Old 12-19-2005, 07:53 AM   #947
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Quote:
Originally Posted by cr250
A 35-amp discharge does not "teach" cells anything. Many people, including matchers talk about their grading and matching techniques as if they magically induce some sort of artificial intelligence into the cells. Marketing is an incredibly powerful tool and ignorance is marketing's #1 ally.
Here is an area where science and application diverge. You are wrong. Cells that are discharged at a higher amperage feel more punchy on the track. You won't see this during cycling on a T35 or Turbo Matcher but any decent driver can certainly feel it on the track. I like to say that we race cars not not cell matchers. The track is where it counts.

Here is an example of what I perceive as training

Both packs have identical numbers.

Pack 1

4 cell Oval pack. Mod Races are 4 min and they use up 98% of the capacity on the track. They draw ~30-50A average during a race.

Pack 2

4 cell On Road pack. Mod Races are 8 min and they use up 98% of the capacity on the track. They draw 20-30A average during the race.

After a month of racing every weekend if you swap the pack between cars and try to go racing you will have very interesting results.

Pack 2 in an oval car will feel soft and lack punch.

Pack 1 In an On Road car will start off like a rocket and go soft at the 5 min mark and will most likely dump before 8 min.

I know consistent use does something to the way cell release energy. I have seen it over an over for every cell I have used in my last 20 years of racing.
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Old 12-19-2005, 07:59 AM   #948
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Even if you prove I am wrong and it is just some sort of crystal formation the work "Training" is still a valid plain speak term for expressing this behavior of the cells to R/C racers. You have to understand that 90% of the guys out there don't visit R/C tech, don't read instruction manuals, don't know how to program their own speedos, chargers, radio, etc. They understand "Training " not "Crystal formation on the Cathode and Anode ".
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Old 12-19-2005, 08:03 AM   #949
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cr250- How much chemistry do you understand? NiMH still have "memory effects." It's technically called the false bottom effect and occurs when the cell is not fully discharged. This can cause cadmium hydroxide (nickel dihydroxide in the case of NiMH) to passivate the electrode, or the battery to wear out.
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Old 12-19-2005, 08:09 AM   #950
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Guys, Adrian is absolutely right. There is a specific issue here where the *current* science and actual application diverge.

As being a part of both camps (the racing aspect and the tuning aspect), I know this is the case. I believe in part it is due to the very linear and simplistic way matchers discharge cells.

The discharge curves we work with really don't simulate what's going on the track as well as how the energy is actually released by our electronic equipment, etc. What we use currently is what's available. Having said that, I personally have been playing around with some different ideas for the matching process.

Honestly, Adrian's 'seat of the pants' feelings are completely valid to the seasoned racer.

Oh yeah, and the supposed 'lack of memory' in NIMH cells is a bunch of baloney. You better believe they behave similarly to NiCads. I looked at that whole issue as nothing more than marketing a new product.
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Old 12-19-2005, 08:23 AM   #951
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Originally Posted by Jon Williams
Guys, Adrian is absolutely right. There is a specific issue here where the *current* science and actual application diverge.

As being a part of both camps (the racing aspect and the tuning aspect), I know this is the case. I believe in part it is due to the very linear and simplistic way matchers discharge cells.

The discharge curves we work with really don't simulate what's going on the track as well as how the energy is actually released by our electronic equipment, etc. What we use currently is what's available. Having said that, I personally have been playing around with some different ideas for the matching process.

Honestly, Adrian's 'seat of the pants' feelings are completely valid to the seasoned racer.

Oh yeah, and the supposed 'lack of memory' in NIMH cells is a bunch of baloney. You better believe they behave similarly to NiCads. I looked at that whole issue as nothing more than marketing a new product.
Amen.

Acutally, if we want to get really technical about it, neither NiCd or NiMH batteries have a memory effect. However, they do suffer from a voltage depletion or voltage depression phenomenon. But practically speaking it is the same thing So as far as we are concerned (as R/C'ers) they suffer from memory effects.
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Old 12-19-2005, 08:26 AM   #952
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Old 12-19-2005, 08:33 AM   #953
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Old 12-19-2005, 08:35 AM   #954
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Quote:
Originally Posted by cr250
True science/engineering and correctly interpreted applications should provide similar results. Many times though human subjectivity muddies the comparisons. That being said, a 35-amp discharge absolutely does not make a cell better just because it was discharged at 35 amps.
I hear what you're saying, but what I'm proposing is that if you took those two packs and they turned out similarly on a linear discharge but yet felt completely different on the track, 'true science/engineering' is most likely *missing something*. Can I get a witness, Adrian?

The highest combination of 'true science' & laptimes is where it's at.
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Old 12-19-2005, 08:48 AM   #955
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Quote:
Originally Posted by daniz24
Maybe your battery is false peaking, you charging with a fan?
I've never experience that kind of problem with new batteries.
yes sir, im fanning my batts while charging. is that bad? if so, whats the bad effect? tnx for the reply.
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Old 12-19-2005, 08:54 AM   #956
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Old 12-19-2005, 08:55 AM   #957
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Quote:
Originally Posted by EAMotorsports
To get .03 like Danny suggest would be 30mV on the MM Cell Master. The cell master used Millivolts. I would start with 20 on the Cell master and check the temp. Then adjust till it peaks at 130 degrees F.

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ah ok, i tried 10 and the temp is just fine, around 98 deg F, i only engage to stock racing. If you recommend 20-30mv delta peak is it not too much for 5 min run in a medium built race track? tnx
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Old 12-19-2005, 09:07 AM   #958
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Old 12-19-2005, 09:09 AM   #959
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Originally Posted by curious mind
yes sir, im fanning my batts while charging. is that bad? if so, whats the bad effect? tnx for the reply.
Don't use a fan when charging
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Old 12-19-2005, 09:12 AM   #960
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Quote:
Originally Posted by cr250
I hear you also! Typically science lacks true capabilities to model a dynamic model or application. That capability though is improving daily. As you probably know many other factors may have influenced the two packs you are referencing and the differences you experienced.

A true scientific/engineering study would require a controlled environment and incredibly controlled parameters. Eight identical cells, assembled as smilar as possible. Both packs tested for IR, static voltages and core temperatures before cycling to verify nothing went wrong during assembly. Charge each under ideal conditions and discharge under identical simulated, varying loads while measuring the required data. Then and only then could an exact comparisons be made.
Agreed. Nothing to dispute on my part here.

As far as your earlier post re: voltage depression, etc. that would be a mini-holy grail IMO--recovering 'bad' cells/packs. Unfortunately, after trying all kinds of methods to return cells to their former state using current 'analog' methods, nothing really works that well. (Testing done of course on current linear equipment )
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