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Old 05-31-2007, 09:47 AM   #226
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Quote:
Originally Posted by Leodis
That's a great example of the half-truths I was talking about. Of course people will always try to come up with new ways to optimize their performance. However, I'm not a battery wizard and even I know that lipo packs these days are already "matched".
They are not matched by discharge curve on a per cell basis, like we are doing with NiMH cells. There are some individuals that are doing it, and they are noticing performance gains associated with doing this. Manufacturers ARE NOT yet doing this. What you are espousing are half-truths to propagate the LIPO will save the world argument.
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Old 05-31-2007, 09:55 AM   #227
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Dose anyone know what shops are selling the GP4600's ?
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Old 05-31-2007, 10:03 AM   #228
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Cypress,

Thanks for the info. Who are these folks that are doing it? I'd like to ask them what kind of performance gains they are seeing. I'd buy a more expensive lipo pack if it had better performance and was just as durable as the current lipos. Heck, they last so long that I wouldn't mind shelling out an extra $20 - $40 for one when my current lipo packs go soft in a couple of years.

I'm not spreading half-truths like a lot of company representatives on rctech and I don't think lipo will save the world or this hobby for that matter. I'm just going off my own personal experiences with lipo and NIMH and I can tell you that it will be just as hard to sell a discharge tray on rctech in 2 years as it is to sell a lathe nowadays. I've also noticed that the same people who were bitching about BL two years ago are the same people who recently switched over to BL and are currently bitching about lipo. Humans usually don't like change and this hobby is a great example of that.
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Old 05-31-2007, 10:03 AM   #229
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my only problem with any of this, is that the current electric environment is a "perfect storm" of sorts that will conspire against our hobby.. we have fantastically high performance batts with a horrible failure rate and serious durability issues which (more prominent at higher competitive levels) are almost required to compete.... on the other side of the fence we have new technology that shows "some" promise of alleviating cost concerns and durability concerns and maybe even helping to level the playing field between the have's and have nots, but they are virtually condemned by the major sanctioning body (which contrary to popular belief trickles down to even casual non-roar clubs). here is my problem. i am one of those people that have an extremely tight rc budget and need new batts but can't afford to buy anything that won't last or be legal for racing...
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Old 05-31-2007, 10:20 AM   #230
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Quote:
Originally Posted by Leodis
Cypress,

Thanks for the info. Who are these folks that are doing it? I'd like to ask them what kind of performance gains they are seeing. I'd buy a more expensive lipo pack if it had better performance and was just as durable as the current lipos. Heck, they last so long that I wouldn't mind shelling out an extra $20 - $40 for one when my current lipo packs go soft in a couple of years.

I'm not spreading half-truths like a lot of company representatives on rctech and I don't think lipo will save the world or this hobby for that matter. I'm just going off my own personal experiences with lipo and NIMH and I can tell you that it will be just as hard to sell a discharge tray on rctech in 2 years as it is to sell a lathe nowadays. I've also noticed that the same people who were bitching about BL two years ago are the same people who recently switched over to BL and are currently bitching about lipo. Humans usually don't like change and this hobby is a great example of that.
The only people I know of are a few electric pylon racers, who match them for their ridiculously fast planes. They say they achieve a higher voltage output, similar to the difference between the stick packs, and matched packs we car folk are used to. They say that they're the only people crazy enough to do that, but I think we all know the car community will push lipos to their limits.
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Old 05-31-2007, 06:13 PM   #231
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"matched lipo's".........seems like I read somewhere that the bigger lipo manufacturer's match by internal resistance (might have been Thunder Power, Kokam or Tanic, can't remember for sure). It's easy and quick to do, and can give some indication of cell performance. But the cells have to be in the exact same state of charge for the "matches" to be meaningful.

I'm sure SMC, Promatch, Competition Electronics and others are already looking into buying/building matching equipment for lipos. It's definitely coming.
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Old 05-31-2007, 07:10 PM   #232
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Damn, I come on here to read about GP4600 cells and all I get is lipo arguement! haha.. Stupid idiots.. haha I guess I'll have to ask my sponsor about them since most here have nothing better to do than argue about non GP4600 issues. Oh.. and before you bash me.. I do race lipo at the local club races... So there!
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Old 05-31-2007, 07:14 PM   #233
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(Originally posted by Mr. Black on lipo legalization thread)

Here is some insight:

#1 - ALL LiPo batteries are matched they have to be or they will not perform and quickly fail. Balancing does the same as matching since all LiPo's top out at 4.2v per cell. if you where to create a LiPo pack with un matched cells the pack would quickly fail this is also why you are not supposed to use cells of different lifespan as one older cell may be aged to the point where the cells will not stay matched.

#2 - Lipo batteries do come in different grades and the difference does not make them faster or slower is simply makes them safer or last longer even the cheapest Lipo will top out at 8.4V and be listed niminal 7.4V We choose what we feel is the highest level of LiPo cell in the world Kokam SLPB. Lower grade batteries will have less cycles and be more prone to going out of blance wich will further lesson their cycle life.


#3 - The advantage going forward will not be more voltage but higher C-rating, higher capcities and smaller price and size.

Last edited by hobbipro; 05-31-2007 at 07:26 PM.
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Old 06-01-2007, 08:11 AM   #234
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Quote:
Originally Posted by hobbipro
(Originally posted by Mr. Black on lipo legalization thread)

Here is some insight:

#1 - ALL LiPo batteries are matched they have to be or they will not perform and quickly fail. Balancing does the same as matching since all LiPo's top out at 4.2v per cell. if you where to create a LiPo pack with un matched cells the pack would quickly fail this is also why you are not supposed to use cells of different lifespan as one older cell may be aged to the point where the cells will not stay matched.
Again, They are matched by IR, and their nominal capacity, not discharge curve. Two cells with identical discharge curves will perform better as a pack, just as NIMH do. With Lipos it is very important that IR be matched to prevent one cell from dragging the other down, discharge curve isn't taken into account when manufacturers release their packs. The markets they've catered to in the past aren't as demanding as RC racers are, so it wasn't necessary. There can be significant differences in performance from pack to pack, and that is how those differences were explained to me by a very experienced electric Heli/Plane pilot.
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Old 06-04-2007, 12:36 AM   #235
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...our series rules allow upto 4600 mah currently (We currently run 4 cell...so don't tell me...LIPO, blah blah blah... We'll be doing LIPO in the near future, but that won't happen until NEXT season)

My question is - IS ANYBODY matching these cells in the US? If they are, what do they look like compared to the good 4200's?

Who has these cells available?
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