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Old 11-29-2006, 11:04 PM   #841
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A new pack of matched 4200's is faster than a 7.4V LiPo pack. You might see a bit of advantage with LiPo toward the end of the race, since it's got a smoother voltage curve, but the newer NiMH batteries are pretty good. As long as weight limits stay the same, NiMH is probably going to be faster than LiPo in terms of sheer voltage.

But, LiPo isn't about trying to be faster than NiMH. It's about the amazing convenience, the tiny amount of equipment required, and the consistency and longevity. A new 4200 pack will be faster... a 3 month old 4200 pack will not. The consistency of LiPo is king, and one of its biggest draws. Head to head, though, it's not going to be faster, and probably won't get much love from pro racers in competitive events. Luckily, that's about 0% of the R/C population, and nobody but that 0% actually cares about a tiny voltage advantage. It's certainly not worth the mountains of extra equipment required to make it happen.

Now, if minimum weight limits change, LiPo will reign supreme. And, wouldn't you know it, the wear and tear on cars and tires would be reduced as well.
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Old 11-29-2006, 11:27 PM   #842
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Quote:
Originally Posted by AdrianM
Advil - Take a decent set of IB4200's cycle it and note the average voltage. Do the same with a 4800 LiPo pack. You tell me which you would run.

Do the same test on the track and again tell me which you would run.

Its not going to come out the way you think.

You have done no testing and you have no clue but you insist on posting here like you know what you are talking about.
Let's all bash Adrian!!

No seriously, you are misinterpreting Advil. His track has fully embraced both LIPO and brushless. No FEAR of change up here in NorCal. Plus Advil forces his wife, son and daughter to race with him...how cool is that?

As for testing - yeah, I have all the data. I'm fortunate enough to have a job testing Lipos all day. I know Advil and I can forward tons of data to Advil so that he knows what he's talking about. The 20 and 30 amp continuos plots shows a huge advantage towards a brand NEW NIMH when compared to just about any LIPO. However, if you do a pulsed discharge at much higher rates, LIPO's far surpass NIMH. In addition, your high dollar 4200 becomes 3500 in about 10 runs. I have life cycle testing of LIPO's at full rated capacity showing a cycle life of over 450 cycles before a 10% drop in capacity for the Kokam cells (and only 100-200 cycles for all the other major LIPO manufacturers)

I've also done safety testing on LIPO's as well. I intentionally abused LIPO's from all brands to find out what makes them ignite. Some of them did ignite in a spectacular way. ROAR hasn't made any effort to understand LIPO's and has chosen to ban them.

All of us got interested in this hobby because the cars are fast. We mock it now, but at one point in time, all of us asked "how fast does it go?". I'm going to have a tough time convincing the kid down the street that my 4 cell touring car chassis worth over $1K with electronics is no faster than his radio shack RTR.
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Old 11-29-2006, 11:33 PM   #843
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[QUOTE=syndr0me]
...You might see a bit of advantage with LiPo toward the end of the race, since it's got a smoother voltage curve, but the newer NiMH batteries are pretty good. As long as weight limits stay the same, NiMH is probably going to be faster than LiPo in terms of sheer voltage...
QUOTE]

Sorry, not true. In my testing, NIMH actually has a flatter voltage curve under a constant current discharge compared to LIPO. However, most battery cyclers measure IR at one point in time - usually 1 or 2 minutes into the discharge cycle. IF you measure IR throughout the entire discharge cycle, the IR of NIMH goes way up, while LIPO remains pretty constant. What the racer "feels" is less voltage sag under high discharge rates with a LIPO so they are tricked into thinking that LIPO has a flatter discharge curve.
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Old 11-29-2006, 11:35 PM   #844
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Quote:
Originally Posted by linger
Sorry, not true. In my testing, NIMH actually has a flatter voltage curve under a constant current discharge compared to LIPO. However, most battery cyclers measure IR at one point in time - usually 1 or 2 minutes into the discharge cycle. IF you measure IR throughout the entire discharge cycle, the IR of NIMH goes way up, while LIPO remains pretty constant. What the racer "feels" is less voltage sag under high discharge rates with a LIPO so they are tricked into thinking that LIPO has a flatter discharge curve.
Ah, thank you for the correction. It seems like there's a lot of misinformation surrounding LiPo, even among people that embrace them.
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Old 11-29-2006, 11:38 PM   #845
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regardless its oval or touring, or onroad or offroad, nitro or electric
IMO, regardless how different their equipment and setup (prior to their field and track),
we would find same language, racing is going faster speed (on each field) and finish first, not the other way ( slower and DNF.. )

good thing is, if 4 cells significantly faster than 6 cells with more run time, then I think this thread is not so long like this,

in real world (we all see 2006 JMRCA thread) 4 cells is clearly one step backwards in the 1/10 TC 4WD speed terms
and one step forward in shorten battery life (at least for the current IB battery)

I am not an auto engineer, but I can said that basically Everything has its own proportion... why so complicated?

if said weight (not load) are reduced proportionally to voltage reduction, then it should give lower load to motor and ESC, bla, bla, bla,..

are people forgot other source of load that makes 6T motor looks as fast as 19T?? and still there reagrdless 6 or 4 cells?

as long as TC still retain 4WD system (either part time or full time), the acute problem will never solved.

its just move from (claimed) ESC or motor problem to battery problem ( see the JMRCA thread..),

yes, there is probably more efficient brushless setup and lower IR NiMH battery in the near future,

so I just wonder if the 4-cells idea is so then slightly change (..during this transition period??..) into >

1- Up to racer's ability and ingenuity to harness and match their cars equipment (..brushed or brushless, still NiMH..) properly prior to their own skills for longer 8 (or even extreme 15) minutes race.
TC 4WD > 4 cells minimum & 6 cells maximum, chassis weight limit proportional to batt selection, 15 minutes race

2- 2WD TC (like a F103GT, proper cars for)> 4 cells are allowed to compete with TC 4WD 4-6 cells??
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Old 11-29-2006, 11:55 PM   #846
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Quote:
Originally Posted by AdrianM
2. Some chargers will not charge or discharge 5 cell packs so some guys will have to run out and get new chargers right away. This is not the case with 4 cell all chargers can handle 4 cells.
Adrian:
Every hobby-grade R/C battery charger I've seen that is able to do 4 cells is also able to do 5 and 6 cells.... I've never seen a "4 cell only" charger (although, if I am wrong, guide me to where I can get one...it'd be nice to have for Mini-Z)

What's kinda odd is now you all are arguing for the status-quo...where-as not to long ago, it was agreed that changes need to be made to the hobby to make it "succeed" What do we need to change to make our hobby more appealing?
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Old 11-30-2006, 12:13 AM   #847
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Quote:
Originally Posted by RacingStorm
Damn, you just might be serious Kyle! I'll take my 3.5 back and run it with you just for fun....
Lets do it... i need to buy a 3.5 friday. Im going to run a 10.9 with 4 cell.
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Old 11-30-2006, 12:26 AM   #848
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Quote:
Originally Posted by linger
Let's all bash Adrian!!

No seriously, you are misinterpreting Advil. His track has fully embraced both LIPO and brushless. No FEAR of change up here in NorCal. Plus Advil forces his wife, son and daughter to race with him...how cool is that?

As for testing - yeah, I have all the data. I'm fortunate enough to have a job testing Lipos all day. I know Advil and I can forward tons of data to Advil so that he knows what he's talking about. The 20 and 30 amp continuos plots shows a huge advantage towards a brand NEW NIMH when compared to just about any LIPO. However, if you do a pulsed discharge at much higher rates, LIPO's far surpass NIMH. In addition, your high dollar 4200 becomes 3500 in about 10 runs. I have life cycle testing of LIPO's at full rated capacity showing a cycle life of over 450 cycles before a 10% drop in capacity for the Kokam cells (and only 100-200 cycles for all the other major LIPO manufacturers)

I've also done safety testing on LIPO's as well. I intentionally abused LIPO's from all brands to find out what makes them ignite. Some of them did ignite in a spectacular way. ROAR hasn't made any effort to understand LIPO's and has chosen to ban them.

shack RTR.
I agree with this 100%

not that t really matters
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Old 11-30-2006, 01:38 AM   #849
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I don't know that this has actually been answered, it's getting hard to keep track.

I'd be interested in having ROAR explain how 4 cell racing is going to help the r/c touring car industry grow. Also I would like them to explain how this is going to bring new racers into the industry.

Helps to better understand what they are thinking.
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Old 11-30-2006, 01:43 AM   #850
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Bob,

I think that is something everyone on here would like to know. WHay is Adrian the only one that chimes in on this subject? Is he the spokesperson for the Excomm?

Kevin
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Old 11-30-2006, 01:55 AM   #851
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Actually current IB cells ( World Champion Edition ) are no longer industry standard 7.2V . Take a look: 1.27V x 6 cells = 7.62 Volts. The numbers could be higher with matched cells. I see no point to ban the use of lipo ( 7.4 Volts ).

Good things about lipo batts:

longer run times
light weight
2 cells , if 1 cell broke, only 1 cell ro replace.
no need discharging and equalizing.
ability to be discharge constantly @ 7.4 V all the way to empty.
no memory effect
high life cycle ( 500 - 1000 charge / recharge )
racer can use only 1 battery set for the whole day racing eg. using 6000Mah or 8000Mah battery..... just top off between heats / finals.
no need battery assembling & soldering, just plug & play.
cheap lipo charger.
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Old 11-30-2006, 05:19 AM   #852
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Quote:
Originally Posted by AdrianM
Every option has its problems. The problems with 5 cell are...

1. In the short run you need 5 close matched 6 cell packs to make 6 5 cell packs. With 4 cell all you need is 2 close packs to make 3 4 cell packs.

2. Some chargers will not charge or discharge 5 cell packs so some guys will have to run out and get new chargers right away. This is not the case with 4 cell all chargers can handle 4 cells.

did you get the information from Japan and their race with 4 cell ? and what are their thoughts ?
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Old 11-30-2006, 06:18 AM   #853
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4 cell is just another dumb ROAR idea. We've been racing 6 cells forever now, and everything is just fine that way. Instead of worrying about how many cells we have strapped in our cars ROAR should focus on more important issues like how it can help prepare tracks to run races more smoothly.
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Old 11-30-2006, 07:24 AM   #854
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Your not going to hear a thing from Roar until they vote. Then you won't hear anything after that.
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Old 11-30-2006, 07:51 AM   #855
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Quote:
Originally Posted by Advil
Actually Adrian, it is you that has no clue. I don't care about LIPO as I don't run them. I care about the guys that do because it is easy for them to use. They bring one charger, some tools, some parts, their car, and a new set of tires. They run competitvely with us. (We make them add lead to their cars to make weight.) How simple is that? No lathes for com cutting (they run brushless), no need for dischargers and balancers. They only have to bring two packs to run. It is very simple for them. And it is BRINGING THEM TO THE TRACK! .

I think Art is on to something (is ROAR listening??)...get rid of NiMH and brushed motors...just fast forward to Lipoly and brushless...sounds like a lot more fun....or just sell all your electric stuff and go nitro.
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