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Tamiya mini cooper

Old 07-16-2014, 12:48 PM
  #21616  
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What I was trying to suggest is that the answer revolves around how small the internal resistance of the battery is, regardless of capacity, C rating, etc. Yes, there are other parameters that count, but because you can not rely on the information available, I wouldn't bother.

Some of your questions are not answerable otherwise. For instance what voltage would a battery show through the discharge all other things equal apart form C rating depends on the internal resistance of the two batteries. In other words, the C rating doesn't matter. In actual fact, our batteries are all of the same type (Li-Mn something or other) which are okay for discharge rates up to 40C temporarily. More than that is hogwash from people who want your money. That is simply because they are limited internally for safety such that they don't overheat to the point of runaway reactions (basically when your battery goes up in smoke). The critical temperature of the chemicals inside decides that and given as I said they're all the same chemistry, well, you do the math.

The C rating in principle is in fact the rating that gives the battery the capacity.

Here's how it works. If you discharge the battery at a current equal to the value of its capacity (say 1000mAh - hence 1000mA), the battery should last for 1 hour exactly. If your battery has 5000mAh capacity, it should discharge a current of 5000mA (5A) for an hour before it is flat. And so on. That is a 1C. Now, if you want to discharge it at 50 times that current (which by the way should be noted is a not-to-sneeze-at current of 250Amps!), it should last 50 times less, right? Wrong. It lasts a lot less than that, because of many things, most importantly energy loss as you guessed it - heat, the scourge of 100% efficiency and perpetuum mobile machines! Now heat is generated because of internal resistance, where have you heard that word before?

In real life, if you tried to deliver 250Amps through a load plugged to your battery I would hazard a guess your battery would perhaps last a couple of seconds before blowing up. Personally I am not willing to try.
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Old 07-16-2014, 12:49 PM
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This is not 'new news'. Even to the local TCS Finals Participants regulars. And I'm sure to many others throughout the US and Canada. Which is all the more reason why this recent debate/discovery baffles me. New race, new pac, better voltage, period.

Just sayin.
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Old 07-16-2014, 03:06 PM
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This is how I test. Light bulb load then take voltage readings every 15 seconds for up to 8 minutes. Higher average voltage will indicate a stronger battery pack. Around 2000mAh is consumed by this test (approximately 15amp discharge).

Used 50c limit as well when I organized races. Some complained, but in the end got a lot of new racers. $30+ to ensure racing was about skill and not $.
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Old 07-16-2014, 04:08 PM
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On a whole different subject: Who has heard any news about a replacement tire for the mushy S Grips? I was looking for some S Grips last night, but found none at my usual sources. I recall seeing something recently about a new model.
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Old 07-16-2014, 06:15 PM
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Mushy S-Grips are fine, without glued sidewalks. just need the rite setup.
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Old 07-16-2014, 07:04 PM
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Originally Posted by Robert_K
Shiny! Thanks.

Regards Robert
No problem!
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Old 07-16-2014, 07:39 PM
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Originally Posted by OSherman
This is not 'new news'. Even to the local TCS Finals Participants regulars. And I'm sure to many others throughout the US and Canada. Which is all the more reason why this recent debate/discovery baffles me. New race, new pac, better voltage, period.

Just sayin.
Nah, there wasn't any debate etc. happening. It's just that some of the recent posts raised a few questions in my mind. nisnai was trying to answer my queries, but missed the point, tho I thank him for the effort..

With the lipo revolution, I stopped thinking much about batteries. Nowadays, i just buy the highest capacity battery that fits in my M03 and go racing. I keep "fresh" packs for race packs and my practice packs are last years race packs.
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Old 07-16-2014, 10:27 PM
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Originally Posted by OSherman
Mushy S-Grips are fine, without glued sidewalks. just need the rite setup.
It's no so much setup as it is burning through fronts every 20-30 minutes, on carpet. After that, they're practice rubber.
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Old 07-17-2014, 04:26 AM
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Originally Posted by monkeyracing
It's no so much setup as it is burning through fronts every 20-30 minutes, on carpet. After that, they're practice rubber.
carpet? whats that?

i wasnt aware that 'they' (they, meaning the fast guys) use mushy-mushy on carpet. what happened to the m-grips for carpet?
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Old 07-17-2014, 05:37 AM
  #21625  
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S-grips and M-grips are both fine on carpet. S-grips on the front are fine with a silvercan, should last for more then 20~30min, rears last a long time on carpet. If you don't get that kind of 'life' out of them use a harder insert or go with the M-grips.
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Old 07-17-2014, 10:08 AM
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S Grips are the standard here right now. They're just what works best in our hyper-competitive club and race series. I've seen a few M Grips and even the occasional A or B slicks. The common factor between them all is fairly limited lifespan, with S tires going first. I'd like to try a set with the new super hard inserts. Might save me from my tire building routine of adding extra plies to the carcass to stabilize the tread.
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Old 07-17-2014, 11:39 AM
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Originally Posted by monkeyracing
Might save me from my tire building routine of adding extra plies to the carcass to stabilize the tread.
Would you explain that? Plies?
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Old 07-17-2014, 12:28 PM
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Sure, here's a link to an older post on the subject. It's just adding a strip of duct tape to the inside of the tire to prevent ballooning and squirming tread.

EDIT: Ordered some super hard foams. Maybe they'll help. Looks like there are no affordable S Grips from any of my usual sources, at the moment. Crap. If u can find some locally, it's $15/pr. (I've been paying $18 for sets of 4 premounts until now)

Last edited by monkeyracing; 07-17-2014 at 06:40 PM.
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Old 07-17-2014, 11:35 PM
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Hi All,

My dad is building a new M05 that we bought as a kit with the mini cooper body. It came with the tamiya brushless esc 02 but the standard silver can brushed motor. Is this normal in the kits now? The instructions doesn't include it, and the one that I built (came in the same box) had the older style esc.

Do we just not use the orange wire?
Is there any advantage/disadvantage?
Are these new ESC's any good?

Ryan
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Old 07-18-2014, 02:07 AM
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Very cool they're starting to include a more versatile ESC. Haven't seen this here yet. Yes, it can be used with a brushed motor. Orange is left out, yellow is positive, blue is negative. Pretty straightforward.
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