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Old 11-21-2008, 02:06 PM   #16
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If C don`t matter how come I can feel a big difference between a 20C & 25C ?

Either you guys are all wrong about C or I don`t really feel the extra power...
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Old 11-21-2008, 02:15 PM   #17
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Originally Posted by Wild Cherry View Post
If C don`t matter how come I can feel a big difference between a 20C & 25C ?

Either you guys are all wrong about C or I don`t really feel the extra power...
If your motor setup will consume more then the 20c pack's amp drain capacity can allow then you will feel a difference.

other then that it's amazing what your mind will convince you of when your wallet is 100 bux lighter and your psyche wants to feel validated for the money you spent.
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Old 11-21-2008, 02:22 PM   #18
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yes it does but it means more then that when you are racing and not just bashing.

IF all things are constant except batteries. (Car, Driver, Motor, Heat length, gearing, track etc etc etc)

Lets set up a hypothetical with those constants and a 3200 mah battery and a 4800mah battery.

The higher the mah of the battery... the more voltage it will have left when the heat is over. Meaning that both lipo's are going to start with the same relative punch/top speed (as long as your c rating is such that the battery is not the limiting factor) as they are both starting out with 8.4 volts. However, as the heat moves forward the 4800 will have more capacity left and should have more voltage at the 5 minute mark. So... for racing stock having more mah is a good thing for this reason.

Make any sense?
What you are saying makes perfect sense to me but, I was told that the power a lipo delivers stays very static through out the run. I have also been told that you can take a 5000mah battery charge it once in a stock class and run the entire day (2 heats and a main all 5 min). Was I informed wrong?
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Old 11-21-2008, 02:23 PM   #19
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I've said it elsewere and I'll say it again. Having a higher C rating is MORE important in the stock classes since they hold a higher voltage under ANY load even if they aren't approaching their claimed current limit. That being said, you can't trust half the C ratings that are being claimed out there so it doesn't really matter...
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Old 11-21-2008, 02:32 PM   #20
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Just remember one crash during a 5 min race will cost you + -10 seconds. Thats way more that 10c can get you.
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Old 11-21-2008, 02:39 PM   #21
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I'm tired of buying new lipos every two months because of the C ratings going up every month or so. Is there some maximum C rating rule anywhere? When will it end?
Like other have said, no need at all to be buying new lipos every 2 months...just make sure you make a wise choice in which pack you choose for your class. Get packs from a manufacturer with a good reputation in the racing world, and look for the pack that best suits your need and budget and HAVE FUN

C rating is not everything or the most important factors. It's only part of the picture, and most people cant even tell the difference between a 20C and 25C pack performance wise.
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Old 11-21-2008, 02:44 PM   #22
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you can't trust half the C ratings that are being claimed out there so it doesn't really matter...
At least SMC has been upfront about their packs and they are doing a great job on posting their packs numbers to we know what we're getting into...it's much better than what others have not been doing
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Old 11-21-2008, 04:28 PM   #23
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Also remember, a lot of companies are lying about the numbers just to sell more batteries at a higher price.

Large thread already on this.
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Old 11-21-2008, 04:30 PM   #24
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RC racers are always complaining about batteries. For years we have heard when will the sub-c cell makers stop increasing the capacity or stop releasing new cells but the fact is technology improves over time and battery manufacturers will always try to make better batteries.

With Lipo it's not any different as there are better materials being developed and used. A true 35C pack wasn't available 4 months ago but now it's possible and we will see 40 , 45 , 50 and so on as technology improves.


Although higher C rates should help performance I don't think it's a big difference in RC cars as were putting allot of loads on the packs. If you take our 24C pack against our 28C pack you will not see a difference on the track in limited motor classes. If a pack has a higher C rate it should typically help it's cycle life as well.

So when you have a pack that gives you good performance it doesn't mean you need to go buy the latest and greatest as you probably won't notice a bog difference. After all driving and car setup is way more important than the latest and greatest pack.
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Old 11-21-2008, 04:34 PM   #25
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Originally Posted by sheetmetal2 View Post
What you are saying makes perfect sense to me but, I was told that the power a lipo delivers stays very static through out the run. I have also been told that you can take a 5000mah battery charge it once in a stock class and run the entire day (2 heats and a main all 5 min). Was I informed wrong?
This is true, but I don't think you would want to do that. Lipo voltage will still drops throughout the run, so not charging it between runs means it will get a little slower each time...
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Old 11-21-2008, 04:38 PM   #26
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This is true, but I don't think you would want to do that. Lipo voltage will still drops throughout the run, so not charging it between runs means it will get a little slower each time...
Depending on what you race this might actually help many people
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Old 11-21-2008, 05:04 PM   #27
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Originally Posted by MACHFIVE View Post
I'm tired of buying new lipos every two months because of the C ratings going up every month or so. Is there some maximum C rating rule anywhere? When will it end?
Don't buy them. It is just a great way to sell batteries to the consumer. Look every business has a way to promote and sell things and for lipo it is the C rating. Your average racer won't notice a difference from 25C from 30C anyways.
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Old 11-21-2008, 06:04 PM   #28
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Well SMC defines C rate as the discharge current limit a pack can sustain while maintaining at least 90% of it's capacity. This means their 4000mah 28C pack will put out 3600mah at a constant discharge rate of 112amps. The problem is that this is not a "standard", so every manufacturer uses a different set of rules & measures. Some use 80%, and other just list their C rating as the max load before the pack explodes...

BTW: Punch is still a function of internal resistance and average votlage just as it was with Nimh. Until packs have this info printed on them, we have no real way of comparing them...

Last edited by 94eg!; 11-21-2008 at 06:36 PM.
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Old 11-21-2008, 06:26 PM   #29
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Our 4000/28C can retain 90% of it's capacity at a 112 amp continous which is 28C. See graph below.

There are some standards for Lipo manufacturers but some will use different methods to achieve different results that normally will give there packs a better C rate as this is important for marketing. Most Lipo manufacturers use 1C to determine capacity but I have seen some that use .5C but they do print it on there website. Maybe the consumer should ask the company selling the Lipos how the calculate there C rate to see if they are using a good method. I think why some seem to inflate the C rate or chose a method that isn't as stringy is because they know that equipment to test C rate is pretty expensive as it requires allot of power dissipation to pull 100-175 amps. So if the consumer can't test the C rate they feel they can claim whatever they want.

As far as printing the IR , Voltage and Capacity on the packs that could help compare packs but the problem with this is that you need to use a GFX and where you decide to attach the voltage sensing leads will impact the numbers. Here are some examples with the same pack.

Voltage leads attached to the balance connector: 5.5 - 7.42

Voltage leads attached to the end of the power leads: 6.5 - 7.39

Voltage leadse attached to the power connector on the charger side: 8.0 - 7.35


Pack and room temp will also have an impact on the numbers and so will the charge rate.

There are also other things such as overcharging or using a charger that tends to charge a bit past 8.40 will also make the numbers look better.

So comparing numbers would only work when comparing packs from the same company.
Attached Thumbnails
When will C rating stop going up?-4000mah-graph.jpg  
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Old 11-22-2008, 03:12 AM   #30
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Hi what is 2s stand for in lipo's label.

is it better to charge a lipo in 1s although its written 2s
or use 2s?

I know its out of topic, but dont know where can i post this question, please advice
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