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Lipo battery confusion RC Cars

Old 07-31-2016, 03:56 PM
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demsea16
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Unhappy Lipo battery confusion RC Cars

Hi, I am new to this site and to RC Cars. I have a RTR Traxxas Rustler VXL. I am looking to make it go 70+ mph. That means I need to upgrade the battery. I know that I need a 3S 20C lipo 8000 mAH 11.1v battery. I find battery with that exact match except it is 30 or 40C. Where can I find the 20C version? Does that matter? What does the "C" stand for? Will the charger that comes with the stock truck work for charging the battery? If not where can I find a battery charger for that battery? I know about the over charging thing and how it can start on fire if overcharged. I will watch it so it will not be a problem. Help, as I am lost.
Old 08-04-2016, 05:14 AM
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BarracudaHockey
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Moved to RC cars
Old 08-04-2016, 07:12 AM
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demsea16
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Wait, so is it moved to rc cars or do I have to move it?
Old 08-04-2016, 07:46 AM
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Moved (ed) past tense

I moved it to RC Cars, hopefully you get some answers now. RCUniverse FAQ forum where it was created was for questions about using the RCUniverse website.
Old 08-04-2016, 07:52 AM
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Actually I looked more closely at the question and its kind of generic.

C rating is the internal resistance of the battery, the higher the C rating the higher the discharge rate w/o damaging or puffing up the pack. So you can use a 30c battery where a 20c is spec'd, the only difference is that the higher C rated battery will likely be heavier. Also, C ratings are often more marketing than technical, some are accurate, some are optimistic, some are....well.....lets just say overly optimistic.

The stock charger will work for the higher C rated pack.

Here's some quick math to show you what the C rating means.

In your example an 8000 mah battery with a 20c rating can discharge at 160 amps w/o damage. (8000 mah x 20C) = 160,000 mah / 1000 to covert to amps = 160

A 40c battery would give you 320amps draw without damage.
Old 08-04-2016, 08:50 AM
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demsea16
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Ok, so just to clarify. Even though it says 20C, I can choose 40C and it will not destroy or wreck my rc car but actually help it against damage. Right?
Old 08-04-2016, 09:55 AM
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Correct, it will help the battery against over current damage at the expense of slightly greater cost and slightly more weight
Old 08-04-2016, 10:23 AM
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Ok, that helps so much and clarified some things for me. Thanks!!!
Old 08-08-2016, 04:05 AM
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I always go slighty higher than recommendations just to make sure everything runs cool. for batteries, having more head room on the C-rating means cooler temps than using bare recommendation. eg. 30C battery at the same capacity would run cooler than 20C at same capacity. but weight is added and dimensions of the battery is higher. i know this from experience..

higher c rating means quicker acceleration not top speed.

Last edited by David87965; 08-08-2016 at 04:11 AM.
Old 08-12-2016, 02:20 PM
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john01374
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The higher the C rating the better off you will be. The VXL motor under full load could easily tax a 20C 8000 battery. Personally I would go at the very minimum 30C but 40C would be better.

Less strain on the battery.
Old 08-13-2016, 08:19 AM
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EXT2Rob
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demsea are you looking at Traxxas batteries? I've read test reviews that they are usually better than the specs on the label. I don't think I've ever seen a Traxxas Lipo labeled any higher than 25C. That said, however, in general you're better off with packs rated at 40C at least.

The thing you need to watch out for is another obscure spec label. The one that tells you how the pack is configured. Most Lipos of 5000mah or less (I'll use 2S packs as example) are labeled "2S1P" meaning that the pack is made of two 3.4V cells in series. Where packs greater than 5000mah tend to be "2S2P". Meaning that there are TWO cells in parallel that make up one 3.4V cell. That means twice the internal connections, and higher internal resistance. Greater chance the pack is going to puff. (Swell) And that ain't good.

I have five Gens Ace 2S1P 5000mah 50C packs that are four years old and still going strong. A while back, I got a couple SMC Lipo packs to try cuz I wanted longer run time. They were 7000mah 70C but 2S2P. At first they out performed my Gens Ace. Greater run time, greater punch....but within six months the packs would get really hot, and eventually, they puffed. Performance went to hell, shorter run times than my four year old Gens...the SMCs got tossed from fear of them catching fire. So try to stick with 3S1P packs no matter what you buy.
Old 08-14-2016, 06:11 AM
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demsea16
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Are you trying to make fun of me? I am new, I said that. "Hi, I am new to this site."
Old 08-14-2016, 07:24 AM
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No it was a spammer, the bot just copies a post and adds a spam link at the end, he will be sent back from whence he came
Old 08-14-2016, 08:38 AM
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demsea16
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Oh ok, lol.

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