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  1. #1
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    Need help with lipo

    I'm new to electric r/c. I have a slash 4x4 and love it. It has the stock vxl system in it but thinking about buying a cc mamba max pro esc for it and also a lipo battery, and thats where i'm having problems. I noticed that the batteries have a "c" rating on them. What exactly does that mean? I can't decide on the battery because I don't know what"c" i should get.

  2. #2
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    C is the rating of continuous current that can be drawn. Now this is a ratio so not all packs are equal. The way you figure it out is the C rating times the pack capacity in amps. So if you buy a 20c battery that has a 5000mAh rating it would look like this 20cx5A=100Amps. So that pack will do 100 continuous amps. Now if you buy another battery that has a 20c rating but 4000mAh it would be 20cx4A=80 continuous amps. So as you can see not all packs are created equal even though the C rating is the same...

  3. #3
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    Also it's important to realize that when talking C rating you are talking about the size of the funnel that the lipo can deliver the power. A 20c batt has a smaller funnel and will struggle to deliver the power towards the end of a cycle but a 40c batt has a larger funnel and can sustain a higher discharge through the entire cycle. This is why in the beginning of a cycle of an equal mah batts but different C rating will yield almost the same speeds (of course not exact but not majorly differently like 10-15mph difference but usually pretty close under 5mph) but the higher discharge battery will outshine the lower discharge battery because its funnel towards the end of the cycle can still deliver more power towards the end of the cycle and now we can see a much bigger difference in speed. Another thing to consider when talking C rating is to understand choosing the right C rating according to the load of the application. I believe Castle recommends nothing lower than 25c for the SLASH 4x4.
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  4. #4
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    try the lipo first, If your new to electric you'll be happy with the performance difference. I gained 10mph in speed over the stock battery using lipo's. Get use to the truck with the lipo them make the step and get the MM pro setup with motor. That's what I'm doing, just my advice, do what is best for you. Have fun, i like the lipo power for now, but will be doing the new CC sct system I think for Xmas.

  5. #5
    RC Turnbuckle Jr.
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    Quote Originally Posted by kingdomracer View Post
    Also it's important to realize that when talking C rating you are talking about the size of the funnel that the lipo can deliver the power. A 20c batt has a smaller funnel and will struggle to deliver the power towards the end of a cycle but a 40c batt has a larger funnel and can sustain a higher discharge through the entire cycle. This is why in the beginning of a cycle of an equal mah batts but different C rating will yield almost the same speeds (of course not exact but not majorly differently like 10-15mph difference but usually pretty close under 5mph) but the higher discharge battery will outshine the lower discharge battery because its funnel towards the end of the cycle can still deliver more power towards the end of the cycle and now we can see a much bigger difference in speed. Another thing to consider when talking C rating is to understand choosing the right C rating according to the load of the application. I believe Castle recommends nothing lower than 25c for the SLASH 4x4.
    An accurately rated pack of 20C and adequate capacity will easily power the Slash 4x4. This whole issue of needing large "C" ratings seems to grow daily and is getting completely ridiculous.

  6. #6
    RC Turnbuckle Jr. Dadx2mj's Avatar
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    Quote Originally Posted by Jakey View Post
    An accurately rated pack of 20C and adequate capacity will easily power the Slash 4x4. This whole issue of needing large "C" ratings seems to grow daily and is getting completely ridiculous.
    I totally agree.
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  7. #7
    Marshal ksb51rl's Avatar
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    4s4 Speed Runs (My Results)

    Stock Gearing (13/54)
    8K / 12C = 29.8 mph
    8K / 20C = 31.1 mph
    6K / 30C = 31.5 mph

    Mod. Gearing (16/54)
    8K / 12C = 34.0 mph
    8K / 20C = 36.8 mph
    6K / 30C = 37.8 mph

    If you are geared to the moon and doing ultimate speed runs, it might matter a little more. Otherwise, 20C is more than adequate, both at the beginning of a run and at the end.
    Last edited by ksb51rl; 11-18-2010 at 07:18 PM.
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  8. #8
    RC Turnbuckle Jr.
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    Quote Originally Posted by Jakey View Post
    An accurately rated pack of 20C and adequate capacity will easily power the Slash 4x4. This whole issue of needing large "C" ratings seems to grow daily and is getting completely ridiculous.
    "Accurately rated" being the key words!
    Speed costs money, how fast do you want to go?

  9. #9
    RC Turnbuckle Jr. rag6's Avatar
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    It is still interesting to see a 10% difference in top speed from the 12c to 30c. Would this gap be even more if the capacity of the 12c was 6k? One other question, is the 12c an older "well used" pack?
    Surprised to see such a large difference.
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