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  1. #1
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    C rating on battery question

    Gotta pick up new batteries for this thing. One question. 2 3s lipos in series with 20C each makes a 40C 6s lipo right?

  2. #2
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    nope. say you have 2 3s 20c 5000mah. series you get 6s 20c 5000mah. parallel you get 3s 20c 10,000mah.

  3. #3
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    Quote Originally Posted by gryzor View Post
    nope. say you have 2 3s 20c 5000mah. series you get 6s 20c 5000mah. parallel you get 3s 20c 10,000mah.
    Exactly!

    Though I think ...in parallel only....a pair of 10,000 mAh lipos vs. one 5,000mAh lipo might have a bit higher C rating just because the "tank" is bigger....meaning...if anything, less tendancy to sag under load since the capacity is so high. C rating is also tied in to capacity to some degree.

  4. #4
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    c rating is relative to capacity but putting two batteries in parallel doesnt change the c rating, only capacity. a single 3s 20c 5000mah 'should' do 100 amps. two 3s 20c 5000mah in parallel you get a 3s 20c 10,000mah which 'should' do 200 amps. this is of course theoretical as most battery companies blatantly lie about c rating, there is no such thing as a 100c battery or even 60c when actually tested. although within a brands lipo lineup, generally the higher c rating they have on them the better battery it is relative to that same brands lower c rated batteries. i used to fly rc helis alot and those guys take lipos much more seriously than the average ground vehicle guy. ymmv, i havent done any real testing myself just passing on the info from those who have.

  5. #5
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    At the very least putting two lipos in parallel should help the lipos resist sag under load...which might be loosely associated with an increased C rating, if not in a literal sense.

    usually in an individual lipo, you can tell a higher C rated as it is heavier and might even be a bit larger....if comparing within the same brand of course.

  6. #6
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    Alright. Well I’ll post a thread in a few months about how 20C lipos run in the UDR.

  7. #7
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    @GT Joe adding lipos in parrallel will help resist sag under load because the capacity is increased thus the amperage ability will be increased. the c rating doesnt change.

    @Peeeenuuutt i dont think i would bother with 20c lipos in the udr. especially no-name brands, a 20c rating is pretty low and likely not up to the task. even if the advertised 20c rating is correct, its like using cheap gas in your sports car, its just not going to last and perform like a better battery will. personally i take the reputation to mean more than the number they put on the pack.

  8. #8
    Marshal ksb51rl's Avatar
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    gryzor is correct in all respects...except for his last spelling of “parallel.”
    Alt-248 on the number pad = °

  9. #9
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    Lol...ksb.

    Gryzor: we seem to agree here on the basics....but then am I wrong with associating increased amperage ability and decreased sag with higher C rating? Isn't that the basic definition of a higher C rating?

    Not arguing....just sort of asking.

  10. #10
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    Quote Originally Posted by GT Joe View Post
    ... usually in an individual lipo, you can tell a higher C rated as it is heavier and might even be a bit larger....if comparing within the same brand of course.
    Typically when looking a two packs from the same vendor and of similar capacity, the lighter weight pack will have the higher C-Rating. Higher C-Rating is directly related to lower cell IR's and lower IR's are generally the result of using build materials of higher quality, such as notably thinner (read: lighter weight) separator layers within the cells. The 6000mAh/80C packs I have do not weigh much more than the 5000mAh/40C, all from the same vendor.

  11. #11
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    I was using my Admiral and Admiral Pros as my gage. Each Admiral Pro is higher C and weighs more and is a bit larger.

    Either way...it's hard to talk in absolute then with so many different products and technologies.

    Are you maybe referring to the new Graphene packs?

  12. #12
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by GT Joe View Post
    ...Are you maybe referring to the new Graphene packs?
    He is not.
    There is a vast difference in materials used to make some LiPos, especially in the thickness of the separator. Certain of these components made in Japan stomp all over the much more common quality and ubiquitous Chinese components. Unfortunately, there aren’t enough consumers willing to pony up the additional cash to pay for these.
    I think I got that right.
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  13. #13
    RC Turnbuckle Jr.
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    Quote Originally Posted by GT Joe View Post
    I was using my Admiral and Admiral Pros as my gage. Each Admiral Pro is higher C and weighs more and is a bit larger.

    Either way...it's hard to talk in absolute then with so many different products and technologies.

    Are you maybe referring to the new Graphene packs?
    ksb is correct! I am not referring to Graphene. I am referring to most RC LiPo packs in general. The more expensive and higher quality materials required to lower cell IR's, typically reduce cell weight, not increase it.

  14. #14
    Marshal ksb51rl's Avatar
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    FWIW, going back closer to the original topic, C-rating refers to the specs of the cells, not of the battery as a whole. It is a product of the cell components and construction. To say that adding two packs together will increase the C-rating is very close to claiming that adding two pine wood blocks together turns them into oak. For the batteries or the wood blocks you will see a decrease in sag under pressure, but that is directly related to the increase in size and sharing of the load, not to the physical properties of the materials.
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