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  1. #1
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    seires and paralel ampage and C rate..help please.

    hi all,

    I new to all this and coming from nitro so could use a liitle help to confirm whats what..

    I was under the impression after researching the internet (which is always controdictory) that when you wire in series and paralel that the ampage remains the same only the mah and voltage differ, it worked like follows:

    EG:

    2 x 3s 11.1volt 45C 4500mah (202amp) in series = 6s 22.2volt 45c 4500mah (202amp) setup
    2 x 3s 11.1volt 45C 4500mah (202amp in paralel = 3s 11.1volt 45c 9000mah (202amp) setup

    but another member has posted the saying that its like this,

    6S1P = 22.2V 4500mAh 45C = 45*4,5 = 202A
    3S2P = 11.1V 9000mAh, 45C but now the total capacity is 9Ah so 45* 9 = 405A

    I was referring to constant discharge, is he is is he talking about the amp capacity? im confused?

    anyone confirm please..

  2. #2
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    series adds voltage, but not capacity, parallel adds capacity but not voltage.
    i.e. 3s 4500mah in series with 3s 4500mah = 6s 4500mah
    3s 4500mah in parallel with 3s 4500mah = 3s 9000mah

    Discharge 4500mah 45C = 4500mah/1000 x 45C = 202.5A
    9000mah/1000 x 45C = 405A

    To work out the discharge rate you need the figures of both the capacity and C rating, C rating on it's own means nothing without knowing the capacity. As you see when the capacity doubled so did the Amps it can supply.
    Last edited by trax de max; 04-11-2013 at 05:16 AM.
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  3. #3
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    so double the mah of identical C rate lipo by running in paralel will in fact double the discharge rate.

    but 404ams constant disscharge 3s is going to be not as punchy on the mmm kv2200 as a 6s 202amp constant discharge because of the increse of voltage too? something like that, is this where you then need to start working out wattage?

    man its pretty complex, but I think I got , I know how to work out constant disscharge but didnt click that when you run paralel you then re-work out the C rate because of the increase of MAH.... so now thats been made clear I know for future.

    so you can run any lipo 3s or bigger upto 6s on the MMM provided it has a constant disscharge of 120 amps min? prob safer to stick to around 140 to leave a little head room for over C rated lipo's too. the greater the constant discharge the bigger the punch.

  4. #4
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    In parallel the C rate is still the same... the cells within the battery system have not changed. The reason they are capable of more amperage is due to the capacity of the new system that was created with the parallel harness.
    --It took me a bit to wrap my head around that one too. lol

    6S is always going to be more powerful than 3S... voltage creates the power. But, if the ESC/motor is demanding more amps than the 6S configuration can deliver, the packs themselves are going to suffer. They tell you this by heating up past the acceptable range of 100-120F. Due to this, I always attempt to have my packs have 10-20% head room as a minimum... meaning if I was running a 120 amp ESC my packs would be able to easily deliver 150 amps continuously.
    Whatever it is I just said... I could be wrong.

  5. #5
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    wow its confusing,

    (main Question) Its safe to use my 2 x 3s 4500mah 45C in both series paralel on the MMM?

    it will be low on power but will it damage or strain the the ESC or Lipo's?

    its ok to use any 2s and 3s (or 4+2s etc up to 6s) in series so long as they work out no more than 6s adn are above 140amp (to be safe)

    and 3,4,5,6s in paralel again provided they work out above 140amps

  6. #6
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    People commonly word it incorrectly:

    "Parallel does not DOUBLE the C rate!" and that's correct in that 45C does not become 90C, HOWEVER it DOES double the throughput OF the 45C. I.E. 1000mah @ 50C = 50amps. If you parallel two of those together, you now have 100amps ALTHOUGH you are still at 50c. It doubled, without doubling heh.

    You can series different cells together such as 4 cell and 1 cell, but they need to be the same discharge rate, and have roughly the same amount of use. You cannot parallel mismatching cells, and you should ONLY parallel same capacities:

    2s 5000mAh + 2s 5000mAh.

    The discharge rate should always be able to provide AT LEAST what the motor wants. You can have batteries that are capable of providing 2000amps, it won't hurt the motor, it's when you cannot provide ENOUGH amperage that issues start happening with the ESC and in turn the battery.

  7. #7
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    yeah, its making more sense now its been explained in a few ways, thank I appreciate the postd guys. I think its making a little more sense now,

    final Q,

    is it ok to run the MMM on only 3s provided its at least 120amps (140/150 to be safe) amps disscharge?
    I know it will be slower but If I was wanting to just potter around.. 3s wont be to low or cause any issue either for the lipo's or esc/motor..

    thanks again

  8. #8
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    3S wont hurt the MMM at all. And, the truth is, too low an amp rating wont hurt the power system, it will only hurt the packs. However, if you have a GOOD 45C, 4500mah pack... that will be enough to sufficiently run an MMM... 50-60C will feel very verly slightly better, but not in a HUGE way.

    On the other hand, if your 45C packs arent good quality and are therefore not truly supplying 45C... the MMM system MAY put to great a strain on them and cause damage.

    Higher C ratings are never a bad thing. But the realistic necessity of anything above about 40C in a car or truck is just opinion. In a boat or airplane... definitely.
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  9. #9
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    I have Team orion carbon sport hard cased. I think these are pretty good dont know anyone elses experience with orions or these inparticular.

    If I keep an eye on the temps on the lipo then when running and make sure they dont get warm (overwokred) I have a temp gun for my nitro's so can see what everythings runs at inc ESC MOTOR and lipo during the runs, I normally run them 6s adn they dont even get a little warm, I just wanted to see what it was like runnin the 3s as it would give me twice the run time which would be cool if I wasnt worried about speed, and maybe use it as 3s if anyone else that wants to have a go, so the slower the better in that case...LOL...

    I also have 4x stock traxxas NIMH batteries 8.4v I use series, logic tells me that the 3s setup will be slower than these being less Voltage, but if I get caught short and just want to potter aroung then the 3s could be an optiong still, I love 6s...

    I did notice the NIMH do get warm when running. should they or am I doing something wrong

  10. #10
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    I secretly have a crush on all things Team Orion, they have some gorgeous 90c packs... mmmm

    Running slower from 3s is of course a result of half the voltage, but while running slower you generally draw more power because you stop and go a lot more, so it is certainly a good idea to keep watch on the temps. But again, if the math adds up to you having enough amperage on tap, it simply will NOT be an issue! =)

    Chemically, NIMH's get hot when discharging, it's just how they work! Lipos get warm too, technically they want to be around 120f at optimal discharge rates!

  11. #11
    RC Turnbuckle Jr. rag6's Avatar
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    120 is as hot as you can let them get... I would not want to run them there all the time unless I had an unlimited supply of packs, and was a professional racer.
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  12. #12
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    I've read a lot of different RC Helicopter forums where they have crazy power draws over short bursts of time. Some people swear 90 is too hot, some people swear 130 is too hot. The point is, lithium polymer batteries chemically work best around 120f whether or not they will last longer running them cooler is still up for debate. I've read once that every degree over 140f reduces pack life by 12 cycles each charge, where as others say "naah who cares anyway, have fun... buy new batteries!" Running them cold isn't as efficient as running them "warm" where warm is 100f +

  13. #13
    RC Turnbuckle Jr. rag6's Avatar
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    Tom From spc told me that 120 is the max. I will take his word for it...
    Sit down, buckle up, hold on, pay me...

  14. #14
    RC Turnbuckle Jr. rjm2519's Avatar
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    I would trust Tom over them...lol batteries are expendable but damaging a pack can damage a lot more than just a pack it's not worth the risk.
    Dont handicap children by making life easy

  15. #15
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    so never allow lipos to get hotter than say 100-120F

    and what about NIMH?

  16. #16
    RC Turnbuckle Jr. rjm2519's Avatar
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    I would be aware if they break 100 and never let them break 110
    Dont handicap children by making life easy

  17. #17
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    thanks again all, once a gain very helpfull, appreciate it.

  18. #18
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    Quote Originally Posted by rag6 View Post
    Tom From spc told me that 120 is the max. I will take his word for it...
    140 is the cutoff temp for spc batteries, never let them got hotter than that.
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  19. #19
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    my temps max read is 111 but normally it's 95-105 straight after it's run. Been ok for a year or two, but i know i could do with some better packs, As they aren't the best of specs.
    Problems.The manual's good starting point. Simple

  20. #20
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by RevoDeano View Post
    I have Team orion carbon sport hard cased. I think these are pretty good dont know anyone elses experience with orions or these inparticular.
    I would be very, very surprised if those packs came close to the performance their 45C discharge rate seems to claim.
    Take T.O. specs with a bag o' salt.
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