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Thread: C Rating

  1. #1
    Join Date
    Oct 2020
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    IL
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    Default C Rating

    I?m looking to get some batteries but I am not sure on the C rating. 2 seaking 180amp escs + 2- 4s 5000mah 70c lipo. 5x70 = 350amps, is this too much?

  2. #2
    Join Date
    Sep 2012
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    Tg
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    Default

    You can be guaranteed of one thing, the 'C' rating is never as good as stated by the manufacturer. That being said the higher the C rating the better it is, so you have no worries about using 70C batts on your setup. The better question would be what is the opinion/consensus of others on the actual batteries you are looking at for your application. I.e., would these (whichever) particular batteries be right for my boat? Don't be shy to ask for advice, it may save you money and grief in the long run.
    NZMPBA 2013, 2016 Open Electric Champion. NZMPBA 2016 P Offshore Champion.
    2016 SUHA Q Sport Hydro Hi Points Champion.
    BOPMPBC Open Mono, Open Electric Champion.

  3. #3
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    Oct 2020
    Location
    IL
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    68

    Default

    The ones I plan on using are from OSE, the Revolectrix. https://www.offshoreelectrics.com/pr...rod=rev-ys5000

  4. #4
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    Sep 2012
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    Tg
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    Default

    Quote Originally Posted by Thegreengiant12 View Post
    The ones I plan on using are from OSE, the Revolectrix. https://www.offshoreelectrics.com/pr...rod=rev-ys5000
    They will just fine.
    NZMPBA 2013, 2016 Open Electric Champion. NZMPBA 2016 P Offshore Champion.
    2016 SUHA Q Sport Hydro Hi Points Champion.
    BOPMPBC Open Mono, Open Electric Champion.

  5. #5
    Join Date
    Oct 2010
    Location
    FL
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    752

    Default

    Glad this thread is going just in time for my question. As long as I have been into brushless and LiPo boats I still don't fully understand the true meaning of the "C rating". Example.....

    My son has the UDI Arrow which comes stock with a 3s 2200mAh 25c LiPo. To give him more instant run time I bought him a couple Ovonic (Amazon special) batteries. They are identical in physical size but they are 3s, 3000mAh and 50c. I figured the extra amps would give him more run time but the Ovonic 3s, 3000mAh, 50c battery kicks the LVC on the ECS in a matter of 4-5 mins where the lower rating stock UDI battery gives him a solid 10-15 mins of hard run time with 90% wide open throttle.

    Just to add a comparison, my Scarab Sport CC has two outboards which run Turnigy 2845-3650KV motors and Turnigy 120 amp marine ESC's and I am using the same exact battery, the Ovonic 3s, 3000mAh 50c batteries and I get a decent run time. Granted not full time WOT like my son runs but I feel the run time is decent. I can run the boat for 15 mins with some decent speeds.

    So...on a 3s...for longer run time.....what mAh and what C rating?

  6. #6
    Join Date
    Apr 2007
    Location
    AZ
    Posts
    8,009

    Cool

    It is difficult to answer your question. First, many battery sellers just make up their C rating, there is no industry standard and the consumer can?t really test it anyway. The hobby industry went through the exact same thing with Ni cells 20 years ago. The safest route is to buy from a known, honest seller. Cheap usually means a higher risk of....fantasy C ratings.

    Assuming the C ratings are factual, if the motor tries to draw a high enough amperage the high C cells will deliver more current than the low C cells will. The C rating is just a way to look at a cell?s internal resistance. If both cells have the same capacity (another area were some sellers fudge the numbers) then the high C cells will run out of juice sooner since they will deliver more current faster.

    For the longest run time, get the highest capacity cells which will fit. For low amp draw applications, honest ratings of at least 30C are recommended - more won?t hurt. Limit current draw by controlling prop size and staying on step the whole time. I usually get high C cells regardless since I am less concerned with run time than with speed.



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  7. #7
    Join Date
    Oct 2010
    Location
    FL
    Posts
    752

    Default

    Understood and thank you. It makes sense too. The higher C rating will deliver the power quicker, in other words the capacity of the battery can be delivered in high bursts. Makes sense if I want to keep the operation of the boat the same but longer run time then just increase the amp of the battery. From 2200 to 3000 but keep the C rating at 25.

    Just to add more new info. Those Ovonic (Amazon) batteries I have found to be inferior compared to others. On my big boat I am running Hoovo brand, two ESC's, two motors and two drives. Two 6s 5200 50c batteries and the boat can be run hard for a pretty long time.

    So...I bought a couple more of the same brand batteries (Hoovo) for the twin outboard Scarab. These are 3s 50c 3200 mAh and the run time and overall performance is night and day from the Ovonic. So I believe the brand of battery matters now. Not that the Hoovo is much more expensive but they are certainly better.

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