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Thread: 3s on stock esc

  1. #1
    Join Date
    Apr 2009
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    la
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    Default 3s on stock esc

    will this boat run on 3s with stock esc 3s 5000 mah 30c ???????????
    Last edited by bigpapa; 07-20-2010 at 10:45 PM.
    THUNDER TIGER OUTLAW,THUNDER TIGER BANDIT
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  2. #2
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    Jan 2010
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    VA
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    16

    Default

    No ....

  3. #3
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    Jul 2010
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    PA
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    Default

    Once.....lol

  4. #4
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    Sep 2010
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    MI
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    44

    Default 2900kv Power Consumption

    I have just converted my Shockwave 26RS to brushless using the Widowmaker/ Shockwave 2900kv brushless motor and a Hobbywing ESC, and ran it yesterday for the first time using an Eagle Tree logger.

    On 2x 6 cell/ 7.2v NiCads (in parallel) the motor drew an average of 40A during 5-10 second bursts using an Octura Y534 plastic prop (similar to ProBoat original size, but the blades broke off mine a while ago.........).

    On 2S lipo (Flightmax 20c 5000 Ah) the motor drew 38-40A during 5-10 second bursts using a smaller prop (Octura X431 plastic prop) which I put on to try and reduce the motor load.

    On 8 cell / 9.6v NiMh (5000Ah Intellects) the motor drew 45-50A during 5-10 second bursts, also with the Octura X431.

    As the standard Proboat ESC is only rated for 30A continuous, not surprised they are getting cooked if people try 3S or even a metal prop with 2S lipo!

  5. #5

    Default

    I've got a grimracer 42 on mine... thing runs great, ESC stays cool as well. But yes the 3s will pop your esc

  6. #6
    Join Date
    Sep 2010
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    MI
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    Default More Eagle Tree Testing

    Did some more testing today on my Shockwave 26RS with the WM 2900kv motor.

    On 2S Lipo (Flightmax 5000mAH 20C) with a Octura Y534 (basically same as stock Pro Boat prop) I got 28mph with the motor pulling 52-56A continuous and 59A peak. Temps all in the 90 degree region for motor, battery and ESC (using a Hobbywing 60A ESC)

    On 3S Lipo (Turningy 3000mAh 20-30C) with an Octura X431 I got 36mph with the motor pulling 62-68A continuous and 70A peak. Temps still in the 90-100 degree range.

    After a few runs on the X431 I switched to a Octura Y531 for a bit more pitch and got 36mph again, but with the motor pulling a bit more current: 64-72A continuous and 75A peak. Temps still OK, but connectors starting to warm up (4mm bullet connectors on battery up to about 110 degrees)

    Will try again with a fully charged battery and the Y534 prop next to see if it goes any faster and how much current it draws - boat getting unstable now at speed and needs turn fins (on backorder at LHS) to stop it spinning out when cornering.

  7. #7
    Join Date
    Oct 2010
    Location
    nc
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    Default

    your research is awsome but one question all your tests with stock size prop nothing over heated

  8. #8
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    Sep 2010
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    MI
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    44

    Default 3S on stock ESC

    In all the testing I did (2S and 3S), the motor temps were fine (under 100F) - except I didn't run long enough with the big metal prop and 3S to find out if it was an issue. I did notice that as the boat ran faster on 3S the water cooling pickup seemed less effective (less water seemed to be coming out of the outlet) as the boat seems to bounce out of the water more on it's flat bottom and the smaller prop might "throw" less water at the pickup.

    The issue really seems to be with the stock 30A ProBoat ESC, which I'm not using as I started from a brushed setup. The temps on my Hobbywing ESC were fine but it is rated at 60A continuous and 120A for 10 seconds bursts so this is well beyond the boat's requirements.

    However now that ProBoat has switched to providing a stainless prop on the Shockwave BL because of the plastic blade breaking problems, the stock ESC will become even more marginal as the SS prop will provide increased load.

  9. #9
    Join Date
    Oct 2010
    Location
    nc
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    Default

    i have purchesed this prop and love it i have a force control 60 amp esc in my widdowmaker as well but im using a 15c 4000mAh 3s lipo not enough thinking about running two 10c 3s lipos at 4000mAh more weight in the front might help stabilize her skipping
    How many amps do i need ? screw it let it burn.

  10. #10
    Join Date
    Sep 2010
    Location
    MI
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    44

    Default Lipo Current Rating

    Based on the testing I did, with the stock 2900kv brushless motor and the ProBoat 1.34" x 2.06" stainless prop (PRB0154) I would suggest the following:

    2S battery: at least 75-80A current rating (I am using 20C 5000 mAh batteries for 100A rating and they barely get warm)

    3S battery: at least 100A rating and ideally 120A+ rating (25C 5000 mAh or 30C 4000 mAh rating). I used a 30C 3000mAh and that wasn't enough - there was a big drop in current after a couple of seconds which you can see in the chart. This was with a 1mm bigger Octura prop, I haven't tested the ProBoat prop on 3S.

    It looks like the Force Control 60A ESC is rated for 80A for up to 12 seconds so the batteries should be able to match that at least.

    FYI - at the end of the chart you can see that the boat was doing 40mph upside down - that's when I let go of the trigger!

    - yellowbird
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  11. #11
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    Oct 2010
    Location
    nc
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    Default

    thats what i thought my esc tops at 80 amps and my 15c 400mAh lipo bursts to 20c thats 80amps max for 12 secs that should be right but im under the notion i can supply as many amps i want the esc will only use whats needed right so i can stuff 120a in it and it will only use 60-80 amps is this correct?
    How many amps do i need ? screw it let it burn.

  12. #12
    Join Date
    Sep 2010
    Location
    MI
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    Default 3S on stock ESC

    The motor actually drives how much current you need - it is the "load". To satisfy the motor "load" the ESC must be able to provide enough current to the motor and the battery must be able to provide enough current to the ESC.

    The motor load also increases with battery voltage - at higher voltages it draws more current.

    So, if you had a small/ low power motor that only needed 10A at 7.4v (2S battery) it would probably need 15-20A at 11.1V (3S). As long as the ESC and battery can provide more than this then everything will be OK.

    If you changed to a bigger/ more powerful motor the current requirement would increase, even if the ESC and battery stayed the same. Eventually you would get to a point where either the battery or the ESC is overloaded and something fails and lets the smoke out!

    For an ESC and battery both rated at 80A max you would ideally want the motor to draw 55-60A max so you have a safety margin. The simplest way to do that with the standard motor on a 3S battery would be to use a small propeller - something around 30mm diameter like an Octura X430 or the glass-filled nylon prop the OSE sells:

    http://www.offshoreelectrics.com/pro...d=ose-2bld-3mm

    FYI - on a 31mm plastic prop (Octura X431):

    http://www.offshoreelectrics.com/pro...?prod=oct-x431

    my Shockwave hit 36mph so you don't need to worry about the boat being slow with a small prop.

    - yellowbird

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