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Thread: Motor size versus Amp draw

  1. #1
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    Default Motor size versus Amp draw

    I have a question regarding amp draw and motor size. Right know on 4s I run a tp 4050 2200kv with a h7 drawing up to 255 amps if I move up to a tp 4070 2200kv would the amps be reality the same or higher with the larger motor. Run in a P hydro.
    :canada

  2. #2
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    If you run the exact same setup I would expect there to be less amp draw, however if you push this motor it will pull pull higher amps. In not familiar with TP motors or your setup so my advice is not definitive


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  3. #3
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    Amp draw seems awful high. What is your speed? I have run similar setups and not drawn even 100 amps. Spec Rigger with a 3630 TP. H7 less than 100 amps.
    Same Motor in a delta force 33" less than 100 amps. (These are smaller motors BTW.) Let's see some Pics too.

  4. #4
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    The boat is a whip I extended by 2 inches and widen by 3/4 inches runs just around 70 mph. I have raced it against a couple of black pearls and was too loose to compete. I will be building a black pearl for next season and that's why i'm looking at the bigger motor. Heres one of the charts from my swordfish 220 esc.
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    :canada

  5. #5
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    The amp draw should be very close with the 4070 if not the same.

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    Weight will play a big factor in your answer.

  7. #7
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    Some other guys should way in. Doesn't seem right.

  8. #8
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    From the outside looking in an H7 on a 32" sport hydro is A LOT of prop! Prior to the newer style ABC props showed up the H5 was what most of us ran. I am still running an H5 on my Black Pearl with a TP 4070 and it's not a set up I would openly recommend as it's a pretty hot set up. Hope you have a good controller!

  9. #9
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    That’s what worries me about using the 4070 finding a controller up to the task. I have a abc 1815.
    :canada

  10. #10
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    I did some testing specifically on this point with datalogging. Different can size with very close kV. The bigger motor and smaller motors were almost similar. The kV difference would have been the reason for the difference rather than the size.

    I have tested a 4074, 4092 and aquacraft 3656 the 3 motors were very close in kV. The 4092 1761kv, the 4074 1741kv and the aquacraft 1732kv. And test was done with data logging.

  11. #11
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    Motor can length is going up which means a bigger rotor. This means magnets of the same strength but of bigger physical size. This means to more current / more amps plain and simple.

  12. #12
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    I’ve have found when you begin to reach the motors max power that’s when you start burning stuff up due to over amping caused by a motor that needs to be more powerful , usually the esc is the first thing to go with high kv motors. however a longer engine of the same spec will only pull more amps but will run more efficiently once the boat has reached its max speed ! ! You want to keep your 2200kv motor but a longer version , I would say expect more current spikes and heat on the esc .... with the longer motor ease into the throttle gradually until you reach max speed and I would expect the system to run less amps at max rpm . Hope this helps
    "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction."
    --Albert Einstein

  13. #13
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    My question to you is how are your engine temps ? and the esc temps based on your original post .
    "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction."
    --Albert Einstein

  14. #14
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    The temps never seemed to bad 120 - 140 depending on summer heat that day. I run on a impba course so I only do 7 laps. The motor is three years old and is the older style tp.
    :canada

  15. #15
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    I think your current spikes will go down with the longer motor, you will still see high spikes but I think they will go down sooner based on your chart. Your running 70 mph in racing conditions that’s going to be hard on stuff. Maybe a less aggressive prop and the longer motor would help a bunch
    "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction."
    --Albert Einstein

  16. #16
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    What esc are you running in your boat.
    :canada

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