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Thread: will this combo work out mathmaticaly

  1. #121

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    Quote Originally Posted by Speed3 View Post
    I gain 8mph just off of one battery vs another battery.
    Huh?? What magic battery gains 8 mph over others?

  2. #122

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    I don't know about that I propped down to the 52 millimeter and now the amps are at 2:45 so I think that 2:55 or around about is very close

  3. #123

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    I just mentioned in another thread about gain 8 mph with another battery I am surprise you already saw it.

    If you try cells like the smc 5400 90c. When you was accustom to let's say 30c cells of some other brands you would might see what I mean.

  4. #124

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    I'll take a look at SMC.

  5. #125

    Cool

    I just mentioned in another thread about gain 8 mph If you try cells like the smc 5400 90c. When you was accustom to let's say 30c cells of some other brands you would might see what I mean.
    This will depend on the load. If you are running a 50 amp RTR then you will not see that large of a speed difference, but if you are pulling 200+ amps in a racing setup then the lower resistance of a “90C” pack will result in higher voltage delivery and thus higher speeds. The biggest issue is, how accurate is that 90C rating, or the 30C rating for that matter? There is no way for the consumer to measure this nor is there an industry standard. Just like in the days of round cells, the seller can put whatever they want on the pack label, often it is.....optimistic. And paying a lot of money for a pack doesn't guarantee an accurate C rating either, whitness the Turnigy HeavyDuty packs or the MaxAmp packs.

    When choosing packs for your boat match them to the boat’s use - low amp or high amp. And it’s best to go by the experiences of boaters you trust to know the difference, not guys who only own a few packs.


    .
    ERROR 604 - Caller's Buffer Is Too Small
    1. Ensure that your port is not configured to a mini plug
    2. If you are still having problems, contact someone

  6. #126

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    Quote Originally Posted by Fluid View Post
    This will depend on the load. If you are running a 50 amp RTR then you will not see that large of a speed difference, but if you are pulling 200+ amps in a racing setup then the lower resistance of a “90C” pack will result in higher voltage delivery and thus higher speeds. The biggest issue is, how accurate is that 90C rating, or the 30C rating for that matter? There is no way for the consumer to measure this nor is there an industry standard. Just like in the days of round cells, the seller can put whatever they want on the pack label, often it is.....optimistic. And paying a lot of money for a pack doesn't guarantee an accurate C rating either, whitness the Turnigy HeavyDuty packs or the MaxAmp packs.

    When choosing packs for your boat match them to the boat’s use - low amp or high amp. And it’s best to go by the experiences of boaters you trust to know the difference, not guys who only own a few packs.


    .
    That being said, what brand is your favorite?

  7. #127

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    The smc 5400 90c 4s have .0052 ohms internal resistance. And yes you can measure it.

    Not with a data logging ESC though. I bought a data logging ESC and found that the ESC don't give the full pack voltage even at no load reving. And the speed control adds resistance to the circuit.

    So when you look at the datalog it shows what is being delivered to the motor and what the motor rev.
    But it doesn't reflex what the cells are capable of doing.

    If you want to test the pack internal resistance get some light blubs, a multimeter and a wattmeter.

    Use the wattmeter to measure ruffly how much amps the bulbs are pulling. The wattmeter has internal resistance so the voltage reading on the wattmeter is not dependable. So the wattmeter is only good to give an idea of the amps in the circuit.

    Set the multimeter on voltage connect them to the battery wires. Then connect the bulbs to the battery and watch the voltage underload.

    Make a note of the loaded voltage.

    Release the bulbs from the battery and note the unloaded voltage that comes up immediately after releasing the bulbs.

    That will show you how much volts you lost underload.

    Remember that you recorded the amps with the wattmeter before.

    So voltage loss/current gives you the pack internal resistance.

    Remember the c rating goes by amp hours * by c rate (5.4* 90) for the smc pack that I mentioned.

    5.4* 90=486amps

    So if you charge to let's say 16.6voltages. We talking about a 4s pack now.

    The internal resistance is .0052 ohms.

    And the load is 486 amps. The voltage drop would be 2.5272 volts.

    So the pack would drop from 16.6 to 14.0728 volts.

    Now let's say cut off voltage is 3.4v per cell that mean 13.6v is cut off voltages. You may only have 700mah at that discharge rate before low voltage. Because as the capacity is consumed the voltage also falls. So after 700mah is gone you are at 13.6v.

    You may only get 5secs of action. But over 6800 watts is a lot of power for a 4s.

    So yes some packs c rate maybe true. Even though it is for a very should burst.

    Problem is we will never get that kind of power because the ESC may add .006 ohms, while at the same time losing .2 v or a little more.

    So you will never know a pack real power by using a data logging ESC.

  8. #128

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    ran the new esc

    The set up is running killer, data log shows 42amps at 100% throttle and 35k rpm '

    I did shred my flex shaft on last run.

    the data log shows when it happen and how the amps and temp shot up.

    flexshaftshredded2018.jpgflexshaftshredded2018.jpg

  9. #129

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    made some improvements on the set up of the hull and got some better numbers. adjusted the trim tabs up past level with hull bottom slightly which loosen it up a lot. went to far first attempt and went back a little to keep it in the water. The tabs are a HUGE influence on how wet the boat runs. wet boats draw higher amps then a dry running boat, the sacrifice would be your boat is out of water riding on the prop so its a balance act keeping it from wrecking.
    MY speed is identical to yesterday BUT, the amps are way down.
    check out todays run ….below
    september14finadjustmentsandstinger.jpg

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