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  1. #1
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    Battery question?

    So I've been thinking about putting a castle sidewinder or vxl 3s system in my merv, my only concern is the batteries. I know if I run a 25c battery in my slash with the vxl system, it will instantly puff it up. The only batteries I have currently for my mrev are 2 2s 2200 traxxas lipos and 4 1600mah nimhs. Will these batteries still work if I install a vxl 3s system or will they puff and or explode (as I've had a nimh explode once before)?
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  2. #2
    RC Turnbuckle Jr. Petertje60's Avatar
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    Just the C-rating says nothing about what a battery can deliver. A 2200mAh 25C will be able to deliver 55A. Two in parallel deliver twice that amount. That is enough for a small car like the Merv. The NiMHs will probably have a problem to deliver enough energy. A lighter gearing helps to reduce the necessary power.
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  3. #3
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    Quote Originally Posted by Petertje60 View Post
    Just the C-rating says nothing about what a battery can deliver. A 2200mAh 25C will be able to deliver 55A. Two in parallel deliver twice that amount. That is enough for a small car like the Merv. The NiMHs will probably have a problem to deliver enough energy. A lighter gearing helps to reduce the necessary power.
    I understand all of that, my question was, if I upgrade to a 1/10 brushless system, will the batteries still deliver enough current?
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  4. #4
    RC Turnbuckle Jr. Petertje60's Avatar
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    Quote Originally Posted by invento123 View Post
    I understand all of that, my question was, if I upgrade to a 1/10 brushless system, will the batteries still deliver enough current?
    Depends a bit on what you are going to do with it. For speed runs with a tall gearing it might become a problem, but as long if you ask not too crazy things from the motor, the 2200mAh 25C in parallel will be enough.
    From what I have heard, Traxxas plays safe with the specs of their LiPos, so they will deliver the 55A a piece as promised.
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  5. #5
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    Quote Originally Posted by invento123 View Post
    I understand all of that, my question was, if I upgrade to a 1/10 brushless system, will the batteries still deliver enough current?
    Doing nothing else but changing the 4000kv 380 vxl motor with a 4000kv 1/10 motor, the amp draw wont change enough to matter.

    What WILL change the amp draw would be changing gearing and/or motor kv. Without knowing what motor you plan to use, all we can tell you is this.

    If you keep gearing the same, but increase motor kv, amp draw will go up. The more you increase the kv, the more amp draw goes up (as well as top speed goes up)
    If you keep motor kv the same but increase gearing (larger pinion and/or smaller spur), amp draw will go up. (Again, so will top speed)

    If you go up on kv AND gearing, amp draw will go up even more.

    If you go with a higher kv motor, but gear down (smaller pinion and/or larger spur) to get the same top speed, amp draw won't change much other than increasing due to the extra weight, handling will also suffer with the bigger motor.

    The main advantage to a 1/10 motor I should it runs cooler for a given power level, which in itself lowers amp draw slightly as higher temps=slightly higher amp draw.

    As for batteries, your lipos or nimh in parallel will work fine at stock power levels, so long as they haven't been sitting around for years. The lipo will work WAY better though
    Last edited by dacaur; 08-03-2016 at 11:44 AM.
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  6. #6
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    Thank you dacaur, that's exactly what I wanted to know
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  7. #7
    RC Turnbuckle Jr. Petertje60's Avatar
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    From a well balanced situation, everything what dacaur explained so well is correct.

    Bear in mind that when you go from a point where a smaller motor is not up to its task (and heats up fast), putting a larger/better motor with the same Kv rating will probably cause more strain on ESC and/or battery.

    Hardest task is finding that balanced situation: everything within safe bandwiths (temperature is the best point to keep an eye on).
    Nobody is born with experience

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