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  1. #1
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    Question E-Maxx 3903 to Brushless and Nimh batteries

    Hello,

    Well, first sorry for my english, it's not my natural language.
    Second, I'm new in the RC world and not sure to understand.

    I have a E-Maxx 3903 with EVX2, 2 Titan Motors and 2 Nimh batteries with 7 cells each (so 14 cells?).
    I would like to replace these 2 brushed motors by one brushless but would like to keep my actual Nimh batteries.

    So my questions are:
    1. Can I keep my 2 actual Nimh batteries if I use this brushless combo: Hobbywing Combo Ezrun WP-SC8 + Moteur 2000kv COMBO-SC-C4 ? Because in features for this combo, I may read: - Lipo 2/4S Lipo Nimh 6/12. So "6/12" means that if I add cells from the 2 batteries, I must not exceed 12 cells. But actually, I have 14 cells right?
    I definitively need explanations

    2. What are other parts I need? Just 3977R and 3997X parts or is there something else?

    3. And last but not least, I don't understand why my actual 2 motors are 14,4V and my actual batteries are 8,4V? Because 8,4 x 2 = 16,8v. How it's possible that my Titan 550 work fine with this?

    Thank you in advance for advises and explanations you could give it to me.
    Best regards.
    Kasi

  2. #2
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Due to the limitations of the ESC you are choosing, you cannot use the stock 7 cell packs.

    You can bolt the 1/8th scale brushless motor to the stock mounts... just tape off the unused hole in the mounting plate; unless you feel the need to buy the single motor mount, that is.

    The stock packs are actually closer to 21 volts when fully charged. The 8.4v stated on the pack (or any battery pack) is nominal voltage... same as the voltage listed on the motor. Brushed motors can be slightly over-volted and run fine... especially with NiMh because when the throttle is pulled voltage drops quite a bit.
    Whatever it is I just typed... could be wrong.

  3. #3
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    Thank you Jimmie for your reply.
    So If I understand well, the only thing I have to do (and to buy) is an ESC that accepts 14 or more cells.
    Right?
    But there are many many ESC and motors in the Brushless world, can you advise me for a combo (ESC + brushless motor) which support 14 or more cells and which is working fine? Don't know what to choose but not a Castle Mamba Monster, it's too expensive.
    Best regards

    EDIT: Is this one ok "Hobbywing Combo Xerun 150A + Moteur 2200kv COMBO-M6B-BLUE" to be used on my car and with stock nihm pack?
    I think I have to buy adaptator with serial cable to connect my 2 nimh packs?
    Last edited by Kasimodo; 09-08-2013 at 12:35 PM.

  4. #4
    RC Racer
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    Yes that combo is great, you need lipos i you are oing brushless.

  5. #5
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    Thank you for your reply.
    But as I said previously, I will use my nimh packs with the new brushless motor. I don't want to buy Lipo for the moment.
    It must work with this combo, no?

  6. #6
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    You can use NiMh once the correct ESC is found.
    Whatever it is I just typed... could be wrong.

  7. #7
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Can you link us to the ESC you want to use? I don't want to accidentally study the wrong one and give bad advice.
    Whatever it is I just typed... could be wrong.

  8. #8
    RC Racer
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    The esc Xerun from hobbywing can run your's nimhs's if you want to.

  9. #9
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    Quote Originally Posted by Jimmie Neutron View Post
    Can you link us to the ESC you want to use? I don't want to accidentally study the wrong one and give bad advice.
    Yes... but it's a french website.... := http://www.rcteam.fr/combo-variateur-moteur/10173-hobbywing-combo-xerun-150a-moteur-1800kv-combo-m6c-blue.html
    But it seems it can run nihm until 18 cells... so 2 x 7 will be accepted if I understood well

  10. #10
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Yes... that ESC will work great on 14 NiMH cells.

    I would hard wire the ESC so the batteries are in series. That would mean 1 less connector therefore 1 less bottleneck.
    Whatever it is I just typed... could be wrong.

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