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  1. #1
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    I want a 50mph Slash

    I want my slash to be able to beat my buddies savage. I have the VXL ESC and motor in my car now. I plan on getting a 4000+mah Lipo pretty quick. With stock 23/86 gearing, should I be able to get this? If not, what else do I need to do?

  2. #2
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    get a 8000+lipo that would do it
    FRANKINRUSTLER,when bored build your toys

  3. #3
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    50 should be pretty easy to reach.

    Doing anything but driving in a straight line will won't be, though.

    I'm sure if I geared high enough with my 5700kV I could reach 50mph with my 8K 2S lipo. ... ... ... for only a couple of passes though. I'd get bored, and the motor would get hot.
    English. It's your language. Learn to type it.

  4. #4
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    Pardon my ignorance, but how does a higher mAh lipo, net higher speeds? I thought speed and top end were dependent on Voltage, and not Capacity.

  5. #5
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    more power you got more juice u get to the gears more fastter you go,
    FRANKINRUSTLER,when bored build your toys

  6. #6
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    But how is it a 4000mah lipo can't produce more "power" than a 8000mah lipo? The voltage is always the same. (Or so I think) It's just the "endurance" of the 8000mah should be twice as long.

  7. #7
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    One of the specifications of a battery pack is it's "C." This spec is useful for a couple reasons. It'll indicate the maximum charge rate and maximum discharge rate.
    (Don't confuse people's misnomer when they're talking about NiMH packs and say 6C. That's an incorrect way of saying 6 cell.)

    The 8K pack I use is rated at 20C. C is derived by the packs capacity in Amperes. So 20X8 is 160 amps.

    A 4000mAh pack with the same 20C rating will have a maximum discharge rate of 80A.
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  8. #8
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    Quote Originally Posted by Hordsak
    But how is it a 4000mah lipo can't produce more "power" than a 8000mah lipo? The voltage is always the same.
    Power (in watts) is more than just voltage. By definition, power = volts x amperes.
    English. It's your language. Learn to type it.

  9. #9
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    Quote Originally Posted by Slasher
    Power (in watts) is more than just voltage. By definition, power = volts x amperes.
    your close...

    actually P=VI which is Power= Volts x Current
    Been there, done that.

  10. #10
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    Mamba Max / UBEC / 4s or 4 cell lipo 5000mah+ / 2000-3500kv range motor.

  11. #11
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    Quote Originally Posted by larrydino
    your close...

    actually P=VI which is Power= Volts x Current
    Dude... uh... amperes is the measure of current.

    A biomedical engineering technician didn't know that?
    English. It's your language. Learn to type it.

  12. #12
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    Quote Originally Posted by Slasher
    Dude... uh... amperes is the measure of current.

    A biomedical engineering technician didn't know that?

    haha im sure he does know that. i think he meant since you put ampere you should said it as watts=volts x ampere

    You have to keep it as measurement or name. sorry hehe its a technical writing thing. if i put power=voltage x ampere, i would get 20 points off a paper or drawing.
    Mud-Maxx
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  13. #13
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    Talk about mincing words.

    While we're at it, he also said
    Power= Volts x Current
    Volts is the name. "Voltage" would coincide with the other two terms; those being the "names."
    English. It's your language. Learn to type it.

  14. #14
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    hmmm i stnad corrected....larry must be going nuts cuz of that MMM

    too soon?
    Mud-Maxx
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  15. #15
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    Quote Originally Posted by Slasher
    Talk about mincing words.

    While we're at it, he also said Volts is the name. "Voltage" would coincide with the other two terms; those being the "names."
    not trying to start a flame war..

    the correct written formula in electrical engineering is P=VI
    p=power
    v=volts
    I=current

    did you think C is for current?
    I is the correct nomenclature for current..look it up

    if you find differently. let us know! here are 2 websites you may find informative

    http://en.wikipedia.org/wiki/Electric_current

    http://www.sengpielaudio.com/calculator-ohm.htm
    Last edited by larrydino; 07-28-2008 at 04:41 PM.
    Been there, done that.

  16. #16
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    Quote Originally Posted by Andrew32
    hmmm i stnad corrected....larry must be going nuts cuz of that MMM

    too soon?
    andrew, dont worry..you were correct
    Been there, done that.

  17. #17
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    still waiting
    Been there, done that.

  18. #18
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    Quote Originally Posted by larrydino
    the correct written formula in electrical engineering is P=VI
    p=power
    v=volts
    I=current
    You are correct, and I agree with you -- that is the way to write the formula. However, above, due to the splitting of hairs, I continued that trend indicating the meaning of each word.
    "Volt" is the unit of measure.
    "Voltage" is the word given to define the potential difference. So to keep the same terminology as Andrew32 said, you would have to use the same words as I stated.

    Quote Originally Posted by larrydino
    if you find differently. let us know! here are 2 websites you may find informative
    Dictionary.com is also helpful.

    Quote Originally Posted by larrydino
    did you think C is for current?
    I is the correct nomenclature for current..look it up
    I never said anything about C equaling current. I said C is a battery specification that is derived by the current capacity in amperes.
    I'm aware that I=Current.
    Quote Originally Posted by Slasher
    C is derived by the packs capacity in Amperes.


    Quote Originally Posted by larrydino
    not trying to start a flame war..
    Of course not. This is a discussion. There is oftentimes unneeded trepidation (or disclaimers like yours) in posting because of the moderators and the rules. Discussions/debates do not equal flaming. (Sorry, I couldn't make that into a formula. Ha!)
    English. It's your language. Learn to type it.

  19. #19
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    The VXL system is never going to need 80 amps of current. It may draw close to that as a burst or when at full throttle from a dead stop, but the difference would be nill when all he is trying to do is get a slash to do 50 mph.

  20. #20
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    Quote Originally Posted by Chris Moon
    The VXL system is never going to need 80 amps of current. It may draw close to that as a burst or when at full throttle from a dead stop.
    What is this based on?
    English. It's your language. Learn to type it.

  21. #21
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    Based on logic. If your motor drew 80 amps of current, a 4000 mah pack would only last 3 minutes. 6 minutes on a 8000 mah pack. I am not saying the burst current doesnt meet or exceed the 80 amps, but to say that having an extra 80 amps available of current output from the battery will make the car significantly faster, it cant be true. It MIGHT have a little more punch off the line, but he said he wanted to do 50mph, not get there the fastest. Even then, the extra weight of the larger pack will add weight, which may also make the difference.

  22. #22
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    Hi,
    what is a recommendable 8000mah 11,1 Lipo for a VXL BL powered Slash?

    Would be great if you could you could tell me a shop too, that shippes to Germany.

    Thanks

    mannie

  23. #23
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    Quote Originally Posted by mannie
    what is a recommendable 8000mah 11,1 Lipo for a VXL BL powered Slash?

    Would be great if you could you could tell me a shop too, that shippes to Germany.
    Maxamps appears to ship everywhere.

    Here's their catalog of lipos.
    English. It's your language. Learn to type it.

  24. #24
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    Yeah, I wanna go 50, too. Sooo...

    I'll be jamming the 50+ mph Maxamps/Mamba 7700 set-up that's currently in my 'Pede into a brand spanking new Slash later this evening. We'll see if 6000 mah can push this wide body past 50mph with ease (the 'Pede does it, no problem).
    Tim

    Slash w/Mamba 6900 and MaxAmps 6000HV

  25. #25
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    I remember you sure like that 7700.

    I actually want the contrary, a lower (than 5700) kV motor. I wish Castle makes one less than the 4600. The Traxxas 3500 is somewhat expensive and I am a fan of Castle Creations.
    English. It's your language. Learn to type it.

  26. #26
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    The 7700 is nice, but a bit limited. It can only take 2S-so mid to upper 50s is probably the best I can do in any platform given the voltage limits. When I first bought it I was making 8 even 9 cell packs-made sense then. Now, with all lipo power, I'd get the 5700 (or lower, like you want). The 6900 is a better bashing motor, too (also limited to 2s, but better behaved, cooler temps and longer run times). The 7700 is probably the LAST motor I'd buy out of the bunch now if I were gonna purchase another.
    Tim

    Slash w/Mamba 6900 and MaxAmps 6000HV

  27. #27
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    You can get the Traxxas BL system for 140. You can't find the Mamba system that cheap.

  28. #28
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    Quote Originally Posted by Hordsak
    I want my slash to be able to beat my buddies savage. I have the VXL ESC and motor in my car now. I plan on getting a 4000+mah Lipo pretty quick. With stock 23/86 gearing, should I be able to get this? If not, what else do I need to do?

    That is right about the speed that mine pops a wheelie, regardless of throttle, and becomes very, very unstable.

  29. #29
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    Quote Originally Posted by Chris Moon
    Based on logic. If your motor drew 80 amps of current, a 4000 mah pack would only last 3 minutes. 6 minutes on a 8000 mah pack. I am not saying the burst current doesnt meet or exceed the 80 amps, but to say that having an extra 80 amps available of current output from the battery will make the car significantly faster, it cant be true. It MIGHT have a little more punch off the line, but he said he wanted to do 50mph, not get there the fastest. Even then, the extra weight of the larger pack will add weight, which may also make the difference.
    And yet, logic must be denied, since on traxxas's own gearing charts you can see that a Rustler VXL geared at 31/76 on 4000mah lipo is rated for 65+mph, while the same rustler, geared the same 31/76 on 8000mah lipo is rated for 70+mph.
    If it didn't make a difference, you can bet they wouldn't have put that on the chart, and they'd have just put 70+ on the 4000mah lipo column...

  30. #30
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    Quote Originally Posted by Chris Moon
    Based on logic. If your motor drew 80 amps of current, a 4000 mah pack would only last 3 minutes. 6 minutes on a 8000 mah pack. I am not saying the burst current doesnt meet or exceed the 80 amps, but to say that having an extra 80 amps available of current output from the battery will make the car significantly faster, it cant be true. It MIGHT have a little more punch off the line, but he said he wanted to do 50mph, not get there the fastest. Even then, the extra weight of the larger pack will add weight, which may also make the difference.
    The more amps the motor draws, the lower the voltage on the battery goes momentarily. The higher amps the battery is capable of supplying, the less this will affect it.

    A 4000mah 20C batt will drop twice as much voltage as an 8000mah 20c.

  31. #31
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    Quote Originally Posted by Super Dude
    The more amps the motor draws, the lower the voltage on the battery goes momentarily. The higher amps the battery is capable of supplying, the less this will affect it.

    A 4000mah 20C batt will drop twice as much voltage as an 8000mah 20c.
    That is an incredibly vague statement even if it is possibly true (at some point) it does not account for the fact that it is untrue more times then not.

    The real question is at what rate of discharge will the 4Ah drop twice the voltage as the 8Ah? 1 amp, 5 amps, 20 amps, 100 amps?
    [QUOTE=Billstmaxx]if the water can't get out how does it get in??[/QUOTE]

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