Results 1 to 8 of 8

Thread: Nimh

  1. #1
    RC poster
    Join Date
    Oct 2011
    Posts
    13

    Nimh

    is it bad to run a 5000mah NIMH in the snow or in the cold?

  2. #2
    RC Turnbuckle Jr. Petertje60's Avatar
    Join Date
    Jan 2011
    Location
    Rotterdam, Netherlands
    Posts
    7,336
    As long as you can keep it dry, that will be no problem. In fact it gets more cooling that way.
    Nobody is born with experience

  3. #3
    RC Turnbuckle Jr. Greatscott's Avatar
    Join Date
    Mar 2004
    Location
    N. Idaho... Da Sticks!
    Posts
    3,381
    Quote Originally Posted by Petertje60 View Post
    As long as you can keep it dry, that will be no problem. In fact it gets more cooling that way.
    X2!

    Getting them wet is to be avoided, but as long as you don't make a habit out of it, it isn't too bad.

    The most common way people mess up batteries is to run them after the battery dumps.
    Submarine Qualified, Chief Inducted, Navy Retired

  4. #4
    RC Enthusiast
    Join Date
    Feb 2012
    Posts
    20
    Quote Originally Posted by Greatscott View Post
    X2!

    Getting them wet is to be avoided, but as long as you don't make a habit out of it, it isn't too bad.

    The most common way people mess up batteries is to run them after the battery dumps.
    What do you mean by this sentence?

  5. #5
    RC Turnbuckle Jr. Greatscott's Avatar
    Join Date
    Mar 2004
    Location
    N. Idaho... Da Sticks!
    Posts
    3,381
    Quote Originally Posted by Greatscott View Post
    Getting them wet is to be avoided, but as long as you don't make a habit out of it, it isn't too bad.
    Look at all of the videos of Traxxas RCs bashing in water, some going completely submerged, there is no protection on the batteries, they are taking the full force of the water. I, for one, only do this to my batteries on accident, but I have never lost a pack due to water damage.


    Quote Originally Posted by Greatscott View Post
    The most common way people mess up batteries is to run them after the battery dumps.
    NiMh batteries will run to a certain point, then will provide significantly less power. This is where the pack has 'dumped', the RC, at full throttle is significantly slower. This is the time to stop the truck, remove that battery, and let it cool down before charging it again. Many people run a truck until the battery can no longer move it, this cause battery breakdown due to heat and chemical stress.

    In other words...
    A six cell battery is normally charger (or peaked) to around 8.4v, but its nominal, or useful voltage is 7.2volts. As the pack is discharged the available voltage decreases until the there is no longer any amperage, this is where the pack dumps (normally around 4.5-5v). There is still power in the pack, but the stress of trying to use that power greatly increases the heat produced by the pack, which causes chemical breakdown in the cells.

    LiPos:
    LiPos have close to the same process, but their peak and nominal voltages are closer together. Plus, their discharge curves are nowhere as steep as NiMh, which means you have a stronger run over the life of the discharge cycle. This is why a 2S (7.4v) seems to have better speed and punch than a 7 cell NiMh pack (8.4v), it maintains that nominal voltage for a longer period of time.

    If a LiPo dumps and you continue to discharge it at high amps the chemical reaction turns violent, expand the pack (puffy pack), and will catch on fire. This is why you should always run a LiPo cutoff or a warning signal; and why you should always ballace your packs when charging.
    Last edited by Greatscott; 02-19-2012 at 07:40 PM.
    Submarine Qualified, Chief Inducted, Navy Retired

  6. #6
    RC Turnbuckle Jr. El Sob's Avatar
    Join Date
    Feb 2010
    Location
    El Sobrante, Ca
    Posts
    7,910
    I just put a balloon over the end of it to keep the water out.
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  7. #7
    RC poster
    Join Date
    Oct 2011
    Posts
    13
    I just bought a venom 5000 mah 8 cell, I run it in my stampede 4x4 and when I run it in the snow it does not last very long

  8. #8
    RC Turnbuckle Jr. Greatscott's Avatar
    Join Date
    Mar 2004
    Location
    N. Idaho... Da Sticks!
    Posts
    3,381
    What kind of run times are you getting with that battery when you are not running in the snow? Are you getting more run time with the same set up and a different battery? Have you changed your gearing?

    Snow puts a lot of stress on the drive train, makes it work harder, so run time will be shorter.
    Submarine Qualified, Chief Inducted, Navy Retired

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •