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  1. #1
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    let nihm batteries cool I before start charging ? and before use?

    Okay so after running ,the battery gets hot, (nihm 7 cell ) Do i have to let them cool before i start charging them? And after they are done charging they are also hot, do i have to let it cool before using it?
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  2. #2
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    Yes let them cool. If you don't you can cause damage to the cells.
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  3. #3
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    emaxx is correct. definately let them cool after use before you charge and let them cool after charge before use.

  4. #4
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    They shouldn't be hot coming off the charger. They need to be warm but not cool. If you're after power for racing get them very warm.
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  5. #5
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    Unless a Nimh pack grossly overheats while charging, it is NOT necessary to wait for it to cool before running. In fact a Nimh pack will run best fresh off the charger while still warm and will suffer no ill effects doing so.

    After running, definitely wait for the pack to cool completely before charging.

  6. #6
    RC Turnbuckle Jr. O.G.'s Avatar
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    Back in the day I always let them cool before and after charging. Also, make sure you completely discharge them before charging so they don't acquire a memory.
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  7. #7
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    Other than a noticeable performance loss, there is nothing wrong with letting Nimh cool after charging, however it is completely unnecessary.
    Memory effect does not really happen with Nimh packs, therefore complete discharging is not only unnecessary, but will definitely damage the cells of the pack. Never, ever completely discharge Nimh cells!!!!

  8. #8
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    years ago when i only had 2 nicd packs i would recharge the pack in the freezer to keep it cool. as i didn't allow time for cooling between charges.
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  9. #9
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by Jakey View Post
    Other than a noticeable performance loss, there is nothing wrong with letting Nimh cool after charging, however it is completely unnecessary.
    Memory effect does not really happen with Nimh packs, therefore complete discharging is not only unnecessary, but will definitely damage the cells of the pack. Never, ever completely discharge Nimh cells!!!!
    That's what is called "hitting the nail on the head".

  10. #10
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    if they become hot after charging allow time to cool, if warm go ahaed and use them all ways allow cooling after running. to be more specific buy a lipo.
    Slash 2wd Vxl, ERBE; Crash N Learn

  11. #11
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    Nimh Batteries SHOULD NOT BE HOT in first place, if they are hot, your batteries are going down for sure, if they are slightly worm, then you dont have to cool them down as it is no damage to the battery when they are slightly warm.
    Do you charge your batteries with 6a current ? (this is the only reason they would become hot) if yes, then lower you charging rate to 3 amps and you will be fine.

  12. #12
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by Agriganosa View Post
    Nimh Batteries SHOULD NOT BE HOT in first place, if they are hot, your batteries are going down for sure, if they are slightly worm, then you dont have to cool them down as it is no damage to the battery when they are slightly warm.
    Do you charge your batteries with 6a current ? (this is the only reason they would become hot) if yes, then lower you charging rate to 3 amps and you will be fine.
    What exactly do you consider hot? And all this talk about charging amps is irrelevant without knowing what mah the pack is. Nimh charging rates are basically the same as lipo. If you're pack is 4000mah, charge it at 4 amps. If it's 3000mah, charge at 3 amps. The peak sensitivity setting on your charger is every bit as important as what amp rate to charge at.

  13. #13
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    What do we consider hot ? i know it may be confusing and i assumed HOT meaning above 90 degrees, my batteries dont get hot after charging them, after running yes they do get warm but not hot. I've noticed if i charge my 3000mah nimh at 6amp rate they get above 90 degrees, if i charge them at 3amps they stay warm, thats it, thats my proof that it does actually affect the temperature of the battery, i wont argue anybody because it is my personal experience.

  14. #14
    RC Turnbuckle Jr. harry697's Avatar
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    No doubt charging a 3000mah pack at double the standard rate will make them hot. But 90 degrees is not really what I would consider hot. Your pack should be coming off the charger at somewher around 110-120. If it's not in that vicinity, it's most likely not done charging. If it comes off the charger hotter than that, you might as well toss it and start over because your pack is damaged.

    I used to let my nimh packs cool before running them. Then I had an extensive phone conversation with Jakey. After that, my packs peaked off with the temp right around 120 degrees and went directly into the truck. It was a little hard to time it correctly at the track, but I got it figured out after a few race days.

  15. #15
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    For someone that isn't after proformance and has no idea what they're doing nor understanding of different methods(beginner) its better to be on the safe side with advice and just let everything cool down before using. In the long run the hobby will be more enjoyable for a beginner BC the equipment will last a lot longer.
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  16. #16
    RC Turnbuckle Jr. harry697's Avatar
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    Good point, but then again, that same beginner is probably discharging the packs all the way down too. Either way, they lose. I really think that's where a lot of the internet myth about nimh running strong for a few minutes before losing a noticeable amount of power comes from. I can't even begin to count the amount of posts claiming that "nimh gradually loses power, but lipo runs full power til it hits LVD". It's really not true in either case, but it's a popular belief. And handling nimh packs wrong will provide the exact symptoms that many people think is just the nature of the beast.

    But what do we know? We're still filing brushes and truing comms.

  17. #17
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    Quote Originally Posted by harry697 View Post
    Good point, but then again, that same beginner is probably discharging the packs all the way down too. Either way, they lose. I really think that's where a lot of the internet myth about nimh running strong for a few minutes before losing a noticeable amount of power comes from. I can't even begin to count the amount of posts claiming that "nimh gradually loses power, but lipo runs full power til it hits LVD". It's really not true in either case, but it's a popular belief. And handling nimh packs wrong will provide the exact symptoms that many people think is just the nature of the beast.

    But what do we know? We're still filing brushes and truing comms.
    LOL true. But you honesty cant expect a 6cell nimh to hold over 9volts during a run. Nimh cells self discharge rate is very high compare to lipos. Plus You needed discharge trays and matching machines if you really wanted to keep their proformance at Max. A good quality nimh might not suffer like older cells but under high discharge they do not provide the power under loads that a lipo can easily handle. Maybe its not a problem with brush motors but brushless setups can put a strain on batteries.
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  18. #18
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    Using the Onyx 235 charger

    I am using the onyx 235 charger and it allows to charge at 110 to 130% of the battery capacity , allowing my 3000 nimh mah to charge at 3900mah, it's recommended by the owners manual , so I'm doing the charge at 3500 mah, at 4 amps with trickle off , so yes it gets kind of hot , is it because of the 4 amps rate or the 3500 mah charge I'm putting into the battery?
    Last edited by vchirinos; 04-18-2012 at 12:21 AM. Reason: Wrong numbers
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  19. #19
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    let them cool.

  20. #20
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    Can I charge them to 3900 mah ?
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  21. #21
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    Higher amp charge will make the pack get hotter on the charger but shouldn't damage it. I use to charge my 3300 at 6 to 7 amps at the track they be hot but where you can still hold them in your hand. Something in temp like a foam cup with freshly poured hot coffee in it. (Probably cooler then that). Anyways Higher amp charge gives the pack more power but lower the overall runtime where a lower amp charge makes the pack feel softer but increase runtime and cycle life. My old 3300 use to get over 4000mah but these were top dollar matched gp3300 cells.
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  22. #22
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    I'll say it once again for the OP and anyone else who wants to listen - It is completely unnecessary to wait for a Nimh pack to cool after charging as long as the pack did not grossly overheat (130F and above). There is absolutely no harm in running a warm, freshly charged pack and doing so will in no way damage the pack or reduce its life cycles.

    I have personally tested tens of thousands of Nimh cells and thousands of assembled packs, so I have complete confidence in what I have posted regarding Nimh use.

    Tom Himes
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  23. #23
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    Thanks everyone.
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  24. #24
    RC Turnbuckle Jr. O.G.'s Avatar
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    I didn't know there was such a controversy with nimh's. If its bad to discharge the battery before charging, why is/was there so much equipment designed to do just that?
    Does anyone remember light strips with the alligator clips to attach to the charge plug? Those were all over on race night. And thunder power, among others, makes a charger/discharger.
    My Black & Blue Rally is faster than your color...

  25. #25
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    Quote Originally Posted by harry697 View Post
    Good point, but then again, that same beginner is probably discharging the packs all the way down too. Either way, they lose. I really think that's where a lot of the internet myth about nimh running strong for a few minutes before losing a noticeable amount of power comes from. I can't even begin to count the amount of posts claiming that "nimh gradually loses power, but lipo runs full power til it hits LVD". It's really not true in either case, but it's a popular belief. And handling nimh packs wrong will provide the exact symptoms that many people think is just the nature of the beast.

    But what do we know? We're still filing brushes and truing comms.
    Its not a myth, when nimh batteries are in use they are gradually lose their power and when the battery is dead its output is 0. When lipos are in use, with no charge in a battery it is still capable of throwing 70% output. Different battery structure and material makes lipo be a lipo lol

  26. #26
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    I had a similar question. I was under the impression the Lipos were not meant for a standard 12T motor..is this true? I am not looking to upgrade to a brushless system just yet.

    I am still using a 2400NIMH battery. Ideally, id like to get some batteries that can be used for other Traxxas models and wouldn't mind "investing" in getting some decent batteries that will last a while. PLease help!

  27. #27
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    You can use 2s lipos with the stock 12t Titan.
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  28. #28
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by Agriganosa View Post
    Its not a myth, when nimh batteries are in use they are gradually lose their power and when the battery is dead its output is 0. When lipos are in use, with no charge in a battery it is still capable of throwing 70% output. Different battery structure and material makes lipo be a lipo lol
    I give up. Keep damaging your equipment. But don't say we didn't try to help.

  29. #29
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    Damaging ? how ? i just stated that there is a difference in output within 2 types of batteries

  30. #30
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by Agriganosa View Post
    Damaging ? how ? i just stated that there is a difference in output within 2 types of batteries
    Never mind. I can only beat my head against the wall for so long before it starts to hurt.

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