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  1. #1
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    I need help charging my NiMH battery

    I got a new TRAXXAS Stampede today and i need some help charging the battery. It came with a cell phone like charger and that thing takes 8hrs To charge. It's a 3000mah 8.4v 7cell NiMH battery. So i put it on my Thunder ac 680 charger and i set it to 3.0 amp and started charging. I have no idea when the battery is done. The battery sais it's an 8.4v battery but the voltage was going in the 10.80v range and the battery was veary hot, So i stoped the charge. The battery sais to charge it at 3amp for the best charge and it should get warm at the end of the charge. But it was HOT. I dont know how i should charge this battery, My charger is capable of charging these kinds of batts and when i use it to charge my 11.1v 2200mah 25c heli batterys, Those batterys dont even get warm.

    So how do i charge this NiMH battery?

    This is the charger i have, http://www.hobbypartz.com/73p-ac680-accharger.html

  2. #2
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    i would reduce the amp to 2.5amps so the battery doesnt get hot like that again. a new battery sometimes being maxxed out at the charge voltage new will at times do that. mine did that when new. just reduce the charge rate 2.5 and wait just a little longer for like the first hand full of charges and then increase to 3.0amps if it does it again then keep charging at 2.5amps for longer battery life span helps the nimh's by doing that.

    about the battery reading 10.80v its because it will always read higher than the stated on battery because its being peaked charged once the battery comes off the charger and sits for a little bit it will reduce down, self discharging nimh's have.
    Hope it helps you
    DEU 8:18 ESV

  3. #3
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    Thanks for the help, I figured i would have to just reduce the mah. And i figured the voltage thing was normal too. On my heli batterys they go up to 12.60v i think but they are 11.1v batterys.

  4. #4
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    nimh and lipos are different for sure. you cant count on nimh packs to charge up to the excat voltage each time you charge it.
    DEU 8:18 ESV

  5. #5
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    Ok i charged at 3.0amps, 2.8amps, and 2.5amps. And every time my battery was finished it was veary HOT. Is this normal for 7cell NiMH 8.4v 3000 batterys? If you hold the battery for a few seconds it would be too hot to touch. I dont have any experience with NiMH batterys so i dont know if this is normal. I am useing a thunder AC680 charger, It is almost the same as the traxxas ez-peak plus charger. I dont know if i am doing anything wrong, Ir if this is normal. Because now i have to let my batterys cool before i go drive and it takes a while for them to cool. I charge my lipos on the came charger and they do not even get wam to the touch. So i dont know what the deal is.

  6. #6
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    how are the nimh's performing when you use them? are you running the packs all the way down or stopping when you see the lose of performance seeing it start to slow a little. thats when your suppose to stop and let them cool then charge up. letting them cool after use is like 30mins-1hr before charging to rest the cells good and be ready for a charge.
    DEU 8:18 ESV

  7. #7
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    The battery has plenty of power and get up and go. I do let them cool down before i charge. When i start the charge they are well coold down and there is no heat. Throughout the charging my battery will get warmer and warmer untill it gets really hot then its done. And i do stop driveing when the truck gets slow and weak. I am getting 2 traxxas ezpeak chargers in this weeks so maybe they will charge my pack better. I dont know.

    How warm are your batteries when they are done charging?

  8. #8
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    mine get warm to the touch but no where near hot. i usually charge at about 2-2.5amps and seems to work. i have 2 chargers and 1 gets it warmer near hot but thats because its charging at 3amps on that one. try the traxxas chargers and see if the same happens. it might be false peaking the batteries on that charger your using. nimh's tend to die alot faster than lipo as far as life span goes. i've had 2 nimh packs die in less than 8months proper charging and they were traxxas power cells.
    DEU 8:18 ESV

  9. #9
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    Yeah. i will run the battery down tomarrow and then wait for my chargers. I bought 2 ezpeak chargers so i can cgarge 2 packs at the same tine in 45min. If the battery gets hot on the traxxas charger should i through it in the trash?

  10. #10
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    try reducing the charge rate to like 2amps then if after doing that it still gets hot after charging then i would either call traxxas support about it if the batteries arent that old or just keep using them at a charge rate of 2 amps or even lower you'll still have the battery even if you charge lower amps but you really shouldnt have to charge them that low but sometimes you have to, to keep them going i have and worked ok takes longer but if you have other batteries to use for the mean time then its ok.
    DEU 8:18 ESV

  11. #11
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    It is almost new. I think less the 10 cycles, I will try at 2amps tomarrow. If it still gets really hot on my traxxas charger i will give them a call. Thanks for helping me out,

  12. #12
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    no problem i would call then if its that new, they should last longer than that and be able to be charged at 3amps without over heating. you've tried 2.5 and still so if it does it with 2amps then something is wrong with the pack, might be a couple bad cells in the pack.
    DEU 8:18 ESV

  13. #13
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    I have the EX-Peak 4 amp charger and my 7 cell NIHM gets REALLY REALLY HOT as well

  14. #14
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    I think it may be my AC680 charger over charging my packs. I chaged it at 2.7amps today and stoped it when it was at 10.40v and the battery was just warm. I let it cool and i had a good 20 min (Well if felt like 20 min anyways) Of driveing.

    I hope my packs dont get really hot with my new ez peak 4 amp charger. If it dose i will be calling traxxas.

  15. #15
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    Okay i got my traxxas ezpeak charger in the mail today and as soon as i got home i put my battery on charge. First off, It took longer then 45min. And the battery is so hot it is not even funny. So i guess i will be calling traxxas. I have a brand new stampede 2wd comeing in the main tomarrow so i will put that battery on my new ezpeak charger. Hopefally that battery dose not get hot.

    Also i drove this battery in a stampede i allready have and i drove it through some big puddles and water well moisture got into the battery. Will that kill a battery?

    I am going to use this battery one more time to drain it of power, Then i will give traxxas a call. Do they replace them for free?

  16. #16
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    water in the battery can mess them up fast if it happens often or if it gets alot of water, they arent really made to get wet when they are working on a load.
    question when you store them for like over night or anything and also after running them and letting cool off do you repeak them to store them? nimh cell batteries are suppose to be stored fully charged and checked every week and repeaked. if you have not done that and you are draining them when performance drops and leave them like that for even over night doing this a couple times will damage the batteries. nimh's self discharge on their own and when they sit on a low voltage they can drain too far down and damage. if this is the case traxxas might not replace them but then again i havent noticed on the batteries it says to store fully charged just about the chargeing rate amps is all i've seen on some.
    if you call just explain whats going on and they might ask you when you bought them, let them know you tried also their ez peak charger as well and its happening still ok. post back with results. I hope it works out for you.
    DEU 8:18 ESV

  17. #17
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    When i am done running my truck, I let the batterys fully cool down and if it is not to late in the day i will charge them. If it's too late i will charge them fisrt thing in the morning. I got my new stampede and i charged the brand new battery on my brand new ez peak charger and that battery still got hot. Both batterys get hot and they are both new. They both work just fine and have alot of power. Maybe i should just get some traxxas lipos

  18. #18
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    Hi to all....I'm new to this RC trucks, been flying planes for about 4 years and just got this traxxas Stampede and man do I love it...I think I'm hooked...lol. Ok well for those who are having some problems charging a nimh 3000 mah 8.4v battery. I just use a charger at 3.0 amp and leave it ,and when the battery shows at full charge it's at 10.96v and lasts for about 20 minutes driving. And yes the battery is pretty hot but it's normal!!!! A lipo is different it will not come hot. Hope this helps and fun bashing!!!!!!



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    Last edited by Double G; 09-24-2013 at 01:06 PM. Reason: content

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