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  1. #1
    RC Racer
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    How to refresh batteries?

    So I was driving my Merv that I purchased yesterday and I noticed that my batteries seemed to have really poor performance. The truck came with 2 stock nimh batteries and 1 3s lipo. The lipo lasted for maybe 2 minutes and the nimh batteries lasted only 5 minutes in parallel which is supposed to give me more runtime. I have a traxxas ez peak plus charger and I'm wondering if there is a way to refresh the batteries. If so can someone please guide me through the steps to do it?


    You break you buy

  2. #2
    RC Enthusiast
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    For nimh i normally put a few charges through them and they run better. I havent owned lipos very long.

  3. #3
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Look into NiMh form charging... basically controlled discharging and charging a few times. This may or may not (probably won't) work... NiMh's really don't last that long being abused in a brushless system.

    For the LiPo... what are the cell voltages? The charger should display them.
    Whatever it is I just typed... could be wrong.

  4. #4
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    I tried charging my lipo and all of the cells balanced to 4.20 per cell, but it only put in about 500 mah out of the 1200. My charger only reads how much mah it puts in. Not how much mah are in the battery. I drove it till lvc kicked in and then I charged it till it said it was full. How come there was only 500 mah put into it instead of the full 1200?


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  5. #5
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    You don't get to use the full 1200... if it is a 1200 pack. More than 500, for sure, but not the full 1200.

    If it is only letting you use 500 mAh the pack is shot and needs to be replaced.

    What are the cell voltages at LVC?
    Whatever it is I just typed... could be wrong.

  6. #6
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    Each cell is about 3.90 when it shuts off.


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  7. #7
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    That is way early... above storage voltage even.
    Whatever it is I just typed... could be wrong.

  8. #8
    RC Turnbuckle Jr. Petertje60's Avatar
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    Maybe your lipo is at the end of its life and the voltage drops fast under load. Afterwards it can easily bounce back up to 3.9, but maybe it was way lower at the moment where the ESC shuts off.
    Nobody is born with experience

  9. #9
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    One way to see is to check IR... does your charger have this capability?
    Whatever it is I just typed... could be wrong.

  10. #10
    RC Champion Jimdog's Avatar
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    Are you running the nimhs in lipo mode? That would cause the problem.
    Whatever you are, be a good one.

  11. #11
    RC Racer
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    I'm running the batteries in the right modes and make sure it is in lipo mode when I run lipos. Does IR mean internal resistance? If so I think my charger can do that.


    You break you buy

  12. #12
    RC Turnbuckle Jr.
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    Quote Originally Posted by cjbajaboy35 View Post
    Each cell is about 3.90 when it shuts off.


    You break you buy
    Just curious - how do you know the LiPo cells were 3.90V each?

    For the Nimh packs, did you ever run the RC vehicle/packs until it was just barely moving, if even just one time?

  13. #13
    RC Racer
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    I knew the pack was at 3.90 per cel because I plugged in the battery to charge and my charger lets me see how much voltage each cell is at.


    You break you buy

    I tried discharging the lipo an recharging it and it only put 600 mah into it. Looks like I'm gonna need some new batteries.


    You break you buy
    Last edited by cooleocool; 05-13-2013 at 06:57 PM. Reason: merge

  14. #14
    RC Turnbuckle Jr.
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    Quote Originally Posted by cjbajaboy35 View Post
    I knew the pack was at 3.90 per cel because I plugged in the battery to charge and my charger lets me see how much voltage each cell is at.


    You break you buy

    I tried discharging the lipo an recharging it and it only put 600 mah into it. Looks like I'm gonna need some new batteries.


    You break you buy
    By the time you get the pack out of the vehicle and hooked up to a charger, the cell voltage can rebound by 200mAh or more, so the 3.90 volts per cell you noted is most likely somewhat higher than the true cutoff voltage.

  15. #15
    RC Turnbuckle Jr. Petertje60's Avatar
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    Quote Originally Posted by Jakey View Post
    By the time you get the pack out of the vehicle and hooked up to a charger, the cell voltage can rebound by 200mAh or more, so the 3.90 volts per cell you noted is most likely somewhat higher than the true cutoff voltage.
    Sir, please use the proper units. 200mV...
    Nobody is born with experience

  16. #16
    RC Turnbuckle Jr.
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    Quote Originally Posted by Petertje60 View Post
    Sir, please use the proper units. 200mV...
    Oops, my bad. Thank you for pointing it out.

    Tom

  17. #17
    RC Champion Jimdog's Avatar
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    Storing lipos fully charged builds up ir. Right?
    Whatever you are, be a good one.

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