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  1. #1
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    Battery Discharge question

    Hi all,

    Thanks for the advice you have given over the last two months, new toys always require questions...I have 8000mAh 35c batteries. I run them pretty hard and eventually the low voltage setting on the truck kicks in. The problem is that it kicks in when the batteries reach 3.9 V per cell. This seems pretty low as fully charged they show 7.2V per cell. Is it normal? Is there a way to set it so the batteries will run longer? Also, I have one cell that will not fully charge. Would the LVD kick in as soon as that cell reaches the low voltage cut off or is it an average of the 4 cells? If 1 cell will trigger LVD, I think I solved my issue (I hope).
    Last edited by mjbinks; 02-18-2017 at 10:44 AM.

  2. #2
    RC Racer
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    Quote Originally Posted by mjbinks View Post
    Hi all,

    Thanks for the advice you have given over the last two months, new toys always require questions...I have 8000mAh 35c batteries. I run them pretty hard and eventually the low voltage setting on the truck kicks in. The problem is that it kicks in when the batteries reach 3.9 V per cell. This seems pretty low as fully charged they show 7.2V per cell. Is it normal? Is there a way to set it so the batteries will run longer? Also, I have one cell that will not fully charge. Would the LVD kick in as soon as that cell reaches the low voltage cut off or is it an average of the 4 cells? If 1 cell will trigger LVD, I think I solved my issue (I hope).
    The LVD is averaging the cells, as far as I know it cannot detect individual cell voltage so it's going to be set conservative.

    Here's a good LiPo chart, I run 'em down to 20% capacity is left, about 3.73 cells per volt.

    "For we walk by faith and not by sight" 2 Cor. 5-7

  3. #3
    RC Racer
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    Are you balancing cells every charge?
    "For we walk by faith and not by sight" 2 Cor. 5-7

  4. #4
    RC Turnbuckle Jr. Greatscott's Avatar
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    How are you getting the voltages on the cells?

    Each cell's nominal voltage is 3.7VDC, and around 4.2VDC fully charged. The packs are wired in series, so if you have a 2S pack, overall it is 7.4VDC, 3S is 11.1VDC, and so on. LVC operates off of overall voltage, it reads the voltage when you first turn it on, and from there sets the LVC for that run.

    LVC is reading the pack under load, so if you stop to take voltages, they will be higher than what the LVC is reading.

    Yes, you should do a balance charge every time.
    Submarine Qualified, Chief Inducted, Navy Retired

  5. #5
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    I am. I charge them one at a time on balance. Lot's to learn and charging is a big one. There is so much more to it than I thought. My run time seems really low too...I rarely get much more than 30 min but it could be because the one cell is shot.

  6. #6
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    Quote Originally Posted by Johnybravo View Post
    Are you balancing cells every charge?
    I am. I charge them one at a time on balance. Lot's to learn and charging is a big one. There is so much more to it than I thought. My run time seems really low too...I rarely get much more than 30 min but it could be because the one cell is shot.

  7. #7
    RC Racer
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    I am getting close to three hours on 7600 mAH Lipos but I'm rock crawling and trailing not bashing. You must be running the Summit very hard to get only 30 minutes on that size pack.
    "For we walk by faith and not by sight" 2 Cor. 5-7

  8. #8
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    Quote Originally Posted by Johnybravo View Post
    I am getting close to three hours on 7600 mAH Lipos but I'm rock crawling and trailing not bashing. You must be running the Summit very hard to get only 30 minutes on that size pack.
    If you are bashing, mudding or otherwise driving primarily in high gear; that time seems to be par for the course. I run 2S 7600 mAh LiPo and would estimate 30-40 min run time, maybe as long as 60 min when bashing. I have not had a chance to take my Summit trailing/crawling yet, just bashing & mudding. Probably something to do with LVD setting? Not sure how much you want to tinker with it.


    Which would lead me to ask: is a voltage sensor a necessity? or just good idea? Can you rely solely on the LVD and just stop when it kicks in and reduces throttle power to 50%?
    Every crash/ broken story: This one time...

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