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Thread: SkyRC MC3000 help with Termination setting

  1. #1

    Default SkyRC MC3000 help with Termination setting

    Got my SkyRC MC3000. When charging 26650 lithium batteries at 1.0A, default termination is 10% of charge current which is 0.1A. What will happen then if charging to 4.2V with 1.0A and Termination set to the default 0.1A? Trying to get my head around to understanding it.
    Last edited by klrman; 05-20-2018 at 01:26 AM.

  2. #2
    Flashaholic* maukka's Avatar
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    Default Re: SkyRC MC3000 help with Termination setting

    The charger will charge the battery at 1.0A until it hits 4.2V. This is called the constant current (CC) mode. Afterwards it tops the charge off by trying to keep the voltage steady at 4.2V while at the same time decreasing current (constant voltage mode, CV). The charging stops when the current has decreased to you selected termination current. The default value of 10% is usually low enough to get pretty much the last drop of capacity from the battery.

    If your termination current would be 100% of charge current, you would see an instant big drop in voltage after the charging stops.

  3. #3
    HKJ's Avatar
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    Default Re: SkyRC MC3000 help with Termination setting

    I played with different termination voltages and currents in this article: https://lygte-info.dk/info/batteryCh...Test%20UK.html
    My website with battery, charger, usb reviews, comparisons & information: https://lygte-info.dk/
    Latest addition is multimeter reviews

  4. #4

    Default Re: SkyRC MC3000 help with Termination setting

    Thanks for the good explanation Maukka, I got it now. I have to drain the same batteries I put in yesterday a little and try again today as one charged to 4.191V and the other to 4.201V and both said "Timer Cut". Timer was at the default 180min setting, and I don't think it actually ran 3 hrs before the time cut, but I need to try again and see what went on there.

    Still learning, but today I noticed that if I would have just press the SNB button when I saw the timer cut msg, I could have strolled through the menu and seen the actual amount of time the 26650's were in the charger.
    Last edited by klrman; 05-20-2018 at 12:39 PM.

  5. #5

    Default Re: SkyRC MC3000 help with Termination setting

    HKJ, very informative tests thank you. So termination settings do affect the capacity either up or down, thanks for that. Through your 48 cycles capacity was noticeably lost as well. I'm trying to find a happy medium if I charge to 4.1V where it doesn't take too long to terminate but still gives the most reasonable capacity. Might as well use everything this charger has to offer since I got to play with it now.

  6. #6

    Default Re: SkyRC MC3000 help with Termination setting

    If you are satisfied with the 4.1V open circuit voltage on the charged Li battery, you can save some time while charging. Then you set also for example, 4.2V as the end-of-charge voltage, but choose a relatively high termination current, e.g. 0.8A and see if you come out at about 4.1V after the voltage has droped down (measured some time after charging).
    With Li - batteries I would neither set a capacity- nor a time limit.

  7. #7

    Default Re: SkyRC MC3000 help with Termination setting

    Any idea how the higher termination current would affect the battery overall? I've read 10% termination current is the industry standard, so if I am charging at a current of 1.0A then 0.1A would be 10%. Your suggested 0.8A would be 80% but I don't know what that does to the battery.

  8. #8
    Flashaholic*
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    Default Re: SkyRC MC3000 help with Termination setting

    It's not clear what you mean by "affect the battery overall". Terminating the charge sooner by using a higher termination current will be healthier for the cell because it will reduce the time it spends at higher voltages and temps. But it has the disadvantage of yielding lower capacity charges. You can look at the charts HKJ linked above to gain some intuition on the relationship between termination current and charged capacity, and how this depends on health (IR) etc.
    Last edited by Gauss163; 05-20-2018 at 02:10 PM.

  9. #9

    Default Re: SkyRC MC3000 help with Termination setting

    Thanks, I'll look at HKJ charts in more detail this time and try and understand it better.

  10. #10

    Default Re: SkyRC MC3000 help with Termination setting

    It means that you can achieve the 4.1V open circuit voltage after charging with two different strategies.
    1. Conventional: charging end voltage set to 4.1V with 10% termination current from standard charging current
    2. Modified: charging end voltage set to 4.2V, termination current selected so high that after charging end, a voltage drop of about 0.1V is formed.

    In comparison, the second method is significantly faster, because the time consuming constant voltage charging phase is shortened, but inaccurate at the desired voltage end value.

  11. #11

    Default Re: SkyRC MC3000 help with Termination setting

    Thank you for the explanation sbj. I'm going to try 4.2V with 0.8V termination right now and see where voltage lands at. I have a flashlight where I use two 26650 in series, so I want to see if both batteries terminate very close to the same voltage using this method so that I can continue to use them in series safely.

  12. #12

    Default Re: SkyRC MC3000 help with Termination setting

    If you want to use two batteries in series, I would advise against the second method. Because this can lead to different levels of charging capacity even with different internal resistances despite the same battery type. Since the result is more uniform in the first method.
    That is why it is always important to provide as many details as possible about your requests. Otherwise, a well-intentioned piece of advice can be counterproductive.

  13. #13
    Flashaholic*
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    Default Re: SkyRC MC3000 help with Termination setting

    If you are also varying the termination voltage (such as in post #10) then analyzing the impact on health is more complicated. Because the "modified" charge goes to higher voltages (and attains higher currents at higher voltages) it will be less healthy for the cell than the "conventional" algorithm.

    Generally if you want to design fast(er) charging algorithms with minimal impact on health then studies show that is best to do the fast charging at lower voltages - where it causes less degradation (e.g. I gave links in the past to charging algorithms using these ideas: Philips old BoostCharging algorithm, and some multistage CC/CV fast-charging algorithms described by Tesla in patents). I'm not sure if the MC3000 has the capability to implement such multi-stage CC/CV algorithms. If so, that would be a healthier way to do fast charging.
    Last edited by Gauss163; 05-20-2018 at 03:26 PM.

  14. #14

    Default Re: SkyRC MC3000 help with Termination setting

    Good to know and yes, will be careful about details in the future. So that gives me an idea though to set one program with the MC3000 for single cell use and a more safer program for batteries used in series. It's all part of learning and I appreciate everyone's help with this. Whether I really need it or not, the SkyRC has to be the best charger I've ever had and I really like that I can set the voltage to my wants.

  15. #15

    Default Re: SkyRC MC3000 help with Termination setting

    Quote Originally Posted by Gauss163 View Post
    If you are also varying the termination voltage (such as in post #10) then analyzing the impact on health is more complicated. Because the "modified" charge goes to higher voltages (and attains higher currents at higher voltages) it will be less healthy for the cell than the "conventional" algorithm.

    Generally if you want to design fast(er) charging algorithms with minimal impact on health then studies show that is best to do the fast charging at lower voltages - where it causes less degradation (e.g. I gave links in the past to charging algorithms using these ideas: Philips old BoostCharging algorithm, and some multistage CC/CV fast-charging algorithms described by Tesla in patents). I'm not sure if the MC3000 has the capability to implement such multi-stage CC/CV algorithms. If so, that would be a healthier way to do fast charging.
    I'm not sure if the MC3000 can do multi-stage either, but it can be set to run a few programs in succession by initiating each program cycle manually.
    Last edited by klrman; 05-21-2018 at 11:54 PM.

  16. #16

    Default Re: SkyRC MC3000 help with Termination setting

    ................... any chance we can have the ability to delete some of our posts?
    Last edited by klrman; 05-23-2018 at 10:03 PM.

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