XTAR VC4 PLus vs MC3000

[atomictorch]

Hello, I just joined this forum and I'm hoping you guys can sort out some questions. I bought an XTAR VC4 Plus based on the comments in the "absolute best charger thread," but I'm wondering if I should have gotten the MC3000.
Thread: https://www.candlepowerforums.com/t...r-on-the-market-21700-and-18650-cells.484281/

I'm charging 18650s, 18350s, CR123Rs, Nicad AA, Nicad AAA. I'll probably end up with other lithiums in the future.

I started charging the Nicads, but the VC4 Plus was showing different internal resistances for the same cell in different slots. Is this normal for chargers or is it an example of lack of precision in the XTAR? Would the MC3000 be more precise and accurate?

Should the charging data equal the listed battery specifications on the cell? For instance should I be able to multiply the capacity times the charging voltage to get the watt hours?

When should I make a custom charging profile in the MC3000 or change the default current in the XTAR? How do you know the optimal profile for a given cell? Usually I won't need or want to fast charge; is .5C the usual rate?

Thanks very much

 

[aznsx]

I started charging the Nicads, but the VC4 Plus was showing different internal resistances for the same cell in different slots. Is this normal for chargers or is it an example of lack of precision in the XTAR? Would the MC3000 be more precise and accurate?

Welcome!

I'm not familiar w/nicads, but w/ Li-ion cells, internal resistance (aka: DCIR) is dependent on SOC (State Of Charge), and thus is always measured with fully-charged cells, so keep that in mind. Variation of same-time, same-cell measurements between different tests &/or different slots is another matter.

I'm not familiar w/ that Xtar model, but do have some data with regard to this question / subject from testing done with my MC3000, (using 16340 Li-ion cells), which provides some hard data to consider when comparing performance. (Note: When measuring milliohms using simple point contact terminal connections under spring tension, all such contacts obviously must be clean and free of surface oxidation. DeOxit D100 is optimal for this application. In lieu of that, use whatever you have.)

I'm not a 'math guy', but when talking about numbers, there's often no substitute for using numbers, so here are the numbers the MC3000 produced:

Note: I have no idea why this system is showing this extraneous text with this bookmarked link, but the link does work correctly anyway

SkyRC — IFA 2014 — MC3000 charger-analyzer

yeah, the lack of release notes is f'd up. you could email them and pester them for info, but i won't because i sorta don't care. i'm on 1.17 and staying for a while. i don't feel like inputting my settings again.

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