Painful. Just painful. C4 meets 21700s.

Finally got my 4pak of Sofirn 21700s. Like always, I put new cells through a few cycles of up’n’down and measure their capacity.

Packed some stuff into boxes to “get organised”, and can’t find my almighty Miboxer or feverish Opus, but did find my… umm, pretty?… Zanflare C4. Worked great on my 14500s (EBL), so lemme used it on these.

Loaded up all 4 cells into the bays, they fit nicely albeit very snugly, and fired it up for a capacity-test on each cell.

Wait… WHAT?? Only 500mA or 300mA?!? Good God, I’ll have to leave ’em ’til New Year’s…

Good thing there’s no such thing as a refresh cycle on it, else I’d have to come back in March.

It’s been like 5 hours since I started, and 3 cells finally just hit 3.80V.

:weary:

but at least it’s working :smiley:

Wow, can’t find 2 of your chargers…? You must have waay too much stuff :wink:

20lbs of crap in a 5lb bag…

Just checked ’em, they’re finally discharging.

C4s were the ones that were generally about 10% “optimistic” compared to other chargers, neh?

Imagine that especially with a paltry 500mA drain on the way down, they ain’t gonna be stressed out at all. Probably have to shake ’em to wake ’em up after.

500 mA builds character, only 10 hours on a depleted 21700 cell. I personally like slow charging, I just plug them in before bed and unplug in the morning. It’s like Santa Claus every night I recharge. Merry Christmas.

For longevity, absolutely. But I want to stress-test the critters to see their actual capacity, especially when new.

Every now and then you can get a lemon, so it’s nice to find ’em out up front.

Well, I got nothing but crappy figures from my Zanflare C4. It’s not only the general optimistic offset of 10% I observed on my C4 but I also experienced deviations between each charging slot. Slot #2 always indicated far more/less than the other ones.

I asked Gearbest about it. Their answer was: „This is just normal“.

I asked Henrik (HKJ) about it. He said it’s no professional device and those deviations are within the specs.

Wellp, this spread is from 4300 to 4500 across all 4. Will check on the Opus or almighty Miboxer if I figure out wherenahell I put ’em.

At least it doesn’t cook itself to death. The fan on my Ope would be buzzing like an angry bumblebee all night long.

Then again, it would’ve been done with at least 2 of 3 cycles of a refresh. :neutral_face:

Mine got blazingly hot during discharge portion of fast test on 4 18650’s, I won’t be doing more than 2 at a time with this thing, maybe if I had a cooling mat. I do like being able to see the resistance in any mode tho, even if its inaccurate, but I think if I somehow need to to 4 discharges the opus is safer