Keep in mind that the Opus BC-3100 has its problems as well. The last time I did any research on them there were multiple versions of this charger and you didn’t always know which version you were buying. I think some of the versions also had noisy fans that were prone to going out and it was fairly common for people to replace the stock fan with a higher quality aftermarket fan. These are the reasons I decided not to buy it. Maybe someone can comment on the latest versions of it?
I think it was also a bit weak. What was the most you can charge 4 cells at? Was it 1A or 1.5A?
I’ve got an almighty Miboxer (regular, not the –12) and an Opus, and I use the Ope for doing refreshes (discharge then charge, 3×) and for capacity testing, because it does it in all 4 bays at once. Think the ’Box just does that in bay 4.
Just used the Ope to test a coupla batches of EBL 14500s I got.
I’ve got an almighty Miboxer (regular, not the –12) and an Opus, and I use the Ope for doing refreshes (discharge then charge, 3×) and for capacity testing, because it does it in all 4 bays at once. Think the ’Box just does that in bay 4.
so the C4-12 can discharge in bay 4? Am i understanding that correctly? If so, how do i do that?
No idea which version I got, but yeah, the fan’s pretty useless. When I got it cooking away on all 4 bays, it’ll start whirring away like an angry bumblebee, yet I can’t even feel the slightest wafting of warm air coming out the pipe. So what exactly is the fan doing, I have no idea. Doesn’t seem to be sucking out too much hot air.
Pffft. I think I tried doing all 4 bays at 1A, maybe 1.5A (can’t recall), but it got pretty hot and pretty noisy, and after a while it tripped the thermal breaker. Like I said, the fan’s pretty useless, so maybe sitting on top of a laptop cooler it’d fare better, but I wouldn’t push it otherwise.
I’m generally not in any particular hurry when it comes to charging, so I try to keep it down to 700mA or even 500mA per bay if I can.
It’s some convoluted method like you gotta press the mode button ’til one thing flashes/blinks/whatever, then hold it or press again ’til the 3 squares on the upper-right of the display start blinking.
Setting the charge/discharge current is a whole other matter, too. I somehow just stumbled on the method at random without having to go back to the instruction book.
I don’t have the charger handy (I keep them in their respective boxes so I don’t lose anything), but maybe someone can jump in here with the actual instructions.
Usually doesn’t work with my C4-12. Manually selected override rates for my 30Qs and other problematic cells will fall back down within a minute.
There appears to be an improvement in the newer style C4 firmware though, as manual overrides do stick in that one, but it’s only an 800 mA maximum rate charger.
Not really. The new C4-12 is a completely different design from the older C4. It has an externally mounted power supply, power brick, and the display and controls are also all completely different. The only similarity between the two is the name and the number of slots.
I have some 650 mAh 14500 IMRs that my Miboxer will automatically select a 800 mA charge rate for.
That is more than 1C, which usually produces a noticeable amount of battery heating, in addition to not being conducive to battery longevity. I let it run that way for about 3 minutes to see if it would automatically step down, but it didn’t. Maybe the C4-12s built in temperature sensors would have kicked in before any damage was done, but I didn’t want to wait to see how/if that worked.
Although the instructions I got with my C4-12 said you should be able to manually select lower charge rates like 100, 200, & 300 mA (the later being an appropriate .5C rate), I couldn’t get it to go below 400 mA with those cells installed, so I just used my 2nd Generation Miboxer C4, which incidentally also selected a too high initial automatic charge rate, but COULD easily be manually overridden to 100, 200, or 300 mA.
Just another case where a flawed implementation of uber high-tech good intentions interfere with, rather than facilitate the task at hand.
My C4-12 shuts down and reboots itself when temperatures hit about 52C. I’ve had it happen numerous times when trying to charge 4 button top 30Q cells at 3A. Although, I seem to be the only one having this issue. I have not seen anyone else report such reboots, and apparently Miboxer upgraded firmware in later versions of this chargers to automatically reduce charge rate if temps get too high, so that it does not reach the reboot level.
In hindsight, those cells that I was charging are the ones with higher IR (from Richard) - maybe that’s why they heated up so much when I tried to push 3A into them.
I do not have 4 30Q flat tops that I could try to see what temps they’d reach.
Interesting. This is another confirmation that Miboxer is making running firmware changes on these products, apparently without adding an easily identifiable product model/revision number change. The labels on the back of my 1st & 2nd Generation C4s look the same at first glance (in terms of Model Name/Number), but you can see a difference in the lower end of their output current specs (“V1”=350mA, “V2”=100mA). Maybe they’ll get everything right someday (or at least a little better).
My C4-12 is probably also a relatively early one, bought the day after they became available on Amazon.
I have had my 30Q reached 60C and no reboot was observed. This was during the day when the ambient temperature was in the high 20s C (maybe even low 30s). Ever since I observed the temperature getting that high, I have stopped charging my batteries with it set to auto during the day just to be on the safe side.