Really annoyed and upset by my Opus C3100 v. 2.2, it’s been giving me nothing but headache since I bought it months ago. Today it overheated one of my Sanyo 18650 cells to about 45 degrees C, and combined with its other problem and shortcomings, I decided I’ve had just about enough. I did some research in Google and on BLF as well for possible purchase candidates, but didn’t actually find anything good. There are some units that get good feedback, until someone comes into the thread way down the line and says the charger is great but its voltage readings are off by a fair bit, and I want my 18650s fully charged to 4.2 V for optimal operation of the BLF Q8 flashlight, if nothing else… Kinda reminds me of this XKCD: xkcd: TornadoGuard
So, I hope you might suggest some device that I’ve missed. What I want:
4 slots.
4.2 V Li-Ion/Li-Pol, NiMH, NiCd support.
Selectable charge-discharge current up to at least 1 Amp.
Proper -dV/dt charging termination for NiMH/NiCd, unlike Opus’s CC/CV nonsense.
Reasonably accurate voltage readings / cut-off, +/- 0.02 V at most (my Opus is off by about 0.06-0.1 V, and it’s not a constant offset error, so basically I never know what voltage the cell is actually at).
Capacity measurement during discharge cycle, bonus points for adjustable cut-off (2.7 V / 2.5 V).
Bonus points for temperature sensor / fail-safe.
I know SkyRC MC3000 ticks all the boxes and many more, but it has two severe shortcomings: the price, and the compilcated UI / the need to setup your profiles before you can reasonably use it as a “plug in and forget” charger.
Is there really no decent device in between Opus’s $30 and MC3000’s $100 (-ish)?
Not really. Only for capacity testing which may be nice to have to check a brand new or a very old cell, but really it’s more for toying around. In fact, now that I think about it, I’d place IR measurement above capacity testing in the list of ncecessary features.
What do you have in mind?
Thanks, interesting indeed! I’ve seen their 8-slot monster, but missed these two.
C4 Plus seems a step down from C4-12, unless I’m missing something?..
I’ve had an Opus BT- C3100 2.2 working great and reliable for the last 4 yrs. 45C doesn’t sound like it’s over heating to me. Start worrying if it hits 80C. You can get 45C just about any cell with a 1A discharge. Especially a cell like an NCR18650B or a no name chinese cell with a higher internal resistance.
I would have thought same springs, but dont have that charger to compare.
I have had 3 of them break where they attach to the slide(post end are fine, just popped off when back removed)
Easy fix, i actually got a spring kit in the end. Little tricky to adapt to hook in and do feel more resistance now when placing larger cells in. Hopefully the posts will be strong enough. It frustrates me no end, especially when a good charger, using cheap beep internal parts. In fairness, its took quite a bit of use(used daily 7 days a week , at least 2 bays and more than once a day).
That is the only fault i can find, the auto select from the IR has proven accurate, once tested the terminating V (little low at 4.18 but no issue) and no trickle charge(which it should not, i take no chances though). The ease of just placing a cell in, leaving to do its thing has been great.
Me also Robert, my 3100 v2.2 has been excellent and issue free. Cant fault it in reliability at all, only down side now is it feels cumbersome having to press buttons!! This is a charger i have recommended in the past, still believe its one of the better chargers for near $30 out there.
It never did that before. This is a somewhat worn-out Sanyo cell, specced at 2000-ish mAh, some 1500 left in it. It could get slightly warm, 34-36 C, perhaps, but never hot. And the most bizarre is not the fact that it got hot but the circumstances. It was charging at 500 mA, the process was some 30 minutes in, it was nearing the switch from CC to CV. Voltage reading was something like 4.13 V. In fact, I think it might have switched to CV already but I’m not sure. Then I went out for ~50 minutes, and when I’m back it’s at 500 mA and 4.1 V, and the cell is hot. Clearly, it’s not normal for the voltage to go down during charging, the charger should have detected that as a suspicious behavior and stopped charging.
I restarted the charger, let the cell cool off and reinserted it. I discharged it with 1 Amp for several minutes and it didn’t even start getting warm, the voltage was fine as well. Then I charged it with 500 mA, just as I tried before, and it went without a hitch. Does anyone have an explanation what has actually happened? I don’t understand what was going on and why it got warm.
Also, CC/CV charging for 1.2 V cells is a joke, they might have as well said they don’t support NiMH/NiCd at all. It always overheats my Eneloops, so I have to break out Opus for Li-Ion and the good old LaCrosse BC-450 for NiMH, it gets tedious and a waste of time and space to have to fiddle with both. Combine this with significant error in voltage reading, and you may see why I can’t recommend this charger to anyone.
I really like my Zanflare C4. Had it 2 years. It does everything you could need except it doesn’t have a dedicated discgarge mode and the max current is 1000 mah on 4 slots. It’s reasonably accurate on the calibration, and seems to slightly undercharge my batteries (+/- 0.1-0.2v) which isn’t terrible. Charge, analyze, 2 test modes current 300, 500, 700 and 1000 mah, 0v battery recovery. Around $30 on Amazon. If you want discharge lps, Nitecore SC4, MiBoxer c4-12, or xtar dragon.
I have the newest Opus BT-C3100 myself and while it works good, I'd prefer something slightly simpler with better information on the LCD. As it stands now, I won't let my kids charge batteries since I have to choose my preferred settings (each time) for the 18650's and Eneloops.
I'm a battery noob, but one of the reasons I bought the Opus was the breadth of features such as discharge and refresh. However, I'm not sure if I need it. Is there a reason to have that for modern 18650 3400mAh or Eneloop AA/AAA batteries?? I'd love to buy the new MiBoxer C4Plus but I understand it doesn't have that feature. Is there any reason I would miss it considering my battery choices?
The MiBoxer also seems to tick the most boxes for the OP. Is there a better “plug in and forget”...yet SMART...charger on the market?
I got 2 MC3000's, had them for a while, and really love them. I don't know what you are talking about with complicated profiles - thought mine were easy to setup. I never use the BT phone I/F, do everything from the panel - easy. What's great is the 3 amp charging on those big 5500 26550 cells, and the minute charge levels for the 10440's. The 21700's fit, though it's a tight fit, but been charging a ton of them - got wide variety of brands.
I try to keep the settings on the 2 units in sync, and "profile 1" is the lowest level, up to profile 10 or so for 2.8 amps. Above 10 is for NiMh, etc. Of course I got about every possible cell in LiIon, so needed to use 10 profiles with differing charge rates, but think it goes up to 20 or so.
I usually set my charge level to 4.22V, because by the time you take the cell off, it's dropping, or drops a little after removing it, depends on the cell - older ones typically drop more. Most come off at 4.20, some at 4.21, older cells or poor ones like many of the 10440's and 16340's come off at 4.18 or 4.19.
The voltage level doesn’t really matter when it has completed the CV phase.
The reason the voltage drops, as you probably already know, is that the cell’s internal resistance comes into play once it’s not subjected to a potential difference.
Therefore, even fully charged, the cell voltage will drop it a little. As long as it doesn’t go below 4,17V when you instantly remove it from the charger, and you are good.
For lithium-ion cells, and NiMH cells, internal resistance goes down as the voltage goes down. So it’s not actually bad, since under heavy load, instead of dropping 4,20V to 4,09V, the cell drops from 4,15V-4,09V.
It is a strange phenomenon indeed, but a good one.
No, never heard of that. When I test lights, I like using 4.19V to 4.21V at a starting point. Never heard anyone say that off the charger, 4.15V is the same as 4.20V - just doesn't ring a bell. Guess there's still a lot I don't know, though I sure would like some tech ref info on this, again, because I've never seen that written here on BLF, least I can recall, and I'd think that would be something important to me.
