Opus BT-C3100 - Have I made the wrong choice?

Hi,

I recently got an Opus BT-C3100 version 2.2, to replace my broken no-name AA/AAA only charger, as I will be getting some 18650 headtorches. I picked it because it seemed to have excellent reviews, was reasonably priced, and also measures battery capacity.

I haven’t got any 18650s yet, but I have masses of Ni-Mh AA and AAAs. When I pop them in I can hear a quiet ticking noise. It comes from near to the fan, but it isn’t the fan - it happens when the fan is off or on, but is almost drowned out when the fan is on. It seemed to happen when either charging or discharging. Is this normal?

The other thing is that it says ‘NULL’ when I put in some old AA batteries that haven’t been charged for a while, and I cannot get it to do anything with them. But if I put them in my friend’s Nitecore D4 they charge straight up.

I’m wondering if I have made a mistake getting the Opus - while the capacity measuring is nice, first and foremost I need to reliably charge my batteries. I’m worried I have a potentially faulty example of a model that doesn’t actually charge as effectively as others.

For someone like me, where performance is secondary to utility, is the Opus still the right choice?

Thanks!

I have been using a couple of them for a few years now and they work reliably for me. The fan can be a bit noisy but that’s about it.

Regarding batteries that won’t charge, it happens when a cell is way below it’s low voltage. I don’t have much experience with Ni-MH, but when this happens with a Li-ion, specifically with protected ones, i jump start it by coupling it with a fully charged batteries for a few seconds to reset the protection or at least get a bit of voltage so that the charger will recognize it. A non protected Li-ion should not be discharged below some voltage though and it is somewhat the right thing to do for the charger not to try charging it.

BTW: welcome to BLF D&C :wink:

Thanks. So you don’t hear any sound apart from the fan? This is definitely an additional sound.

I’ll try ‘jump starting’ my batteries and see what happens. It’s strange that the Nitecore charges them though - if it was unsafe I’d expect it to also not charge them.

Edit: So looked up how to jump start them on YouTube by wiring them + to + and - to - for 3 seconds, and low and behold they’re now charging fine at 500ma (I presume that’s OK for both AA and AAA, as it’s the charger’s default).

The ticking noise is very faint, so I wonder if other people don’t hear it - especially when the fan is on.

Thanks!

Null/dead batteries will charge in….some……smart chargers, but not all. That is normal behavior. I keep a couple of dumb chargers around just to get them going and then put in the Opus, or other smart charger. Occasionally a jump as described above is necessary, but that bodes poorly for the longevity of the cell.

It is not good for them to go all the way dead. You might want to cycle those and check the IR. If the IR is really high, and they have trouble charging correctly (terminate too soon, get hot, don’t terminate), then they may be shot.
The IR function of the Opus works, but like ANY charger using a slider like this the IR is kinda flaky. There is simply too much resistance in the circuit to be very accurate. Under 100 is good, low hundreds is, well OK. High hundreds is not so good.

I’ve got a BUNCH of smart chargers, Opus, Liitokala, Maha, Zanflare, Xtar, Eneloop. The most versatile of the lot is the Opus. If I had to have only one, that would be the one.
The Opus is a ‘pulse’ charger. You may be hearing that cycle. My hearing isn’t very good so I don’t.

People bitch about the fan. Without the fan it’s charge and discharge would be more limited.

I charge AA at 500-700, 1000 when in a hurry. AAA at 200-300, 500 is a tad high for them. Not ‘deadly’ but I wouldn’t use it unless in a hurry.

Same here. Lots of chargers, but the Ope is my first grab. Only downside is the fan, which buzzes like an angry bumblebee most of the time.

Just this Wednesday pulled out my Thorfire TK4A and sure enough it was in low batt situation.
One of the Duracell 2000mAh NiMH was flat, actually read .12 volts on meter but Opus said no way, just read Null.

Popped it into The Zanflare charger and it took it and started charging and did in fact bring it all the way back.
That one batt is always lower than the others and they were bought as a set but after charging the Ir is not really that different form it’s mates so don’t know what the deal is.
As long as I don’t wait too long to recharge it is not an issue and the battery never gets overheated so it will stay for now.
Have taken to unscrew the tailcap almost all the way off and now there is no contact/parasitic drain.

On my first Opus I pulled the fan and peeled back the sticker covering the shaft and gave it a shot of Mobil 1 oil using a needle oiler.
Quieted it down pretty good but still a noisy fan in general but the upside is it reminds you that you have batteries charging as to keep an eye on them.

Have mine on a shelf that is in the hallway. When charging I pull the charger diagonal so the corner of it is hanging off the edge of the shelf to remind me it is in use for when the fan is done running but the charger is still in use.
This reminder works great for me.
YMMV

Later,
Keith

You can, and should lube the fan, even when brand new. They are tiny low quality fans. Pretty much any fan that small will whine.
If you wait until they are failing then you get more wear in the bearing, and more slop. I tried a number of lubes. Best one I found was to pressure inject some pure silicone grease (scuba shop). It was a bit sluggish to get going at first but that would last 6 months. Oils didn’t last quite as long.

I finally replaced it with a better fan. I also keep it propped up on a angle bracket with a USB fan pointed at it. The little fan seldom runs if I do that. I use a USB fan for any of my chargers if they are working hard; meaning multiple cells and higher rates. Heat is the enemy of batteries…any kind.

I have an opus BT-C3100 too. If I want to charge a 0.00v battery, like a NiMh, I set my power supply to 1.5v and 0.25ma. I hold it against the battery for 20 seconds or so, then pop it in the charger. Works every time. Of course if it’s this dead because of self-discharge you should just trash it anyway.

Thanks everyone. The fan sounds pretty smooth, but I’ve got some silicone lubricant spray anyway - I’ll pop a little squirt in through the grill if I can.

Is the Opus’ discharge/refresh cycle worth doing on older batteries? Does it actually refresh them to any useful degree?

Edit: I asked about mA again, but just realised that someone has already answered mA for charging. I’ll try 200mA for AAA and 500mA for AA and see how that goes.

The temp of NiMh is supposed to rise during charge, so stick with that. As for refresh, heck yes, it’s absolutely worth it.

Please don’t “pop a little squirt in through the grill if I can.”
You have to get to the bearing, only way to do that is to take the charger apart.
If it sounds smooth but is loud, that is normal, leave it alone at this time.

The refresh cycle takes forever, I never use it for that reason, the Nimh are too cheap to worry about saving.
HTH

Don’t worry - I wasn’t going to just blindly spray through the grill! I was hoping I could get to the bearings using the little spray tube without taking it apart - I hadn’t had a chance to inspect the unit to see what the access was like. If I couldn’t, I wasn’t going to bother taking it apart as it sounds OK to me. Given you suggest the same, I’ll leave it for now.

I’m happy to try a refresh - I’ve got the time, and if I can get a few more reuses out of them before recycling I might as well.

Thanks for the help everyone. I’ll stick with the Opus and see how I get on.

Welcome to BLF ” Dazed and Confused ” :+1:
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I would not leave it unattended while charging. Does it emit any electrical smells ?
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I had to bend the movable negative contacts towards the positive contacts to get any contact on big batteries like a 26650.
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Here is a good tear-down thread to look at. Review: Opus BT-C3100 V2.1 (with teardown and video)
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If you keep hearing strange noises when the fan is off, you probably should not use it until determining what that is. :wink:
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Please come back here and keep asking, guys with a lot of experience are in and out here so try to give them time to notice this thread.
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You did not make a bad choice, the Opus BT-C3100 v2.2 is a good charger, I use mine a lot with no problems.
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I had some AA NiMh that tested between 0 and 5 mAh each. I ran a full refresh cycle on each battery twice. Then they tested at 500 to 600 mAh. Thats like new for some brands. Totally worth the time.

To lube, the fan needs to be taken out, a sticker on the back removed, THEN you can access the bearing. FWIW pretty much all computer fans are similar and can be lubed that way.
Clean up the area well to get the lube off, cut a new disk of duct tape or similar and seal it again. Put a sticker (I use easily removed painters tape) on the outside and date it.

I used the same tape sticker process to track my batteries, until I got one of those labelers. It’s a good idea to be able to track their status over time.

I also have an Opus BT-C3100 charger (version 2.0). I’ve had it for years and never had an issue with the charger or the fan. The fan has been quiet since I first got it and I’ve never lubed it.

I also hear a slight fast ticking sound that you are concerned about Dazed and Confused. I believe that is from the pulse charging and shouldn’t be a concern. But maybe you’re hearing something different? Either way, just monitor it for awhile until you feel comfortable that it is working properly.

Be very careful with silicone spray lubes. Some of them use solvent carriers that act as plastic glue, similar to the type of solvent glues used in plastic model assembly. I inadvertently ruined a plastic calculating device that used rotating rings marked in increments by not reading the directions on the spray can and ended up gluing the rings solid.

I've had a Opus 3100 2.2 for a few years. It's always worked well. I stand it on end when in use, fan end up, to let natural convection aid with heat removal.

slmjim

Be aware that the thermal protection may fail so don't leave it unattended :(
https://budgetlightforum.com/t/-/61627

The BT-C3100 has temperature sensors, but the software ignores them during the charge cycle. At least that’s what I observed.

Thanks everyone. I’ll leave the fan alone for now, and it sounds like other people have heard the very faint fast ticking, which is reassuring. I think I’m good to go! I’ve chucked a bunch of AAAs on refresh, and I’ll see what happens.

I do plan to use it in a car overnight when camping too, and picked the Opus because it supposedly had protection from overheating. It seems from the comment above like it is designed to do that, but in practice maybe not?