Difference between Opus BT-C3400 & BT-C3100 v2.1?

I dont have any help for most of your problems but one of mine became very noisy and the fan was “sticking”. I took it apart in a matter of minutes and gave the fan a good whack and it’s working fine again now.

I’m tempted to put a better fan on mine as the fan really is noisy and annoying!

GearBest is the worst company I have ever dealt with. A better name for this company is GearWorst. If I had known they were a Chinese company before I ordered, I would have never ordered from them, but they fooled me by offering me PayPal for my payment. Chinese company policies are very different than US company policies. They don’t care about their customers in China. They just want your money.

This is nothing more than a scam company. After sending me an $85 defective XTAR Dragon Plus charger, they said I could keep the defective item and they would refund me $15. WTF, and here’s the punchline. They will only refund me credit to be used when I buy another item. My refund goes into my GB Wallet. Who in their right mind treats their customers like this? I’ll tell you who. Scam companies in China!

I will never do business with GearBest again. I went to a GearBest review site and found hundreds of similar complaints about this company. Don’t believe the fake positive reviews or the employees. They are lying. I wish you the best of luck should you choose to do business with this scam company.


Try another 12V power supply.

Fans issues are known with this unit they give out eventually and it has thermal shutdown if it gets to 60c inside it cuts current not much higher the system shuts down until it cools enough. With your fan not working might be something thermal GearBest sells replacement fans for under $2 I bought a couple a week or so ago just to have on hand. To me its s great charger even if I have to change a fan occasionally no big deal takes 5-10 minutes

^ A multimeter could be handy right about now. Viper could check the input voltage from the PSU, and check whether there’s power getting to the fan header. No sense in replacing a fan if there’s no power getting to it. I mean yeah it is handy to have a spare, might as well order one considering the price and time it takes to ship, but usually you can just take your finger and see how the old fan is rotating…

If it’s giving some resistance or wobbling then it’s time to lube it. If wobbling, it was overdue to be lubed and you’re going to need a thicker goop to pump out less and make up for the play in the bearing (bushing). Personally, I mix 0W-20 or 5W20 synthetic oil with standard automotive lithium grease to salvage badly worn fans, till it’s just thin enough to flow.

Everyone has their own philosophy about lubing fans but there is some science and reason behind this. If your fan wasn’t worn you would want a thin oil, that is absorbed through capillary action into the bronze bushing. Once it is worn it most likely has an elliptical wear pattern and a thicker film strength is useful to reduce wobble and resultant lubricant pump-out, but with a thin base oil so it can still seep into the bushing better.

I’ve gone steps further in some cases to include a felt pad for a reservoir or a plastic backing sealed with epoxy to provide a lube reservoir, but in this case the fan is so small and inexpensive that the effort may not be worth the bother to do more than a basic lube.

I appreciate all replies.
And I do have a multimeter, but I need more info regarding what I should check exactly.
How do I check the power to the fan?

Good tips I’ve heard of people lubing the fans and trying to. Havnt heard of a opus failing at sending power to the fan. But its a big enough known issue if replacement fans are readily available. Just like sky rc its big brother they sell just the shells because the case isn’t that tough. I’ve ran my opus heavily daily for several hours or more for 3+ months roughly no problems yet. I’d just rather be prepared with a fan. They can still charge at low currents without a fan. Usually with 2 batteries at 500mah the fan won’t even come one. Especially with just one cell it won’t come on. Next time GB runs a sale like this last one. I believe imma pick up a second unit. I’d like a rc 3000 but I can justify $80 on a charger. I like the 2amp discharge rate without going to a full on hobby charger. That’s more realistic to what flashlights use 2-3 amps for stock lights.

I have the BT-C3100 v2.2 and have always heard someone oem’d the “3400” to make people think it was a newer charger which it isn’t. Same exact charger as the 3100 2.2. The vape community has been discussing this for close to two years. Also heard the only difference between the 2.1 and the 2.2 was supposedly a fan upgrade.

Fan issue….rises like a Phoenix from the threads.
What about similar chargers……without a fan……that do a similar job? Seems the Opus at least tries to keep cool. The others don’t bother. Is there something “special” in those that doesn’t get hot, or do they just get hotter?

I lube my fan. 10 minute job, good for 6 months. I don’t see this as a big deal.

It’s a typical DC fan, when you think it should be spinning, you should measure voltage on the two power leads. While I’ve read that it’s a 12V fan, that doesn’t necessarily mean the charger is giving it the full 12.0V, but it might be, and I’d expect at least 5V to get it spinning reliably. You could insert thin meter probes into the back of the fan connector, or flip the PCB over and measure at the connector solder joints, or if the sticker is off the fan, measure at where the two wires are soldered to the fan PCB, though being a tiny fan, clearance might be an issue there.

Since it’s supposed to spin intermittently, rather than constantly holding multimeter probes to the pin header, it could be easier to tack (temporarily solder) jumper wires to the pin solder joint on the back of the PCB, then wrap the other ends of those wires around the multimeter probes if you don’t have probe alligator clip tips or equivalent to latch onto the wires.

The other option since it is a 12V DC fan, is see if the PSU is outputting 12V, working still. If it is, observing the correct polarity, take a couple scraps of wire and jumper from the PSU barrel plug to the fan connector, or use a bench 12V supply, or whatever. Describing what is easiest to do depends on what you’re familiar with and what equipment you have at hand. For example if you had a spare fan from some other PSU, like a PC PSU, often they have a similar if not identical connector so you could just plug a different known-working fan into the fan header, but personally, I’d just measure for voltage at the pins, then decide what to check next based on whether there is any.

Lii - 500

:+1: … +1:wink:

And if one ever does wear out or quit working, like ‘Speed4goal’ says; GearBest sells replacement fans for under $2.
I have a couple on hand myself, just in case they are ever needed.

You pretty much hit the nail on the head ‘RobertB’ concerning the C3100 v2.2 & the “3400”. No difference at all, just the model #’s.
Click on the link and it will explain the v2.1 & v2.2 difference, which was just two little items.

Have and Lii-500. Bought it just to check it out. IMO it’s not in the same league as the Opus. The Opus has a lot more capability and just flat works better. The Lii is a $20 charger, and amazing because of it, but it’s just not as good.

Both can charge and discharge and measure capacity. What are some important Opus capabilities that Lii-500 does not have? How does Opus work better?

I’m genuinely interested. I own products from both companies.

I also would like to hear your thoughts ‘flydiver’. I know which one of mine I use the most but I really have nothing sound to base that on. :wink:

I don’t have the Lii-500 but would have considered it for the price if it was a US merchant so the delivery wait wasn’t based on use of a calendar. A few things I noticed were… and I could be wrong, just throwing some things out there.

Only one bay status visible at a time
Max 1000mAh charge rate - and no fan but needs one less due to this
only two thermal sensors between banks 1/2 and 3/4

More flimsy spring contact rail, wider PCB opening and fewer soldered down attachment points, and

soldered down spring arrangement, and that solder looked poor on pictures I’ve seen

Another thing that struck me was barely any capacitors, one tiny electrolytic on the input but then only a

scattering of SMD ceramic. I don’t have one to scope but that seems like a tight budget omission.

No 3.7 / 4.2 / 4.35 selector switch

Old style open inductors - potential high freq noise source (yes I’m ignoring fan noise on BT-C3100)

Negatives about BT-C3100

Display zebra strip contact may go bad over years’ time. Display death = charger death, not reasonable to try to fix that beyond wiping the contacts and hoping for the best while any other discrete component besides main processor can be desoldered/replaced. Lii-500 is all soldered up display AFAICT.

25mm fan! Who needs to stack something on top of a BT-3100? No inherent need for it to be as short as possible. If only it were about 5mm, 10mm at most taller (original fan sits above the bottom plate of the housing so wasted space) to fit a 40mm fan, it could have been more reliable due to size AND lower RPM, and then had more room for airflow and case venting. With the right 40mm fan it could have been just about inaudible and last much longer.

… then again, I have a much better selection of higher flow to noise and current ratio 50mm fans but that’s large enough that it would require another level of customization to make it fit.

I looked at the SkyRC for $80.00 on a decent offer to compliment my two Opus chargers. Instead I purchased three replacement fans and used points to get them for £3 delivered :open_mouth:

I have posted these photos before in other threads here in BLF but since this Fan thing is again hot, I am sharing my mod that will not win a beauty contest yet fulfills my intention and experiment of a quieter fan, cooler operation, virtually no additional cost, and controlled by the charger’s own power for hands-free operation, just like the OEM fan. The fan is a 12vdc, .13A taken salvaged from a busted pc psu.

The fan sucks air from above, drawing fresh air from the atmosphere downward, passing through the batteries and cooling them in the cradle as the air pass through the rails, then go down below to cool the pcb, then exiting through the holes at the bottom of th the casing, all automatically controlled by the charger’s fan requirement as needed.

Note the holes drilled in the charger housing bottom.

The finished product:

For all intents and purposes, the current v2.2 OEM fans are already improved and good enough actually, but hey, we want to mod, don’t we?

Another negative for C3100 is that it uses PWM/pulse charging instead of constant current. Personally, I haven’t been able to find any proof that it harms Li-Ion batteries, but HKJ seems to think constant current is better.