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

The sparks are actually caused by the high voltage smoothing capacitors, due to the high current while they’re filling. Ideally the power supply should have an inrush current limiter (usually NTC resistor) on the input to prevent this but not all of them do since it’s not mandatory.

http://lygte-info.dk/info/SMPS%20workings%20UK.html

Search for NTC.

As a normal procedure , for most of the chargers and power supplies, first insert the main power cable in the 110-220 V , and then connect the secondary to the charger , WITH NO BATTERIES INSERTED ! Somehow , this is common sense...

This won’t prevent the sparking since it has nothing to do with whether the output is connected to a load or not.

If the preventing is the problem , just leave the 12V plug in inserted in the battery charger , and connect and disconnect the main supply . As for me , I have the 12V or 5V input for chargers connected ALL the time , and the mains are connected and disconnected thru few wireless plugs in ,with a remote control , as is needed.., I do think that is an elegant and reliable solution (I'm using it for many years ). A professional power supply has the NTC resistor placed in series with the high voltage capacitors , in the main voltage area , so , problem solved...

Thanks ferongr for your informative link and appreciate the helpful not so common sense answers for us newbees…

Side by side comparisons with two BT-3400 v3.1’s and 8 fresh batteries.
The fans have cycled several times. I think they’re quiet.

Hello,

I just ordered a new BT-3400. I hope that it comes with some sort of upgraded power supply that Henry mentioned in those back and forth emails. If it does not, would anyone have a link to a recommended replacement? Lite-On or otherwise?

Also, is there a good source of replacement fans for this unit? I can go ahead and buy the PS and fans now for future use.

You can get the replacement fans from gearbest for like 2 dollars or less. I got one just incase. I’ve had my opus for about 18 months roughly. And it’s used almost 24 hours a day I go to recycle bins and strip tool and laptop packs on top of 3 tomo power banks used daily and my flashlight at work and my vape units. There are batteries always waiting to be charged. Only had a couple issues with the opus. One was the power supply only when doing 4 batteries at 1 amp when they are low voltage it would reset and go to the default 500ma. The first power supply recommended before the lite on was supernight I believe 12 volt 5 amp. Never had a issue with that again. Never have had a fan issue. My opus froze one time and overcharged my batteries to 4.5 volts when I caught it. Discharged them instantly in a Fet driver flashligjt then did a capacity test. Didn’t damage the batteries. All my batteries have a label with the capacity and date last tested. Once a year they all get retested. I plan on buying a second opus. For the money it can’t be beat in my opinion. My unit undercharges slightly. It is .7 volts off. 4.2 on my opus is 4.13 on my dmm. My xstar and lii chargers go between 4.17-4.21. I’m fine with 4.13 honestly. Easier on the batteries. And only about 80 to 100mah short of completely full. It will help the batteries last longer. I have so many batteries a lot sit for long periods of time before being used. Sometimes you get lucky at the recycle bins. Example about 6 months ago. One bin had a couple packs I got about 20, Samsung 20r batteries all testing above 2000mah. A few good runs like thst batteries pile up. Not to mention all the laptop packs that only had 1 cell go bad all the rest perfect. It’s to the point if a cell is below 1800mah it goes back to recycling

Speed4goal,
Thanks for the boost of confidence in the opus. I own 3 LaCrosse 700s, 2 Xtar VP2s, an Ambient Weather 3100(opus clone) v2.1 and now the 3400 3.1 and Lii-500. I bought these last 2 mainly for lion batteries so I was quite interested in the upgrades to the 3400. Not sure if I’m ready for the MC 3000. :slight_smile:

mine use to undercharge , it's wasn't really undercharging it was more like reading the voltage lower than it actually is , to make it read more accurate I desolderd the j1 bridge on the mother board , now it reads the same as my fluke DMM & it charges to 4.2.

Im still on my original fan , it made a funny noise once ,I just gently taped the fan casing with my finger and the funny squeeling noise stopped & it's never done it again, mine is the 3100 v2.2.

https://www.google.co.uk/search?q=opus+c3100+motherboard&safe=off&client=safari&hl=en-gb&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwje6sT818HZAhUCJFAKHbXICfQQ_AUIEigC&biw=1024&bih=672#imgrc=sMvxF0rRBXkPdM:

Zoom in and look at about the 3 o’clock position near the big black circle , desolder the bridge.

Nev,

I found your post w/the before and after pics on CPF:

However, I haven’t been able to find out why desoldering the J1 bridge makes it more accurate. Can you provide any add’l info? Also, can this be done on the 3400 as well?

Also curious. I just got mine and its reading full cells at 4.15v. I pulled them off at full and stick them in my other charger and they read 4.19v. My DMM is on the fritz, so dont have that option to test…

Oh you found it , I tried to look for that thread but couldn’t find it , I thought it was on this forum lol.
As I understood it ,it was the maker being cautious by making them undercharge as the general public would be using it with no knowledge of lithium cells.
Also it depends on each individual unit , some may be spot on ,some may read over and some may read under , so the soldering of the bridge will lower it by .04-.05 voltsto be on the safe side ,mine was reading 4.14to 4.15 when full so I desolderd j1 & now it’s reading 4.2 when full.
I don’t know about the 3400 but I would assume they have the same motherboard,you just have to open it & look , you’ll need a magnifying glass to see it as it’s very small.

Without me reading through this whole thread, can someone please let me know the difference between the Opus BT-3100 v2.2 and the 3400? I ordered the 3100 and was not even aware there was a 3400.

Stick with the 3100, the main difference is that the 3400 discharge down to 3.1 volts instead of 2.8

2.8 v is good , below 2 v isn’t wise.

Whats difference between opusc3400 and xstar.vp4 dragon plus

so… basically total mah readings are lower on the 3400? because if on test mode it dischanrge less mah….(to 3.1v) this will lead to a little less total mah

Ok thanks