Opus BT C3100 Test/Review = Not so smart 18650 battery cell capacity tester with many flaws

[@antonioveloy9107]

Easy. It doesn't discharge to 3V or 3,2V because most probably the cells you are testing there have different internal resistances, therefore some cells will drop to 3V or 3,2V for an instant, but then go back up slowly to nominal voltage (that's not uncommon). Nontheless when applying a load to the battery it should drop back to 3 or 3,2 V in almost an instant. This is due to internal heat and change in the internal resistance for that matter. A good test would be made so the cell has time to discharge and charge back up again after cooling down (keep in mind that 1 amp causes a bit of stress to the cell itself). An "intelligent" charger knows that and will retest and keep discharging the cell after a while, adding the mAh values obtained in each go until the cell stays on 3V or 3,2V, another thing to keep in minde here is that tester are designed that way so the SPECIFICLLY dont underload a cell - this is due to different manufacturers having different cut-off voltages for their cells), so many times those chargers misinterprete the actual state of the cell.. basically that all "intelligent" it gets, it basically just waits for the cell to relax, then keep discharging more. A note at this point: A cell that drops below 3,2V, then goes back up again is considered a "bad cell" because it's internal resistance didn't withstand the load of the tester (we always test amps according to what the application the calles or running will draw from them logically, and not just 500 so the cells feel good TOTAL NO GO!). Does this make the tester "bad"? Not really because it always depends on how much you charge and discharge a batter, and from the moment it leaves the factory and is used in certain applications it's internal compositon changes to whatever the application it's running wants it. In the end it's just a tool for you to check the state of the cell, and for some cells you will need more than 1 go, no charger can deal everything on the fly and always be right, even your multimeter has a brainfart from time to time, right? Btw. a Samsung ICR18650-22P for instance has a cutoff voltage at 2,75.. Tell me how you tell this charger, or any other charger to go to that specific voltage ^^

[@gixxerboy555]

My Opus BT-C3100 just works fine allready 4 years..

[@simon7030]

Great Review I've just ordered 3 more Opus

[@elibukin4840]

i dunno what's with your gear... my OPUS works flawlessly, for three years now...

[@rubenayla]

16:02 Because it charges them full, then discharges them completely, and then charges them back, without counting that power?

[@rooibergfarm]

I have same model and after watching you video, was concerned about the Ah measurement. You mentioned that the cutoff happens at various voltages, all being too high. I connected my trusted Fluke's and measured - my unit stops discharging at 3V, as advertised & expected. I think the higher voltage displayed is after the load was disconnected and the battery has time to recoup a bit. p.s. in my opinion, you should have come to that conclusion, as the Ah ratings on the Opus compared very well to the other chargers on test, if the Opus did in fact disconnect at higher voltages, then the Ah measurements would have indicated same i.e. mush lower

[@skivsamlarnastream]

Cells does not go up to random voltages beetween 3.3-3.6V after discharge, then the unit is clearly defectivt, also i bought 2 units 2 years apart from different sellers and BOTH had the same issue. Opus is pure crap and its so strange that so many people try do defend it, i cant even found out what the company name is and is clearlly defect/QC failed units being branded as Opus.

[@johndoe528]

This is why dislikes should be visible. What a crap take for views

[@outsourced-fd7vf]

In June 8 2024 it has 35 dislikes

[@Herny-Orozco]

Agigo, que sucede si por error incerto la celda con la polaridad invertida?

[@mrlee6810]

Thank you for the video, I have a question about the Opus BT 3100, if I want to test 2x18650 battery connected in parallel and if I use an alligator clip to connect it to the charger to test it, will this work? I just don’t want to disassemble it too much since it’s from a Ninebot scooter. It was difficult enough taking it apart and snipping the nickel plate off the cells, so most of them are now connected in pairs and I would like to test them.

[@jimmybrad156]

I think I read in its manual that if it gets too hot that it will pause until cooled enough.

[@michaelelkin9542]

I have a Lii-M4S and have a similar situation with some smaller cells. They stop discharging at a low voltage, but then the voltage is about 3.6v. If I start a discharge again the voltage drops very quickly and the test stops almost right away. I also noticed that if I discharge at 250 I can get a significantly higher capacity. Is the issue with the tester or does it mean the cells are going bad?

[@ericklein5097]

You really are one of the more unknowledgeable people in the community. If you see a cell at 3.6V after discharge it is entirely possible that it has high IR and it bounced back up to 3.6V after discharging down to whatever the minimum cutoff is. Without doing an IR test right then and there with a real IR meter or using a proper load. Temp is also another issue with the OPUS (don't get me wrong the OPUS is a flawed tester but your reasoning is entirely incorrect)

[@TheBatteryDoctor]

Sorry but have tested more then 50000 cells on various machines, OPUS is a crap product, most likelly QC failed VOLTCRAFT devices meant for conrad being resold cheap for the EU marked. Why would conrad charge 51.99€ and you got it for half that on Aliexpress? Aliexpress, temu, bandgood and amazon is a dumping ground for QC failed products, sure you could get lucky but it most cases its just not worth it. A cell does not go from 2.75V to 3,6V. Dont know why so many belive Opus is "good", the only thing is really is is cheap. It does not not measure temp on cells from what i know, you need MC3000 for that, but it might turn of if the PCB/mosfets temp is hot and that why it failes?

[@mogaal]

I didn't even finish the video after you said it is crap because there is not the company name on the box. You might be right about the product being crap, but if your first argument is: it is crap because it is unbranded......

[@TheBatteryDoctor]

Well good luck with your opus! May i suggest using ultrafire cells to go with it?

[@ibringthelastwords1358]

He sold out his souls to liitokala I guess 😁

[@christopherowens2635]

I just bought 2 brand new BT-3100. The (quick test) internal resistance reading is different from my other separate digital internal resistance tester. Is the interal resistance accurate on the OPUS? I trust my other digital internal resistance tester.

[@eddiekytia]

I just found your channel as I was buying the opus 3100. I need a reliable charger for 18650,21700,and 26650 batteries. I'd like a 4 slot charger and IF POSSIBLE that I can choose the current on each slot. What would be the most reliable charger. THANK YOU FOR YOUR HELP

[@TheBatteryDoctor]

Then the choice is MC3000

[@supercurioTube]

Does the Opus drain cells at significantly higher current during testing than the other one, therefore reaching the cutoffs point sooner especially on cells with higher internal resistance? That could explain how some cells bounce back higher in the end, once recovered from significant voltage sag from the high load. Then when adding your idea on capacity estimation on the remaining lower voltage, that might explain what we see. If the estimate is close enough on some cells, other cells with different voltage sag characteristics will show either too high or too low estimate. It's just a theory, what do you think?

[@wim4245]

I think you're right. To confirm you could test some cells with high difference with 500 mA instead of 1 A. I also have an Opus, it does cut off at 3 V. Depending on the health of the battery, the voltage bounces after the discharge is finished.

[@gopronomad4381]

I disliked because this guy just sound too sarcastic even in his responses in the comments section, shouldn't be making videos if that's the case asking one of the guys to buy an ultrafire without actually making a logical discussion. I've used my opus chargerS (yes many opus chargers) with no issues until I messed them up I.e. accidentally shorted due to my laziness. And yes it has temp sensor per cell slot (I've repaired one and saw those sensors) also they tend to cut off it it feels the cells can no longer discharge the preset discharge current .. if it cuts off at 3.5 all the time, you probably need to adjust the switch at the bottom of the board and select the correct parameter for li-ion instead of LiPo. Btw these chargers use some sort of algorithms to determine an approximation of cell capacities.. and just because you don't understand how they work, it doesn't mean they are crappy... Many of my peers use the same unit for testing cells etc and never had any issues

[@Batteridoktorn]

Why the actucl f*uck are people buying this noname chinease charger that is obviouslly rejected QC wolfcraft and then getting mad when i tell the it's f'ing crap! Dont you want accurate testing!? Do you work with selling opus chargers!? Of cource not every single charger has the same defects but most of them have some or many defects! Why the F! would i make a video about them not working properlly if they where perfect! i DARE you to even find the Opus webbsite! Have you even watched the video?? They are cutting of premasserully and when they don't the give happy ending result so that your bestfire/ultrafire crap looks better! And that you think "li-ion instead of LiPo" is different is just meeh. Do be rude if you dont know the absolute basics!

[@jimmybrad156]

I'm curious to know how you shorted the input?

[@OldSkoolF]

What is a scharger???

[@mikaeljonsson4686]

What is schinese??? ☺

[@gerardjachymiak5822]

i have been waiting for this

[@itsme-rf6qk]

thanks foir the review. cancelled my purchase for the opus. I need a 4 cell aa nimh analyzer/health check/resistence so I can tell what situation the cells are in. it MUST BE accurate. MUST! not this opus trash nonsense of being all over the place. unfortunately the Skyrc MC3000 is $160 with shipping/customs so that is way out of my budget. does panasonic have any analyzer chargers worth buying?

[@DIYwithBatteries]

Nice review 👍

[@gerardjachymiak5822]

thanks for helping i ordered 3 lii 500 with your link.

[@ibringthelastwords1358]

Liitokalas are shit too! They are using cheap components and not reliable at all. I have the Lii-s4 died in just less than 6 months and I even didn't used it regularly. Maybe just 1-2 times a month for my nimh Fujitsu pros and some 18650s.

[@DavidSmith-dm8ew]

I had one of those...it burned up after 8 months.

[@hullebikerfishing]

Good honest review, thank you.(i nearly bought one)!

[@emostorm7]

Opus Instrument Company

[@wattsworking2938]

Finally! The Opus is no good. The Lii 500 is a better unit but there the DC resistance is all wonky and messed up. Fine if you are just after a general status I guess. If you wanna do tests on new cells against mfg's specs forget all of these testers entirely :)

[@ibringthelastwords1358]

Liitokalas are shit too! They are using cheap components and not reliable at all. I have the Lii-s4 died in just less than 6 months and I even didn't used it regularly. Maybe just 1-2 times a month for my nimh Fujitsu pros and some 18650s.

[@noway0815]

indeed, the Opus BT C3100 is crap. With no logical reason 2 of them ware shorted and gone. So I bought 2 LII 500 and then 600... Realy GREAT devices... again: Opus is CRAP

[@ibringthelastwords1358]

Liitokalas are shit too! They are using cheap components and not reliable at all. I have the Lii-s4 died in just less than 6 months and I even didn't used it regularly. Maybe just 1-2 times a month for my nimh Fujitsu pros and some 18650s.

[@jimmybrad156]

What do you mean when you say they were shorted? What part of it was shorted and how did that happen?

[@noway0815]

@@jimmybrad156 I put one 18650 cell with reversed polarity... that was it! the opus bt c3100 started to smoke and gone forever... crap

[@jimmybrad156]

@@noway0815 Ouchies. Do the little koalas beep when finished, and do they give the option to disable trickle charging when finished? Kind of a shame that it trickles whether you want it or not.

[@noway0815]

@@jimmybrad156 even if it does not. this is a quistion of firmware update, but the problem with bc 3100 is a hardware issue so it can not be solved of at least not easy zo fix