Several days ago I received an OPUS BT-C3100 v 2.1 from Gearbest.com. After reading the instructions I put a batch of potentially decent laptop pulls in for a capacity test. All was well until I noticed one of my Samsung 26c cells climbing over 2600 mah. All three of the 2600mah rated Samsungs climbed to at least 2750mah according to the OPUS. A moderately used 2400mah rated Sony laptop pull discharged to 2450, a Panasonic PD 2900 to 2944, and an e-fest 700mah IMR to 898. I tried both the discharge alone and the charge/discharge test feature and both reported obviously inaccurate readings. Have any of you OPUS owners observed similar issues and if so,is there a fix? I would much rather fix the issue myself than deal with Chinese "customer service".
Its a measure, that’s all. I tried a pair of new 3400mah 18650s and I think is reported these correctly. Many of the older cells were rated to minimum capacity and were often more.
What I am learning while checking NiMh cells is that testing them at 1000mah settings, they report very bad. However a 500mah test or refresh cycle is much better in getting some real numbers back.
Most of the function of this charger is built into a microprocessor. Unless you want to reprogram the code, you probably will not be able to fix anything.
I would try a comparison discharge/charge test on a hobby charger using the same settings, to verify if there is a problem with the charger or you just have overachieving cells.
What end voltage are you getting when the charger finishes? maybe the selector switch is on 4.35v termination instead of 4.2v
Before GPS, mariners brought along either one or three compasses. If you have two, and they point in different directions, which one is right?
My Opus seems anecdotally accurate. So far it hasn’t given me any reason to question its measurements. Well, it seems a little quirky for 16340 cells but it seems solid for everything else.
Due yourself a Favor and DO NOT get this charger.
You are expecting far more than this unit can provide. It is not a Commercial charging unit.
It is not an accurate Lab unit. It is a useful consumer unit, and that is all it is.
You can not have Champagne on a Beer Budget.
I am not being Coy, it is just that I have seen you ask for information about this charger and you have made it clear that you will pound this thing and expect lab results and commercial run time between failure rates, and that is not going to happen with this unit.
Find another unit or curtail your expectations because this isn’t the “Holy Grail”
Call em’ as I see em’
HTH
Keith
The charge and discharge rate can affect what the reported readings are. That is the nature of batteries..all batteries. What this charger and any other analyzing charger try and take into account (in the processor code) is temp and resistance. To get a perfectly 100% accurate reading an analyzing charger would be out of reach of the average person and that kind of accuracy would not make much of a difference to people like me.
202bigmike - I have tried a few different chargers. I like the analyzing feature of the Opus but other than the 4.35 ability (which I have not needed) the Nitecores have been reliable for me. Whether you buy the Opus, Nitecore, or Xtar you will not go wrong. For $40 the Opus is a decent unit.
I have also same problem with 2.0 version. I can’t trust the result.
1.pansonic 3400 2.samsung 2900 3.samsung 3000 4.lg 3000
And I am not satisified with 4.35 charning option
3.0~4.2v charging speed is okay.
From 4.2v to 4.35…the charing current is below 100mA. that is too slow.
Your readings are off by, what, 2-6% vs what you expect?
Have you considered whether your expectations are realistic?
Have you considered whether 2-6% is a reasonable cumulative error for both the rating of the batteries and the testing equipment?
Have you considered whether your readings were taken under the same conditions (discharge rate, etc) as those the manufacturer used for calculating the capacity rating?
On the latter point, I doubt you have, because if you had, you would have specified the discharge rate you used for your tests.
There may well be a problem with the Opus, or your particular example, but we don’t know enough to know that.
In general though you can expect that you’ll get higher capacities at lower charge/discharge rates. It looks like Samsung uses 0.2c charge (520mA) and discharge rates for their testing. Also worth considering that repuatable battery manufacturers would probably rather underestimate capacity of their cells than have customers unhappy about cells coming in under their rating. Age will diminish that capacity somewhat, but from what I recall, some of my 4-year old Samsung new-old-stock pulls measured over their rated capacity.
My Opus 2.0 seems to track relatively close to what the LiitoKala analyzer reports for Lion cells and Lacrosse BC900 for NiMH cells. To me, a couple of hundred mAh difference between actual and measured capacity on what are essentially 3000mAh cells would be no cause for concern. If I stuck a 2200mAh cell in there and it read 3000mAh, then I would start to have some doubts. What’s more important is consistency between runs on the same cells. I’m more interested in what the relative decline of a cell is compared to when it was new than how close to within a few mAh of what the label says. Plus I doubt that every cell that rolls off the Panasonic assembly line is exactly 3400mAh. The voltage offset mod between the 2.0 and 2.1 versions could also account for some differences in reported capacities between them.
Isn’t there a known issue with it testing Panasonic 3400 cells? Either way, those results above don’t look unreasonable to me, although I’m not an electronics engineer. I also test 18650s in real world use with my USB charge doctor. I’ll put an 18650 in a power pack or the miller charger, put the charge doctor on it with some device that needs to be charged, look at the charge current, and capacity is just load over time.
So if my Opus claims that a 3000 mAh 18650 checks out, I’ll double check that it charges my phone at 1 amp for 3 hours-ish when I put it in a power pack. I guess what I’m saying is that the Opus is the reality check that decides if the cell is worth putting into a device in the first place. I still keep tabs on my cells once they go into the wild. They still have to perform.
Maybe the Opus isn’t a laboratory grade scientific instrument, but it’s still a fine tool. I think I paid $36 for mine with the group buy, and couldn’t be happier.
As HKJ has noted in his reviews and I experienced it myself and to those who have used this charger for a while, the EARLY v2.0 has two main problems:
1. The Charge Capacity figures shown after a charge or test mode is about 15 to 20% exaggerated.
2. The 4.35V setting takes a very long time to finish, as the charging rate after 4.2V is very much reduced.
(But if your 2.0 does not show the exaggerated Charge Capacity figures, it is the later, and improved 2.0 by way of a resistor addition, released and delivered sometime last June, and still the same stock power supply)
All other parameters are working normally, especially the accuracy of the more important Discharge Capacity, as tested and compared repeatedly to my iCharger 106B+ hobby charger (both charge and discharge)
In the v2.1, both problems mentioned above are already corrected. (a few samples of the 2.1 has a low terminal voltage (4.14V) and has been discussed in the Gearbest 2.1 thread.)
Thanks all for the constructive comments. It looks like I will need to play with this charger some more and perhaps develop some sort of correction factor to alleviate some of the perceived error. The charger does seem to give similar discharge readings for the same cell on consecutive tests. I should at least be able to weed out the bad cells and keep track of deterioration as cells age and maybe that's enough for my purpose.
Muto/Keith ; While you’re trying to send me in the
right direction about battery chargers, you have made
some wrong assumptions about what I expected from
and my use of the battery chargers. But not a problem.
What type of personal use info about the Opus 2.1 can
you give me ? Do you have other battery chargers for
me to consider ? Your input and help is appreciated.
