But if the problem were only to show up on high capacity cells, why wouldn’t I have noticed the problem when I charged up a triple Sony still welded together from a laptop pull? It took about 7700 mAh to charge the 3 - 2550 mAh cells.
It is not something I have analyzed in details, but the error is due to the current peak and that peak is large with low battery voltage. The Panasonic NCR cells does have a lower voltage than 2600mAh batteries.
Of course, the used power supply will also affect the result.
I would like it to show correct charge as well, I wouldn’t like to have to discharge it just to see its capacity. To see it at a glance every time I take it off charge would be great.
Plus it’s also about having a device that works as it should.
Note I haven’t received mine yet and am not an expert in this matter but these are general comments.
Henry Xu, please reply
just an update on my misbehaving power supply - gear best refunded me $5
i am using my own dc 50w psu with good results
Up until now, all cells I have charged were within a few % of the discharge mAh.
That changed with these Panasonic 3400’s
Discharge mAh
Charging mAh
I have an unopened NOS laptop pack that has 4 pairs of 2 cells. Tonight I will open it up and leave the cell pairs connected. I will charge them as pairs, discharge and note the discharge mAh. Then I will charge them and note the charging mAh. It will be interesting to see how the charger handles these “5600” mAh twin packs
Have to pay 30$ in toll and costums, then it wasnt as cheap any more…
Yeah, tell me about it. I don’t mind paying taxes on the amount I paid, but then to also get charged $15 in processing fees, and get taxed on the fees themselves? It’s just ridiculous and a huge scam.
That’s pretty annoying and disappointing. This is my first proper charger I’m buying and I wish it was one that’s going to work as described.
If you charge at lower current, or spend an extra $10 on a better power supply, you’ll still have a good charger. It’s still very good for what it does, albeit it’s not quite perfect.
where is the better power supply we need ?
it seems like gearbest should buy 500 new good power supplies and send them to us at cost….
could you please do that for us gearbest…
because the power supply you sold us is not as good
as it should be for a “special” company like you .!!
The BT-C3100 2.0 might not meet the expectations of those who demand a very good to perfect Charger/Discharger/Analyzer.
Personally, for me this is the best value-for-money $39 item I have so far bought. I own an iCharger, Pila IBC and a Maha C9000, used it for years, so I know how this BT-C3100’s performance compares against them.
It might not give the desired CHARGE figures as some people wanted it to have, but hey, it does everything else decently like the chargers I own. I am happy with it.
So go figure it out! 
HKJ: Thanks a lot for your detailed review with 2.0v version. I now understand the problem: our charge measure the current at the first 2ms when the channel starts charging. As HKJ’s current curve for Panasonic battery revealed, the current is not a square wave form: the current quickly dropped and goes up again. So this lead to wrong current measurement. While for Samsung 2600maH or even 3pcs sony batteries in parralell, the charge current is still a square wave form and thus current measuring is still correct.
I think it might to do with the chemistry behavior or characteristic of the panasonic li-ion battery. I didn’t find this strange charging current wave with other brands batteries. Even with 4000mAH 26650 batteries, it is still normal charging square current wave.
So we need some expert opinion from the battery industry. Do we have any one can answer?
I have that same point of view as well. Coming from years of using NiMH charger analyzers, which typically always showed higher charged mAh figures, I’ve gotten used to ignoring it. It’s the discharge figure that matters in actual use for evaluating the battery performance. However, the high heat and current demands on the power supply does give me concerns about its longevity. Granted it’s not super expensive to purchase a better one, but I would’ve preferred to pay slightly more up front for a more robust one to begin with. The fan is another potential point of failure that could’ve been better designed. The noise I can learn to tolerate, but given my past experience with PC fans of similar size, the high RPM and constant cycling make it prone to premature failure. In the end, I feel it’s still a decent unit for the GB price we paid, but I would’ve been willing to pay slightly more to eliminate those shortcommings.
KuoH
Looking at the results using the external power supply capable of supplying the current demand, the charging pulses were normal square waves even with 4x1A. I think the implication is that the charging circuitry is unable to meet the current demands due to the factory power supply sagging under load.
KuoH
At this point I am happy I bought my bc-1000 charger from nkon for charging my NIMHs. If in the future I need to have lion recharging capabilities, a cheap Xstar ($10) after being reviewed by HKJ will do 
edit: It’s a great charger at this price point, but I personally prefer more specialised chargers for different chemistries.
There seems to still be some other problems even with the power supply upgrade. Quote HKJ
Anyway, as an amateur user, all I really want is:
-a charger that works as it should
-accurate charge figures because I like to quantify things
-charges well and is reliable.
Some of the more modern LiIon chemistries charges at lower voltage, Panasonic was first with it, but is not the only one.
You can check my battery reviews, they do always include a charge curve, where the voltage can be seen.
I have not checked for at what charge voltage the charger starts to accumulate mAH wrong, but there is probably also a small error when starting on a 2600mAh battery.
For a $39 value charger I think I have made a right choice! I may order one more tomorrow!