Test/Review of Charger Opus BT-C100 early version

Batteries and Chargers Chargers
1

Charger Opus BT-C100 early version



Updated review of the shipping version











This charger is a single channel analyzing LiIon and NiMH charger, i.e. it can both charge and discharge while measuring, the charger can also work as a power bank. The total number of function is large and for that reason the technical section in this review is very large.

I got this charger from Gearbest for review, before it was completely finished. This means that some of the issues I find in this review probably will be fixed very soon.







I got the charger in a “retail” box, but before any printing was done.







The box contained the charger, a power supply and a manual.







The charger can be powered from the supplied 12V/1A power supply or from usb. I did not test the usb power, the connector was misaligned and broke off when I tried to connect to it.







The usb output is usual disabled, it is required to hold the “CURRENT” button down for some time to enabled the usb mode function, then press the button again to turn usb output on.







When the charger is turned on, it displays test where all the text can be seen.

When startup is finished it is possible to select mode:

  • CHARGE: Charge battery with 200 to 2000 mA.

  • DISCHARGE: Discharge battery with 100 to 1000 mA.

  • DISCHARGE REFRESH: Discharge and charge the battery 3 times.

  • CHARGE TEST: Charge, discharge and charge the battery, show how much current was discharged.

  • IMPEDANCE TEST: Measure the internal resistance of the battery.


When display is flashing it is possible to select mode and current.
Holding down the MODE button enables selection of chemistry.
Holding down the CURRENT button enables turning usb on/off.

When charging or discharging it is possible to use the DISPLAY button to select between V, mA, mAh, resistance and time.



Here I have select some functions.



Usb output is enabled, it can show either A or Ah delivered (I took this picture just as the numbers was changing).



The charger uses the classical slider construction to handle most battery sizes, but notice how far up the plus pole goes, this means it support 32xxx and D sized cells. The slider works smoothly and can handle sizes from 33 mm to 73.5 mm, this means even the longest 18650/26650 will fit.









Measurements

  • LiIon batteries will be discharged with 8mA when power is off.

  • LiIon batteries will be discharged with 2mA when power is on.

  • NiMh batteries will be discharged with 0.8mA when power is on or off.

  • Voltmeter shows wrong values when charger is unpowered.

  • Voltmeter do not freeze, but shows the actual cell voltage all the time (Very nice).

  • The voltage is measured with current off and is within 0.05 volt.

  • From 0.05 volt on the battery the charger will recognize it and start charging.

  • Up to 2 volt NiMH is assumed, above 1.6 volt they will be reported full immediately.

  • Above 2 volt LiIon charging is used.

  • Charger will restart if battery voltage drops below 4 volt.

  • Charger will restart charging after power loss, or battery insertion.



CHARGE LiIon batteries

The charger supports 0.2, 0.3, 0.5, 0.7, 1.0 and sometimes 1.3 and 1.6A charge current, default current is 1A



Due to the pulsing current the voltage line is rather thick. It looks like the charger terminates premature on this charge, maybe because it has a 900 minutes charge limit.
Display shows: 2968mAh in 15:00 hours



With 1A charge current it looks much better. The charger uses a simulated CC/CV charge curve and because the voltmeter is about 0.05 volt to high it stops when the battery hits 4.15 volt with a terminating charge current of around 100mA.
Display shows: 3142mAh in 3:59 hours





No surprise with the above two cells.
Display shows: 2728mAh in 3:21 hours and 3448mAh in 4:15 hours



With this older cell the problem with pulsing charging can be seen. The voltage is too high when current is on and well below termination when current is off.
Display shows: 2492mAh in 3:25 hours




These two smaller cells are handled fine.
Display shows: 825mAh in 2:08 hours and 622mAh in 1:40 hours



The current from the power supply is drawn in pulses, but no high pulse.



M1: 45,0°C, M2: 47,2°C, M3: 32,5°C, M4: 53,8°C, HS1: 67,2°C
When charging with 1.6A stuff gets warm.



When charging with lower currents the pwm pulses are around 0.75A, this is a good improvement for charging smaller cells.



At high charger current the pwm pulses are around 2A.



The current draw from the power supply is very close to 1A, there is no high current pulses.



Usual I check the charger from power on, until it charges, this was not possible with this charger. Instead the chart shows from the battery is connected.


CHARGE LiIon batteries with 4.35 volt

When selecting Li-3.8 volt cells the charger will charge to 4.35 volt



The result looks more like 4.30 volt, than 4.35 volt, but that is due to the voltage error on the charger.
Display shows: 3086mAh in 3:39 hours


CHARGE LiIon batteries with 3.6 volt, i.e. LiFePO4

When selecting LiFeO4 cells the charger will charge to 3.6 volt, that is the charge voltage for LiFePO4 cells.



This looks exactly as expected with a 3.6 volt charger.
Display shows: 1351mAh in 1:39 hours



But with the small cell there is a small problem, due to the voltage drop after charging (This voltage drop is rather large with LiFePO4 cells) the charger will restart charging a couple of times.
Display shows: 702mAh in 1:45 hours


DISCHARGE LiIon batteries

The charger support 0.1, 0.2, 0.3, 0.4, 0.5, 0.6A and sometimes 0.7A in discharge current.



The charger discharges to about 3.2 volt while measuring capacity.
Display shows: 2529 in 25:27, it looks like the long discharge time affect the precision.



With LiIon the maximum discharge current is 0.7A due to heat.
Display shows: 2997 in 5:59



M1: 45,4°C, M2: 58,3°C, HS1: 77,2°C
Discharging at 0.7A



Discharge is done with pwm



The same current is used for all discharge currents.


DISCHARGE REFRESH LiIon batteries, cycles batteries

This function will cycle the batteries 3 times, the discharge current must be selected. Charge current will be twice that. Display will show discharged capacity. This mode is not really designed for LiIon batteries, only for NiMH and sometimes the charger will hide it in LiIon mode.



Here the 3 cycles can be seen and a careful study of the curve will show that there is a small pause between each step. Note that 1300 minutes nearly 22 hours.
Display shows: 3002mAh in 2:32 hours.


CHARGE TEST LiIon batteries, measure capacity

Test capacity of battery, this means charge, discharge and charge, the charge current must be selected. Discharge current is half the selected charge current. Display will show discharged capacity.



One cycle.
Display shows: 3082mAh in 3:58 hours



IMPEDANCE TEST LiIon batteries, i.e. measuring internal resistance

I tried with the same LiIon cell a couple of times:



The result is average for the 5 values and is supposed to match the +XXmOhm value.
Generally the result is good.



The measuring is done with a couple of short high current pulses.



CHARGE NiMH batteries

The charger supports 0.2, 0.3, 0.5, 0.7, 1, 1.3 1.6 and 2A in charge current.



It looks like a good charging, the temperature has just starting to increase when the charging is stopped.
Display shows: 2090mAh in 10:29 hours



Good charge curve and termination.
Display shows: 2263mAh in 2:16 hours



This charge curve looks fine, it is terminated shortly after the temperature starts to raise.
Display shows: 3945mAh in 2:57 hours



The charger is terminated slightly premature.
Display shows: 2412mAh in 2:25 hours



Again a slightly premature terminations.
Display shows: 2629mAh in 2:38 hours



The temperature has started to raise, showing a full cell.
Display shows: 822mAh in 1:38 hours



This looks like a classic -dv/dt termination, but as can be seen on the other curves the charger is not depend on that. The charger do not maintain 2A charging current for the full charge, but reduces the current to 1.5A after some time.
Display shows: 2322mAh in 1:23 hours



I asked for a 2A charge, but the charger decided on 1.6A and reduced it further after some time. The termination is fine.



M1: 48,1°C, M2: 56,1°C, M3: 33,4°C, M4: 74,0°C, HS1: 88,0°C
Charging with 2A.



The charger uses pwm and can also select between different charge currents.



Here the current was stepped up.



And for a 2A charge it is much higher.



Usual I check the charger from power on, until it charges, this was not possible with this charger\*. Instead the chart shows from the battery is connected.
\*At least with LiIon, I could probably have done it with NiMH.


DISCHARGE NiMH batteries

The charger supports 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 1A in discharge current.



Discharge is terminated at about 1 volt.
Display shows: 1943mAh in 19:32 hours



Display shows: 2025mAh in 2:02 hours



M1: 35,3°C, M2: 35,6°C, M3: 39,4°C, HS1: 47,2°C
The power when discharging NiMH is much lower than LiIon, this means the charger will be cooler.
Discharging at 1A.



Discharge is controlled with pwm pulses, they are a bit above 1A (Depends on battery voltage).



Maximum discharge current with a nearly full battery.


DISCHARGE REFRESH NiMH LiIon batteries, cycles batteries

This function will cycle the batteries 3 times, the discharge current must be selected. Charge current will be twice that. Display will show discharged capacity.



Display shows: 2042mAh in 1:23 hours



CHARGE TEST NiMH batteries, used to measure capacity

Test capacity of battery, this means charge, discharge and charge, the charge current must be selected. Discharge current is half the selected charge current. Display will show discharged capacity.



Display shows: 2039mAh in 2:14 hours


IMPEDANCE TEST NiMH batteries, i.e. measuring internal resistance



The results with the loose battery looks fine, but with my box something goes wrong.



With NiMH the test current is only 1A, not the 3A from LiIon.



USB output (power bank) function

  • When usb output is enabled the battery is discharged with 15mA

  • Usb output uses automatic coding with Apple 2.4A as maximum.

  • Usb output can be used as ups

  • Usb output must be manually turned on when battery it put into charger.

  • When under voltage or over load trips the battery must be removed to reset the circuit.

  • Voltage, current, etc. on charger part of display is not correct





As a power bank it can deliver 2A, the over current protection is at 3A.



It will also work when the charger is powered, i.e. it can be used as a ups, but if the battery is over discharged or the output overloaded the power must be manually turned on again.



Output looks fine with a 0.5A load.
Display shows: 1.6Ah, this matches the above chart.



1A load also looks fine.
Display shows: 1.5Ah, this nearly matches the above chart (I get 1.4Ah).



With 2A output current the charger has problems when the battery is running low.
Display shows: 1.2Ah, I got 0.7Ah that looked fine and a total slight below 1.2Ah



Noise is 4mV rms and 32mVpp, this is very good.



Noise is 6mV rms and 57mVpp, this is very good.



As long as the battery has high enough voltage the noise is 11mV rms and 68mVpp, this is very good.


Testing the power supply with 2500 volt and 5000 volt between mains and low volt side on power supply, did not show any safety problems.



Conclusion

This charger is the most advanced single cell charger I have seen to date, it can do everything the larger Opus (C3100/C3400) can and then some.
The high charge current pulses has been mostly addressed in this charger, it do still use pwm, but not always at full current (good).

Being an early version of the charger, it do have some issues, hopefully most of them can be fixed in the software before it is released, but as can be seen above the charger works even with the issues. The micro usb input connector requires some changes to the design and may not be fixed for the initial release, but as long as the charger can be used on 12V it is not a major problem.

I see this charger as a very useful tool for people with a few LiIon/NiMH cells or as supplement to a less capable charger.



Notes

When measuring charge current with an oscilloscope I has a 0.1 ohm resistor in series with the battery, this means that the measured currents is lower than reality.

The charger was supplied by Gearbest for review.

Here is an explanation on how I did the above charge curves: How do I test a charger
2

HKJ,
Thank you for this extensive review, I have been waiting to purchase this charger from gearbest the release date has changed from March 15 to sometime in April…
I intend to supplement my workhorse charger (I4) with this one.

3

Interesting charger, but are there any major disadvantages by using pulse charging vs true CC? such as increased charge time or battery wear?

4

There is definitely a need for this at that price point.

5

There is usual two problems:

  1. Voltage is measured with current off, this means the charge voltage will be too high
  2. Due to the pulsing the peak charge current will be considerable higher than selected average current

Generally it is not a big deal, but I would expect it to cost a little bit in lifetime.

6

Buttons are too small.

7

Great review, thanks!

8

Looks like it has a nice feature set. Thanks for the thorough review HKJ! Excellent, thorough, useful information, as always :-).

My main gripes with chargers like this, are: a) I would prefer something with at least two charging banks. I have a lot of 18650 lights, and often like to charge as many batteries as I can, at one time.

Also, I’m not too crazy about chargers that require wall wart power supplies. I’m glad this Opus supports USB power. The only two chargers I own (for lithium ion battery charging), that use wall wart supplies, are a pair of XTAR VP-2 units. Wall wart power supplies are generally not very dependable (the cables are often very flimsy, and the connection points are poorly constructed), and can run pretty hot, under heavy use, as compared to modular power, like USB-cable-driven hub charging. Because of this, they tend not to be very travel-friendly, as opposed to USB-powered chargers (like the XTAR VC2 Plus, or VC4, to name a few). If you need to charge numerous batteries, simultaneously, this could become an issue.I really like the ability to simply change out a cable, if the cable fails (which is very rare, given the superior, heavier jacket construction of higher quality (not usually the ones that come, stock with any unit) USB power cables. My hope is that they’ll beef up the USB connector, since that’s the only way I would want to run this type of charger, at home, or during travel.

Not an issue with this Opus, since I realize it can also run on USB power. Nice!

Do Opus make a similar unit, with the same features, but in a two, or four-bank model? How do they compare to XTARs VC2Plus, VC4, and VP-2 chargers, during heavy use? Probably too early to tell, since this is a new model.

I’ll look forward to reading reviews on this charger.

9

Have you seen the Opus BT-C3100 its a four bank charger with the same features. Allot of reviews also here at the forum.

10

I don’t believe I have, but I’ll definitely check it out. Thanks!

11

I consider wall warts superior personally, the 5V USB provides is too low for the currents used by most multi-cell charger and you have great power loss at the connectors and cables. Plus, you can’t do 4 cells at 1 amp or higher with USB due to the 2-2.5 amp limitation. Furthermore, you have to actually buy a safe USB PSU of good quality and that adds to the costs, while, with an included wallwart, you have something that will power the charger adequately.

USB power is nothing more than a cost cutting measure. Less SKUs (no need to have different inventory for US/EU/UK), smaller materials cost, smaller packaging.

Back to the BT-C100, I’ll be purchasing if they fix the small issues it has. It will supplement my “dumb” Lii-400 nicely.

12

Thanks for your response. Yes (to piasca’s question) - I have seen the C3100 (v2.5, which is supposed to have worked out some of the bugs of the original C3100), and it seems like a very capable charger, and at a pretty reasonable price point, for all of the features, offered. I’ve heard good things about Opus chargers, which is why I was considering getting one.

I would not want to charge any of my higher capacity lithium ion batteries at higher than 1 amp/hour, for battery longevity reasons, though; and I tend to simply top off my batteries (I never run them down enough to where I have to charge an almost dead battery. It’s not good for the battery - at least, not lithium ion (ICR) batteries); so my charge times are usually minimal, in most cases. 1 Amp/hour covers that need very nicely.

It (the 3100) would be a great charger to consider for stationary use (not traveling). It’s got a a huge wall wart power supply, so it would be completely impractical for use, for travel, for someone who needs to charge multiple devices simultaneously, and who would, otherwise, be carrying multiple wall wart power supplies. That’s why I prefer using a pair of VC2 Plus chargers (for travel), since I can use a high quality USB hub (which is also very light, and has a user-replace power cable), and get 1 amp/hour for each of the four batteries. I also carry a pair of direct-plug-in dual 2 amp hubs that work very nicely, and take up minimal space in my bag:

Yes, the loss in output would be absolutely true if you were using sub-standard USB charging cables and a poor quality USB power source. Also true - with many multi-port chargers the amperage/charge level drops (Trying to use a USB port straight out of a laptop, would be worthless, because of the super low output), if you use more than two charging slots in that charger. Such is the case with my VC4 units (which drop, from 1 amp/hour x 2, to 500 mAh x 4). For that very reason, I tend to go to my four VC2 Plus chargers first, before resorting to using any of my other chargers, and I’m willing to travel with at least two of these VC2 Plus units, and a pair of direct plug in 2-port hubs, in addition to these 5-port hubs:

http://www.amazon.com/Anker-Charger-PowerPort-Multi-Port-Samsung/dp/B00VH8ZW02?ie=UTF8&keywords=anker%20powerport&qid=1459541353&ref\_=sr_1_3&sr=8-3

It’s important to stop, after using the fourth port, so you can get the 2 amp/hur max rating out of each of those four ports, on this unit. Of course, they make a heavier unit, which I have yet to purchase :slight_smile:

Each of the two ports on these direct plug-in units (link below), will easily provide 2 amps/hour to a plugged in device, provided you’re using a suitable cable (in general, not the crappy cables that come with most electronic devices. They’re extremely compact, and I always carry at least one of these in a pouch in my pack, wherever I go, for power on the go (if I don’t want to use one of my external lithium ion battery chargers).

http://www.amazon.com/Anker-Charger-PowerPort-Foldable-iPhone/dp/B012WLUKHC?ie=UTF8&psc=1&redirect=true&ref\_=oh_aui_detailpage_o02_s00

My observation was that, with many chargers that use the wall wart power supply (or wall wart power supplies, period), I haven’t seen too many that offer up a nice, high quality power cable. My main gripe is that this flimsy cable (usually poorly reinforced at the connector ends(s) is almost invariably hardwired into the power supply, itself. So, if that were to fail, you would have to replace the entire unit, not just the cable. Such is not the case with the Opus cable, though (Although it is hardwired). It looks like a nice, solid one, with what appears to be decently reinforced elbow connection at the output end.

Still, the features of the 4-bank Opus 3100 unit, that Piasca mentioned, are very appealing. So, I’ll probably end up buying at least one; but I won’t ever be taking it with me, for travel purposes, since I already have multiple good quality USB multi-port chargers, and since I have so many other devices that I need to charge (usually simultaneously). I prefer not to be winding a bunch of hardwired wall wart cables, or packing large, clumsy power supplies, and I don’t carry any with me, when I travel. The same holds true with power supplies for my iPhone and iPad. I haven’t used those in years. I simply use high quality USB cables and run them out of one of my USB hubs, and that saves me time (better output out of that than the stock iPhone supplies), and space, while providing a reliable, high speed charge to all of my devices.

I liken the investment of high quality USB cables to the purchase of better headphones, when you buy a portable electronics unit (An mp3 player, for instance). They almost never come with good headphones. Stereo equipment NEVER comes with good quality cables - just the cheapest cables they can give you. I usually discard those, and buy high quality cables, to enjoy the full benefit of what those units are capable of providing, sound-wise. Even expensive iPhones come with crappy earbuds. An investment in decent earbuds is necessary, to really hear what your Apple device is capable of (That and an external player app, that offers up elaborate tone control and dynamics processing, to breath life back into the squashed mp3 files -but that’s another thread lol).

It may be inappropriate to make such comments, here, since the subject is Opus’ new 1-bank charger, which would appeal to people who only need to charge one battery at a time; but most of the information is still relevant, just in case they’re considering a larger than 1-bank charger (like the 3100, for instance), for home, or travel use.

Thanks for your thoughts . They’re much appreciated :slight_smile:

13

The C100 is useful in many ways, but sadly I could not check how good it was on usb power. I believe all the chargers I have tested has problems delivering full power on usb power, sometimes I wonder why. Even at a fairly low voltage a well designed charger could deliver full current. Maybe the limits are implemented to protect the usb equipment, i.e. to prevent overloading the power supply used.
The 3100 is not as versatile as the 100, my guess would be that Opus would make a more versatile 4 slot charger in the near future (Near future may be a year or more).

I hope (I do not have any confirmation yet) to review another version of the 100 soon, but that review will probably be a supplementary review, not a full review.

14

In light of this, I think I’m going to hold out until Opus come up with an enhanced version of the 3100, that offers up the same feature set of the C100. I’ve got plenty of chargers to hold me over, in the meantime. I’m in no hurry.

Thanks, HKJ!

15

One feature I do not expect on a four channel charger is usb output, I do not see any reason for it. Usb output are useful on compact chargers, but not on large multi cells one (IMHO).

16

If you’re talking about the powerbank feature (the ability to charge a phone, or other device, directly from the battery charger, itself, while the charger’s input power is unplugged, utilizing a high capacity battery in one of the charger’s banks, for instance); then I agree, wholeheartedly. It doesn’t make sense to incorporate that feature in a larger (4-bank) charger, since the power is only being fed from one bank of that charger, anyway. I feel-the makers that include that feature, did it to give the consumer a way out (as an alternate charging method for their portable device), in case they had to charge their depleted device on-the-fly, but didn’t have a dedicated charging device (or suitable power supply available (like a car outlet or a wall plug to plug in their charger) for the phone (as an example), but happened to be carrying the charger and a high capacity battery. Otherwise, it makes more sense to just use an external lithium ion battery charger, but not everyone carries those with them.

I’m afraid I didn’t do an exhaustive comparison between the C1 and the 3100 v2.1 (What’s the newest version of Opus’ 4-bank charger, anyway?); but I’m sure you have. Is that the only feature that the 3100 lacks, compared to the C1? If so, I’ll pick up on of the Opus units right away! If that’s the only “missing” feature, I have other chargers that will do that, so it’s not a deal breaker for me.

It’s mainly the analyzing feature that interests me, in this Opus unit. The only way it works, in my (XTAR) VC4 units (the only lithium ion chargers I own that actually have an analyzing feature), is to install a completely drained battery in the charger, then wait for it to fully charge, after which time it gives you a readout of the battery’s true capacity. Is that also the case with the Opus chargers, or does it work, otherwise? Seems like an extremely time-consuming way to test a battery’s actual capacity. Some of my older chargers used to have a “cycling” feature, which would completely drain the battery, in the charger, then fully charge that battery (It was for NiMh batteries only), but with no diagnostic readout, afterwards. That, too, was extremely time-consuming and frustrating to use. I only used it about once every ten charges, because it was advised, to maintain the overall longevity of the battery, and not for analyzing purposes.

17

The main differences are: Official support for 3 charge voltages and usb power bank.

You do not need to discharge the battery before analyzing it in a Opus charger and it will measure capacity during discharge (Much more precise for NiMH).
The only way to measure capacity in batteries is to discharge(charge) them and it do take time. For LiIon you can get a estimate of the charger state from voltage, but not all cells uses the same scale!

18

Good to know. Thank you, kindly!

19

I’m quite interested in this charger, though I think I’ll wait for a revised version. It would also be nice if it could come with an Aussie plug and could be purchased from less dubious retailers.

20

Thanks for the review!

I just got in a BT-C100 and it seems to reads about 0.05v too high. A cell at 4.17v reads in the C100 as 4.22v. Pretty sure all chargers are spec’d to be +/- 0.05v so this one is at the limit.
I think the designer/engineer gave us a “fix” to lower the readings on the BT-3100’s - pretty sure I did the mod. Wondering if another fix might be available for this one. charging to 4.15v is not very useful to me. I need max voltage most of the time for testing FET based drivers.