Test/Review of Charger Opus BT-C2000

[size=+3]Charger Opus BT-C2000[/size]





This charger is new on the market, with a design that looks very much like the BM200 charger. This is because the charger is an improved version of the BM200. I have not tested the BM200 and will not be able to say exactly what improvements it has.






The charger comes in a cardboard box with a little explanation about the charger on the outside.



Inside the box is the charger, a power supply, two C/D cell adapters and a manual.
The power adapter I got is the EU version, it has universal voltage 100-240VAC 50/60Hz and delivers 12V 1.5A.



When the charger is turned on, it first displayes the formware version (2.0 for the tested charger), then does a display test where all the text can be seen.
When the text is blinking , it is possible to select mode:

• CHARGE: Charge battery with 200 to 1000 (1400)mAh.
• DISCHARGE: Discharge battery with 100 to 500 (700)mAh.
• DISCHARGE REFRESH: Discharge and charge the battery 3 times.
• CHARGE TEST: Charge, discharge and charge the battery, show how much current was discharged.
• QUICK TEST: Measure the internal resistance of the battery.

After having selected mode, it is possible to select current.
When putting multiple batteries in the charger at the same time, it is possible to select mode and current simultaneous for all of them (Very nice).

When charging or discharging it is possible to use the DISPLAY button to select between V, mA and mAh (Can be Ah for large cells).



When the slots in the charger is empty, the display will show "null".



Here is an example where I have selected different functions for each slot.



Each time a button is pressed, the light turns on for a 30 seconds.



The charger uses an external 12 volt power supply (Specified input voltage range is 10V to 16v).



The charger has two minus connection points, but they are not used to select default charging current, it is always 400mA. The metal at the side is probably a temperature sensor.



AAA is placed very low in the charger, the AA has more air around them.
The slots are not equal, slot #1 and #4 can charge and discharge with higher current, but only if slot #2 and #3 are empty.
I.e.
Using only slot #1 and/or #4, the maximum charge current is 1400mA and maximum discharge current is 700mA.
In all other cases the maximum charge current is 1000mA and maximum discharge current is 500mA.



The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters).



Here is the adapters with a C and a D cell.
Remember to select higher current when charging/discharging C/D cells, or it will take a long time.







[size=+2]Measurements[/size]

• The LCD background light turns off 30 seconds after the last keypress.
• Discharge battery with less than 0.1mA when power is disconnected.
• Charge battery with about 15mA when power is connected and charge cycle is done.
• Charge will restart charging after power loss or battery insertion.
• The volt display matches my DMM within 0.02 volt when current is off.
• The voltmeter will measure from 0.2 to 1.8 volt and probably more.
• The current display shows a slightly high value when charging, I got 998mA on display and 982mA with a DMM and a cold charger.
• The current display shows a slightly low value when discharging, I got 501mA on display and 507mA with a DMM and a cold charger.

The charger cannot really sustain the 1400mA charge current, it might be due to heat that it reduces the charge current (It has temperature sensors both for the electronic and the batteries) or it might be because it cannot drive the full current when the battery is nearly full.
The termination looks fine.




Slot #2 and #3 can only do 1000mA charge current, here the current is constant all the time.



Slot #4 can also charge with 1400mA and it also reduces current.



The eneloop XX has more capacity and takes longer to charge. The termination looks fine again.



With AAA I uses the default 400mA charge current.



Testing with a D cell did also work (This cell has more than rated capacity).



A 2000mAh eneloop at 400mA, forgetting to select charge current means 5½ hour charging time, instead of 2 hours.
The charger terminates perfectly, even with this low charge current, this is very good.



Doing a charge refresh shows the 3 cycles.



The charge test with a charge, a discharge and a charge again.



A simple discharge.



The charger can spot a full cell in 6 minutes with 1000mA charge current.



All slots together with 1000mA charge current. The thermo probe is on the battery in slot #3.



With two batteries and 1400mA charge current the temperature is much lower, there are two reason for that: the total current is lower and I did measure at slot #4.


M1: 40,4°C, M2: 46,3°C, M3: 47,0°C, M4: 40,6°C, HS1: 64,3°C

The two batteries in slow #2 and #3 receives most heat from the charger, as can be seen on the temperature.
Note: This test was done at 1000mA charge current, using a lower charge current will also lower the temperature.


M1: 36,5°C, M2: 45,8°C, M3: 46,3°C, M4: 39,4°C, HS1: 63,8°C

With a thermo camera it is very obvious where the energy goes when testing a discharge.



The charger uses a fixed charge current and uses pwm to adjust the actual charge current.
At 200mA the duty cycle is about 13% (It might change with battery voltage).
The pwm frequency is 33 Hz.



At 400mA the duty cycle is about 30% (It will probably change with battery voltage).



At 1000mA the duty cycle is about 77% (It will probably change with battery voltage).



The charger cannot reach the full current when I have connected the oscilloscope. This is because I has a 0.1 ohm resistor in series with the battery and this means the charger must supply 0.14 volt extra.



Discharge is also done with pwm. Here using a duty cycle of 87% to discharge with 500mA.



As expected the quick test is a couple of puls loads.
The Quick Test showed 0.167 ohm with the resistor and 0.064 ohm without resistor (The 0.003 difference is due to connections and tolerance on the resistor).


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



[size=+2]Conclusion[/size]

The charger has a lot of functionality and does a good job with charging and analyzing. The user interface is easy enough to use, but requires a few tries and some reading in the manual to really know what is going on (It is a bit difficult to guess that "discharge refresh" means 3 cycles).
I believe this is a good NiMH charger/analyzer.



[size=+2]Notes[/size]

The charger was supplied by DanaCo for review.

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

I'm keen to understand how this charger sets itself apart from the C9000 and perhaps the NC2500. Based on price point, they may not be differentiated much. C9000 has set the bar for the last few years and considered to be the charger/analyzer to beat. NC2500 attempts to match that performance and incorporating in their design, cooling fan to keep overall temperature down when charging. In addition, it has thrown in features that differentiates itself from C9000 like bluetooth connectivity for battery analysis and usb port for mobile device charging.

The CT2000 may have made some usability improvements over the BM200 (in navigating through the menu options). The CT2000 claims material and design improvement over the BM200 and looks to be the "final prototype" (after BM100, BM200, and even possibly BM210). But since they are claiming a new design over the BM200, I can't help but feel that this could be a "new prototype" that will possibly soon see "newer improvements". In fact, I am seeing CT3000 and CT3100 in some ads but may not be marketed under the OPUS banner.

austinios said:

I'm keen to understand how this charger sets itself apart from the C9000 and perhaps the NC2500.

Click to expand...

Without having tested them it is difficult to say.
I do have the C9000 and has used it for a long time, but I have never put it on the test bench.

The C2000 is supposed to be better for marginal batteries, but as you can see in my review I have not tested this.
The internal resistance may be a very interesting function, that makes it possible to spot bad batteries very fast. If somebody got the C2000 and some old batteries, it could be interesting to see IR readings.

HKJ said:

Without having tested them it is difficult to say.
I do have the C9000 and has used it for a long time, but I have never put it on the test bench.

Click to expand...

I don't have the C2000 so i cannot compare the 2 chargers head to head like this:

1. since the C9000 shows accuracy in the readings for every channel, do a Refresh&Analyze (always 1.0A charge rate, -0.5A discharge rate) on all your Eneloop AA's repeated times until the capacities don't change anymore. then pick the 4 cells which have the same capacity and label them in order, say (#1:1960/#2:1962/#3:1965/#4:1971)mAh. do a final R&A on these 4 cells to confirm that they are indeed the ~same capacity and that their resting time in the C9000 is identical. C9000 applies trickle charge afaik when the cells are left in the charger after completion of the R&A program and the top-off charge. after hours of trickeling the 4 cell voltages will settle to a steady-state voltage in correspondence to the trickle charge. the cells are now equally conditioned and perfect ready for the tests (ECPR)
2. quickly remove the cells from C9000 and quickly insert them in C2000 and start the DISCHARGE program at -0.5A. after program completion take note of the discharged capacities and evaluate:
   • The readings should be the ~same (or at least in the same ascending order, i.e. #1<#2<#3<#4) to indicate consistency. If they aren't, then there is hardware variation between the four C2000 channels.
   • The readings should coincide with the C9000 reference values. If they don't, then there is software discrepancy between C2000 and C9000.
3. recharge the cells in C9000 at 1.0A and leave them in the charger for many hours to get back to ECPR
4. repeat: go back to 2., i.e. DISCHARGE at -0.5A. The readings should be ~equal to 2. to indicate reproducibility. If they aren't, then repeat 3. and 4. again to confirm that the C2000 lacks reproducibility.
5. to confirm hardware variation between the four C2000 channels, simply 'rotate' the cell configuration in the C2000 for the DISCHARGE program and compare the results. if you don't know how to interpret the results, then change the C2000 cell config once again and discharge to collect even more confusing data lol
6. once you have established to which degree your tested charger, here: 1 sample of C2000, gives consistent AND reproducible AND accurate readings and you are satisfied, recharge the cells in C9000 at 1.0A for the last time and leave them in the charger for many hours to get back to ECPR, then do a concluding DISCHARGE at -0.5A in the very C9000. Since the C9000 is accurate and you've been using Eneloop AA, you should get a reading close to 1., maybe (#1:1958/#2:1961/#3:1967/#4:1969)mAh. Done. Perfect score for the C9000!, and you can calculate your own score for the C2000.

Simple but effective testing methodology to compare capacity readings between chargers and between the channels of a charger. It is not even necessary to check the voltage of ECPR. The whole testing takes up a lot of time (days!) because of the time to reach ECPR and because of the repeated test runs to establish data integrity. A room with constant temperature is required too

To me the above methodology sounds logical and fail-safe. If you believe that something stinks or i am wrong, lemme know, thanks. :thumbsup:

Another excellent test review. HKJ!
Thanks a lot for your effort and time as always. :bow:

There is "The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters)" in your review.
Could you please explain in detail?

candle lamp said:

There is "The included adapter are for use in slot #1 and #4 and makes it possible to charge/discharge C and D cells (Notice that internal impedance will give wrong result if used with these adapters)" in your review.
Could you please explain in detail?

Click to expand...

Internal resistance is very low ohmic values, because the adapter adds two more connections and some short wires, the value will be too high and you will see more variation in the value, due to the connections (The resistance of a connection will often vary).

Excellent review HKJ!

It's a little disappointing that the 1400mA cannot be sustained in any of the examples you show. Maybe it's the algorithm. As you noted, the temp is lower with two cells @1400mA than four cells @1000mA. So, a thermal reason doesn't seem likely. The lower charge rates were maintained in your examples, even the 4@1000mA with higher temps. It would be interesting to see if the MH-C9000 maintains it's higher rate throughout the charge. Perhaps with all the C9000 info here on CPF it has been shown.

C & D charging/analyzing on a smart charger is a welcome idea but it seems to fail here with unreliable variation in values. This can lead to premature charging'discharging termination due to higher contact resistance and the resulting capacity numbers are unreliable.

All-in-all, this might be a nice addition to the MH-C9000, especially for AAA cells, but not a replacement.

kojack6319 said:

It's a little disappointing that the 1400mA cannot be sustained in any of the examples you show.

Click to expand...

My guess is that it is a voltage limit, the charger can only sustain 1400mA up to about 1.45 volt.

kojack6319 said:

C & D charging/analyzing on a smart charger is a welcome idea but it seems to fail here with unreliable variation in values. This can lead to premature charging'discharging termination due to higher contact resistance and the resulting capacity numbers are unreliable.

Click to expand...

I would not worry about the connection resistance when analysing capacity, a couple of mOhms is not going to affect that result much at 700mA discharge current.

HKJ said:

The charger has a lot of functionality and does a good job with charging and analyzing. The user interface is easy enough to use, but requires a few tries and some reading in the manual to really know what is going on (It is a bit difficult to guess that "discharge refresh" means 3 cycles).
I believe this is a good NiMH charger/analyzer.

Click to expand...

I wish you could review the La Crosse BC-1000 using the same methodology so we could compare them.

IT_Architect said:

I wish you could review the La Crosse BC-1000 using the same methodology so we could compare them.

Click to expand...

I do not expect to, but maybe the new BC-1020

"Using only slot #1 and/or #4, the maximum charge current is 1400mA and maximum discharge current is 700mA.
In all other cases the maximum charge current is 1000mA and maximum discharge current is 500mA."

Click to expand...

Thank you for your review of the BT-C2000. It provided needed clarification not found in the Operating Instructions. The Opus provided documentation is basic, so I appreciate your thorough analysis. The graphical analysis is very helpful. Curious why the maximum charge and discharge is limited to slots #1 and #4 only. Cost consideration I suppose. Unit is reasonably priced as is. Perhaps future versions will permit maximum charging/discharging in all slots.

Welcome to the Forum! :welcome:

May I say BT-C2000 is the ultimate charger? I am considering buy a MH-C9000, but it seems it is better to wait :naughty:

gbuyer said:

May I say BT-C2000 is the ultimate charger?

Click to expand...

Not more than other analyzing chargers:
MH-C9000
BT-C3100
SKYRC NC2500
BCxxxx

Until now I have only tested the BT-C2000 & BT-C3100, but I will be testing more.

I just purchased this tester and like it very much. I have a few questions about operation that I haven't been able to answer just by using it.

1. When using "Discharge Refresh" or "Discharge Test," I can set the discharge current, but is it also possible to set the charge current independently (i.e., to a number different than the discharge current)? I have tried switching first to "Charge" and setting the charge current there and then changing to one of the Discharge modes, but I don't know if the charge current "sticks" when I change modes.

2. I build battery packs and wanted to test some sub-C and 4/5A cells. I was easily able to electrically connect them, simply by using a spring fitted at the positive terminal. What I can't tell is whether the charger will still be sensing the heat from the battery. Does anyone know whether heat is sensed from the positive and negative terminals; from the metal contacts near the actual contacts; or via some sort of IR sensor buried in the charger case?

I had some 10-year-old, but never used NiMh AAA cells that have been in the fridge, forgotten, for a decade. They are supposed to be 500 mAh cells, but the initial Discharge Test only showed about 40 mAh of capacity. I did one Discharge Refresh cycle and that got the cells up to about 200 mAh. However, because I couldn't figure out how to independently set both charge and discharge currents, I instead did a discharge using a really high current, followed by a charge using a really low current. I then tried again, this time using a low current, and then higher charge current (about 0.8C). I then tried the remaining variations. However, I realized that I don't know which combination might be the most effective for resurrecting a cell that is old, but has not been used much.

Thanks for any help anyone can provide!

I too have a new BT-C2000 and have been testing it a bit.

As for the Charge/Discharge functions/selections.....it behaves like the BC700/BC900/BC1000 series chargers.

Meaning that your 'charge current' is always 'double' your 'discharge current'.

Or you can think of it the other way around, your 'discharge current' is always 'half' of your 'charge current'.

You CANNOT set them independently of each other. When you set one, it automatically adjusts the other.

So.... When you insert a battery and select 'Discharge Refresh' and then you select a discharge current of 100, 200, 300, 400, 500, or if using the outside slots 600 or 700, your charge current will be double ( i.e. 200, 400, 600, 800, 1000, 1200, or 1400) the discharge rate you select. See table below.

Let's say I insert a battery, select 'Discharge Refresh' and then select 500 mA as my discharge rate. It will proceed to discharge the battery at 500mA, then charge the battery at 1000mA. It will do it 3 x. I have to double check this one as far as when it finishes...whether it displays the 'discharged' capacity of the cell (useful) or the mA accumulated during charging (useless). If you do not select a discharge rate, it will default to 200mA, which means a charge rate of 400mA. Here the BCxxxx series charges are better, in that they will repeat the process up to 20x checking the capacity each time and only proceeding if it increases each time. The BT-C2000 just seems to do it 3x no matter what and seems to just remember the last cycle.

If you insert a battery and select 'Charge Test' and then select a charge rate of say 800mA. It would proceed to charge the battery at 800mA until full, then discharge the battery at 400mA, then charge it again at 800mA. At the end it would display the 'discharged' capacity of the battery, which is exactly what you want. If you do not select a rate, it will default to a 400mA charge rate, which means a 200mA discharge rate.

Charge / Discharge
200 / 100
400 / 200
600 / 300
800 / 400
1000 / 500
1200 / 600 (outside slots only)
1400 / 700 (outside slots only)

As far as refreshing your old batteries. I always start off very gentle and work my way up. Since you said they were only 500mA batteries, I would recommend the 200mA charge / 100mA discharge for 1 or 2 Discharge Refresh cycles. That would mean a total of 3 or 6 discharge/refresh cycles. Then if the capacity has improved, move up a little. I probably wouldn't go higher than 400mA charge/200mA discharge as they will probably get quite hot if you try to. Trying to hit them too hard right off the bat, can cause a variety of bad things (overheating, hot spots, separator thinning, etc.) to happen inside them, none of which would be good for them. Sometimes it helps to run a few charge discharge cycles on them. Then let them set for a day or 2, then run a few more charge/discharge cycles. The bad thing is that even if you can manage to nurse them back up a bit near their original capacity, they probably will not really perform like a newer cell, and they may have a very limited number of cycles before they are too far gone.

For sensing the 'heat'.... see the little metal strip by the negative end of each battery slot, on the side. That is connected to a thermistor inside and senses the heat of each battery. It has a sensor for each battery and supposedly 2 on the motherboard...for a total of 6 heat sensors. So...unless your battery is actually touching that little metal strip, it will not be able to sense it overheating.

FYI.... I am currently doing some basic testing comparing its accuracy as far as discharging to a CBA II and an MH-C9000. I want to see how accurate the 3 are compared to each other when it comes to determining the capacity of a battery. So far I am extremely impressed at the accuracy of the CBA II compared to the MH-C9000. (within a couple/few milliamps of each other during discharges). Checking the BT-C2000 now.

Note - Should have my BT-C3100 within a week or 2. Will be doing some serious battery testing with it as well, especially Lithium battery capacity testing on some of my 'surplus' 18650's.

Hope this helps....

Excellent answers. Thanks.

So, the Charge/Discharge ratio is 2:1, hard wired. You also answered a question I forgot to ask, namely whether the mAh reading at the end is for the charge (which is useless, as you noted), or the discharge, when doing the "Discharge Refresh." I didn't know that other chargers remember the previous capacity reading, when doing multiple charge/discharge cycles, and only keep repeating if some improvement is noted.

That is a good idea.

As for actually being able to rescue the old batteries, I don't have high expectations, but I thought it was interesting to try because these were brand new batteries, still in the blister pack. With NiCd batteries, I actually built a high voltage "zapper" that is basically a strobe light circuit that dumps its charge into the battery instead of into a strobe light. It does a great job getting rid of the "whiskers" that develop in older NiCd batteries. However, as you pointed out, batteries that have been "rescued" often don't perform well for very long, although my experience with NiCd is that if you drained them quickly (e.g., in a headlamp) and recharged them right away, they were often as good as new. However, once they sat around for a few weeks, they went bad again.

It is amazing that the charger can sense much heat through those metal strips because they don't seem to be in very solid contact with the AA or AAA battery. When using the C/D holder, the temperature transfer must be even less. I'll keep this in mind when I use the charger to refresh some of these old, odd-sized battery pack cells because they don't make contact with the charger enclosure in the same was as the AAA/AA/C/D batteries do.

Finally, I'll be interested to hear your experience with the BT-C3100 tester. I saw the reviews, but couldn't find any place to buy it. I don't have any Li-ion batteries at this point, so I wasn't too disappointed not to be able to get it. It does seem like the most versatile of the 3-4 testers that always seem to be mentioned in various reviews.

Oh, one quick question: since you obviously have charged a lot of batteries, do you have an "ideal" charge rate for Eneloops that would yield the longest life? Absent any other information, I was going to charge mine at 0.3C. It seems that using a lower current might make it difficult for the charger to calculate the correct cutoff, and anything much over 0.5C might start generating too much heat.

Take a read on the other thread regarding the proper charge/discharge rate for an eneloop....in particular my post near the end.

http://www.candlepowerforums.com/vb/showthread.php?240121-Appropriate-Charge-Rate-for-NiMH-Batteries

Generally speaking go as high as you can as long as the batteries are not getting HOT. Warm is OK. Hot is NOT.

I would not hesitate to do 1A on newer batteries, but if they start coming off hot, go down a bit.

Thanks! I've read dozens of posts here and elsewhere about NiMH in general and Eneloops in particular. From those posts it is pretty clear that when using a smart charger, 0.5C to 1.0C is the range which provides the best compromise between achieving a full charge in a reasonable amount of time, while not degrading the battery, thereby achieving a maximum number of recharge cycles and only minor degradation in capacity as the battery ages. However, even though the subject of Eneloop charging has been well-covered elsewhere I thought I'd ask again here because clearly the people here have lots of personal experience that they can add to what is stated in various spec sheets, including those provided by Sanyo/Panasonic in their Eneloop datasheets.

Sorry for the noob question, but this is my first "pro" battery charger. How do you know how much charge a battery has on it? When I insert a battery on the charger it shows 1.34v and when I use the Quick Test option it shows a number like "50".....what that it means? there´s no easy way for the device to display something like "1850 maH" so I can do the math if we are talking about a 2000 maH battery and say "oh, great, this battery is at 90%" or something like that? I apologize for my poor english, my native language is spanish. TIA Alx