Opus BT - C3100 V2.1 Li - ion NiCd NiMh LCD Smart Intelligent Battery Charger with EU Adapter

- ROYAL BLUE EU PLUG 101062401

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Main Features:
● The charging current can be selected for 200mA, 300mA, 500mA, 700mA and 1000Ma (1500mA and 2000mA can only be applied when only slot 1 or 4 is selected). Default discharging current is 500mA
● It provides four independent charging slots for rechargeable batteries. The charger can charge batteries of different type and size and with different capacity at the same time
● The charger integrates the minus delta voltage (-ΔV) for NiCd or NiMh battery charging termination, and for Li-ion batteries charging to 4.2V with pre-selected constant current.(3.7 Li-FeO4 and 4.35 type high voltage batteries charging mode can be selected through switch on board)
● The charger also includes overheat detection to protect rechargeable batteries and charger itself from overheating
● New added quick test mode to test the battery impedance
● Four Working Mode Available at User's Choice: Charge, Discharge, Test, Quick Test and Refresh
● Easy to read LCD with back light Showing Battery Voltage, Charge / Discharge Current, Charging Time, Battery Capacity etc.
● Designed for AA (LR6) and AAA (LR3)NiCd, NiMH or 3.7V Li-ion rechargeable batteries in size type of 10440, 14500, 16340, 18500, 18650, 26650, 26500
● Ideal for office and home use
● Operating Temperature: 0 - 40 deg.C
● Max Charging Capacity: 20000mAh
● Power Adapter: Output: DC 12V, 3.0A, Input: 100-240V, 50/60Hz

1. Voltage update rate is 30s instead of 60s.
2. Charging voltage is regulated to 4.7V instead of 5.0V, thus loading on power adapter when batteries are flat is less. 5.0V charging voltage has problem in regulating the correct current level due to this over loading current on power adapter, which lead to Panasonic brand Li-ion batteries showed wrong charging capacity value (+25 percent). With 4.7V charging voltage, the load on power adapter is greatly reduced and thus can make all types of batteries are charged properly.
3. 4.35V charging time can be very long because charging current is regulated in entering the CV stage at 4.12V, which is same as 4.2V type. Now 4.35V charging algorithm is changed to 4.27V.
4. Better safety feature: PCB temperature was used to in controlling fan on/off only with 2.0V, now this function is enhenced so that temperature is monitored for entering thermal shutdown mode when excessive high temperautre is reached. It is especially helpful when fan is not running and which can lead to plastic melt down happening.
5. New fan cover make better protection for cooling fan.



Brand: Opus
Type: Charger
Model: BT-C3100 V2.1
Plug: EU adapter
Charging Cell Type: NiCd,Ni-MH,Lithium Ion
Compatible: AA,AAA,18650,26650,14500,22650,16340 (RCR123)
Input Voltage: AC 100~240V 50/60HZ
Output Voltage: DC 12V


LCD Screen: Yes
Circuit Detection: Yes
Over Voltage Protection: Yes
Over Charging Protection: Yes
Over Discharging Protection: Yes

Dimension and Weight

Product weight: 0.2 kg
Package weight: 0.54 kg
Product size (L x W x H): 14.4 x 4 x 10 cm / 5.67 x 1.57 x 3.93 inches
Package size (L x W x H): 21.5 x 16 x 4 cm

Package Contents

Package Contents: 1 x Battery Charger, 1 x EU Power Adapter, 1 x Manual
This charger is a analyzing LiIon and NiMH charger, this means the charger can both charge and discharge while measuring. The total number of function is large and this means the technical section in this review is very large.


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 1000 (2000) mA.
  • DISCHARGE: Discharge battery with 200 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.
  • QUICK TEST: Measure the internal resistance of the battery.

When display is flashing it is possible to select mode and current.
Using the slot button it is possible to reselect a slot and change parameters for it, also when charger is working.
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.
The display button can also be used when the charge/discharge is finished, but the charger will change back to FULL display rather quickly.

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 20 seconds.
The FULL and NULL message can also be seen.

The charger uses an external 12 volt power supply at 3A (see later).
It has a fan, this is necessary to handle all four channels at full power. Even with only one channel in use the fan, it start and stop very often. The fan is not very loud, but due to the starting and stopping it is very annoying.


The charger uses the classical slider construction to handle most battery sizes. The slider works smoothly and can handle sizes from 32 mm to 72.5 mm.
For measuring internal resistance the slider is not very good, it often has a HIGH connection resistance.


A couple of different NiMH batteries in the charger.

And some LiIon batteries.

Using only slot #1 and/or #4, the maximum charge current is 2000mA.
In all other cases the maximum charge current is 1000mA.
The maximum discharge current is always 1000mA.

Charge currents: 200, 300, 500, 700, 1000, 1500, 2000
Discharge currents: 200, 300, 500, 700, 1000



The charger can easily handle 
70 mm long batteries
It is recommended to charge smaller batteries in the two center slots.
The charger has an internal switch marked with 3.7V, 4.20V and 4.35V. I have not tested this switch, because it is internal, but it might be possible to charge other LiIon chemistries.


  • The LCD background light turns off 20 seconds after the last keypress.
  • The charger has very high current spikes from the supply.
  • When charging 1 battery at 0.5A the fan turns on/off all the time, it is very annoying when sitting close to the charger.
  • When charging 4 batteries at 1A the fan runs continuous.
  • It will discharge NiMH batteries with up to 0.8mA when not charging.
  • It Will discharge LiIon batteries with up to 2.1mA when not charging.
  • Power cycling will restart charging.
  • Reinsertion of batteries will restart last mode selected.
  • Falling voltage will not restart charging.
  • When batteries are put in and no buttons is pressed a 0.5A charge will start.
  • Voltage is measured with current off and is within 0.01 volt.
  • Voltage display is updated once a minute.
  • When charger is powered on it always starts in charging mode with 0.5A selected.
  • While power is on it remembers last mode selection, but will always start at 0.5A.


The text was supplied by https://lygte-info.dk/review/Review%20Charger%20Opus%20BT-C3100%20UK.html

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Customer Reviews

4.9 out of 5
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  • p5bdkw
    Has features not found on other charges.
    Color:Royal Blue Size:US Plug
    Opus BT-C3100 v2.1 Charger

    It has a backlight.
    It's well made.
    It does other things besides just charge.
    It can show the battery capacity.
    The fan keeps the unit's internals from getting hot.

    This just may be the best charger out there. It does everything you need a modern charger to do, namely Charge, Discharge, Test, Quick Test, and Refresh your batteries. It charges NICd, NiMH and Li-ion.

    Mode explanation:
    Discharge - Reduces the battery's memory effect, by discharging the battery, a preset number of times.
    Discharges to 0.9v for NiCd and NiMH, and 2.8v for Li-ion.
    Test - Charger displays capacity by fully charging, then discharging, then fully charging battery.
    Quick Test - Analyzes the dynamic internal battery resistance.
    Refresh - Charges and recharges the battery 3 times to bring the battery to full capacity.

    I guess the biggest question will be how long will it last. It's a well-made charger, so I suspect that it will last awhile. I'm going to baby this charger, along with my batteries. The only moving part is the fan, so just in case I have a fan issue, I bought a couple of the replacement fans from GearBest. As I'm writing this, the fan came on for the first time. It's very tolerable, and doesn't sound like a jet plane. The fan can be replaced by unscrewing the bottom four screws and unplugging the fan connector.

    GearBest sent me this item to Chicago, and I got it in 2 weeks. Now, that's service. I'm still waiting for the fans, as GearBest didn't ship them out at the same time as the charger. They should arrive very soon.

    I must&nbsp

    Apr 19,2015

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  • TimothyGaray
    Great for Finding Good 18650 Batteries
    Color:Royal Blue Size:US Plug
    This has the most recent firmware (v2.1).  It does a great job charging 18650 batteries and you can increase the current to charge them faster but I've been more than satisfied with the default settings.  However, charging batteries is not why I bought this. This also has features to discharge, refresh and test batteries.  I bought this to test my current 18650 batteries and new ones that I buy.  For this it works great and I am very happy with it.  I found my "Ultrafire" 18650 batteries which are stamped at 3000 mAh are really only providing around 1000 mAh.  I also found that my Tenergy 18650 batteries which are stamped at 2700 mAh are actually providing between 2600 and 2700 mAh according to this so I am very happy with this device and highly recommend it for anyone who uses the many different battery types it supports.
    It is kind of expensive as just a battery charger.  I haven't been able to find these in the USA.

    Oct 26,2014

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  • ross
    Best Li-ion charger out there.
    Color:Royal Blue Size:US Plug
    This is an awesome unit - I've used the La Crosse charges for years but they only do Ni-MH. I've been looking for a Li-Ion charger that can do test and refresh for ages and finally found it in this unit.

    It happily charges pretty much every type of rechargeable battery but best of all allows you to check the capacity of Li-Ion batteries. So many of the 18650 / 26650 batteries out there are either fake or the manufacturers just flat out lie about their capacity. I use these batteries in cave diving lights so lies about capacity are a major safety concern. Now once month I run a check of the capacity.

    Supports up to 2A charging so I can fill 4000 mAh batteries in just two hours. Has a built in fan which makes the unit noisy but allows such fast charge rates.

    Easy to use and each slot can be selected independently.
    Despite claiming to charge 4 batteries at once it will only actually charge 2 x 26650 Li-ion batteries at the same time due to the slots not being wide enough.

    Feb 02,2015

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  • Jinzhong
    Charger works like wonder and Fast Delivery
    Color:Royal Blue Size:EU Plug
    Charge works like wonder. My old battery recharger is boiling the batteries and complained nearly all my batteries are bad and not rechargeable anymore.

    This one just gracefully takes all my batteries and charges them wonderfully.
    It gives me all the details during charging - Really amazing. This prompts me to throw away my old charger immediately.

    Battery is not hot at all, although I tested to use 500mA and 1000mA to test.

    Fan noise is ok for me not like other people complains - I never put charger in my bedroom anyway.

    More bonus point: Seller saw that I order from Singapore, he even ships for free a travel adapter for Singapore use. Really a very nice surprise.

    Thank you the seller for your kindness and thoughtfulness.

    Feb 17,2015

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  • Romaldas
    The best battery charger
    Color:Royal Blue Size:US Plug
    This charger is a analyzing Li-ion and NiMH charger, this means the charger can both charge and discharge while measuring. When display is flashing it is possible to select mode and current. All functions works perfectly. You can combine the types of batteries colored, so you can simultaneously charge different capacity NiMH batteries and lithium ion batteries. Each span can individually adjust the charging current and the function. Good quality, compact charger . Bright and high-contrast LCD display . Nicely packed with FREE EU power adaptor and English manual. I will continue to buy here. Conclusion: excellent charger handyman. Thanks Gear Best for good deal .

    Feb 03,2016

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  • Sean
    Nice Charger, great price
    Color:Royal Blue Size:US Plug
    + Can charge almost anything - accommodates many sizes and chemistries)
    + multiple diagnostics for batteries (test, quick test, refresh discharge, internal resistance).
    + independent functions for each slot
    + trickle charge after main charge is finished
    + Independent slots to mix and match battery types and capacities
    + independent slot displays to see what each slot is doing.
    + independent functions for each slot (one can be charging while another is testing).
    + User interface easy to understand
    + Wide range of currents (though 1.5A and 2A are only available on slot 1 and 4)
    + feels nicely constructed with smooth spring slots.
    - Uses PWM (pulse width modulation)
    - peak charge and discharge current is a tad high, but not really a problem.
    - switch to change to 4.35v or 3.5v charging is internal (have to either open up the case or drill a hole to charge IFR batteries or some ICR batteries - these are not commonly used battery types however)
    - discharge current and charging current are not independently set, they will both be the same (e.g., if you select 1,000mAh for charging, that will be the discharge rate as well).
    - some fan noise, but not too bad (this is also making sure the pcb and batteries stay cool so....probably better to have it)

    Nov 07,2015

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  • Valeriy
    Opus BT-C3100 V2.1
    Color:Royal Blue Size:EU Plug
    Заряжает, разряжает, восстанавливает все виды пальчиковых аккумуляторов, что у меня есть в наличии.Показывает реальную емкость и внутреннее динамическое сопротивление. Каждый слот можно настроить отдельно. Разные форм-факторы можно использовать вместе. Дисплей с подсветкой. Ток заряда в 200,300,500,700,1000mA для 4 аккумуляторов или до 1500, 2000mA для 1-2 аккумуляторов. Даже самые дорогие интелектуальные зарядки уступают Опусу по возможностям и цене.
    Пока не нашел. В интернете на форумах много писали о шумном вентиляторе - полная чушь, у меня системный блок шумит на несколько порядков громче.(настенные часы тикают раза в 3 громче.

    Apr 13,2015

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  • belik1982
    Great Universal Charger
    Color:Royal Blue Size:EU Plug
    - Greater versatility.
    - Supports all types of standard sizes of batteries.
    - Easy and intuitive operation
    - wide selection of charging currents.
    - Convenient mode backlight. The backlight turns on only when the button is pressed and goes out after a period of time.
    - It is possible to charge the lithium batteries to the voltage of 4,35V (Although this feature is not documented). To switch charge lithium batteries hidden under the bottom cover of the device. Access to the switch may be accessed by removing the cover.
    Noisy fan at high loads.

    Nov 02,2014

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  • Evgeniy
    Отличное многофункциональное устройство!
    Color:Royal Blue Size:EU Plug
    Отличное устройство, умеет заряжать, обслуживать и тестировать любые цилиндрические аккумуляторы, а также если соорудить переходник то и многие другие.
    Пользоваться очень легко приятно, управление интуитивно понятно, дисплей хорошо читаемый, хорошая подсветка.
    Столь же функциональных аналогов, на сегодняшний, просто не существует.
    По сравнение с предыдущими версиями очень радует защитная решетка не вентилятор.
    Не очень качественное изготовление корпуса.
    Шумный вентилятор.

    Oct 08,2014

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  • Ben B
    It's accurate
    Color:Royal Blue Size:US Plug
    - Has useful modes, refreshing batteries, internal resistance test, charge to 4.18 or 4.2 selected in menu, test for capacity.
    - Internal switch select if you need to charge 4.35v cells.
    - I tested it on a 3.8v li-ion phone battery too (using a custom carrier). It refreshed without issue.
    - Quality construction inside.
    - Accurate, confirmed all readings.
    - Your batteries should last. Read about Li-ion on battery university.
    - I don't know if there is really any cons to owning this. It's a good charger.
    - I had to mill an access hole on the bottom cover so I could get to the voltage selector switch without taking it apart every time.
    - Sitting it on a quiet, big fan is a good idea. This will keep the little internal fan from spinning up.
    - It can't fit four 26650, 26700 on up... at the same time. I had to add in an extra carrier for the middle two slots. The stock carrier could be a bit wider.
    - The power supply is 3a. Not really a con but if you like charging over 700ma (maybe in a rush) with 4 cells at a time, you'll have to pick what cells get more or less. 700ma does a perfect charge to full capacity with li-ion.

    Dec 05,2014

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