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August 27, 2014

Opus BT-C3100 V2.0 Intelligent Battery Charger Review and Teardown

at 1:05 am. Filed under Reviews

Opus BT-C3100 V2.0 Intelligent Battery Charger Review and Teardown_8214 


Thanks to GearBest for sending in this Opus BT-C3100 V2.0 Intelligent Battery Charger for review. at a quick glance this charger might look like any other charger that you see at the grocery store.  Your generic store bought brand probably also has 4 charging bays for AA and AAA batteries, it probably has 2 charging circuits which places 2 cells in series to charge them, it most likely has 2 charging lights which just turns off when charging is done. If you leave the batteries in your generic charger you will most likely have batteries that have been overcharging or running down. Also your generic charger can probably just charge one chemistry of battery.

When you have a closer look at the Opus BT-C3100 V2.0 Intelligent Battery Charger you can see how this system differs from your every day generic battery charger. It can auto detect and charge NiCd, NiMH and Li-ion batteries. It charges each cell independently preventing bad cells from interfering from other cells from charging properly. Forget charging lights, this has a full LCD display that provides tons of status. It will monitor batteries that are left in the charger and keep them topped up and ready to go. From here the features go on and on. Don’t let the small package fool you, there is a ton of smarts and features built into this small package.

Have a look at the pictures below and in the video for a look inside the charger. The construction is a dual sided SMD load, the construction looks very professional. The battery contact spring tensioners work well and the connection to the PCB has been beefed up with a thick metal bar. The heat management in the unit is great, there are no hot spots when operating and if there was a problem one of the 6 thermal sensors would be sure to catch it. The processing and display is done using a chip on board which can be seen under the epoxy blob in the pictures. 

The case is well built and feels nice in the hand, the buttons and battery sliders feel like they will last. The plug in power supply came with an adapter which changed it from a European plug to a North American style but this caused the plug stack to be quite long and might cause a problem if it was to be plugged into a wall plug. I was using a bench mounted power supply so I didn’t have any issues but this could be a concern.

The price of this unit is a bit higher than your grocery store version but don’t be fooled, this unit is worth it.  Best of all GearBest is offering all Hacked Gadgets readers an 8% discount using the coupon code Anna08.



There is a fantastic display screen on this unit. The LCD screen is backlit when you are pressing buttons and is clear and easy to read. The screen is divided into 4 equal sections, one for each battery in the unit.The upper unit of the display tells you what function is being performed, the lower section is for data such as cell voltage, charging current, discharge current, etc.


Cell Selection

You can use the slot button to select each of the 4 battery bays to adjust what operation is to be performed on that bay. This adds flexibility since now you can perform any task you like in any of the positions. For example you could charge cell 1 at 500mA, charge cell 2 at 1A, discharge cell 3 to put it into storage and do a discharge refresh on cell 4. You can also easily opt to perform the same function on all slots with the press of a button.



In charge mode you simply pop in a battery, you will be shown the initial battery voltage before the charge starts. You can then select the current you wish to charge the cell at.

In Discharge mode you can discharge the inserted battery to a preset level. You will also be shown how many energy was discharged from the cell after the discharge is done. It is then trickle charged to prevent it discharging any further.

In Refresh mode the charger will discharge and charge the battery 3 times to allow old batteries that have not been used in a long time to restore some of their capacity. After the 3 cycles are complete you will be able to see the total mAH of the cell. This lets you track the health of the battery over time if you like.

Test mode checks the capacity of the battery by immediately discharging the battery after it is charged.

Quick Test allows for a check of the internal resistance of the battery. This test is quick (under 10 seconds) and will show you if the battery is a good contender for high current applications. You can test batteries with other chemistries using this function such as alkaline and any other 1.5 volt battery.


To see the full size hi-res pictures please click here.



Opus BT-C3100 V2.0 Intelligent Battery Charger Review and Teardown_8186





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8 Responses to “Opus BT-C3100 V2.0 Intelligent Battery Charger Review and Teardown”

  1. Tony Says:

    The end of the video is missing…

    I’m curious to see how crap the batteries are, I’m assuming they’re just 600mAh NiCads with ‘NiMh 3000’ written on them?

    (You can tell battery type by weight, NiCads are very light compared to NiMh.)

  2. Jody M Says:

    Hey Alan. Interesting video. I’d be curious in the Internal resistance measurement readings. I have found that batteries with lower internal resistance tend to work better in high current demand applications. Have you had a chance to read and compare the internal resistances of the good quality NiMH vs the low quality NiMH batteries? Also, older rechargeable batteries develop internal shorts which can self-discharge batteries (or even stop them from charging at all). Have you tried a battery that won’t take a charge from other chargers. Really enjoy your website!

  3. Alan Parekh Says:

    Thanks for the comment. Not sure what happened to the end of the video, it got chopped off somehow. It has been re-uploaded and now shows the entire video.

  4. Jody M Says:

    In the video, there were capacitors with an “ESR LOW ES” marking. I believe that these are quality capacitors that are of slightly better quality than standard capacitors and may be use here because of better temperature stability. I found this webpage to contain some more details about LOW ESR capacitors
    I also noted the internal selector switch had different voltage settings. Although not likely intended to be “user changeable” I am suspecting these voltages may be for setting voltage limits for Li-Ion batteries.

  5. Max Says:

    Maybe it’s just me, but those solder blotches left and right of the spring’s end are way too close for comfort for me. I accept they’ll probably never touch the spring in normal use, but I’m distinctly bothered by the fact that they easily might if the spring twists just right – to not even mention what might happen if one of the springs ever unclips or breaks.

  6. mrpear Says:

    Hi, useful review. Thank you. Would be great to see more battery chargers tested!

  7. Pete Says:

    Great Video review, so good I sat down and watched the whole hour of it! Luckily the PVR recorded Big Bang Theory.
    Now being the tail end of 2015, I see there’s a version 2.2 of the opus charger. Cheers m8.

  8. dave Says:

    @Tony – No Tony, NiCd are not very light compared to NiMH, unless you have a very low quality NiCd cell. The batteries are probably about the same as most overrated generics, around 2200mAh real capacity, alarmingly high self discharge rate, alarmingly low cycle endurance, and poor QC so a high % don’t even meet the 2200mAh threshold.

    @Jody – Of course low impedance batteries work better at high current. Nothing new there, is why they are chosen by the R/C, cordless too, and custom vape crowd. While there are low quality cells that don’t consistently perform to their own specs initially or long term, it’s not all about quality but rather purpose as you don’t need to pay a lot for low impedance cells when the app doesn’t require them, and can often get higher capacity per dollar instead. For example Panasonic 3400mAh 18650 cells are great for capacity but don’t try to run a cordless saw with them unless you have about 5 in parallel to share current, but one is more than adequate for a 5W LED flashlight.

    @Max – Take a closer look at the pictures. Those solder blotches attach the metal slider rail on the other side of the PCB that the sliding battery contact and spring electrically connect to anyway. Touching would make no difference. However, if a spring were to break and fly off to Who Knows Where, then sure bad things could happen but that’s true of most battery chargers with a sliding contact rail.

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