BT-C3100 intelligent battery charger teardown

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.

BT-C3100 intelligent battery charger teardown

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.


For more detail: BT-C3100 intelligent battery charger teardown

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