Review: Opus BT-C3100 V2.1 (with teardown and video)

Gearbest were very kind to send me this updated charger to review.

Much of the performance improvements have been covered already by HKJ, so I hope members find my review useful!

Opus BT-C3100 v2.1

Opus branded retail box, feels more like a product now:

Back of box with CE and FCC logos:

Contents include manual sheet, charger and 12V 3A PSU:

Back of charger, shown beside included Meic branded MN-A036-E190 adaptor:

It is a small detail, but I preferred the right angle plug on the adaptor that came with v1.0. There is also no power indicator on this adaptor.

Rear cooling fans, with v2.1 (above), v1.0 (below):

Underside (left v2.1, right v1.0):

PCB comparison (left v1, right v2.1). Has yellowed slightly from use in v1.0:

Most notable is the inclusion of a 1000uF capacitor to smooth input from PSU. Lower case molding now covers the fan, where before there was black tape. There is also some adhesive foam to help isolate vibration from the casing.

Some of the resistors are a light green colour, so might be from a different source.

v2.1 PCB (click for full size):

Other side:

Close examination of PCB showed many small solder flakes which can cause shorts. I used an anti-static brush to clear them. Here are some stuck to inductors:

On power up 2.1 is very briefly shown. Note the blueish tint to the backlight:

Also different, the screen is not as bright as v1.0, and I find it harder to read.

This is how it looks with no ambient light:

A travel adaptor was also included since the PSU has Euro plug connector. A little warning about these, they do not conform to BS 1363 standard.

Since I don't have any spare 3A supplies I removed the earth contact inside because it was uncomfortably close to the other terminals.

Display showed cells 0.03V higher than v1.0 and my DMM, which is within the stated ±0.03V tolerance.

I do wonder if this might cause the charger to terminate too early (I have an ML-102 that terminates at 4.16V). I will update with my findings.

Cell DMM v1.0 v2.1
1 2 3 4 1 2 3 4
Eneloop AA 1.4 1.39 1.39 1.38 1.37 1.37 1.37 1.37
Sanyo UR18650FM 4.19 4.18 4.18 4.18 4.18 4.21 4.22 4.22 4.21
Warsun Protected 18650 4.13 4.13 4.13 4.13 4.12 4.15 4.16 4.16 4.16

I made a short video to demonstrate the improvement in fan noise:

Thanks for reading! ^_^

That is a useful addition to HKJ's review, thanks!

Great comparison shots, thanks! :slight_smile:

Very helpful comparison review, thank you!!

I like the video

Thanks Chloe :slight_smile:

The teardown was missing from HKJ’s review. Thank you. :slight_smile:

Thanks Chloe! I now realize that the voltage selector switch doesn't face toward the side of the case like I thought. Has anyone come up with a solution to allow switching the switch position with the case closed?

-Garry

Thanks! :bigsmile:

I forgot to check it. Here it is:

Best youtube channel! :bigsmile:

Nice! Thanks for the review :slight_smile:

Good Day Chloe,

GREAT review....

Thank You Very Much,

George

Hi,
If a person was good with electronics could you buy the 1000uF 16v capacitor and solder it on to the board in the same spot as in v2.1 and have it work on a v1.0 or a 2.0?
Thank you.
Dan

Hi Dan, you could add a capacitor but it will only address some of the spiking. There was some discussion about this and using a different power supply, I think in HKJ review thread of V2.0.

I do wonder about adjusting the circuit in earlier models to regulate to 4.7V but I don’t have the equipment to properly test the results of such mod. From Henry Xu:

The capacitor needs to be about 100 times as large to handle the spiking in V2 software.

It is fairly easy to see on my oscilloscope traces of the charge pulses.

I don’t have an oscilloscope. :wink:

Hi chloe, have you tried switching the fans to see if they both make the same sounds on the opposite charger, because that v2 fan has a horrible wine to it.
Thanks for the teardown, and great pictures.

Excellent. Thanks!

Fantastic review Chloe, thank you. Please buy yourself a good B1363 adaptor that has a kitemark, throw away the rubbish one.

+ 1

Beautiful comparison review, thank you for it!!

Maybe the difference of voltage is due to the low updating frequency?

I haven’t tried yet but will look into it. The fans are sealed to the case with what looks like potting compound.

I will say, although I was more used to the broader spectrum of noise from v1.0 fan, v2.1 is less intrusive because it is quieter overall and it doesn’t cycle on/off when internal temperature is close to the 40ºC threshold. It still cycles on/off but not as often.

The updated version also doesn’t have the rapid high pitch clicking/switching sound which would often be out of sync when beginning a new program (charge or discharge) whilst another is already running.