The opus BT-C3100 V2.2 is an intelligent 4 slot lithium-ion battery charger with a easily readable backlit LCD display. This charger supports up to 2Ax2 or 1Ax4 charging current. The BT-C3100 is a great choice for charging multiple 18650s at once and especially testing different cell’s capacitys with its numerous functions.
This charger can be found on amazon for $37.99
https://www.amazon.com/Opus-BT-Intelligent-Compatible-Batteries/dp/B0185...
Specifications Listed by Manufacturer
Main Features:
The charger integrates the minus delta voltage 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 )
Easy to read LCD with back light Showing Battery Voltage, Charge / Discharge Current, Charging Time, Battery Capacity etc.
Operating temperature: 0 – 40 deg.C
Max charging capacity: Up to 20000mAh
Power adapter: DC 12V, 3.0A ( Output ), 100 – 240V, 50 / 60Hz ( Input )
Highlight:
1. Voltage update rate is 30s instead of 60s.
2. 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
3.35V charging algorithm is changed to 4.27V.
4. New fan cover make better protection for cooling fan.
5. Charging current range ( mA ): 200, 300, 500, 700, 1000, 1500, 2000
6. Discharge current range ( mA ):200, 300, 500, 700, 1000 ( li-ion cell battery only )
7. Max. charging capacity: 20000mAh
8. Voltage deviation: max 0.03V 4.2V
9. Current deviation: max 5%
Type: Charger
Brand: Opus
Model: BT-C3100 V2.2
Rechargeable Battery Qty: 4
Input Voltage: AC 100~240V 50/60HZ
Output Voltage: DC 12V, 3.0A
LCD Screen: YES
Auto Circuit Detection: YES
Built-in Protected Circuit: YES
Over Voltage Protection: YES
Short-Circuit Protection: YES
Over-Charging Protection: YES
Over-Discharging Protection: YES
Battery Quantity: 4
Packaging
Package weight: 0.558 kg
Product size (L x W x H): 14.4 × 9.8 × 3.9 cm / 5.66 × 3.85 × 1.53 inches
Package size (L x W x H): 16 × 22 × 5 cm / 6.29 × 8.65 × 1.97 inches
Contents
1 x Opus BT – C3100 Battery Charger
1 x US Power Adapter
1 x English User Manual
Included AC-DC adapter outputs 12v 3A Max
Physical Attributes
The Opus BT-C3100 is made out of ABS plastic and feels like is has a very sturdy structure and is built well. The buttons below the LCD feel very solid and have a nice click to them when used. The charging bays adjustable negative poll is attached via spring which also is very strong and holds the battery in place very well.
This charger holds 4 18650 cells comfortably and is very easy to extract them from the bays when they are done charging. Protected versions of all compatible cells fit snugly inside the charger except for protected 26650’s.
The negative end of the cell is just barely not connecting thus the problem with this charger and holding protected 26650’s
Cooling The unit
The charger has a cooling fan built in to cool down the internal components when charging at high currents
The fan is somewhat loud but not loud enough to be bothersome when in listening vicinity
Measurements
The unit is approximately 4”× 5.75” or 10cm x 14.5cm
Display and Selectable Modes
The BT-C3100 has multiple different modes (Charge, Discharge, Test, Quick test, Refresh) and charging currents to choose from including 200,300,500,700,1000,1500,2000 mAH
Operating the Unit
Pressing the mode button will cycle you through the 5 selectable modes (Charge, Discharge, Test, Quick test, Refresh)
Pressing the display button will cycle you through the 4 different informational displays (Voltage, Current, Capacity, Charge time)
Pressing the current button will allow you to select the desired charging/discharging currents
Pressing the slot button will cycle through the 4 slots in the charger
Volatge
Current
Capacity
Charge Time
The Modes
The unit has 5 selectable modes including Charge, Discharge, Test, Quick test, and Refresh.
Charge Mode: The rechargeable battery is charged up to its maximum capacity. Accumulated charging capacity is displayed at mAH display mode.
The charger will charge 4 cells at once charging each at 1 amp. But if you are charging only 2 batteries you should put them in the outer slots (slots 1 and 4) to increase the charging rate to 2 amps a piece. This is especially good for charging 2 26650’s at the same time
Discharge Mode: Discharge mode is used to reduce memory effect, The rechargeable battery is discharged to a preset battery voltage (0.9v for Ni-Cd & Ni-Mh, 2.8v for Li-ion batteries). Once discharge is finished, total accumulated discharging capacity is displayed at mAH display mode.
Refresh Mode: The rechargeable battery is charged and discharged repeatedly to optimize to its maximum capacity. Old rechargeable batteries or rechargeable batteries that have not been used for a long period of time can be restored to their rated capacity
Test mode: Checks the present capacity of a rechargeable battery. The maximum capacity is determined by discharging the rechargeable battery after it was fully charged.
Quick Test mode: The charger will analyze the dynamic internal battery resistance by applying a load and the current reading is referred to the voltage drop detected on the battery. Within 10s, the tested battery resistance will be displayed in the unit of milliohm.
Supported Batteries/ Technical Data
This charger can only hold 2 26650’s in the outer slots
Final Thoughts
The Opus BT-C3100 V2.2 is a great all around charger option for all those who want to charge multiple cells at a time and for those who want to test the capacities of their cells. This charger can be used by anyone with any experience level due to the simplicity of the operation of the device. My favorite aspect of this charger is its ability to discharge your cells to get the exact readout of mA to see if your cells capacity is infact true to what the label says. The charger also fully charges all cells to a even voltage of 4.2 volts and trickle charges them to keep the cells topped off if you leave them on the charger after they are done charging.
The only thing I would have liked to see in this charger would be a higher charging current when charging 4 cells at a time, especially for high capacity 18650s it will take about 3.5 hours for them to fully charge at 1A
All in all I highly recommend this charger to anyone who wants a well built, multi mode charger that will act true to its specifications.
Current collection
Olight -Smini Br -X7R -Smini Cu Nitecore -TM06S Thrunite -TN42 -TN40 Manker -Mk34 -MC13 Cu -MK38 50.3 Noctigon Emisar -Meteor -D4 -D1 -D1S -D18 -D4S Lumintop -BLF GT -GT Mini -Tool AA 2.0 -FW3C Acebeam -X80GTvn -W30 -X50 2.0 Imalent -R90C -MS18 -MS12 Mini FireFlies -E07 Br Reylight -Pineapple Br Haikelite MT03 Br
Product Reviews
Chargers:
Opus BT-C3100, MiBoxer C4-12, MiBoxer C8, Folomov A1
Flashlights:
BLF GT, TN42, TG06S, Emisar D4, GT Mini, S70S, TM36, EDC-C4, BLF Q8, W30
Custom Builds
XPL-HI C8, Aspheric XHP-70, OSLON D1S
nice review, these can fully discharge protected cells?
Thanks, it will drain protected cells as low as the protection circuit will allow
Current collection
Olight -Smini Br -X7R -Smini Cu Nitecore -TM06S Thrunite -TN42 -TN40 Manker -Mk34 -MC13 Cu -MK38 50.3 Noctigon Emisar -Meteor -D4 -D1 -D1S -D18 -D4S Lumintop -BLF GT -GT Mini -Tool AA 2.0 -FW3C Acebeam -X80GTvn -W30 -X50 2.0 Imalent -R90C -MS18 -MS12 Mini FireFlies -E07 Br Reylight -Pineapple Br Haikelite MT03 Br
Product Reviews
Chargers:
Opus BT-C3100, MiBoxer C4-12, MiBoxer C8, Folomov A1
Flashlights:
BLF GT, TN42, TG06S, Emisar D4, GT Mini, S70S, TM36, EDC-C4, BLF Q8, W30
Custom Builds
XPL-HI C8, Aspheric XHP-70, OSLON D1S
So I guess you can’t really tell the true MAH of a protected cell, as I doubt you could get it to zero? Good to know, all I have are protected batteries
Nice review! just ordered one.
Slow is smooth, smooth is fast.
I have this charger but when performing a discharge test it stops at 3 volts sharp. Did you experience different behavior with your specimen?
Yup, mine stops at 3v too. Opus is due for an update with this charger. It’s been over two years with this 2.2 version. I bought mine Dec 24 2015, and the v2.2 had already been out a while.
There are features they need to add like a storage function for all 4 slots, where it charges or discharges to 3.7v then stops. The resistance is wildly inaccurate, redesign the case so it fits four 26650’s at one time, lengthen the slot so it fits protected 21700’s, needs a better fan, and a few other things.
AFAIK, the Opus BT-C3100 does trickle charge Li-ion cells (as said in the conclusion of the OP), which would be a bad thing. When the batteries are full, the charger stops charging entirely and only when the voltage falls below a certain value it starts charging again, and so on.
link to djozz tests
It already has that ability, but you have to get at a hidden switch on the bottom of the mainboard. I cut a small hole to access it with a probe. Works fine. You can also set it for higher voltage cells that way. Also works fine.
Resistance could be better, but it does sort of work. It seems to be better on the Zanflare C4. I’ve found a ‘reasonable’ correlation between the Opus and Zanflare IR. No good at all on the Lii-500-should be improved or removed.
If you want to go through the hassle putting in a superior fan isn’t too hard.
I also use a 5A laptop power supply for mine. Overall I think it’s my best charger now, certainly the most versatile, especially when I want higher charge and discharge features. The C4 and Li-500 are much more limited there.
To Air is Human, to Respire….Divine.
I think the IR accuracy depends on the unit, the care in placing the cells, AND the quality of the cells seem to affect it….a lot. Decent cells seem to have ‘reasonably’ consistent readings. As the cells become more degraded, meaning higher IR, the readings show MUCH more erratic readings and less consistency. OTOH, that shows the cells are going to hell, so it’s still useful info.
To Air is Human, to Respire….Divine.
Because I will put in an 18650 to charge and it will say for example, 90. Take the cell out and put it back in the same slot, it will read 53, take it out put it back in the same slot it will read 125, and so on. And many other have reported the same thing
I have a hole cut in mine as well, for the occasional 4.35v setting. But that flimsy little switch is likely to fail. They need a slot selection setting for storage. Yes, they need to update the fan, and that was the other thing. 5A power supply needs to be included. And you still can’t fit 4 26650’s side by side.
It’s been 2+ years. They need to update this stuff
I’ve tried cleaning both terminals on the charger and both ends of the cell. Seems to make no difference. All 60 of my lithium ion cells are inside the same room with the charger, inside the house. So they are all the same temp.
So what irks me is that no one can keep milliamps and milliamphours straight,
“charging currents to choose from including 200,300,500,700,1000,1500,2000 mAH”
“to get the exact readout of mA to see if your cells capacity is infact true to what the label says.”
both should be the opposite, good day.
First “Real” Light: Olight S20
Youtube: www.youtube.com/user/SuperBrainAK
I'm running the test/discharge on two 26650 protected batteries at .5A and the fan does not come on with my opus. Is that normal? I thought fan should come on when discharging.
Did the fan turn-on when plugged? It should run when plugged, then turn-off.
The fan is temperature controlled. It will only run when the factory calibration for temperature threshold is reached, and run only when the threshold is reached.
I don't know if it came on when I first plugged it in. Good to know it's temp controlled thanks. I may take the risk and let it run as long as things don't seem to get too hot and when the test cycle is finished I will make sure the fan turns on when plugged in.
Anyone know where I can get a 12v car adapter to fit the opus charger?
It uses DC 5.5×2.1mm plug, isn’t it? Maybe something like this will work:
https://www.aliexpress.com/item/XCGaoon-Diameter-5-5mm-Port-Car-Charger-...
(it indicates up to 1.5A only though, which may not be powerful enough if charging at full speed)
I noticed the BT-C3400 comes with a car charger plug and was hoping to get that one as it looks a little more sturdy.
That is the one I purchased , OPUS BT-C3100 V2.2 Charger. I use it on all rechargeable batteries. So far so good.
I purchased 10 EBL 18650 Li-ion 3.7V 3000mAh Rechargeable Batteries on Ebay for $16.00 and tested them at 2600 mah so i kept them. Then i purchased 4 LG HG2 18650 3000mAh 20A Batteries | Authentic Original Battery LGDBHG21865 on Ebay and checked them at 1800 mah
so i’m returning them for a refund.
This charger is a big help for me, bad for Ebay, Never buy from them again.
Water Cooled MT35 PLUS RE-MODDED------MT35 Plus with SBT90.2 mod ( GT90 kit from Texas Ace )
7th annual BLF/O-L contest Haikelite MT07 upgraded-----8th annual BLF/O-L contest “SKELETON”
Water Cooled 20K lumen POT LID LIGHT------ Cyclops 18M cd flashlight Mod------Q-beam mod to led
Convoy 4x18 Luminus 90.2 mod with 86mm reflector
Think outside the box too long , cannot find your way back in
yes it is a great charger i’ve had it for about 2 years now and it is still running strong
and for the battery problem, the place I buy all of my batteries is: https://www.imrbatteries.com/ (link is external) every cell I have ever purchased from this site was real and I trust them, this is another site in case the first one was out of stock or vise versa https://liionwholesale.com
Current collection
Olight -Smini Br -X7R -Smini Cu Nitecore -TM06S Thrunite -TN42 -TN40 Manker -Mk34 -MC13 Cu -MK38 50.3 Noctigon Emisar -Meteor -D4 -D1 -D1S -D18 -D4S Lumintop -BLF GT -GT Mini -Tool AA 2.0 -FW3C Acebeam -X80GTvn -W30 -X50 2.0 Imalent -R90C -MS18 -MS12 Mini FireFlies -E07 Br Reylight -Pineapple Br Haikelite MT03 Br
Product Reviews
Chargers:
Opus BT-C3100, MiBoxer C4-12, MiBoxer C8, Folomov A1
Flashlights:
BLF GT, TN42, TG06S, Emisar D4, GT Mini, S70S, TM36, EDC-C4, BLF Q8, W30
Custom Builds
XPL-HI C8, Aspheric XHP-70, OSLON D1S
I just bought this charger and it behaves the same way for the IR test.
EDC
Aurora Clone S11 || S21A, w/Mtn17DD Zener Guppydrv, TIR, XHP-50 || SC31 Pro, SST40 6500K
Recent/ongoing Mods:
S2+, TexAven 17mm, LH351D | L2, Crescendo Mtn20mm, SST40 6500K | C8+ OP, DD XHP-50
SP32A w/SST40 5000K | TIR Upgrades | EagleTac clip | Ultrafire C2 w/6A 20mm & LH351D | S2+, Biscotti, Nichia 219C 2700K
Reviews:
Sofirn SP31 v2.0 Tactical Flashlight (Cree XPL HI) || Sofirn SD05 Scuba Diving Flashlight || Sofirn SC31 USB Rechargeable (XP-G3) || Sofirn SC31 Pro 5000K
HKJ says to take the lowest reading when jiggling, rotating, putting the cells a few times in and out as chargers do that. I got the SM8124A tester and confirmed a few times that the lowest IR reading from the chargers is accurate. The chargers use a different method to determine cell IR than my tester, so I add 60% more from what my tester shows and so far it always ends up at the lowest IR reading from any charger.
@klrman: Thank you for filling me in. Sounds like there’s a method but a bit of a squirrelly one.
I have a MiBoxer C4-12 on the way so I’ll have two references. I got a great price for one on Amazon Prime Day (according to some our other members).
EDC
Aurora Clone S11 || S21A, w/Mtn17DD Zener Guppydrv, TIR, XHP-50 || SC31 Pro, SST40 6500K
Recent/ongoing Mods:
S2+, TexAven 17mm, LH351D | L2, Crescendo Mtn20mm, SST40 6500K | C8+ OP, DD XHP-50
SP32A w/SST40 5000K | TIR Upgrades | EagleTac clip | Ultrafire C2 w/6A 20mm & LH351D | S2+, Biscotti, Nichia 219C 2700K
Reviews:
Sofirn SP31 v2.0 Tactical Flashlight (Cree XPL HI) || Sofirn SD05 Scuba Diving Flashlight || Sofirn SC31 USB Rechargeable (XP-G3) || Sofirn SC31 Pro 5000K
No problem. All my chargers annoyed me first too with their swinging IR readings, but I finally got the hang of it and always double check with my tester as a backup and it has always been consistent now.
Hello guys,
I just came across this deal on BT-C3100 on BG (no affiliate):
https://www.banggood.com/Opus-BT-C3100-V2_2-4Slots-LCD-Display-Smart-Intelligent-Universal-Battery-Charger-p-1183072.html
Do you think this deal is legit? (I’m considering the fact, the price is double at local shops).
BT-C3100v2.2 for $34
Thanks
I like my BT-C3100, except the fan.
So far I used it only for NiMH but even at charge current 4× 300mA the fan is audible. The noise come and go, switch from noisy to whisper.
But overall it´s my favorite charger, it works well with my cells and it seems it load more to the real capacity than my Vapcell S4. The current selection is good, I use mostly 300mA for AAA (400 would be nice, but I can live with 300), 700mA for AA cells also nice (miss it for the S4 and VC4SL)
Price sure has fluctuated on this model. Original price stated back in 2017 was $38. Right now it’s about $70. But back in late Jan 2022, it had gone down to $39. Maybe a spike of purchases triggered the Amazon pricing model to a new high test ceiling price. 5 years later, I wonder if it’s exactly the same or if Opus made any minor improvements.
I’ve been using the BT-C3100 since 2015 and like you, my main peeve is the whining fan
How do you like the Vapcell S4 over the BT? I know the S4+ can do max 3A, compared to BT at 2A
I’m thinking of retiring the BT and go for the S4+, mainly to charge Li-Ion, as for Ni-Mh I will use my MiBoxer C8
Thanks
Wire up a 80mm computer fan with a 12v wall wart. pointed at it and the onboard fan will rarely turn on, if at all. Careful what you choose or that fan will drive you crazy. Or, just use an aftermarket laptop cooler.
Some personal USB/battery fans work fine and are quieter.
The stock fan is kind of lousy. There are replacements that are better. But, ALL fans of that size with any kind of decent RPM whine.
If there is no cooling, your batteries will get warm>hot. That’s physics. At least the Opus does have some attempt at cooling. Most do not.
To Air is Human, to Respire….Divine.
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