BT-C3400 V3.1 Battery Charger Analyzer Li-ion NiMH 18650 AA AAA Car Adapter

DC Workshop

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US $52.19/ea

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8 available452 sold

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Located in: Sacramento, California, United States

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eBay item number:331523442603

Last updated on Oct 28, 2025 16:46:53 PDTView all revisionsView all revisions

Item specifics

Condition: New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is ...

Brand: OPUS

Compatible Battery Sizes: 26650

Type: Car Charger

Battery Capacity: 4

Voltage: 3 V

MPN: BTC3400

Chemical Composition: Li-Ion

UPC: 0727908590739

Item description from the seller

About this seller

Joined Sep 1998

Usually responds within 24 hours

Battery Chargers and Rechargeable Batteries. Battery test and analyzing chargers.

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Average for the last 12 months

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4.9

Reasonable shipping cost

5.0

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5.0

Communication

5.0

Battery Chargers TestersOther

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4.9

170 product ratings

160 users rated this 5 out of 5 stars
10 users rated this 4 out of 5 stars
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Would recommend

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by jewellmd99
Jun 07, 2018Top favorable review
Not your ordinary battery charger
I purchased the OPUS BT-C3400 battery charger to test a large pile of 18650 batteries. I already had an Intelligent charger for these batteries, however the OPUS is different. Not only does it charge, but it will test and do a complete discharge & recharge batteries. Each slot is independently controlled. I am a person who farms 18650 batteries from old laptop batteries. I will then test & charge these batteries, separate them in piles and use the better ones in my TOMO 4-slot battery bank. The battery bank is then used to charge USB devices (i.e. phones, wireless headset, etc) while camping. With the OPUS I can identify high capacity batteries over ones that need to be recycled. I couldn't be happier with this charger. A little pricey, but it is well built and has the features I ... I purchased the OPUS BT-C3400 battery charger to test a large pile of 18650 batteries. I already had an Intelligent charger for these batteries, however the OPUS is different. Not only does it charge, but it will test and do a complete discharge & recharge batteries. Each slot is independently controlled. I am a person who farms 18650 batteries from old laptop batteries. I will then test & charge these batteries, separate them in piles and use the better ones in my TOMO 4-slot battery bank. The battery bank is then used to charge USB devices (i.e. phones, wireless headset, etc) while camping. With the OPUS I can identify high capacity batteries over ones that need to be recycled. I couldn't be happier with this charger. A little pricey, but it is well built and has the features I mentioned above.
Verified purchase: YesCondition: NewSold by: rdana
by grantdcol
Nov 05, 2019
Excellent user interface, well made. I prefer it over the LiitoKala Lii-500.
Great charger. I bought 1 of them, tried it out, then bought 3 more. I like it better than the LiitoKala Lii-500. It is built slightly better but more important to me is the user interface. It shows battery monitoring information for all 4 batteries simultaneously - charging current, voltage, cumulative mAh in during charge, cumulative mAh out during discharge, and time elapsed. The cell capacity testing feature is nice - you pop in a cell and it charges it all the way up, then discharges to a safe low voltage, and then back up. It records and displays the mAh discharged at the end of the process. Setup is super easy, you do it once, and you can pop in new cells over and over again without having to hit any buttons at all. This model discharges Li-Ion 18650 cells to 3.1v. I believe the ... Great charger. I bought 1 of them, tried it out, then bought 3 more. I like it better than the LiitoKala Lii-500. It is built slightly better but more important to me is the user interface. It shows battery monitoring information for all 4 batteries simultaneously - charging current, voltage, cumulative mAh in during charge, cumulative mAh out during discharge, and time elapsed. The cell capacity testing feature is nice - you pop in a cell and it charges it all the way up, then discharges to a safe low voltage, and then back up. It records and displays the mAh discharged at the end of the process. Setup is super easy, you do it once, and you can pop in new cells over and over again without having to hit any buttons at all. This model discharges Li-Ion 18650 cells to 3.1v. I believe the BT-3100 discharges to something like 2.8v, which is arguably too low for some cells. It charges to 4.20v exactly which is what I wanted. The LiitoKala goes a little higher. The internal resistance test ('quick test') seems to vary quite a bit. I take it with a grain of salt and use the value only as a relative measure for comparing cells. I don't consider it an absolute value that can be compared to other values obtained on other devices. One final feature is that it can do 4x batteries up to 1A each, or it can do just 2x batteries at 2A! That's higher than I need but nice to have. On the other end, it goes as low at 200mA for slow charging deeply discharged cells. Input power is 12v 3A with a 2.1mm x 5.5mm jack which is super common. All in all I highly recommend this charger.
Verified purchase: YesCondition: NewSold by: rdana
by jb52486
Sep 01, 2018
Good versatile chager for the price
Charges batteries individually so you're assured a full charge on each battery. You can choose the charging rate for a slow or fast charge. The analyzer function can take a while,(like all day). But it will give you the current battery capacity in mah. This helped me identify which batteries were weak and so I could take them out of service. The charger is of good quality and even has its own little cooling fan. It has been working very well for me so far. Seems to be a good value for the money especially if your looking for a charger that does more than just charge batteries.Charges batteries individually so you're assured a full charge on each battery. You can choose the charging rate for a slow or fast charge. The analyzer function can take a while,(like all day). But it will give you the current battery capacity in mah. This helped me identify which batteries were weak and so I could take them out of service. The charger is of good quality and even has its own little cooling fan. It has been working very well for me so far. Seems to be a good value for the money especially if your looking for a charger that does more than just charge batteries.
Verified purchase: YesCondition: NewSold by: rdana
by legaleagle12
Aug 07, 2019
I haven't found a better charger.
I haven't found a better charger at any price. It just rocks. It has all the user selectable features you could need, four independent channels each separately selectable for 'charge', discharge, internal resistance test, plus its main attraction over the competitors: refresh and multi- refresh which tell you the actual storage capacity vs the 'mAh rated' claims. Auto detection of battery chemistry and charge settings. User selectable charge or discharge current rate from 200 to 2000mA. Real time voltage and current display while charging or discharging. All the protective circuitry for both the battery and the charger currently available. There is nothing more to want other than a model with more than four battery channels.I haven't found a better charger at any price. It just rocks. It has all the user selectable features you could need, four independent channels each separately selectable for 'charge', discharge, internal resistance test, plus its main attraction over the competitors: refresh and multi- refresh which tell you the actual storage capacity vs the 'mAh rated' claims. Auto detection of battery chemistry and charge settings. User selectable charge or discharge current rate from 200 to 2000mA. Real time voltage and current display while charging or discharging. All the protective circuitry for both the battery and the charger currently available. There is nothing more to want other than a model with more than four battery channels.
Verified purchase: YesCondition: NewSold by: rdana
by egeekmctroyd
Feb 23, 2019
Amazing machine.
This isn’t your average discount store charger. This particular model has selectable charging, test and refresh modes, where one can also select the current in milliamp-hours (mAh). These can be selected on a per-slot basis, or across all four slots. Discharge runs to 0.9v on NiMH-type cells, and 3.0v on LiIon-type cells. Charge runs to 1.5v on NiMH-type cells, and 4.2v on LiIon-type cells. The charger will auto detect the cell type when the battery is inserted into the spring clip. Those clips handily accommodate a range of sizes. I’ve been using the NiMH-range “Discharge Refresh” (DR) mode for a couple solid days now, attempting to restore a 4-pack of (potentially-sacrificial) AAA cells. These were Panasonic-branded, with a 750 mAh advertised rating. Initial DR cycle yielded an actual ... This isn’t your average discount store charger. This particular model has selectable charging, test and refresh modes, where one can also select the current in milliamp-hours (mAh). These can be selected on a per-slot basis, or across all four slots. Discharge runs to 0.9v on NiMH-type cells, and 3.0v on LiIon-type cells. Charge runs to 1.5v on NiMH-type cells, and 4.2v on LiIon-type cells. The charger will auto detect the cell type when the battery is inserted into the spring clip. Those clips handily accommodate a range of sizes. I’ve been using the NiMH-range “Discharge Refresh” (DR) mode for a couple solid days now, attempting to restore a 4-pack of (potentially-sacrificial) AAA cells. These were Panasonic-branded, with a 750 mAh advertised rating. Initial DR cycle yielded an actual capacity of ~20 mAh (yikes!). Repeating the DR cycle at increasing mA ranges (200-700 mAh) over the span of a couple days eventually restored two batteries to a 600 mAh capacity, and two to 700 mAh capacity (!). Running them down in a test flashlight and measuring the time to discharge seems to verify the charger’s measurements. I was also able to resuscitate some ~8-year-old 18650 cells from a laptop battery I had lying around. They aren't storing anything like their rated current (rated 2600 mAh, tested 1000 mAh with this charger), but are good enough to repurpose in DIY battery housings. I only really see two “cons” with this unit. First, the user interface is a bit clunky. It doesn’t always respond on the first button push. And, while it does a good job indicating which slot is selected, it’s not really apparent what options can be changed at a given time. Some options seem locked out while a cycle is in progress. The second issue is the single folded-page instruction sheet. While it makes a valiant effort for what it is, it does assume a degree of familiarity with battery chargers. Coupled with the clunky interface, this could be bad news for non-technical sorts (or technical sorts who aren’t familiar with battery technology). I would also note that charging and discharging can take a long time. My AAA cells took days to complete this refresh, for example, and they’re relatively small cells. I expect it will only take longer as the capacity goes up. Even the instruction sheet warns DR can take “tens of hours.” Having said this, I personally consider this a “pro” more than a “con”... one will get better service life out of a trickle-charged battery than a fast-charged one. However, if you do need that fast charging capability, it may be better to look at a different model. Obviously none of these is a show-stopper for me. If one likes pressing buttons, and can be patient while it works, this is a fantastic value. I intend to get another and migrate back to regular use of my rechargeable cells. Amazing machine.
Verified purchase: YesCondition: NewSold by: rdana

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BT-C3400 V3.1 Battery Charger Analyzer Li-ion NiMH 18650 AA AAA Car Adapter

Additional service available

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Item specifics

Item description from the seller

About this seller

DC Workshop

99.8% positive feedback•111K items sold

Detailed seller ratings

Popular categories from this store

Seller feedback (40,546)

Product ratings and reviews

Most relevant reviews

Not your ordinary battery charger

Excellent user interface, well made. I prefer it over the LiitoKala Lii-500.

Good versatile chager for the price

I haven't found a better charger.

Amazing machine.

More to explore :

Shop Top Sellers and Highly Rated Products in Other Test, Measurement & Inspection

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DC Workshop

99.8% positive feedback•111K items sold

Detailed seller ratings

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BT-C3400 V3.1 Battery Charger Analyzer Li-ion NiMH 18650 AA AAA Car Adapter

Additional service available

Shop with confidence

Item specifics

Item description from the seller

About this seller

DC Workshop

99.8% positive feedback•111K items sold

Detailed seller ratings

Popular categories from this store

Seller feedback (40,546)

Product ratings and reviews

Most relevant reviews

Not your ordinary battery charger

Excellent user interface, well made. I prefer it over the LiitoKala Lii-500.

Good versatile chager for the price

I haven't found a better charger.

Amazing machine.

More to explore :

Shop Top Sellers and Highly Rated Products in Other Test, Measurement & Inspection

Best Sellers

Top Rated

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