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132 Reviews
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 mentioned above.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
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 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.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
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.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
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.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
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 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.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
The Cats Meow
The BT-C3400's are a great little charger. Some great working features and simple to use. If all you want to do is just charge, once set it is load and go from then on. I wanted more, condition and confirm the mah rating on the particular battery occasionally. This is the second one purchased, one for home, second for travel. No complaints about the quality.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
Best universal battery charger ever!
This has got to be the best battery charger I've ever come across. It charges Lithium-ion, NiCd and NiMH types of batteries of almost any size except D. It does not charge LiPO4 batteries.
It has a fan to make sure everything is nice and cool; protecting your charger and batteries from overheating with two thermostats, one for the unit and one for the batteries. It will turn on the small fan when necessary automatically.
It also has several modes of operation, instead of just plain charging. It can be set in the following modes:
Charge - just like other chargers, but with different modes for different chemistry batteries
Discharge - doesn't overdo it
Discharge then Refresh - 3 cycles of charge/discharge to recondition old, neglected or stubborn batteries
Charge then Test - determines the true mAh - the capacity of the battery - using 1 cycle of charge, discharge, recharge
Quick Test - tests the resistance in Ohms of the battery
I can't recommend this charger highly enough. Good batteries are expensive, and you have to pay for a good charger which will care for your batteries safely. Don't waste your money on other "intelligent" chargers. This one's definitely the real deal!
Let's save the environment by using rechargeable batteries, and use them safely.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
Works great and easy to use!
Tried it out by performing capacity tests on 8 18650 Li-Ion cells, and 12 AA Nimh cells. Performed exactly as it should. I've had one like this of the same brand (for AA/AAA cells only) for years, and it's been working perfectly. Bought this one because I needed capability for the larger Li-Ion cells.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
Great Charger
It is not a put your batteries in it and walk away type item, even though it could be. It just has so much more capability. I have used it to recondition some older batteries, but I have yet to use the batteries afterwards. So I really can't give a detailed review. I like it so far. I think anyone who purchases this will be pleased.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana
Opus BT-C3400
Great battery charger, this is the one to get. It charges everything. I ordered the D adapters for mine and I can charge every battery I have. Easy to use and does what it says it will do. Worth the cost, you can set the charge rate and this really helps your rechargeable batteries last. This one does Nickel Metal and Lithium. The test feature is nice too.Read full review...
Verified purchase: Yes | Condition: new | Sold by: rdana