Opus Battery Charger Analyzer Tester for Li-ion NiMH NiCd Rechargeable Batteries C3400 BT-C3400 AA AAA C 18650

I have been using this Opus BT-C3400 for days now on NiMH and NiCd AA and AAA batteries. I have used it on Modes "CHARGE", "CHARGE TEST", and "DISCHARGE REFRESH" with good results. One poor, worn-out 100 mAh AAA NiMh battery was restored from 17 mAh (normally a throw away condition) to 74 mAh - it probably wasn't much higher than that when brand new. Unlike regular chargers, which just tell the voltage on a battery (which is just how charged up it is right now and has nothing to do with its capacity), the BT-C3400 will tell you what the batteries capacity is in mAh. If a meter doesn't give the batteries mAh (so you can compare it to the mAh the battery is supposed to have), don't buy it!! Also important is that you can set the charge current to 200, 300, 500, 700, or 1000. This is very important for AAA batteries so you don't ruin them with excessive charge current. You should not exceed 200 mA charge current for AAA batteries under about 400 mAh. And 300 mA for about 800 mAh. Have some patience! Two Year Review: Charge still works as well as it did when new. I have two things to add to my initial review: 1) The charger automatically detects what kind of battery you put in it. The annoying side to this is if you put a completely discharged battery in it (i.e., one at 0 VDC), it won't know you put a battery in and will stay "NULL". Don't throw it away! I've found that if you run a couple wires to a second (non-dead) battery then the charger will recognize THAT battery and start charging. After a few minutes you can disconnect the second battery and the charger will continue charging up the 'dead' one - and it'll work fine. : ) 2) Minor annoyance: You can't change the charge current until you change the mode. Even if the mode you want is the one already selected, you have to cycle through the modes until you get back to the one you want. THEN you can select the charge current you want.

This charger appears to work well and the instructions are good. I used this charger on 25 NiMH batteries to charge them up and then I used the "Quick Test" function to determine the internal resistance. The "Quick Test" identified three bad batteries (all three were Enercell batteries) with internal resistance of 2.5 ohms to 4.0 ohms (should be no more than 0.2 ohms or less). I then performed the "Discharge-Refresh" function to attempt to reclaim these three bad batteries; it did not work on them. I tried the "Charge Test" function on good batteries and according to the User Guide I should see "FULL" flashing alternately with the mAH number. However, I only saw the mAH remaining statically on the LCD. This means, I am unsure if the charger completed the charging part of this function. ALERT: This charger prevents exceeding the 4000mA charging current limit, which means you can only charge 2 batteries at a time using the 1500mA or 2000mA setting. If you attempt to charge three or more batteries at these higher settings, the charger automatically reduces current to 1000mA to prevent exceeding the 4000mA limit. This information is in the User Guide under "Current Selection." CONCLUSION: This is a nice charger and I recommend it.

I got this as an update to my old my old Powerex MH-C9000, but it's way more than an upgrade. It can charge each battery with a different program, or all four with the same settings. Charge/discharge current goes down to 200ma, which I think is best for AAAs. It will charge both button top and flat top lithiums, which is a big plus. Some have complained about the fan noise; it's more of a rushing sound than a buzz or hum, and I just keep it in another room and it's no bother. The fan does help keep the unit, and the batteries, cool. Really nice unit, worth the money if you do a lot of charging.

This unit works very well. In addition, the customer service is excellent. I had an issue with the display on my unit and despite that it was out of warranty, customer service promptly responded (on a Sunday, no less) and offered to make it right.

Great unit. I’ve tested a few hundred cells now. On the last run this bad boy started getting tired. Fan started whining like an old car from the cartoons (think technicolor) but pushed through nonetheless.

Works as advertised charges AAA batteries all the way to 18650s .. just set your charging amps wait for it to stop blinking and let it charge yeah there's better ones in the market but this is a great bang for the buck a lot of features just read instructions are YouTube videos about it

So far so good. I’ve been using it to charge and analyze my new & old Eneloop NiMH batteries. I like the option of setting different charging rates. I set a max charging rate of 1,000 mA for my AA Eneloop 2,000 mA NiMH, it automatically drops it down to about 200 mA toward the end of charge. I set a max charging rate of 300 mA for my AAA Eneloop 750 mA NiMH, it automatically drops it down to about 100 mA toward the end of charge. By using the test / analyze options, I was able to get rid of some old Eneloops made in 2012 that weren’t holding a charge (only 1,300 mA for a 1,900 mA NiMH Eneloop) and had very high internal resistance (about 400 miliohms). And I verified that my new AA Eneloop 2,000 mA NiMH hold a charge of about 2,050 mA with internal resistances of about 50 miliohms.

Great, versatile charger. Good/informative display that actually shows the charge rate. It also allows you to preset the initial intended rough charge rate (200ma - 1000ma). I seriously like the 'conditioning' mode, which automatically does three charge/discharge cycles ending with a full charge, giving you an excellent capacity status on the cells. Nice to know. I subsequently label my cells with that capacity. Knowing that capacity helps you match your cells (with near-same capacity cells) when powering any multi-cell device. That way the chances of ever driving any single cell into reverse polarity (and harming that cell) are minimized. EXCELLENT little charger. 5-stars.