Neither one of those is an analyzing charger
You* REALLY* do want an analyzing charger. If you don’t now, you WILL later, I guarantee it.
There is no ‘perfect’ charger. Decide what is important, pick a charger and go on.
What is the difference in an Analyzing charger? I thought they all did the same the C4-12 and Opus BT. But if that is not the case the only one that I see that qualifies in my price range, found in US would be the Opus BT-3100 V2.2 as I can get that on Amazon.
Analyzing charger can more accurately measure cell capacity
by using a discharge test.
Opus 3100 can do that. Miboxer c4-12 cannot.
An analyzing charger will charge > discharge > the charge the battery and give you the capacity determined from DISCHARGE. This is the only accurate way to measure capacity.
Lii-500, Zanflare C4, and the Opus BT-C1000 are analyzing chargers.
The main advantage of the Opus is more control and options for charging and discharging. It has some ‘quirks’ that some people dislike. But, it IS more flexible, more powerful, and has more charging options.
A ‘charge only’ charger cannot do this.
The Miboxer C4-12 appears to be only a charger, but a good one. It’s fine if you don’t really want an analyzing charger. But I think you will.
See, the problem is that almost all analyzing chargers aren’t actually all that good.
They use resistor based dischargers, meaning current drawn goes down as voltage goes down, meaning capacity can easily be overread.
Got a better SIMPLE/REPRODUCIBLE way? What other ways are there to discharge accurately?
I assume you mean, “not all that good” at discharging? The charging is NOT in question?
That is a good question there. OK comparing the LiitoKala Lii-500 and the Opus BT 3100 v2.2 I have opted for the Opus and ordering it from Amazon. It is the same price as on BangGood but I get it delivered in 2 days 
Opus supports more types and the larger battery sizes so that will be the charger I order. I appreciate the advice and assistance and the explanation of what an Analyzer/Charger is.
No, charging isn’t in question. They charge fine.
Get something like this:
https://www.ebay.com/itm/DC-12V-Battery-Capacity-Tester-Battery-Life-Internal-Resistance-Analyzer/263358206343
And a battery holder like this:
https://www.ebay.com/itm/Plastic-Battery-Holder-Storage-Box-Case-for-1x-2x-3x-4x-18650-Batteries-Wire/332855641026
These work quite well, and you can test capacity very accurately, along with internal resistance.
? Looks like a resistor to me.
One * rating. Not encouraging.
Not a resistor.
Uses a linear FET to draw constant current.
It’s like an LED4Power driver, but wastes as much power as possible.
And don’t look at the review. I wouldn’t worry. Just lacks clear instructions.
Bought mine from the same seller.
Was easy to test internal resistance that way.
Right on spec! Actually, better than most 30Qs. 
Ok my new Opus arrived today and I have Eneloop Pro Double AA batteries. These are brand new batteries so I want to verify them. Would I set mode to Test and just insert battery? Also should I change the current discharge rate from default 500mAh to say 700mAh and charge to something like 1000mAh? I’m a newb to an Analyzer charger.
Be aware that one of the limitations of ALL the analyzing chargers is the limited ability to do high amp discharge, if you want to test for that. They use resistors, resistors get hot, so they have to shed the heat. Opus will give you a few more options than many of the others.
That said: pop them all in. Plug in. In a moment all bays will start blinking with [500] displayed. I’d leave it there for now. Press [Mode] until [charge test] come up. Leave it, it’ll stop blinking, and start working. Walk away, it’ll be done tomorrow.
It has to charge them up, then discharge-the part where you get the capacity-then charge back up. When finished you can hit [display] and it’ll cycle through the settings/results. You can hit [display] at any time to see what it is doing.
Ok great and thanks for the assist.
you can purchase a XTAR Dragon VP4 Plus from ebay with Paypal
First capacity test should have finished. How did things go?
Test went great… Really like the Opus. Though batteries were fake and I have requested refund so now just waiting for return instructions. I do not plan to buy anymore Eneloop I have read about fakes being found by purchasers even on Amazon from reviews. I think there is so many fake ones that even buyers are getting scammed as some of them are getting to really look like the regular packages… I’ll buy the Amazon or Lada batteries they are rebadged Eneloop’s.
Batteries were from 1878-1898 for all of them… they were suppose to be 2500mAh.
Don’t recommend the 2450 unless you really need the extra mAh. They don’t hold up in the long run as well as the 2000.
I have both and the internal resistance on the 2450 goes up significantly faster than the 2000. More is not always better. They are fine cells, just not as long lived.
The Amazon Basics ‘can’ be re-branded Eneloops, they can also be Chinese instead of Japanese. That’s not necessarily a reliable source anymore.
These guys are reliable, but expensive: https://www.thomasdistributing.com/Panasonic-Eneloop-Batteries_c_1207.html
Your Eneloop Pros were obvious fakes. You didn’t need an analyzing charger.
How else would he verify that they were fake?
In this case you would have to be familiar with the packaging of Eneloops.
1st - they are 2450, not 2500.
2nd - the packaging is obviously not Eneloop….but, you would have to know that.
3rd - [ I paid $24 for 12 batteries] That statement alone is proof for me, but again, you would have to know that.
Several people have jumped into the ‘fake’ thread with good suggestions.