Chargers - different capacities

Hey everyone,
Long time reader of the site,
Ended up buying my first torch from recommendations on reading the site.
Also enjoyed doing research on different ‘battery analysers’

I have around 300 18650s all branded old laptop batteries…

I ended up buying a multismart 3000 from the UK so this was my first initial tester
This works by discharging from 4.2v and giving the capacity than charging back up.
I also bought a liitokala 500 and opus c3100 from China, which came this week.

I have noticed quite big difference in the grand scheme of things…

And wanted to build an ebike battery and later a powerwall. I would like to use the best possible battery’s I have.

For example the multismart gives me around 200mah less per cell…
And the liitokala and opus are around 100mah different normally the opus gives the higher reading.

For example


Capacity is 2500mah standard on this cell

Opus reads 2606mah
Liitokala reads 2480mah
Multismart reads 2420mah

My understanding was the opus would be the most accurate, but surely this reading cannot be right.
Because this cell is a used cell.

At the moment in time I have a brand new Samsung 30q 3000mah.

I’ve only been getting around 2400-2500 with the littokala and multismart
Going to guage what the opus has to say about the mah.

Any help gents on the ‘accuracy’ of these units

Depends how deep they discharge Some discharge to 3.2V other 2.7V

The difference sounds like them having different discharge cutoffs

Also if the charger reduces discharge current or do a hard cutoff makes a difference

Lii and opus have a hard cutoff, Lii and 2.85V



Think of them as ‘rulers’, not quite accurate but it’ll do for the analogy. As long as you measure the same thing with the same ruler your results will be more comparable. You will generally get mildly different results from different chargers. My opinion, don’t sweat it.
Your multismart measures by charging…not as accurate. OK for Lion, but there are better.

The Opus has known issues with pulse charging, a questionable fan, and a weak power supply. If you upgrade the PS you will get more accurate results. If you upgrade the little fan (there’s a whole thread on it here), OR put the entire unit on a laptop cooling bed (or similar), you will get better results. The Opus CAN charge/discharge at MUCH higher levels IF you change the PS and do the cooling. This can be useful for turning over a lot of cells and for cells that will be used at higher amp draw levels as you sound like you intend. The internal resistance kind of works-useful bit of info. The IR function on the Li-500 is useless.

In general the Li-500 is considered more accurate. But it’s a lower powered unit so can’t use higher discharge rates. It will show you capacity but not help reveal weak cells. FWIW I put mine on a cooling fan when using. Never hurts to keep the electronics cool.

If I were you I’d upgrade the Opus and use that.

Those numbers look very close when you look at them as percentages

All are +/- 5%. Did you do multiple runs and get the same numbers each time? Remember that the equipment that you are using is consumer grade, sourced in China. The Opus is roughly $40 and the Littokala runs around $20. Expecting a greater level of precision between even the same brand of charger is an exercise in futility IMHO. If you have 300 batteries to test and quantify, I suggest that you go spend a good amount of time on HKJ’s website and develop your own testing methodology based on his.

Another interesting website to spend some time on would be DIYPowerWalls the guy who owns this site also says (I have read in the past, can’t point to a particular post) not to get too worked up over exact numbers. Basically: match your cells, but realize that you can spend forever chasing ‘perfect’ and miss out on ‘good enough’.

Factory standard 2 pin European into a adapter,I do have a 4amp laptop charger thought that fits.
The factory charger which came with the opus feels solid compared to the liitokala one.
I will have a look at using that tomorrow

The laptop PS ought to be superior. I’m using a 5A model to power my Opus.

The Li-500 is a lower power unit (2A). I’m using the old Opus charger (3A) for one of my Lii-500 models I got cheaply without PS.

Far as I’m concerned it’s likely none of the PS for these cheap chargers are any too ’wonderful.

Adaptor of my Miboxer C4-12: 12vdc, true 5A, same barrel, works perfectly for my Opus too.

Thanks gents for the warm reception.
Bought a laptop cooler should be coming tomorrow.

I’m working night shifts atm and not at home I will update thread in the morning
Thank you

I don’t know how to add photos

I’m wondering about the Opus power supply adapter issues.

I think Gearbest has both EU-plug and US-plug adapters for their Opus BT-C3100 v2.2.
Any idea, which of the two might be the better one (ie. get the better power adapter, and just use a universal plug adapter to change to the correct country plug)?

For instance, how is this power adapter? (seems to look similar to sutty86’s)

I was cooking 4 cells in my ’3100, and it got nice and toasty. So much so that a relay/thermostat/something physically clicked inside and cut power ’til it cooled off and I restarted it. :smiling_imp:

Lowered the charge/discharge rate and it ran fine.

So, yeah, I take readings with the proverbial grain o’ salt.

Also, the “quick test” (measure the cell’s internal resistance in mΩ), same cell, undisturbed in the holder, can give wildly different readings in quick succession. No idea how accurate/repeatable it’s supposed to be.

I wouldn’t trust any of the Opus PS adapters if you plan on using higher charge and discharge rates, which is one of the main reasons to get an Opus over the Lii-500 or Zanflare C4. Get a better/more reliable/more powerful one. It’s not hard to get a decent 12v/5A switching laptop supply for cheap.

Agree with flydiver, even the newer versions of the Opus pull some nasty 6A spikes out of the wall adapter when fully loaded. Check its review: Charger Opus BT-C3100 V2.1

I would grab the biggest wall adapter on sight for it just to make sure.


Here are my solutions.

Delta fan- 12V/0.12A/1.44W


side view in Opus BT-C3100 W/Delta fan


Dr. Gauss recommendation,still working FLAWLESSLY,the LiteON 12V DC Power Supply AC DC Adapter Transformer 5A 66W

With these 2 editions my Opus is b/w 1% and 3% accuracy to HKJ’s numbers. A few were only several mAh off- 0.009%! :+1:

These threads have ALL the info.

Here was my ORIGINAL SMPS that came w/ the Opus. several others also reported problems with this one. Specifically re setting during transition from discharge to charge phase and also STOPPING for ~ 1 minute while discharging until it could recover.