MegaCell Charger Consistency/Accuracy Testing vs Opus BT-C3100 & Thoughts

After using the MegaCell charger for about a month now, here are my thoughts and a very detailed consistency test in comparison to the Opus BT-C3100.
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[@RonMDavis]

Couple things I like your testing approach I think I’m gonna do the same thing using my LiitoKala chargers..... Definitely explains the chip controlled variances I was seeing also. I think you have some valid points in your review of the software and especially the cell holders the newest versions already been adjusted for the latter. I think the perspective that you’re missing here is there’s no other charger in the marketplace that even compares to the automation data and reporting functionality and feature set that this is providing at this price point.... in the end your video gives me hope that It will work for me.....having never use the opus and seeing the wide variances I was seeing from My LiitoKala numbers had me alarmed. Now I have a somewhat scientific way to evaluate that . Thanks for doing the tests, I know how time consuming it is.

[@healeydave]

I'm not an advocate for Megacellcharger, I don't even have one yet but I think an important point to make is the Megacellcharger is technically still in Beta and can be improved upon through updates! I'm not that impressed with any of the hardware charger / testers, they do a reasonable job for the price point and that's about it AFAI concerned. I do hope the Megacellcharger evolves into the preferred product for mass cell testing workflows with its data capture capabilities which is why I am one of the backers.

[@LithiumSolar]

I do agree completely about being in Beta, however, they are now mass-producing them and I'd expect a more refined product at that stage.

[@healeydave]

I'm not an advocate for Megacellcharger, I don't even have one yet but I think an important point to make is the Megacellcharger is technically still in Beta and can be improved upon through updates! I'm not that impressed with any of the hardware charger / testers, they do a reasonable job for the price point.

[@LithiumSolar]

I agree on all points, it is in beta, not overly impressed, but does a good job. However, some of these points could and should have been addressed prior to starting a mass funding campaign and collecting $70,000. Just my opinion...

[@pleasecho2]

FYI It's good practice to charge and discharge all cells in testing at not more than 500ma. Also a lower indicated capacity by the Opus *can* mean that the cell is capable of a higher discharge rate like in power tool cells, If they charge properly and have the proper internal resistance test those cells at the higher rates before chucking them

[@DavidPozEnergy]

LOL, at about 2 minutes in you just skip over the fact that you built a software page. Wow! You built something to see the cells. That's crazy.

[@LithiumSolar]

Yeah the stock software is junk... I complain about it more later on ;)

[@jontscott]

@@LithiumSolar I would love to hear more about your software. Maybe even see the code if you want to share it?

[@BartCerneels]

Open source the code. I'm sure there are people that will contribute. I'm one of them.

[@christopherstaples6758]

@@LithiumSolar can you please share code on github , I only use Linux and all their software is for Windows ... has anyone else thought about integrating a data logger onto the board ? if mine ever arrives it will be the first modification I will make

[@BILLYKRYSTAL]

@@LithiumSolar please supply the api. Dont need the code but would love to know what to post and get to set up my own site for my android device.

[@ahaveland]

That was a good and interesting analysis! I have some similar sockets with snagging issues, so I bend the tip of the metal strip like the front of a ski to avoid snagging. Always best to insert positive end first, extract positive last to avoid shorts.

[@messor01]

It's a bit difficult to handle! First: The display is small, you can't see anything on it. Second: It requires a computer, so it's an extra cost! Third: According to the test, you have to set the bays one by one! (This is very time-consuming!) Fourth: I also need a printer so that I can later search for the cells from which I want to build a pack! Fifth: It also needs a barcode reader! (Costs keep increasing!!!) Sixth: If I were to sell something, I would have at least made a transparent polycarbonate or plexiglass cover for it. Seventh: Unfortunately, as far as I can see, it still only has a beta version! In summary: You have to buy so many accessories for it to work that my costs will cost at least 1000 dollars if you also buy the accessories I described! And the worst thing is that since I have little space, the many accessories take up a lot of space in the basement, where I have to leave the computer too!!! So it's all very fiddly and expensive!!!

[@pianojacq]

I would recommend pulling the negative out first if you are concerned about damage to the shrink wrap, also to fold over the tabs on the plus (or shorten them a bit).

[@LithiumSolar]

It grabs the heat shrink on both the positive and negative. I've tried to bed the tips of the contacts a bit. They don't bend well... (at least I haven't been able to in a way that works).

[@pianojacq]

@@LithiumSolar Hm, so that means that even if you lift the negative out first there is still a chance that it will rip the positive. Worst case it will short out and weld the tab across + and -, you don't want to be around when it does that! This is a pretty serious design flaw, and if they don't fix it that would count as a serious strike against this charger, testing is supposed to be a non-destructive affair. In that case I would recommend using a dremel with a small cut-off wheel to cut about 4 mm off from the end of the tabs, and then to round it off and grind it smooth again (no burrs). Push in on the cell then lift the top, then pull the cell forward rather than outward to avoid snagging on the minus tab. I'm halfway tempted to design my own charger by now, this is worth doing properly, I think this is a great idea but the execution is lacking. Also, it'd be nice to have a more modular setup, with a single HTTP capable endpoint and say i2c or CAN to talk to the cell modules. Then you could for instance add cell modules in batches of 8 to whatever capacity you'd want. Excellent job on the testing by the way, nice to see you go through this so methodical. Temp compensation probably wasn't a huge factor but good to mention it, the bigger problem with these cheap battery holders is the varying resistance of the contacts from one slot to the next.

[@BartCerneels]

I'm assuming the "chip controller charging" end is at 10% of charge current cut-off. This is the standard and only correct way of charge termination for a full charge. For capacity testing only a full charge makes sense. The variance you are seeing is the actual cell variance, not an inconsistency of the megacellcharger. You don't have a stable temperature environment and these are old cells, so the chemistry will behave different from one charge to the next. If you have the chance, do the test again with both Opus and MCC in the same, stable temperature environment, letting the cells cool between every charge. I predict variance will be less, but still not as consistant as you are expecting.

[@LithiumSolar]

So when the Opus stops and they are resting at 4.18-4.20V, you're saying it's actually over charging the cells? I guess what I would expect here is consistency though, not having some cells resting at 4.05V and others resting at 4.20V minutes after the tests completed. I will try to run a few more tests in a temperature-controlled environment.

[@Lagittaja]

@@LithiumSolar No it's not overcharging them. At least not the V2.1 that lygte-info tested. Sure it might overshoot the voltage slightly during the charge because it measures voltage when the current is off but the Opus does terminate around the 10% mark (~110-120mA termination on the PA18650-31 cells #1-4 charging at 1A, I'm not going to bother checking the other results). If some cells rest at 4.05V after charge then there's just something dumb happening like the chip skipping the CV stage or terminating the CV stage way too early for whatever reason. Also, the TC4056A is specified to have a float voltage of 4.2V +-1.5% or 4.16V min 4.26V max. Perhaps what you're witnessing is part of that inherent variance? Each chip being a different snowflake. Add to that the different internal resistances of every cell being slightly different altering what the CC/CV shape looks like i.e. that could also be a factor making a chip behave differently on different cells. But for whatever it's worth, for capacity testing I would rather have software control.

[@kennethalmond8922]

Made me feel better about my OPUS(s) :)

[@LithiumSolar]

I love my Opuses! They need some repair though.

[@pianojacq]

@@LithiumSolar What typically breaks?

[@Boz1211111]

huge variance on last test is because chip controlled charging charges to 4.2 not 4.24 probably, and removing first test from your calculations because cells in first test were charget at 4.24 would let us compare how consistent it is. either ways, why charge at 4.24 if rated is 4.2? that would give higher capacity readings than they actually are, same as my opus is giving 5-6% higher readings than previous method, in which i charged cells at 4.2, because opus charges untill ocv gets to 4.2

[@LithiumSolar]

Because it doesn't do a proper CC-CV charge, so going to 4.20V actually charges it to 4.10V or so when it stops.

[@cdkr0]

Hello... this charger - tester from what I have seen is very old, if mention is made of the most recent version 2.2 but it is still many years old. Is there any other more modern and better charger - tester?

[@dtvking]

Some nice, to the point testing. I don't think its too bad for the price if set up correctly. Good one, thanks

[@LithiumSolar]

Thanks! It's not bad at all, but does require a lot of effort to get running correctly.

[@BILLYKRYSTAL]

@@LithiumSolar Can you share your server side code for your mobile webpage. I havent recived mine yet but I ordered one from battery hookup. Please also share your data you obtained on the api.

[@HBPowerwall]

I think i want a megacharger even tho it still has minor issues.

[@LithiumSolar]

They sure work well after configured properly ;)

[@RodneySolarCircuits]

???? about the watchman4. What does the expansion board do? Do I need it for a 14s system just like yours.

[@LithiumSolar]

The expansion board just adds a lot of inputs/outputs. You do not need an expansion board unless you want all of the extra relays.

[@gmwtr]

I do have a simple question: What are you doing with all those cells below around 2300 mAh you don´t want to use?

[@LithiumSolar]

Most of them got recycled.

[@dillonmccormick2511]

Any recommendations on dealing with opus pausing capacity test due to over heating? I have two and they both do the same thing. Did you modify your fans?

[@LithiumSolar]

I haven't noticed that behavior on mine. I have not modified mine other than replacing the fans when they fail. I assume you checked to see that yours are spinning? The only other thing I'm doing is I have them propped up about 1.5 inches or so to help airflow from below.

[@98909890steve]

It's true that opus shows 10% more capacity then the rated capacity on the 18650. Whereas the littokala charger shows 10%less capacity than the opus

[@LithiumSolar]

Do you have any proof of this? Have you checked to see if the Littokala is actually charging to 4.20V?

[@98909890steve]

@@LithiumSolar I charge my 18650 on littokala and then transfer those batteries on opus for discharge test. The opus shows voltage at that time 4.21v and discharge starts the moment I insert the 18650.that means the littokala charges till 4.21v. Also I have noticed like if the 18650 has printed capacity of 2600mah but the discharge test on opus shows 2800 and sometimes above. And the same in littokala shows 2650mah or above.

[@MaxGoddur]

I like your video and have a request and a question. Can you please how to use the tester in the same fashion as the littokala as in without connecting it to a computer and wifi? Second, would you be so kind as to please make a video on how to use the charger stand alone without using the clunky SW?

[@SS-pi2yi]

I would like to get your opinion on this; >>>> Is it safe to have / store lithium ion18650 cells randomly thrown in a bucket as seen in the beginning of your video? thx for the video.

[@LithiumSolar]

No. Don't store batteries that way.

[@kmuralikrishna1582]

So finally, are you recommending the megacell charger to get cell accurate internal capacity...? Is it good or bad .?

[@LithiumSolar]

Unless you want/need the wifi connectivity and queryable endpoints... The Opus will run around the same price, if not cheaper, and does the exact same thing as this. I would probably recommend most people go that route until some of these issues have been ironed out.

[@sandfox7775]

i would also like to get a couple of these mega chargers, but waiting 5 months for it? no thanx then. ill build my own charging stations and use a good spreadsheet as a database.

[@frankripley5188]

Your knowledge on this is almost intimidating.

[@mocmaniac1571]

Just saw your video, I have the same battery holders and same problem with the tab catching the shrink. To avoid that I always pull on the negative side first. This way I can't short the battery if it removes the shrink. For the fans, you can try noctua. Really silent and they have a 6 year manufacturer warranty. Go checkout amazon for that. BTW, great video!

[@user-dk1cv2zu3t]

hi Is the 16-cell big charger an OPUS serum specification or a regular charger, please, please, the buying link, thanks

[@ahmedfarouk1571]

I want to get a piece of Mega Cell, how much does it cost?

[@lnxpro]

I found it easier to use my thumb and remove the cells from the negative end and none will catch under the metal contacts of those holders. other than that, love the charger, waiting on a dymo labeler so I can print the labels as opposed to using a sharpie and writing on each cell.

[@LithiumSolar]

I don't understand the point of the dymo printer. Thermal labels have an average lifespan of 6-9 months. If I'm going to label my cells, I want to be able to pull it out in 5 years and read it. I've never heard of a thermal label that lasts many years...

[@hacklordsniperdotcom]

@@LithiumSolar I printed about 600 labels with my Dymo thermal label printer. They are still fine 7 years later, exposed to sunshine

[@kna60]

To begin with, this device is based on crappy chinese clone of the TP4056 chip, which was designed to charge at low cost cells in consumer gadgets, not to provide a trusty platform for acurate capacity measurements. These clones are simply unable to do a proper constant current / contant voltage charge cycle without pushing the 4.20v standard end voltage up to 4.25v to get a fully charged cell. This exceeds the maximum voltage recommended by the cell manufacturers. This is exactly what happens in chip controlled charge mode, where the voltage reaches 4.25 / 4.26v, while the firmware and the program intentionally lie to you by never displaying numbers or curves above 4.20v, so as not to scare you and hide the nasty trick. This mode was implemented to provide capacity values similar to Opuses, even if they are known to give too high values. (I've four Opus, which overestimate the capacities by 2 to 7%). With MCC, compared to a trusty reference, capacities will also varies according to different Li-Ion chemistries, different internal resistances, different wear levels, in non-negligible proportions according to your requirements. Reported temperatures and internal resistances values are also simply way off, so unusable. If you want trusty comparison, you should compare to a high-end charger-analyzer like SKYRC MC3000, not any (relatively) low-cost device. In conslusion, not to tell myself that I have totally wasted my money by buying a MCC, I only use it to pre-test (maybe good or to be recycled) or cycle and stabilize my cells before measuring their capacity with my Opuses, calibrated with my MC3000. If you want to feed a database with fancy numbers and graphs, MCC is probably made for you. If you want a technically and ethically respectable device, look elsewhere. That's just my opinion. Forge your own guys, with rigorous testing, hundreds of various cells and dozens of hours, some reference and stable brand new cells, a good multimeter, and a good reference charger.

[@LithiumSolar]

GREAT feedback, thank you! You mentioned you use yours to pre-test before running them through the Opus. Considering I run mine differently than other people, do you think the software-controlled charging to 4.24V is still worthwhile in comparison to the Opus? Honestly, the main reason I started looking at it is I'm getting tired of repairing my Opus and while I've heard a lot of people recommend the MC3000, I would need minimum 10 chargers to keep up and it gets expensive fast. You get what you pay for though I guess...

[@DavidPozEnergy]

Awesome kna60. Thank you for such a great explanation as to why these mega cell chargers perform like they do.

[@kna60]

You're welcome. I use my MCC with fixed max voltage @ 4.24v, not "chip controled" whicht gives inflated capacities. After all the tests I've done (I was beta tester), with current firmware 4.28, it's the closest on average to the measurements made by an MC3000. I use MCC to pretest with one run in "mcap" mode: charge to 4.24v @ 1A, discharge to 3v @ 1A, recharge to to 4.24v @ 1A. Cap

[@scottf4277]

Do you think some of the issues you identified can be rectified with code revisions by its creator

[@LithiumSolar]

Yes. In my opinion, software-controlled charging should be defaulted. To what end voltage - I'm not sure. Someone more experienced than I would need to determine that.

[@kna60]

For more than a year they have sold hundreds of flawed boards because of the choice and implementation of some components. They have released many software and firmware revisions to try to correct those flaws. As it is impossible to correct all the defects, they have chosen to try to hide the main one which is that this device is unable to perform a correct constant current/constant voltage charge, in order to obtain correct capacity values, while respecting the cells manufacturers' recommendations. The program and the firmware therefore rig some voltage values by lying to the user. You can't polish a turd. Without fundamental changes, it is impossible to change a donkey into a racehorse.

[@GEORGE-jf2vz]

The battery holder is always the crappy part of a battery charger. You would think they could make one that works without getting caught on the end. The spring load ones seem to work the best but come on, they can design a better one.

[@ChVovan]

Perfect job!

[@toybotgaming9634]

I have not checked your other videos yet but shouldn't this test be done with new cells? Aren't the random grade of cells just making things skewed and random? Thanks for the test non the less and putting a fire under Alex's feet :)

[@LithiumSolar]

No. The board was specifically designed to test used recycled cells. Also, I did multiple tests with the same cells in the same slots, then switched chargers to ensure consistency.

[@toybotgaming9634]

@@LithiumSolar I understand it's suppose to be for testing/charging used cells :) However, if you want to test how well the charger/tester itself works, why use cells of unknown use/origin for testing purposes? It seems like alot of the batteries were just being completely inconsistent regardless of charger. Just my .02c. I would like to get your advice on a Power Wall Project I got going. Could ya email me at [e-mail] or let me know the best way to reach ya :)

[@BILLYKRYSTAL]

@@toybotgaming9634 the fact that all the cells are used means he is getting the most accurate results because the cells are not spitting out the same mah numbers. New cells would give the same/simular capacity for every cell. You want to test used cells cause the mah is going to be different on every cell. This gives you the most accurate info possible.

[@IAmZen_007]

When your battery are charged, what do you with them?

[@LithiumSolar]

I leave them sit for several weeks, then recheck the voltage and discard those that are self-discharging.

[@IAmZen_007]

LithiumSolar Sorry, I should have asked my question differently. If the batteries are in good condition, for what purposes are you going to use them?

[@LithiumSolar]

Oh sorry, after testing is complete they're being used for off-grid solar storage.

[@jean-clauded5823]

Some people build power walls to shift electric usage to lower time of use rates, and some build electric cars or skateboards. Still others use them to save power from solar systems, or build UPS systems to back up computers or in some cases, the entire house.

[@IAmZen_007]

@@jean-clauded5823 I don’t think you do this in my country. It must 100% separated from the standard electric installation

[@johnmirbach2338]

😁✌🖖👌👍😎