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Dodgy: Megacell Charger - 16 cell 18650 tester

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I try to help where I can and I like to support promising projects.  I like it when people innovate and create new products. I've supported probably 15 projects in the past 6 years related to battery technology, motor controllers and motors. I'm an avid EV builder with an EE degree. Some of these projects work out well and others are bomb shells. The Megacell Charger/Monitor looks promising and innovative so I got on board to see for myself. Unfortunately this project is a bombshell and needs serious improvements to make it worth having! The short answer is: Do NOT get one!

This is the youtube channel (The Cell Doctor) for this project:

I tried to buy one probably a year ago when I found a video about them on youtube. I have to honestly say that I'm glad that this didn't happen! A year ago, this project was so premature that it was mostly useless. I was able to pay for one in November 10, 2020 and it arrived January 20, 2021...almost 4 months wait!!! I used the cell tester for a little while and decided to buy another one. I have since requested a refund.

I thought I'd post my results and experiences with this cell tester after near continuous use since I got it...
1. This is an Indiegogo project. It is common that crowd funded projects are "works in progress" and what you get may be far from a complete product.

2. The Megacell Charger is definitely a "work in progress" and far from reliable and trustable.

3. The charger has 2 button on it. They are oddly placed and they are the entire input method for accessing the functions of the charger directly.

4. The "Reset" button is highly problematic! It's location is such that it is easy to press and that stops all testing as the charger reboots. Any test results are lost! I pulled out the plastic riser and shortened it so it can't get pressed accidentally. I've reset the charger by accident far too many times! GRRR! What's more, you need this button to get to lots of functions in the charger.

5. The other button is labeled "Function" this button scrolls through all the cells one at a time and it also is how you access the menu of options. Honestly, these things need at least 2 more buttons. The interface is simply too hard to navigate with it's current 2 buttons.

6. The battery tester has fixed size cell holders that fit 18650 cells only. It can't be used as a universal charger/tester for other LION cell sizes.

7. The charge control IC's can support LIFE cells and yet the charger does not have this capability. It could also support LIPO and HV LIPO and does not.

8. The cell holders are very poor at holding cells. It is common that cells fail testing because of the cell holders NOT securely holding cells in place. The springs are too weak and the cell holder design is cheap.

9. Good cells fail for no reason. I have 16 brand new Panasonic cells. I filled the charger with them and set it to do a 2 cycle capacity test on all 16 cells. It failed all of them with a status of "BAD"! This is simply preposterous and highly improbable! Failing 10-20% of cells tested is pretty common, but 100%...well that's a serious issue with the charger! To date, ALL cells that this charger has failed, test good every where else. Rerun the same test and those same new Panasonic cells all tested as good with varying capacities. WTF?!

10. Initial set up is painful at best. It communicates with your phone or PC via WIFI instead of bluetooth. This means you need to get it authenticated with your WIFI router before you can access it with the software. The steps are not particularly obvious if you are not familiar with ad-hoc WIFI. I'd toss out the WIFI functionality and use bluetooth instead! Data rates are not high enough that bandwidth matters.

11. The phone apps are garbage and mostly NOT usable. The latest Android app crashes more than it runs.

12. The windows app is pretty clunky and NOT user friendly. Non-intuitive is the word I would use. I test complex software that configures and manages routers, firewalls, cable modems and other networking hardware for a cable company. Of the existing apps for this charger it is probably the "best" of them and it's not great.

13. There is a browser interface, but it's buggy, incomplete and lacking functionality. Honestly, I'd dump all the other apps for the charger and develop the web interface exclusively! It has a tendency to run away with CPU and RAM. Leave it running for 30 minutes and these will start climbing like crazy! YEAH!!! A browser app sucking up all resources!!! WTF?!

14. The windows and phone apps and what happens at the charger are seriously laggy. Select some function to perform, wait like 10-20 seconds and maybe the charger will start doing something. This means you'll probably press the button several times thinking the command never got to the charger. This lagginess has bit me every time I use the windows app. The web interface does not have this issue.

15. Completeness and quality  is lacking. The plastic shell is flimsy and thin and clunky. The screws are too short and strip out easily. The "humps" that cover the fans means you can't stack these things for storage. The screw terminals for power are so deep inside the shell that they are hard to get to for adding fork terminals under them. Unscrew one of the screws too far and you will have to take apart the charger to get it out...GRRR!

16. Inside 12 of the 16 bays are 2 solder pads for a JST connector. Why just 12 and not all 16 bays? These through holes are dead center in the bays. If you put a connector here, you can no longer use the bays for testing cells. Why not have JST connectors already in place in the front face of the charger? Why not use universal cell holders so none of this is needed?!

17. I soldered wires to each contact point for each bay and brought them out the front so I could add my own 21700 and 18650 battery holders. This improved reliability quite a lot and doesn't effect the existing 18650 cell bays at all.

18. In each bay is a small temp sensor. It is dead center in each bay which means the cells rock back and forth on the sensor. Placement is poor and they will get broken off. I covered mine in conformal so this would be less likely and to blunt the sharp edges on the temp sensor.

19. My charger is now 1 month old. Both fans are making groaning sounds since they are sooo cheap! I need to replace BOTH fans after 1 month of use!!!

20. Communications and support from the people that make these chargers is seriously lacking. Ask a question via email or the Indiegogo Contact option and expect to be ignored. IF you get a response back after a week, you are lucky! I've had the vast majority of my communication attempts be 100% ignored! Most of them are to report bugs and issues with the charger and software.

21. I have tested around 300 new and used cells in mine now. You would think the same cell in the same bay would test to close to the same capacity when tested twice. This is rare! I'd call 100mah variance reasonable. One test may result in 2600mah and the next one 2100mah. This sort of test result is simply NOT usable!

22. Same cell in another bay has similar results. Capacity results are speculative at best and not really trust worthy. I've tested the same 16 cells 6 times in a row and each result can be wildy different.

23. Cell Ir is an important detail. I cam measure this on the Megacell Charger, ISDT D2, iCharger 4010 Duo and the XTAR VP4+. However, the results on the Megacell Charger will vary for the same cell so much that this measurement is not reliable.

24. I compare results with an ISDT D2, iCharger 4010 Duo and an XTAR VP4+. They all produce consistent results test after test on the same cell. The Megacell Charger does not. I do this to get consensus or "similarity of test results". I can't trust what the Megacell Charger tells me!

My conclusions:
This cell tester is a great idea, but is unreliable and poorly implemented. It fails good cells far too often. It fails to produce consistent test results for the same cell about 95% of the time. Build quality is poor. The various ways to interface with the charger are clunky and poorly implemented. In good faith, I have to warn people away from buying this thing!

Not really sure why you'd buy this when you can get 7x 4 cell nitecore style chargers for the same price, enough to charge 28 cells at once.
I guess the allure is a PC interface?


--- Quote from: thm_w on February 25, 2021, 10:32:29 pm ---Not really sure why you'd buy this when you can get 7x 4 cell nitecore style chargers for the same price, enough to charge 28 cells at once.
I guess the allure is a PC interface?

--- End quote ---

I think you are referring to a universal charger and they are dime a dozen! I wanted a cell tester. They do a bit more than apply a current to a cell until it gets to 4.1v.

A cell tester...
1. cycles the cell at least twice. That's 2 charge and discharge cycles so that both charge and discharge Ah can be measured.
2. measures the Ir of the cell

Depending on how good the cell is, charge capacity can be much higher than the discharge capacity.
Ir varies widely. This is the Internal Resistance of the cell. You want the lowest Ir possible. Old cells tend to have higher Ir than new cells.

If you know of a Nitecore device that does this for 16 cells, that would be great! I didn't care about having an app persay, it just an aspect of the Megacell Charger so I presented how well it worked.

SkyRC makes a 4 cell universal tester.
XTAR makes the 4 cell  VP4+ tester.
ISDT makes an 8, 16 and 24 cell tester, but they cant hold anything larger than an AA cell...almost pointless!

I have 1400 18650's and 800 21700's to test. I need a lot more test capability than 4 cells at a time!

Yes 4 cell battery testers. Seems simple enough to hook up 4+ units giving you 16cell capacity no?

I paid $20 for Varicore V40, same as above.


--- Quote from: thm_w on February 26, 2021, 12:29:49 am ---Yes 4 cell battery testers. Seems simple enough to hook up 4+ units giving you 16cell capacity no?

I paid $20 for Varicore V40, same as above.

--- End quote ---

I wish these other chargers were as good as the much more expensive SkyRC...and they aren't. It's the only other option besides the Megacell that does logging.
I read through that thread and was already aware of all the chargers mentioned in it.
I've never run across the Varicore v40 and didn't see anywhere to get it in the USA.
By the time you get 4 of any of the better 4 cell chargers, you are well over the price of a single Megacell Charger and still lack all the other cool stuff the Megacell Charger can do. This is why I bought a Megacell Charger. It seemed like the right choice. You can also connect multiples of them together and log/track/control all of them from the same PC app. Its a great concept/idea, just a poor implementation.

With literally thousands of cells to test, I need something that can test a lot of cells and do it rapidly.
Unfortunately, the Megacell Charger is not exactly reliable or trust-able. I trust my XTAR VP4+ far more! This thing seemed like a good idea, but it's not ready for prime time.


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