Yes, as the charger’s reaches 4.20v, the “constant current” phase ends, switches to “constant voltage”, the voltage remains at 4.20v, while the chargers current slowly tapers down to 10% of the chosen charging rate, then terminates at that percentage.
A good charger with a good cell will do that all the time.
Ok thank you for clearing that up for me. Still kinda a newbie with this stuff.
I just ran down my cells and checked the volts of each cell same slot on the Miboxer and they are all at 3.66V. I tested all 4 slots.
Ok forget the ohms and crap. I don’t understand why when I set the amps charge rate manually, the 42% drops down to 8%. This happen to anyone else?
I’m sure you actual batteries are about 30 to 50 milli ohms, but we are just not getting a good measurement. The 30Q is very well regarded as a top notch cell. So 999 or 600 means nothing if it’s not accurate.
I don’t know of you can measure internal resistance of a battery using a DMM simply because I’ve never tried. Maybe it’s possible? I’m sure somebody has tried.
Anyway, if you want to a decent but cheap DMM I would get a VC97+ model which are pretty popular online. I’ve got two of them and they both work really well. Here’s one for $22. It’s got an internal buzzer, auto shut off and a zippered case. All important features.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F123054326491
I mainly use mine for checking voltages and continuity. I have a clamp meter for measuring amp draws.
When your liion cells get down to 3.6v you’ve pretty much used up 80–85 of the power. That’s a good time to charge them. They can safely go down to 2.7v or 2.8v. I think anything below 2.5v will cause them damage.
I’m not sure I understand what you’re describing.
So if you put a battery in at 3.66 volts and let it automatically set the charge rate it will show its at 42%?
And then if you manually change the charge rate to something higher like 1.5 or 2 Amp then the percentage will drop from 42% to 8%?
From what I can remember, if I put a battery in that was at 3.66 volts the percentage number would be quite low like 10% or 15%.
I would not pay too much attention to that percentage read out. They designed it to be helpful, but there is no way it can actually be accurate.
Yes that’s what I’m saying pretty much. Thank you. Thank you all. So just pay attention to the voltage?
Mainly, yeah. Most chargers don’t even tell you the voltage.
If your doing 2 or 4 cells from the same light you want to notice that they all have very close voltage coming out of the light and that their charge capacity in mah is pretty close when they are finished charging. Like 2401mah, 2379mah, 2413mah, 2393mah. Something like that.
These newer, fancier battery chargers are definitely more complicated which means there’s more info that can confuse you. Lol
My old chargers were Xtar SV2. It could do 2 x 2A and had a very simple screen. Some people buy chargers that don’t even have a screen, just a couple of leds to show charge rate, etc…
The C4-12 is pretty fancy, but there are even fancier ones with Bluetooth connectivity, etc…
You just have to learn and get used to it.
Do you know anybody that can solder? If you don’t trust the button tops, then you can do like was mentioned before and carefully remove the outer layer of shrink wrap and take the button top off and then add a solder blob to raise it up. This will definitely give you a good connection with no extra resistance. I’ve got a couple batteries that I need to solder blob, so I was thinking about making a video to show how to do it. It’s not hard to do.
Lol yeah I was SOOOOO confused and really Bluetooth? Do I even want to know what the Bluetooth is used for?
Thanks for the mah put into the cell info (all info really).
My cells just got done charging a little bit ago. Changed from that lower percent to 100% when finished and I seen the mah numbers were pretty close.
I do know someone that solders but he is down in Texas with you. David.
BUT I for sure would like to see how it’s done. I learn better by seeing and doing anything. Like fishing, biking etc…. you get the point I think. About my learning.
Here is a 3 minute video showing me loading some cells into my charger. Yawn. 
Note- about the only thing the percentage readout is good for is to give you a rough idea when they will be finished charging. Especially near the end when the voltage stays at 4.2v. It also let’s you know it’s still working.
Ps, I guess I remembered wrong about my 3.6v being around 10% or 15. 3.65v looks about 30. It might have been 3.55v being about 20% or so. It’s no big deal, though.
I already watched it lol. I could tell you were tired. Other than the ohm being crazy high,the charger does charge them i think. Don’t have a DMM but all my chargers say 4.2V. I didn’t see any change in the % until they were pretty much done charging
Here they are finished charging.
Sometimes it’s a good idea not to start measuring stuff. Next thing you know you’ll be buying a clamp meter, a lux meter, a hot air soldering station and maybe building a pvc lumen tube. (This describes me, btw. I’ve also got a BLF integrating sphere on the way. Yi, yi, yi. :person_facepalming: ) I got sucked into the hobby. If I start assembling and flashing my own drivers… Man, I don’t want to think about it. Lol
This is the part that sounds strange. It should start to slowly count up to 100% from the time you put the cell in the charger. (I wish I knew how to do a time lapse video)
So your charger starts out at say 32, then doesn’t count up? It will just suddenly jump to 100 once it’s almost fully charged?
That would be some bizarre behavior.
Only with the 30Q button tops. Exactly what you said. I pull the cell out of the slot then put it right back in and the auto thing says it went up to let’s say 85% from 2%.
I fell asleep last night watching them charge for a little bit and the percentage I didn’t notice change until it reached 100% for the 30Qs
This does not happen on my charger. You can tell in the video. So this is a 3rd strange thing your charger does after reading the IR way too high (on certain cells) and not showing the percentage slowly increase. I wonder if your charger has a software glitch or something?
It only really does that that I’ve noticed with the 30Q button top cells.
Ok this is creepy. My message to you about the 88% to 50% when I do manual it’s not doing it anymore. Maybe I need to drain the cells more.
This is my Miboxer charger. Short video of how it’s been working. It don’t seem right. Been doing this with most cells lately. Gets the cells charged but it worries me now. Anyone else have this problem?
Something doesn’t look right. The drop in % of charge when you select a different charging rate in particular seems odd. Maybe it’s all a result of the very high IR that it is detecting on this cell, I’m not sure. My C4-12 doesn’t do that, but it does not show such high IR on this cell either.
Take a similar video with different cells (just to eliminate a potential cell issue) and send it to Leo @ Miboxer.