MiBoxer C2-4000 Smart Charger Review

Great review EveryDaySurvivalGear.

Ditto most of the comments as well. The fan’s noise startled me at first until I realized it was only during the optional drain cycle which I seldom use so it doesn’t really disturb me.

The taper charge at the end does take a while but when I’m in a hurry I just pull off the cells at 98% to save time, but mostly I just drop cells in and forget.

The wallwart’s large but I think it’s helpful in transferring some of the heat away from the body of the charger itself.

I am really liking my C2-4000 and even prefer it over my 4-slot Nitecore.

What cells? Are they older cells? Older cells always take longer to terminate.

I should say cells that have aged bad my LG HG2 are not that old but have been driven hard there whole life and take longer to charge then my other cells.

A termination current of under 100ma is good for a 18650 some where around 30-50ma termination is what you are aiming for.

Mine are brand new ncr18650 b and ga protected. I think the protection circuit is tricking the charger .

I’ve found that my C-2 4000 charges all button top batteries at a very low rate when on auto. Probably because it also reads all button tops as having high internal resistance—even new batteries. I’m assuming it’s because—unlike flat tops—the button tops only make contact with one of the little dimples on the C-2’s positive post. That’s my theory anyway.

Even if I manually step the charge rate up , at the end it goes into a very low rate .

Be thankful if it ends at a “very low rate “ , probably at 10% of the charging rate, for it means it’s doing what a proper cc/cv procedure charger should do.

Once the charger shows 4.20v, (the cc stage), the cv stage takes over, the 4.20v stays, but the current tapers down to 10% of the rate used in the cv until its terminated, then displays “full”.

Yes, termination current of 50ma is good , but I think, that
termination current 5-10ma is crasy,
it’s simply additional 30mins for <0.5% capacity.

I did a little experimenting last night with a new ncr18650ga . I first put it in slot 1. It first read very high resistance so I put it in slot 2 and the resistance went down to 110mohm,92,4.2v,.56amp. I tried it back in slot 1. The resistance read 124 mohm,95,4.2v and .09 amp. It took over 2 hours to complete charging. Does that seem like a long time or is that normal?

Are you saying it took 2 hours with the battery having 95% capacity and started charging at .09 amps in slot one?

Yes . Seems long,right? Always get high resistance readings /low auto charge currents. Re inserting them helps reduce resistance reading usually.I think I have to override the auto select feature to get shorter times. I wish I had some unprotected cells to test.

Very long. Battery is practically charged anyway. Just use it as is all you will gain is a few mah anyway.
How long does it take if the battery is fully depleted?

When they came from Liion Wholesale, they read about 3v. Can’t remember for sure , but they took about 8 hours.

Sounds like the charger is trying to squeeze every last electron it can in to the cell.
“Table 2: Typical charge characteristics of lithium-ion. Adding full saturation at the set voltage boosts the capacity by about 10 percent but adds stress due to high voltage.”
Might be better for the cell if it was pulled a little earlier in the CV stage.

Thanks for the tip.

Maybe the charging screen is lazy? I guess this could be resistor feedback of some sort?

It happen on my Liitokala engineer 500 it will say like 99% or 4.20v for ages and if i nudge the cell it will complete the cycle?

When i nudge it i wake it up :stuck_out_tongue:

I agree that the end cycle is to slow on your charger mate. What is causing i am not sure it has to be a feedback problem or a wrong equation with the computer. Unless the charger is trickle feeding the cells to keep them full and that is not completing the cycle?

Pulling the cell at anything under 100 ma charging in the CV stage, I would consider good to go.

If I manually select 1amp , it starts reducing at 88% to .67 amp. Does that seem too early to step down? That also is causing long charge times.

Once the battery hits the 4.2v it will switch to CV stage and it should hold 4.2v, while the current is decreasing to hold 4.2v.
1 amp charge and switching to CV stage around 85% seems normal to me.
1 amp at 3.5 hrs is 3500mah. I would expect about 4 hrs they should be ready to pull.
Charging a ncr18650ga at 1.5 amps would reduce the time to around 2.5 hrs or slightly more.
I would still pull them around 100 ma of charging current.

I will do that. Thanks for your help.

EverydaySurvivalGear,

Does the discharging/charging to check capacity only works with Li-ion? How do you access that feature?