Hobby Charger Behavior - Is this normal?

[ptolemy]

I started charging my 26650 cell, which is a 4000mah. I charged it at 3amps and first time I wanted it carefully.

It reached 4.20 quite fast, maybe 20 minutes but then spend good 40 minutes dropping charge from 3a to .1a and after that it beep that cell was full.

Just charged rcr123 at .8a, it filled up in 20 minutes or so, but then spent 40 minutes dropping charge to .1 before it dinged...

Is this the usual behavior? If so, what is the purpose behind it and anyway to expedite it?

Thanks

p.s I am using thunder ac6 charger

 

[Hack On Wheels]

I started charging my 26650 cell, which is a 4000mah. I charged it at 3amps and first time I wanted it carefully.

It reached 4.20 quite fast, maybe 20 minutes but then spend good 40 minutes dropping charge from 3a to .1a and after that it beep that cell was full.

Just charged rcr123 at .8a, it filled up in 20 minutes or so, but then spent 40 minutes dropping charge to .1 before it dinged...

Is this the usual behavior? If so, what is the purpose behind it and anyway to expedite it?

Thanks

p.s I am using thunder ac6 charger

I believe the purpose of the slow final portion of the charger is to top the cells up to full capacity in a gentle manner, so as to retain a longer service life for the batteries. You should be fine to pull the cells off the charger before this final phase is complete, but you might be short 10% of the full capacity.

Anyway, I'm just regurgitating what I've read, so I'm sure others will chime in soon.

 

[ptolemy]

I believe the purpose of the slow final portion of the charger is to top the cells up to full capacity in a gentle manner, so as to retain a longer service life for the batteries. You should be fine to pull the cells off the charger before this final phase is complete, but you might be short 10% of the full capacity.

Anyway, I'm just regurgitating what I've read, so I'm sure others will chime in soon.

I assumed the same, but then question is: why would charge show 4.20 for 40 minutes...wouldn't it be prodent to slow down after 4.1 and slowly top it off to 4.2

i am just speculating and hoping experts will chime in

 

[kramer5150]

I have a similar charger and it does same thing. I think its the charger switching from CC to CV charge profiles. The latter profile (CV) has the charge voltage fixed at 4.2, while applying a slowly depreciating current into the cell. It charges a long time during the CV profile because the current drops off. Mine drops all the way down to .2A. My (perhaps incorrect) understanding is that this is a much more effective way to top off the cell. Rather than merely terminating the charge when the cell reaches 4.2V. I have never heard / read a detailed explanation on this however.

 

[Mr Happy]

Yes, this is the usual behavior. It is the CC/CV charging profile at work. A detailed description of CC/CV charging of lithium ion cells can be found in many places all over the web and in this forum.

The only puzzle is that 1 hour seems a little too fast. It would normally be expected to take about 2.5 hours or more to complete the charging cycle...

 

[45/70]

Yes, this is the usual behavior. It is the CC/CV charging profile at work. A detailed description of CC/CV charging of lithium ion cells can be found in many places all over the web and in this forum.

Yes, it helps quite a bit actually, to know how to charge Li-Ion cells, (from Battery University) if you plan on using them.

Dave

 

[T0RN4D0]

Its normal. You can't (shouldn't) use higher voltage than specified charging you li-ions (4.2). The problem is, that cells won't take in a 3 amp current any more when voltage of the charger and the cell get too close to a certain range. So when the cell is nearing full charge (and 4.2V), the current is going towards 0.

 

[Meterman]

Maybe this graph helps to catch CC/CV charging more easily?

Wulf

 

[Hack On Wheels]

Yes, this is the usual behavior. It is the CC/CV charging profile at work. A detailed description of CC/CV charging of lithium ion cells can be found in many places all over the web and in this forum.

The only puzzle is that 1 hour seems a little too fast. It would normally be expected to take about 2.5 hours or more to complete the charging cycle...

I'm assume he was just topping up these cells, otherwise it certainly does seem a little fast!

 

[Vikas Sontakke]

AC6 can NOT go below 0.1A for charging. I am little bit surprised that both 4000mAh and 800mAh cell required 40 minutes at 0.1 at CV stage. I wonder if AC6 has timer operated CV stage and that would be bad.

AC6 default timeout is 120 minutes.

- Vikas

 

[ptolemy]

AC6 can NOT go below 0.1A for charging. I am little bit surprised that both 4000mAh and 800mAh cell required 40 minutes at 0.1 at CV stage. I wonder if AC6 has timer operated CV stage and that would be bad.

AC6 default timeout is 120 minutes.

- Vikas

i didn't mean it went .1 for 40 minutes but it ended at that