SkyRC — IFA 2014 — MC3000 charger-analyzer

[panasonicst60]

I use 1.0 Amp for AA and .5 Amp for AAA. Low rates can sometimes cause a missed termination.

I tried .4 for aaa and .66 for aa and it seem to work fine now. I also changed the delta peak to 0. Now the mc3000 terminates the charge roughly at 1.56 volts. Seems good?

 

[hc900]

I use 1.0 Amp for AA and .5 Amp for AAA. Low rates can sometimes cause a missed termination.

Using the low recharging connrents, you risk falling on the recharging timer: try increasing the timer time from the App

 

[hc900]

New to the forum! Hello everyone!

I just got this MC3000 charger in today. I an trying to charge my Eneloop AA/AApro/AAA/AAApro. What's the best setting I should charge them? The last thing I want to do is overcharge them. I tried the standard settings in advance using the preset Eneloop but ONLY modifying the speed of charge to around 0.35-0.5a. I was seeing the voltage climb more then 1.51 and I was a bit worried so I stop it myself.

When I tried in dummy mode all of my eneloop stopped charging at 1.48v. I also tried fully charged, fresh off the charger of the standard oem Panasonic charger and it measures 1.48v give of take a few .01.

From the App you can increase the Voltage parameter over 1.48 Volt.
Better still to have more safety with the Eneloop, bring the parameter -Delta V to 2mV or 4mV

 

[panasonicst60]

From the App you can increase the Voltage parameter over 1.48 Volt.
Better still to have more safety with the Eneloop, bring the parameter -Delta V to 2mV or 4mV

I adjusted the delta v to 0.

 

[NiOOH]

New to the forum! Hello everyone!

I just got this MC3000 charger in today. I an trying to charge my Eneloop AA/AApro/AAA/AAApro. What's the best setting I should charge them? The last thing I want to do is overcharge them. I tried the standard settings in advance using the preset Eneloop but ONLY modifying the speed of charge to around 0.35-0.5a. I was seeing the voltage climb more then 1.51 and I was a bit worried so I stop it myself.

When I tried in dummy mode all of my eneloop stopped charging at 1.48v. I also tried fully charged, fresh off the charger of the standard oem Panasonic charger and it measures 1.48v give of take a few .01.

Do not use such low charging currents, since the charger may not be able to detect the end of charge.
The best thing is to use 0.5 C ( 1 A for standard AA, 0.4 A for standard AAA) with 0 dV termination, backed up by temperature cut off at about 42-45 C and a timer set to 150-160 min. Leave max U at 1.65 V. This is not a reliable termination criterion, and you don't need it as a backup.

 

[panasonicst60]

Do not use such low charging currents, since the charger may not be able to detect the end of charge.
The best thing is to use 0.5 C ( 1 A for standard AA, 0.4 A for standard AAA) with 0 dV termination, backed up by temperature cut off at about 42-45 C and a timer set to 150-160 min. Leave max U at 1.65 V. This is not a reliable termination criterion, and you don't need it as a backup.

I can't respond fast enough as I am new. My replies are getting delayed for a few days. I have been using about 0.7A for AA and .4A with 0 dv and it's been working great.

 

[NiOOH]

0.7 A may be a bit too low for AA, especially for Eneloop Pro. This may cause missed termination, or in the case of 0 dV, an early one. I suggest you stick to the 0.5 C rule, i.e. the charging current for Eneloops should be half of their rated capacity. Terminating with 0 dV doesn't overcharge the cells, so there is no benefit to decrease the charging current below 0.5 C. Observe the charging time (for fully discharged cells) and set the timer cutoff to something like 120 % of that. Also observe the end of charge temperatures. Mind that it is 1-1.5 degrees higher for the inside slots (slots 2 and 3). Set the temperature cutoff to 4-5 degrees C higher than the maximum observed temperature. It should be around 42-45 degrees C. You may need to correct this in the summer, if the ambient temperature is significantly higher than now.
This way, you'll have about the perfect charging program for Eneloops or any other NiMH.

 

[panasonicst60]

0.7 A may be a bit too low for AA, especially for Eneloop Pro. This may cause missed termination, or in the case of 0 dV, an early one. I suggest you stick to the 0.5 C rule, i.e. the charging current for Eneloops should be half of their rated capacity. Terminating with 0 dV doesn't overcharge the cells, so there is no benefit to decrease the charging current below 0.5 C. Observe the charging time (for fully discharged cells) and set the timer cutoff to something like 120 % of that. Also observe the end of charge temperatures. Mind that it is 1-1.5 degrees higher for the inside slots (slots 2 and 3). Set the temperature cutoff to 4-5 degrees C higher than the maximum observed temperature. It should be around 42-45 degrees C. You may need to correct this in the summer, if the ambient temperature is significantly higher than now.
This way, you'll have about the perfect charging program for Eneloops or any other NiMH.

What does the "C" stand for as in 0.5 C? I'm new to all this..So the aa pro is rated for 2500mah I should change at 1.25 a? Is that what it means?

 

[NiOOH]

C stands for capacity, in this case the nominal capacity of the cells. 0.5 C means that you should charge with a current equal to half of the rated capacity, or 1.2-1.25 A for Eneloop Pro AA.

 

[panasonicst60]

C stands for capacity, in this case the nominal capacity of the cells. 0.5 C means that you should charge with a current equal to half of the rated capacity, or 1.2-1.25 A for Eneloop Pro AA.

Got it. Thank you! Can you explain what exactly does the Dv do to affect the charging?

 

[NiOOH]

-dV or negative delta V, or -dV/dt in this context, stands for the voltage drop (decrease of voltage) NiMH batteries exhibit when they enter overcharge. When NiMH batteries are fully charged, they cannot absorb more energy and start to heat rapidly, the extra energy being dissipated as heat. The increased temperature causes decrease of internal resistance and the voltage decreases as a result. This is the so called negative dV or -dV. Sadly, most chargers use this method to terminate the charge of NiMH, thus overcharging the batteries, how much, depends on the value of the -dV the charger is capable of measuring before terminating the charge. Typical values are 10-15 mV for cheaper chargers.
The proper method of charging NiMH batteries is 0 dV, i.e. the voltage plateau that occurs just before the voltage drop, or just before the batteries enter overcharge. If implemented properly, this is the only method for charging NiMH that ensures full charging without overcharge and overheating at charging currents 0.5-1 C.

 

[panasonicst60]

-dV or negative delta V, or -dV/dt in this context, stands for the voltage drop (decrease of voltage) NiMH batteries exhibit when they enter overcharge. When NiMH batteries are fully charged, they cannot absorb more energy and start to heat rapidly, the extra energy being dissipated as heat. The increased temperature causes decrease of internal resistance and the voltage decreases as a result. This is the so called negative dV or -dV. Sadly, most chargers use this method to terminate the charge of NiMH, thus overcharging the batteries, how much, depends on the value of the -dV the charger is capable of measuring before terminating the charge. Typical values are 10-15 mV for cheaper chargers.
The proper method of charging NiMH batteries is 0 dV, i.e. the voltage plateau that occurs just before the voltage drop, or just before the batteries enter overcharge. If implemented properly, this is the only method for charging NiMH that ensures full charging without overcharge and overheating at charging currents 0.5-1 C.

Great explanation. Crystal clear. Much appreciated!!

 

[sim_v]

The increased temperature causes decrease of internal resistance and the voltage decreases as a result.

The increased temperature causes increase of internal resistance and the voltage decreases as a result.
More resistance, less voltage ?

 

[NiOOH]

The increased temperature causes increase of internal resistance and the voltage decreases as a result.
More resistance, less voltage ?

Nope. Batteries do not behave as simple metal conductors, i.e. increasing resistance with temperature. Batteries are electrochemical devices and their electrical behavior depends on the rate of chemical reactions inside. And these reactions accelerate with temperature, leading to a decrease of internal resistance. For the same reason, IR increases at low temperatures. This is the well known deterioration of battery performance in cold weather.
Actually, you do not have to believe me or even the books. You can measure it yourself if you have the equipment.

It is exactly this decrease of internal resistance that causes the voltage drop upon charge. It is a consequence of the Ohm's law under constant current conditions.

 

[sim_v]

thanks for the explanation.

 

[Gaudi]

Hi all, I am trying to figure out if what I propose is posible.
I usually use my SkyRC MC3000 charger to recondition NiMh and LiIon batteries.
I do usually test old cells that have a relatively high internal resistance, and have found that after some charge-discharge cycles this value goes down.


Is it possible to have the charger test IR automatically test after each cycle (either charge or discharge, or both), so I can keep track of its evolution.
The charger already stores some cycle information, as the capacity, so it should not represent an issue.


Also, using DEX the resistance is shown as constant for the whole program, so testing and updating the value should be simple (it will change for each stage/cycle).


I was unable to find such feature in current firmware v1.15.

If it is not implemented, I recall that at some point there were members who had contact with SkyRC, so it could be a feature request.

What do you think?


Thank you!

 

[NiOOH]

IR is measured in the beginning of the program. You can check it during or after the end of the program. It is not measured continuously, it is not possible with this charger.
Also, keep in mind that the way the IR is measured in the MC3000 does not lead to very reproducible results. I wouldn't trust it to track cell wear.

 

[Gaudi]

IR is measured in the beginning of the program. You can check it during or after the end of the program. It is not measured continuously, it is not possible with this charger.
Also, keep in mind that the way the IR is measured in the MC3000 does not lead to very reproducible results. I wouldn't trust it to track cell wear.

Thank you for your reply. I am aware of the limitations of the information, and on how/when the charger measures the value.
I do not intend to do continuous measuring, but rather test after each cycle, that is, if a do a 10 cycle C-D, I would like to test a single value after Charging, then after Discharging, and so on, for a total of 20 values.

 

[NiOOH]

If you wanna do that, you should cycle manually, i.e. execute the programs separately and record the data yourself. AFAIK, there is no other way to do it.

 

[Gaudi]

If you wanna do that, you should cycle manually, i.e. execute the programs separately and record the data yourself. AFAIK, there is no other way to do it.

Thank you, that is what I thought.
It should be a feature request then.

Regards