When I want to test battery capacity I use cycle mode C>D. Then depending on the results I’ll charge it, store it with a storage program or throw it away. You can do C>D>C also, the only down side is once the second charge routine starts it begins measuring charge mAh so you need to catch it between the discharge and the second charge. That amount of time is determined by what you have D. rest set to. The discharge mAh results are redisplayed only after the second charge cycle is done. IR is displayed by clicking up and down at the same time with the slots in ready mode.
D-Reduce will lower the charge current when battery voltage (during discharge test) gets close to V cutoff. Per the manual, this can be used to test capacity of alkaline batteries, and factors in an alkaline's ability to recover. Through experimenting, I found that setting D-Reduce to about 50% (of set discharge current) can get you close to an alkaline's rated spec. For example, a while back I did a discharge test on an Energizer C-cell. Discharge current was set to 100ma (duplicating Energizer's testing spec), and D-Reduce to 50%. From Energizer's rated capacity HERE, I got pretty close (6416mah), but not without using D-Reduce.
An interesting quote from the manual about setting D-Reduce to 0%
What is the “termination” set to? If it’s zero or –zero move it up a little to .01V or 02V. Unless the battery is in very good condition it may never settle in at exactly 3.8V. I have two storage programs saved one at 3500 cap with .05V term and the other at 900 cap with .02V term and I get the green light.
Set termination voltage to 0.01V and it worked, all green lights finally came on but had to rotate two batteries before the green light lit up so maybe I need to set termination to 0.02V and see if that works better, thanks for the help! I think it's much better to go right to the advanced menu and sort it all out from the beginning.
Thank you Frank! Just out of curiousity, is there any difference between the capacity values of a discharge process and a charge process? Let’s just say I put those brand new cells I received with 3.28V into the MC3000. Will I already get the capacity and iR values if I chose to use cycle mode C>D or do I have to run a full C>D>C cycle? At what cut off voltage do you set your MC3000 when discharging cells? According to their data sheets most cells can be discharged to 2.50V or 2.75V, the VTC6 even down to 2.00V. Some people discharge their cells to 3.00V only, so I’m wondering what you guys deem to be reasonable.
Discharge capacity is universally regarded as a more accurate test then charge capacity mainly because of the heat loss during a charge, heat is energy. Yes you will see discharge capacity after a cycle C>D, scroll through SOV and you will see IR and more. Following manufactures data sheets IMHO is a very good safe practice.
Nice infos above, about the storage modes suggestions.
Just sharing what I usually do for capacity testing — (I only use the Advance mode of the MC3000, since that’s where we could get all options) I use the default Refresh cycle of C>D>C.
But usually, I charge the battery first to 4.20v independently (maybe using a lower ending current than the normal “Charge” ending current of 1/10th selected Charge current), that way the battery is closer to really full (or so I think) — lower resistance cells will be quite quick, but high-resistance cells may take a longer time.
So, let’s say I charge an 18650 to 4.20v, but I manually select ending current of 0.03A (normally when one selects 1A charge current, ending current is 1/10th or 0.10A; select 2A charge current, the ending current is 0.20A, which is quite high and may not fully fill up the the battery). Manually selecting the ending current seems to ensure the battery stays at 4.20v even when removing the battery from the charger. (I think doing this is a bit more “stressful” to the battery though. But I do this (lower ending current) only when I want to do capacity testing).
But during the C>D>C Refresh, I usually don’t try to change the ending current anymore (so it stays at the default 1/10th). Usually I test 18650s at 0.50A discharge current (this may be lower than 0.2C for higher-capacity cells, but at least I’m testing the cells in a more “standard across different cells” or comparable way for the various 18650s; rather than testing strictly according to the manufacturer specs).
Thanks for the tip Now that I have Storage mode working perfectly, I'm going to try my first Charge mode in the Advanced menu and see if I can figure it all out. I kind of like charging my batteries to 4.1V instead of 4.2V so it's going to be nice to finally be able to do so for my batteries in series to the voltage I actually want.
Anyone know why the MC3000 needs the battery capacity entered? I was just thinking that if I entered for example 5200mAh for my 26650 keeppowers, what would the charger do with that info. Unless a C>D>C was done, it wouldn't know where the cut capacity would be for it anyway, would it? Someone on the "other" forum suggested changing "Capacity" in the menu to "Cut Capacity", but how would that help unless a full CDC cycle was performed. Maybe I'm over thinking, but it would be interesting to find out.
It’s just a safety option to ensure the cell will not be overcharged or if you deliberately intend to restrict the amount of energy charged into a cell. According to the (German) manual a 20% surcharge to the expected/nominal capacity is a reasonable value to work with. I assume this option can also be set to “OFF” if not needed.
Thanks a lot for sharing your experience! I still have to figure out what values for TERMINATION and D.REDUCE (which seems to be the counterpart of TERMINATION in the discharge process) are the most appropriate in order to measure the cell’s capacity.
I.a.w. the manual I just learned that very low values will ensure that the maximum amount of energy is being charged into the cell at 4.20V cut off voltage (=TERMINATION) and the maximum amount of energy is being discharged from the cell at 2.50V cut off voltage (=D.REDUCE). Using higher values will let the idle voltage rise faster on discharged cells respectively will let the idle voltage drop faster on fully charged cells. The down side on using low values is a much longer charge/discharge process and the battery’s lifetime may be reduced due to more stress.
Makes sense, thanks. Have to look and see if the 20% surcharge can really be set to off or not in my manual.
I went to the MC3000 website and asked them if the rated battery capacity is the number I should enter where the menu askes for capacity and they said "You should set it according to your battery type and charger charging current range. Generally lower than the battery capacity"
So I then asked them if there is some type of calculation I can use to figure that out as their manual says as an example to enter 20% more or 4200mAh for a 3500mAh battery under the capacity info. Opposite of what they just told me. Confusing.
I just turned the capacity limit to off (I wonder if that’s safe) since I used to keep on getting “capacity cut” message (and the heretofore recorded data is inaccessible when that happens) — happens on NiMh, or on old high-resistance Li-ion batteries, where the input (charged) capacity will be much higher than the discharged capacity. So now I just turn it off. I just use the high-temperature limit to prevent batteries from overheating though (some of the old laptop-pulled batteries will overheat, and charging refuse to go higher at around 4.05v — so when this happens, it stops the operation once the old batteries overheat) I set the temperature limit to 45 deg C, not sure if this is OK or too low though. So far, on good batteries, it doesn’t seem to reach that temperature threshold though under normal operation.
If a charge is terminating on capacity, turning off capacity is not a good idea. That 4.05V stall you are seeing is an indication of a bad battery. I have seen that symptom many times with old laptop pulls, the battery is done throw it away. Can you give me some info about the NiMh batteries that are terminating on capacity, size, brand or anything else? That would help determine why it’s terminating on capacity.
I got in contact with a guy named Damien from the MC3000 website. Sent him an email and he said he will give me the info about capacity soon and how that works. His first reply on the chat was capacity is normally set to lower that what the battery is rated at. If we take the Protected NCR18650B from Panasonic, it is rated at 3400mAh, but "typical" capacity is rated at 3350mAh, so I'm guessing maybe that is what he is talking about.
For anyone Interested in how the options look in the advanced menu of the SkyRC MC3000 charger for making a program, I copied the settings I have stored in my text file for storage mode, but these options also display in Charge mode etc with some set to off for obvious reasons. Once you actually see all the settings, it seems way simpler. I just entered some basic info in the program and will start to read up on each option for tweaking. I initially chose 5100mAh for Capacity of the Keeppower 26650 even though it is rated at 5200mAh as the people at SkyRC said Capacity entered normally is lower than rated capacity but they said they will give me more info soon. Text in brown is what you can actually enter in the program.
PROGRAM [03] “Advanced” for Protected Keeppower 26650 5200mAh
BATT TYPE: LiIon
MODE: Storage
CAPACITY: 5100mAh manual says ok to add 20% value which is 6240mAh and tech says to put it under!
C. CURRENT: 1.0A
D. CURRENT: -1.0A
C: RESTING: 0min
D: RESTING: 0min
CYCLE COUNT: OFF
CYCLE MODE: OFF
TAGET VOLT: 3.80V
TERMINATION: 0.01A
RESTART VOLT: OFF
D-REDUCE: -ZERO
CUT VOLT: OFF
CUT TEMP: 45C
CUT TIME: OFF
SAVE TO: [03] <--- Just the program # you choose to save all these settings.
I just have a couple of programs for different batteries stored for storage, discharge, charge etc saved in a text file and after that, you just need to choose whatever program you have and hit the start button.
Now that I have Storage mode working perfectly, I'm going to try my first Charge mode in the Advanced menu and see if I can figure it all out. I kind of like charging my batteries to 4.1V instead of 4.2V so it's going to be nice to finally be able to do so for my batteries in series to the voltage I actually want.