I recently acquired a Skyrc MC5000 charger and I’m looking for some guidance on the optimal settings for charging, discharging, cycling, and refreshing various batteries in my collection. Here’s a quick rundown of the batteries I’m working with:
Panasonic AA BK-4MCC (750mAh, 1.2V NiMH) .Recommendation from the datasheet:
Charge: 80mA for 16 hours
Discharge: 160mA at 1.0V (20°C)
Fujitsu AA HR-3UTC (1900mAh, 1.2V NiMH) .Recommendation from the datasheet:
Charge: 200mA for 16 hours
Discharge: 400mA at 1.0V (25°C)
Fujitsu AA HR-3UTHC (2450mAh, 1.2V NiMH).Recommendation from the datasheet:
Charge: 250mA for 16 hours
Discharge: 500mA at 1.0V (20°C)
GP Recyko Plus AAA (400mAh, 1.2V NiMH)
Fujitsu HR-4UTC AAA (750mAh, 1.2V NiMH)
Acebeam 18650 (3100mAh, USB Type-C Li-ion)
Questions:
Charging Settings:
The spec sheets for the NiMH cells recommend low current (e.g., 80mA for 16 hours on the Panasonic). But as you can imagine, this would take a long time. If I follow these recommendations exactly, should I expect such long charge times to be normal, or is there a more efficient setting I can use without damaging the cells? In Skyrc MC5000, there are many settings. Please let me know what is the recommended settings.
Discharge Settings:
I understand that the discharge function is used to measure the effective capacity of a battery. What’s the optimal discharge current for these cells to avoid wasting cycles or damaging the batteries? I want to ensure the test results are accurate, so should I just use the recommended discharge current from the spec sheet? Also, when is it appropriate to refresh the batteries and what resistance values should I be looking for to determine when performance degradation starts?
Cycle vs. Refresh vs. Break-in:
What are the best practices for cycling, refreshing, and breaking in these batteries? I’ve read differing opinions about how to use these functions and would appreciate clarification on when to use which. My primary concern is to avoid damaging my batteries or setting them to incorrect parameters that might lead to reduced lifespan or risk of fire.
Li-ion Settings for Acebeam 18650:
As for the Li-ion Acebeam 18650, what are the appropriate charging/discharging settings for these cells? I’ve used an Opus BT-3100 charger before, but I’ve moved to the MC5000 and want to ensure I’m using the right settings for this specific model.
Thanks in advance for your help! I’ve done some preliminary research but would love to get some additional insight from folks with experience using the MC5000 with these types of batteries.
My understanding of these is as follows:
Cycle allows a set number of Charge/ Discharge/ Charge (CDC) cycles. Basically a Refresh X N where you choose N
Refresh is just a single CDC cycle.
Break-In is the IEC break-in or forming charge cycle. It is a timed charge and discharge using 1/C where C is the cell capacity.
Typically I will do a Break-In once when I get a cell. If I notice a drop in performance over long periods I will run it again. This takes well over 20 hours when considering the rest periods between charge and discharge. I believe this to be more effective than repeated cycling in reviving cells.
Refresh, I use periodically on cells that I store for long periods. I try to do this on all of the cells that I store about once every 6 months.
Cycle, I don’t use very often. Some believe that cycling a cell a few times when it is new results in higher capacity. I have just not found this to be true in my testing.
Usually the data sheet gives the test conditions that are used by the manufacturer when determining the advertised capacity. You can follow those conditions to verify their numbers. But the ones you mention are typical for timed charging with a “dumb” charger. With my MC3000 I typically charge at ~0.5C and discharge using a rate that reflects my use case for the cell. Again .5C is usually fine for this. This sort of rule of thumb should be safe for about any cell.
There are many setting that you can play with that tweak charge termination and discharge parameters for testing. But they are beyond what I can write now. The above should get you started.
Thanks Mandrake50 for your reply. I’ve drafted the following charging/discharging/break-in settings based on the manufacturer’s datasheets and SkyRC documentation.
Could anyone please review and advise if these are safe and optimized? I’m especially worried about setting incorrect termination thresholds like delta V, discharge cutoffs, or trickle charge—which could potentially fail to terminate properly and lead to swelling or reduced lifespan.
Honestly I have just used the default Delta V settings on the MC3000 for NiMH cells for something like 15 years… because they seem to work fine. If you are having problems with a particular type of cell not terminating, you can experiment. I have seen 5-8 mv listed as acceptable.
For your discharge cutoff voltage for LiIon cells, I usually go to 2.8V. This is not damaging to cells and will typically give capacity numbers closer to those in the specs. I have gone lower if this is what is listed in the Data sheets or the test specs. OTH, I see most of the BMS in my lights cutting off closer to ~3V. So that gives a better idea of real world performance. I think that 3.2 V is a little high.
Just to make sure I’ve understood you correctly, my plan now is to:
For NiMH: Just use the default “Eneloop” profile on the charger. It’s good to know the defaults have worked well for you for so long.
For Li-ion: Use the standard settings but adjust the discharge cutoff voltage to 2.8V when I’m doing capacity tests to get numbers closer to the manufacturer’s specs.
I really appreciate you sharing your experience. This is exactly the kind of real-world guidance I was looking for.
Sounds good to me. On the cutoff voltage, If you want to get real tight on that, find the data sheet on your cell and use the manufacturers listed cutoff. But I generally go with the 2.8 and use that for the setting on my saved capacity testing program.
