I may be wrong here, but wouldn’t the NiteCore SC4 charge rate also be considered sort of automatic (up to max pre-selected current), although its time-share feature sort of negates it (if charging other than only slots 1 & 2).
I think I remember reading a review of this charger and the IR function was accurate, but it looks like you are getting high readings. The GA cell IR is around 50 mOhms. High readings could be caused if the contact resistance is high. Try putting the cell in again to see if the IR changes.
Maybe like someone said, the IR is higher due to the protection circuit?
Clean the contacts of the battery and charger. Try a different slot. And finally, yes you can set it manually to 1A charge rate safely. It will go back down as the battery gets closer to being fully charged and be fine.
I wonder how accurate the IR readings are on some of these chargers. I recently charged a cell then out of curiosity tested the IR in the other bays. At start of charge it read 18 milli ohm. On the second round of testing I got 94, 46, and 6.
as you see they are not very accurate and repeatability is poor.
Not sure about the c2-6000, but on my c4-12 the IR readings are not very consistent. See my review here:
Also, it is normal for IR to be lower on a fully charged cell. Some charger manufacturers specifically state in their user manual to only test IR on a fully charged cell for consistency.
Why can’t the IR be measured with a DMM?
It can be, but typically not just with DMM alone…
Thanks for that but I am afraid it is above my head. Why can’t the IR be measured just like measuring a resistor? Also, all my protected cells read in the 100-200 m ohm range (new cells)and seems high to me .This is from charger.
d-t-a wrote
I may be wrong here, but wouldn’t the NiteCore SC4 charge rate also be considered sort of automatic (up to max pre-selected current), although its time-share feature sort of negates it (if charging other than only slots 1 & 2).
I checked the SC4,and it measures capacity and sets 500 mA up to 1200 mAh and 1000mA over that.The MiBoxers measure IR and set initial current from that(conservatively),until it has worked out capacity,when it boosts current.
Yesterday I had 8 30Q Samsungs in the charger to test IR before and after soldering button tops(BLF GT coming in er April-ish)The currents were different for each cell,and to 2 decimal places.
Yeah,IR was all over the place with 8 new 30Q’s with delivery voltage,30 something to 150 ish milliohms , but the average was always lower after the button tops were added.Longer cells let the spring put more pressure on the contacts,and maybe new,clean contacts.
Because the IR values are too low to measure by a DMM. It’ll likely just show 0 on your DMM. Plus, the internal resistance of DMM leads themselves woud greatly skew the results.
For protected cells, this is actually quite possible/normal. The protection circuitry impacts internal resistance quite a bit.
Thanks, makes sense now.
FYI, I just checked IR with my C4-12 for a few protected cells…
NCR18650GA: 89
NCR18650B #1: 211
NCR18650B #2: 160
But again, the MiBoxer’s IR readings lack consistency, so take it for what it’s worth.
How does it measure capacity? It would have to do a full charge and then discharge to properly measure capacity.
IIRC, it checks cell dimension (length) based on how far the bay slider is extended. Shorter cells get a lower charge rate. Longer cells get a higher charge rate.
The sc4 page says it does it by capacity,but I know some chargers do measure slider length to select current.I don’t know which it uses.
Proper capacity is measured by discharge.
The Miboxer knows start IR,time(0 secs),start voltage and rough cell temp.I’m pretty sure it chooses start current by IR from testing 8 new 3Ah 30q’s yesterday . By seeing the start current,I could estimate what IR would be before it appeared on screen.If cell temp started rising too fast,I,m sure it would reduce current.The Ah in reading is probably just amps x time,but state of charge % may use initial voltage as a one fits all measure but maybe voltage rise over time as well after that.In HKJ,s review charge graphs show spikes for further internal resistance checks .Some of the spikes correspond to current bumps and there are no current bumps without that IR check.
[quote=pennzy]
A multimeter cannot measure resistance on a circuit with voltage, it must supply its own voltage. This makes it impossible to measure a battery.
Thanks for that HKJ. Any idea why my C2-6000 would choose to only charge my new protected 18650ga and b at only .2 amp to start and only increase slightly (.3 A) through out charge period ? Shouldn’t it have increased to 1 amp at some point ? It was taking all day at that rate so I bumped it up manually.
May be the connection, when this happens try removing the battery and put it in again.
I think it is some quirk with the charger since it did it with 3 different cells . Inserted multiple times . After first full charge , they start out at higher rates . Something about new cells that have been shipped in a low power state (26%).